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GLOBAL WATCH MISSION REPORT

Sustainable drainage systems: a mission to the USA

MARCH 2006

Global Watch Missions

DTI Global Watch Missions enable small groups ofUK experts to visit leading overseas technologyorganisations to learn vital lessons about innovationand its implementation, of benefit to entire industriesand individual organisations.

By stimulating debate and informing industrialthinking and action, missions offer uniqueopportunities for fast-tracking technology transfer,sharing deployment know-how, explaining newindustry infrastructures and policies, and developingrelationships and collaborations. Around 30 missionstake place annually, with the coordinatingorganisation receiving guidance and financial supportfrom the DTI Global Watch Missions team.

Disclaimer

This report represents the findings of a missionorganised by British Water with the support of DTI.Views expressed reflect a consensus reached by themembers of the mission team and do not necessarilyreflect those of the organisations to which themission members belong, British Water or DTI.

Although every effort has been made to ensure theaccuracy and objective viewpoint of this report, andinformation is provided in good faith, no liability canbe accepted for its accuracy or for any use to which itmight be put. Comments attributed to organisationsvisited during this mission were those expressed bypersonnel interviewed and should not be taken asthose of the organisation as a whole.

Whilst every effort has been made to ensure thatthe information provided in this report is accurateand up to date, DTI accepts no responsibilitywhatsoever in relation to this information. DTI shallnot be liable for any loss of profits or contracts orany direct, indirect, special or consequential loss ordamages whether in contract, tort or otherwise,arising out of or in connection with your use of thisinformation. This disclaimer shall apply to themaximum extent permissible by law.

Sustainable drainage systems:

– a mission to the USA

REPORT OF A DTI GLOBAL WATCH MISSION MARCH 2006

FOREWORD/ 5ACKNOWLEDGMENTS

EXECUTIVE SUMMARY 7

1 INTRODUCTION 10

1.1 Context and aims of SUDS 10Global Watch Mission

1.2 The importance of 10stormwater management

1.3 The problems of stormwater 11and runoff

1.4 How stormwater is managed 11in the UK

1.5 BMPs, LIDs and proprietary 12systems in the US

1.6 Setting up the visit 13

2. US PRACTICE 14

2.1 Regulations and 14responsibilities

2.1.1 Clean Water Act (CWA) 142.1.1.1 Background 142.1.1.2 Delivering the Clean Water Act 152.1.1.3 Total maximum daily load 15

(TMDL)2.1.2 Institutional arrangements, 19

regulations and standards,planning systems and masterplanning

2.1.2.1 Adoption (permitting) 192.1.2.2 State and tribal program 19

authorisation status2.1.2.3 Issuing of permits 212.1.2.4 Municipal permitting process 222.1.2.5 Drainage review 222.1.2.6 Master drainage plan process 23

and components2.1.2.7 Public engagement (outreach) 242.1.3 Champions and sources of 24

assistance

2.2 Treatment and management 25of urban stormwater runoff

2.2.1 Best management practices 25(BMPs)

2.2.2 Low impact development (LID) 262.2.3 Examples of application 292.2.3.1 SMURFF 292.2.3.2 Downspout disconnection 312.3 Stormwater control, operation 31

and maintenance2.3.1 Legal issues 322.3.2 Observations on operation 32

and maintenance2.3.3 Public engagement 342.3.3.1 Getting the message across 352.3.4 Maintenance and adoption 36

of stormwater facilities in USpractice: utility types anddelivery mechanisms

2.3.4.1 Seattle, Washington 362.3.4.2 Massachusetts Water 36

Resource Authority (MWRA)2.3.4.3 Los Angeles 362.3.4.4 Construction bond 372.3.4.5 Research and development 37

(R&D)2.3.4.6 Public engagement 382.4 Performance and design of 38

the systems used2.4.1 Overall effectiveness for 38

health, safety, environmentalquality and amenity in the US

2.4.2 Examples of technologies 40(new and retrofit) and testing

2.4.2.1 Bioremediation as a 41sustainable drainage BMP

2.4.2.2 Low impact development 41(LID) in Baltimore, Maryland

2.4.2.3 Bioremediation filter strip 42and detention basin.

2.4.2.4 ‘Smart sponge’ advanced 43technology in Norwalk,Connecticut

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SUSTAINABLE DRAINAGE SYSTEMS – A MISSION TO THE USA

CONTENTS

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2.4.2.5 Up-Flo filter technology in 46Portland, Maine

2.4.2.6 The green streets of Portland, 47Oregon

2.4.2.7 SEA streets in Seattle, 50Washington

2.4.2.8 Application of proprietary 52techniques in Los Angeles, California

2.5 Design and selection of 54systems

2.5.1 Center for Watershed 55Protection, Ellicott City

2.5.1.1 Urban sub-watershed 55restoration manual

2.5.2 Baltimore County, Maryland 562.5.3 Seattle – Washington state 59

design criteria2.5.4 Portland, Oregon 592.5.5 Education of the key 60

stakeholder groups2.6 Construction 602.6.1 Introduction 602.6.2 Rigorous controls – 61

construction site regulation2.6.3 Inspection and enforcement 612.6.4 Fees and discounts 622.6.5 Effective contractors – 62

construction process2.6.5.1 Baltimore – Maryland 622.6.6 Good construction practice (GCP) 632.6.7 Construction – summary 652.7 Monitoring of performance 652.7.1 Introduction 652.7.2 Main findings relating to 67

monitoring and compliance2.7.3 Illicit discharge and infiltration (I/I) 712.7.3.1 I/I Programme at MWRA 712.7.3.2 I/I Programmes - relevance 72

to UK2.8 Integrated management 72

and stormwater as a resource

3 CONCLUSIONS AND LESSONS 75FROM US STORMWATERMANAGEMENT PRACTICES

3.1 Drivers, reasons and motives 753.2 Institutions, regulations and 76

stakeholders3.3 Development planning, funding 78

and control of stormwater3.4 BMP planning, forms and 82

performance3.5 BMP construction and 85

maintenance issues3.6 Performance of BMPs 863.6.1 Infiltration systems 873.6.2 Storage systems 883.6.3 Green-roofs, trees, street 88

gardens and inlets3.6.4 Other BMPs, stormwater 89

management and related issues3.6.5 Non-structural BMPs 893.7 Sewer related issues 893.8 Public engagement 903.9 Sources of diffuse pollution 92

4 RELEVANCE TO UK PRACTICE 93

4.1 Water Framework Directive 93(WFD) and other standards

4.2 Institutional similarities 934.3 Stormwater profile and public 94

engagement4.4 Planning and the water company 94

perspective in England and Wales4.5 Redefining UK sustainable 95

drainage5 Top 10 conclusions and 97

recommendations5.1 Conclusions 975.2 Recommendations in relation to 99

more effective future stormwatermanagement in the UK

APPENDICES

A MISSION DELEGATE DETAILS 102

B HOST ORGANISATIONS 105

C VISIT REPORTS 107

C1 Baltimore County Council 107Offices, Towson, Baltimore County, Maryland

C2 Center for Watershed Protection, 110Ellicott City, Maryland

C3 Visit report: Low Impact 111Development Center

C4 Visit report: US Environmental 114Protection Agency (EPA), UrbanWatershed Management Branch

C5 Site visit to Abtech smart sponge 116C6 Hydro International conference – 118

The Changing Face of the Stormwater Industry

C7 MWRA Boston 120C8 John Sansalone: work on 123

surface drainage in Florida and elsewhere

C9 City of Portland, Oregon – 124Bureau of Environmental Services

C10 Eric Strecker, GeoSyntec 127Consultants and Wayne Huber,University of Oregon

C11 Seattle City Council/SEA streets 129C12 CDS Los Angeles City 134C13 Abtech Industries City of 135

Los Angeles

D LIST OF TABLES AND EXHIBITS 138

E GLOSSARY 140

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FOREWORD AND ACKNOWLEDGMENTS

During most of the twentieth century themunicipal water industry met water supplyand wastewater treatment requirements byincreasing its treatment plants and networksand channelling excess surface and wastewater into rivers. The end of the century sawsignificant changes with the privatisation ofthe industry and a consequent increase inregulations. The implementation of the WaterFramework Directive (WFD) will add a furtheroverarching layer of regulation designed tocoordinate water use from resource totreatment and discharge in a sustainable way.

Demographic changes are also increasinglychallenging the industry, raising theimportance of resource management as wellas surface and wastewater discharge, andputting pressure on environmentalprotection. Climate change is adding to thesechallenges and, along with the demands forcontinual urban expansion, is heightening theneed to control surface water drainage tominimise flooding and its impact oncommunities and the wastewater network.Initially, sustainable urban drainage systems(SUDS) were given much attention but theneed to manage the drainage of all surfacewater, whether rural or urban, has changedthe emphasis to sustainable drainagesystems (so maintaining the acronym SUDS)and to integrated water management.

In planning the mission the team was facedwith balancing the opportunities of visitingregions of different climatic, demographic andenvironmental challenges with the timeconstraints of travel. The severe hurricaneseason of 2005 accentuated the extremechallenges for SUDS in the southern states ofthe US and so we decided to target regionswhere the challenges were more comparable

to those the UK faced now or would face inthe near future. Consequently, the itineraryfeatured locations away from the south andup to the east and west coasts of the US toevaluate different solutions for surface waterand drainage problems relevant to the UK.

The mission was planned with assistancefrom a combination of personal contacts andUS offices, or sister companies, of BritishWater members. We met and had full andinformative discussions with many significantexperts, regulators and practitioners. Many ofour hosts also accompanied us on the sitevisits so maximising the benefits of seeingthe application of a diverse range of solutionsto stormwater and drainage issues.

We are extremely grateful to everyone, fromthe UK and the US, who contributed to thedevelopment of our extensive, diverse andcomprehensive programme.

Arranging such an interesting and extensiveseries of visits inevitably affected thetimelines and completion of the plans. We arevery grateful for the support of the GlobalWatch team at DTI, especially to HarshaPatel, whose flexibility and patience,particularly with travel details, was very muchappreciated by us all.

Ultimately, the success of the mission wasdown to the constructive and friendlycooperation of the team. I am extremelygrateful for their support and fortitude as wecovered more than 9,000 air miles and 700road miles in the US, visited 13 centres andheld obligatory end-of-day meetings to reviewthe visits. This report is a tribute to everyone’scommitment and reflects Professor Ashley’sleadership and determination to maximise the

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benefits from the mission. Even on visit 12,day 12 everyone could still raise a smile (seepicture) – testimony to their stamina.

My sincere thanks are due to everyone whocontributed to making the SUDS GlobalWatch Mission so enjoyable, rewarding andabove all so informative.

Ian H PallettTechnical Director, British Water

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Exhibit S.1 The team watching filter maintenance on a drain emptying into Los Angeles bay

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Surface ‘stormwater’ is water that can beseen in gutters and drains and on surfaceswhen it rains. The stormwater arises whenrain falls on to surfaces and complexprocesses result in the water running offoverland and into water bodies or into theground. Stormwater causes problems offlooding, and, by conveying contaminants(natural and man made) picked up from thesurfaces over which it flows, also pollutes.The management of stormwater is achallenging problem which is exacerbated byuncertainty about future drivers such asclimate change. Historically in the UK andmost of the developed world, stormwaterproblems have been addressed usingsystems (drains, sewers and watercourses)to dispose of excess stormwater runoff asquickly as possible away from urban areas inparticular, to points where it is no longerbelieved to be a problem.

The realisation over the last century thatstormwater disposed of in this way can leadto problems downstream due to high flows,flooding, watercourse erosion, pollution andconsequential ecological impacts, has led tothe development of alternatives to piped andchannelled drainage systems that try to morerealistically replicate the natural physical,chemical and biological processes ofevapotranspiration, filtration, detention anddispersion. These systems do not have auniversally accepted collective name, and areknown variously as: best managementpractices (BMP) and/or low impactdevelopments (LID) in the US and assustainable drainage systems (SUDS) in theUK. Elsewhere other terms are used, such aswater sensitive urban design (WSUD) inAustralia and much of the Far East. InScandinavia the term source control is also

used when dealing with stormwater near tothe point at which it first originates.

A major facet of these new ‘natural’stormwater management approaches is theneed for greater engagement of thoseinvolved in development planning,maintenance, operation, use and in generallysustaining the performance of these systems.

There are major impediments to the use ofthese systems in the UK, many of whicharise owing to urban density, regulatoryinadequacies and institutional constraints.Elsewhere in the world, such as in the US,many of these barriers do not exist, asinstitutional arrangements are different to theUK, although there are other challenges toovercome. In some parts of the US ‘natural’stormwater systems, originally defined asBMPs, have been in use for at least 50 yearsas an alternative to traditional piped drainsand sewers. Therefore, there is a long historyof experience in regulating, implementing and use.

The UK, as elsewhere in Europe, is facedwith implementing the requirements of theWFD by 2015. The directive is predicated onthe need to ensure good ecological status ofwater bodies within defined river basindistricts, of which there are 11 in England andWales. The majority of stormwater in the UKis currently collected and conveyed in sewersthat combine both stormwater and foulsewage in ‘combined’ systems. 70% of thesewers in the UK are currently combined;however, there are also networks of separatestormwater drains and sewers that conveyrunoff to a convenient watercourse or otherreceiving water body. These may be ownedprivately or be part of the ‘public’ network

EXECUTIVE SUMMARY

that is operated by sewerage undertakers.Other than oil interception, only in Scotlandare there currently constraints on thedischarge of separate stormwater intowatercourses that require such discharges tobe treated. It is likely, however, that in orderto comply with the WFD, virtually alldischarges of stormwater will in the futurerequire some form of treatment.

There are clear parallels between the WFDand the equivalent legislation in the US, theClean Water Act (CWA). The latter wasimplemented in the early 1970s and, despitesome difficulties in implementation andenforcement, has resulted in significantefforts to improve the quality of America’s‘impaired’ water bodies, much of which hasincluded improvements to stormwatermanagement. US experience has shownclearly that the use of BMPs and LIDs can bea much more cost-effective way of ensuringprotection to receiving waters than the UKapproach of stormwater control using drains,sewers and (when enforced) some treatmentat the ‘end-of-pipe’ prior to discharge. Inaddition to separate storm drainage, BMPscan also help to better manage thestormwater that is discharged into combinedsewers by slowing down the rate of runoff, oreven by removing these inputs altogether.

This mission investigated US practice inrelation to UK practice and concluded thatthere are a number of important lessons andopportunities of relevance. There are apparentsimilarities in the reasons why there is a needto develop innovative stormwater systems,making the US experience very valuable in aUK context. These similarities include aboveall, the perceived and real need to improveenvironmental quality and the regulationsdriving this.

It is clear that the drivers for change need tobe properly understood, influenced wherepossible, and planned for in good time usingapproaches that are flexible and likely to be

adaptable as knowledge advances. Driverssuch as the uncertainties of climate changecan provide an opportunity to engage a largestakeholder community. They help to raise theresources needed to deliver the innovativesolutions required if the responses are to beaffordable. The delivery of these solutionsalso requires ‘champions’- leading individualsor organisations with the vision andcompetence to bring others with them.

A wide range of proprietary technologies isnow available that offers solutions to particularstormwater management problems; newsystems are being developed all the time.Although there are units now available thatappear to deal simultaneously with a range ofpollutants for situations where there arephysical, chemical and biological pollutants, it isessential to utilise a ‘treatment train approach’with a number of separate BMP units usedtogether. It is also vital to ensure that theperformance of proprietary systems has beendemonstrated at least by pilot scale accreditedtesting before any large scale utilisation.

An incremental approach to the improvementof stormwater quality for new developmentsand existing drainage systems seems to offerthe best hope for cost-effective managementof stormwater problems now and into thefuture. A large number of smaller unitsdispersed throughout catchments can utilisevarious innovative techniques and can betested to assess how effective their individualperformance is. Although this does spreadthe maintenance burden to a larger numberof operators, investment in large ‘end-of-pipe’systems is traditional in the UK and risks‘technology lock-in’. There will be a need tocontinue to use these systems even wherethey are shown in the future not to besustainable. Local solutions also provideaesthetic and amenity benefits where theBMPs used have open surface water. Fearsabout health and safety problems associatedwith these seem to be largely unfounded,although there are some concerns in the US

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about mosquito breeding and the spread ofWest Nile virus.

Engagement of all stakeholders in sustainabledrainage systems is essential and specificrequirements under the CWA relate to publicparticipation. Innovative service provisionmeasures via, for example, a separatestormwater utility, coupled with distinctcharging systems for stormwater, facilitatebetter engagement and responsibility. There isalso the opportunity to use financial benefits(via rebates and special offers) to encouragethose willing to take a more active role instormwater management. In parts of the USthis has led to the disconnection of individualproperty stormwater inputs (downspoutdisconnection) from the main drainagenetwork, allowing cheaper alternatives to beused to deal with downstream problems incombined sewer networks.

Although shown to be effective, the 130+types of BMP specified by the USEPA stillrequire more investigation to determinewhen, where and how they should be used.Monitoring for compliance with theregulations, together with a number ofnational programmes in the US, such as thenational urban runoff program (NURP) and theBMP database, have revealed the wideperformance range of structural BMPs interms of water quality improvements.Despite a number of recent research projectsexperience in the UK is even more limited.There is therefore a need to collect more andbetter information about the performance ofthese systems. Clear and statistically validprogrammes of study are needed which willrequire considerable resources if they are tobe of use.

In the UK the impediments to the use ofBMP and LID approaches rest mainly onissues to do with ownership, responsibilityand long-term maintenance. Notwithstandingthe recent UK Water Industry Research(UKWIR)/Water and Environments Foundation

(WERF) project on the whole life costs ofthese systems, there are significant andunquantifiable risks to any party adopting non-sewered stormwater systems in the UK. Theadoption of BMPs and their maintenance inthe US is varied. In some places it is theregulatory agency, usually the localmunicipality, elsewhere it can be the landowner or the property owner adjacent to theBMP who is expected to take responsibility,usually supported by the municipality.Separate stormwater utilities can providethese services, and as they do not need toown any assets (unlike the sewerageundertakers in England and Wales), can alsobe effective at promoting the use of non-structural BMPs through local education andcapacity building.

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1.1 Context and aims of SUDS/Global

Watch Mission

The management of stormwater has becomemuch more complex as urban areas havedeveloped, populations increased andexpectations about environmental qualitybecome higher. Within the past few decades,the developed world has experiencedconsiderable changes in the management ofstormwater. Considered as a means to simplyconvey stormwater away from cities and towns‘as efficiently as possible’ in the 19th and mostof the 20th century, stormwater systems nowhave to balance flood control, environmentalprotection and, where feasible, amenityprovision. In Europe the WFD is now posingnew challenges as it introduces a catchment-wide perspective to all water management,together with new ideas about the protectionof the waters that receive stormwater runoff.

A number of countries worldwide haveutilised systems for stormwater managementthat differ from the established ‘piped’systems traditionally utilised in the UK.

The mission aimed to look at how the USmanages storm and surface water from anumber of different perspectives. Theobjectives were to:

• understand US institutional arrangements,federal and state regulations in relation tostormwater management, and how theseare being applied in practice

• look at methodologies to control and treatstormwater such as BMPs, LID andproprietary systems, and the associatedaspects of these systems in respect ofdesign, application and maintenance (long term)

• investigate how contaminants are removedfrom surface water by various techniquesand technologies, and how these could beapplied in the UK

• understand the costs and chargingarrangements that finance the stormwaterinfrastructure in the US and compare theseto sewerage charges in the US and UK

• review the contribution of stormwatermanagement solutions, and their relativecost-benefits, to the sustainability of waterresources

• look at the methods of engagement of allthe interested parties to see if these areeffective

• understand where stormwater relatedresearch funds are being targeted in theUS and what is driving these activities

• look at the effects on local developments,properties and receiving waters – wherethey could be observed – and to see if thestormwater solutions in use could provideadditional local amenities

• gather information about watermanagement in the US for disseminationin the UK.

1.2 The importance of stormwater

management

Stormwater is a fundamental part of thenatural water cycle; in addition to providing themain input to surface waters, it can alsoreplenish groundwater aquifers. However,when surface and stormwater comes intocontact with human activities pollution, in theform of particles, chemicals and biologicalcontaminants, is picked up from both urbanand rural runoff. Pollution from natural sourcescan also be captured in stormwater when rainfalls on to natural surfaces and water flowsthrough soil, across hillsides, in streams andrivers. Pollution arises via a large number of

1 INTRODUCTION

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‘diffuse sources’. The overall effect from therunoff from a large number of relatively smalldiffuse sources should not be underestimated.When accumulated (downstream), they makea significant impact on environmental systems,which may be immediate (acute) or occur overlonger periods of time (chronic). Because ofthe nature of diffuse pollution in urbanenvironments, it is unlikely that there will everbe a simple and inexpensive solution for thecontrol and removal of contaminants fromstormwater. New ideas and methods areessential for a future solution to the problemsthat contaminants cause. This is reflected inthe requirements in the WFD.

When stormwater is polluted it impacts onthe food chain that supports fish andecosystems in general. The rapid transfer ofstormwater runoff also causes the scouringand erosion of watercourses and silting up ofdownstream areas. This damage by volume,speed and contamination is apparent inwidespread areas: from poorer qualitybeaches to the destruction of the habitats ofshellfish and other species.

1.3 The problems of stormwater and

runoff

There are a large number of factors thatcontribute to making stormwatermanagement a complex challenge:

• The topography and composition of eachcatchment area, soil type, degree and typeof urbanisation etc

• Rainfall events are variable in space andtime, and are likely to become moreunpredictable due to climate change

• Runoff pollution can be characterised asbiological, physical, chemical, withpathogenic impacts being important. The processes are driven by hydrology.These effects, and particulate transport,are coupled and complex phenomena

• The measurement of any aspects of stormevents and runoff is complex, expensiveand time consuming.

The complex issues and problems abovemean that each individual site needs a uniquesolution in order to develop appropriate‘sustainable’ drainage systems, which maycurrently be expensive, particularly where thisis a highly engineered solution. An easy tounderstand applications guide on systemsselection does not currently exist anywhere,although there is a large number of guidancedocuments in the US (See Section 2.5).

1.4 How stormwater is managed in

the UK

Much of the existing sewerage and drainagesystems in the UK originate from the Victorianera. A significant proportion of the sewerscombine the foul and stormwater flows into asingle ‘combined’ sewer. Sewer systems builtsince the Second World War usually keep thefoul and stormwater separate. However, theseinvariably recombine in downstream mainsewers. There is also a problem with thehousing stock as the in-property drainage mayalready be configured for downstreamcombined sewerage.

When rain events occur the combinedsewers have to convey the surface waterrunoff from the catchment areas. As it is toocostly to allow for the largest events in thesewer network (even more so in the futurewith the uncertainty of climate change) thesewers need ‘safety valves’, which areoutfalls known as combined sewer overflows(CSOs). These CSOs are only expected tooperate during exceptional conditions, andthere are agreements with the EnvironmentAgency on how frequently they can operatein any 12-month period. Generally, 6 mm (inany two directions) screens are fitted toCSOs to protect the receiving watercoursefrom litter and any ‘human debris’.

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The main thrust today for controlling orattenuating stormwater flows is byrecommending that all new developmentsembrace ‘sustainable drainage’ techniques.This is in an attempt to ensure that the runofffrom any development does not exceed the‘pre-development’ rate and also mimicsnature as far as practicable. The use of SUDSsystems is encouraged by the Local Authorityplanning system as it is a condition ofgranting the various building permissions.The Environment Agency is a statutoryconsultee in this process. However, it iswidely acknowledged that the UKinstitutional, regulatory and financial systemshave not achieved the desired outcome ofensuring that the newly developed site hasthe same runoff characteristics as a pre-developed site by the use of suitable SUDS.

At best, the planning system may seek tomitigate flood risks; however, virtually nostormwater quality issues are currently beingaddressed in England and Wales, althoughthey are in Scotland. The European WFD will,by constraining the discharge of priorityhazardous substances and discharges togroundwater, have a large impact on surfacewater quality issues in the future. TheFreshwater Fish, Habitats and Bathing WaterDirectives can also impose a need to bettercontrol the quality of stormwater runoff.

1.5 BMPs, LIDs and proprietary

systems in the US

There are two types of approach utilised inthe US: BMPs and LIDs. Unfortunately,definitions vary. One definition of a BMP is atechnique, measure or structural control thatis used to manage the quantity and improvethe quality of stormwater runoff in the mostcost-effective manner. Whereas LID is a sitedesign strategy used to achieve the goal ofmaintaining the pre-development hydrologicregime, or through the use of selected

techniques to create functionally equivalent orminimally changed hydrologic landscapes.1

This was reinforced by the USEPA, whichindicated that: ‘BMPs cover the widestcategory of wet weather flow controls fromupland at points of pollution/flow origin towithin the stream. LIDs are merely smallercontrols placed upland at theresidential/commercial site. BMPs can alsobe soft (education, elimination of pollutioncausing man-induced materials) or hard(ponds etc).’ Elsewhere the mission was toldthat: ‘the components of LID are BMPs.However, not all BMPs are LIDs (at least insome opinions). For example, a bio filtrationsystem is a BMP and can be a component ofLID. Most would argue that an underground‘magic swirley device’, however, would be aBMP, but would not be considered LID.’

According to Field et al1: BMPs arestormwater pollution control measures thatinclude source controls (which keeppollutants from entering the stormwaterrunoff), structural controls (which removepollutants from stormwater runoff before itreaches the water course) and non-structuralcontrols (which seek to change and managewhat people do in drainage areas, such as theuse of garden pesticides). BMPs are alsoused for controlling the quantity and rate ofwater entering a stream in order to reduceerosion and flood risks. BMPs are notstandardised and vary depending on thepolicies of counties, townships and states,many of whom have their own designmanuals and guidance documents (Section2.5). BMPs may be a series of unit processeseach with particular stormwater managementcharacteristics comprising what is known as aBMP ‘treatment train’ (See section 2.2).

LIDs are site level (decentralised) stormwaterand other water and town planningmanagement practices that maintain thehydrologic cycle or meet targeted watershed

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1 Field et al (2006). The use of best management practices (BMPs) in urban watersheds. DEStech pub. Inc, Lancaster Pennsylvania. ISBN 1-932078-46-0

objectives. They also include water recyclingand reuse systems. This is accomplished by acombination of planning and design strategiesthat use conservation approaches andtechniques to reduce the site developmentimpacts along with integrated watermanagement practices.

Proprietary products are engineered artefactsgenerally fabricated offsite in a factory or pre-designed systems constructed on-site. Theyhave specific hydraulic and water qualitydesign criteria and performancecharacteristics and are applied in ‘known’circumstances. Proprietary systems can bepart of a stormwater treatment train.

There are many terms used to describe ‘non-piped’ stormwater management systems. Theterm SUDS is only used in the UK and is notunderstood elsewhere in the world. In the USboth BMP and LID are used, sometimesinterchangeably, despite having distinctmeanings as outlined above. Elsewhere in theworld, other terms are also used, such aswater sensitive urban design (WSUD) inAustralia. In some countries the term forthese systems is simply source controlsystems. The major problem with the UK termSUDS is that such systems are not a priorinecessarily sustainable, as it depends entirelyon the context in which they are used.

1.6 Setting up the visit

The group met on several occasions beforedeciding on the subjects within thestormwater area that it wanted to study. A listof potential contacts was drawn up fromknown US experts and centres of excellenceand matched with the logistics of travelbefore deciding on the final venues andlocations visited. Travel was a major factor inthe process owing to the requirements ofgathering as much information as possibleand meeting the mission objectives. It wasnot possible to do everything that the groupwanted to do within the time constraints.

Each visit usually took the format of thegroup presenting an outline of the visitobjectives, then the host presentinginformation or defining what could beprovided in the time allocated; this wasfollowed by question and answer sessions.Site visits were essential to see what thestormwater problems and solutions were likein practice. The group met at the end of eachday to consider the conclusions – it was usualto have more than 30 –, along withinformation from the hosts. One person fromthe delegation was then assigned to write upthat particular day. These visit reports,summarised, are in Appendix C.

The final report was written by all membersof the group after the mission. Each wasassigned sections that best utilised theirpersonal interests and specialties in stormand surface water management. Severalpost-mission meetings were needed toconclude the report.

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2.1 Regulations and responsibilities

2.1.1 Clean Water Act (CWA)

2.1.1.1 Background

The EPA leads the nation’s environmentalscience, research, education and assessmentefforts and works to develop and enforceregulations that implement environmentallaws enacted by congress.

The agency advances educational efforts todevelop an environmentally conscious andresponsible public and to inspire personalresponsibility in caring for the environment. Inrecent years, approximately half of the EPA’sbudget has provided financial support to fundthe state environmental applications andresearch programmes. The EPA is responsiblefor setting national standards for a variety ofenvironmental programmes and has thepower to delegate these responsibilities tothe various states and municipalities for theissuing of permits and for monitoring andenforcing compliance. Where nationalstandards are not met the EPA can issuesanctions and take other steps to assist thevarious states and municipalities in reachingthe desired levels of environmental quality.

Growing public awareness and concern forcontrolling water pollution in the US, asevidenced by a series of litigations brought byenvironmental activists, led to the enactmentof the Federal Water Pollution Control ActAmendments of 1972. Amended in 1977, thislaw became commonly known as the CleanWater Act (CWA).

The CWA established the basic structure forregulating discharges of pollutants into thewaters of the US. It gave the Federal Agencyand the EPA (see 2.1.3.1) the authority toimplement pollution control programmessuch as setting wastewater standards forindustry. The CWA also continuedrequirements to set water quality standardsfor all contaminants in surface waters. The actmade it unlawful for any person to dischargeany pollutant from a point source intonavigable waters unless a permit wasobtained under its provisions. It also fundedthe construction of sewage treatment plantsunder the construction grants programmeand recognised the need for planning toaddress the critical problems posed by non-point source pollution.

The background is given in Maestre et al2 andreproduced here. The National PollutantDischarge Elimination System NPDES MS4:Municipal Separate Storm Sewer Systemswas developed by the EPA in response to theUnited States Congress to protect USreceiving waters from contaminatedstormwater discharges. In 1972 the CWAexpanded the federal role of water pollutioncontrol. Some of the effects of the CWAwere to increase the federal funding forconstruction of publicly owned wastewatertreatment works (POTW), and to developcommunity participation and a permit for eachpoint discharge, among other activities. TheNPDES established effluent guidelines forpoint discharges that contaminate the nation’swater. The first stormwater regulation wasissued in 19733, but the EPA believed that thetraditional end-of-pipe controls used for

2 US PRACTICE

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2 Maestre, A., Pitt, R. E., Williamson D. ‘Nonparametric statistical tests comparing first flush with composite samples from the NPDES Phase 1 municipal

stormwater monitoring data.’ Stormwater and Urban Water Systems Modeling. In: Models and Applications to Urban Water Systems, Vol. 12

(edited by W. James). CHI. Guelph, Ontario, pp. 317 - 338. 2004.

3 38 FR 13530, May 22

process discharges and treatment workscould not be used to control stormwaterpollution. In addition, it would require atremendous effort to issue NPDES permitsfor each of the stormwater sources in the US.

The initial stormwater regulations (phase I)were developed for large municipalities(>100,000 population) and for certain industrialcategories. Current regulations associated withphase II of the stormwater permit programmenow require stormwater management for allurban areas in the US. The CWA of 1972provided an important tool for communities.Section 208 provided the capability toimplement stormwater management plans atthe regional level. The task was welcomed byplanning offices, which in some cases receivedadvice from the US Army Corps of Engineers.In 1976, the EPA enlarged the planninginitiative through the ‘Section 208: Area-wideAssessment Procedures Manual’. However, in the late 1970s some problems arose with the 208 planning projects underwayowing to inadequate data and lack oftechnological development.

Between 1978 and 1983, the EPA conductedthe NURP that sought to determine waterquality from separate storm sewers fordifferent land uses. This programme studied81 outfalls at 28 sites, monitoringapproximately 2,300 storm events.

In 1987, the amendments to the CWAestablished a two-phase programme toregulate 13 classes of stormwater discharges.Two of these classifications were dischargesfrom large and medium Municipal SeparateStorm Sewer Systems (MS4s). A large MS4serves an urban population of 250,000 or more,while a medium MS4 serves communitiesbetween 100,000 and 250,000. The EPA set upa permit strategy for communities complyingwith NPDES requirements.

Subsequent enactments modified some ofthe earlier CWA provisions. Revisions in 1981streamlined the municipal construction grantsprocess, improving the capabilities oftreatment plants built under the programme.Changes in 1987 phased out the constructiongrants programme, replacing it with the StateWater Pollution Control Revolving Fund, morecommonly known as the Clean Water StateRevolving Fund. This new funding strategyaddressed water quality needs by building onEPA-state partnerships.

For many years following the passage of theCWA in 1972 the EPA, states and first nationindigenous tribes focused mainly on thechemical aspects of the ‘integrity’ goal.During the last decade, however, moreattention has been given to physical andbiological integrity. Also, in the early decadesof the Act’s implementation, efforts focusedon regulating discharges from traditional‘point source’ facilities, such as municipalsewage plants and industrial facilities, withlittle attention paid to runoff from streets,construction sites, farms, and other ‘wet-weather’ sources.

Starting in the late 1980s, efforts to addresspolluted runoff have increased significantly.For ‘non-point’ runoff, voluntary programmes,including cost-sharing with landowners, arethe key tool. For ‘wet weather point sources’like urban storm sewer systems andconstruction sites, a regulatory approach isbeing employed.

Evolution of CWA programmes over the lastdecade has also included something of a shiftfrom a programme-by-programme, source-by-source, pollutant-by-pollutant approach tomore holistic watershed-based strategies.Under the watershed approach equalemphasis is placed on protecting healthywaters and restoring those that are‘impaired’. A full array of issues areaddressed, not just those subject to CWAregulatory authority. Involvement of

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stakeholder groups in the development andimplementation of strategies for achievingand maintaining state water quality and otherenvironmental goals is another hallmark ofthis approach.

2.1.1.2 Delivering the CWA

The CWA is the cornerstone of surface waterquality protection in the US but it does notdeal directly with issues relating to groundwater or quantity. The statute employs bothregulatory and non-regulatory tools to reducedirect pollutant discharges into waterwaysand to assist in the financing of municipalwastewater treatment facilities and tomanage polluted runoff. These initiatives arerequired to support in particular theprotection and propagation of wildlife,including fish and shellfish, and recreationboth in and on the water.

Programmes over the last decade haveresulted in a shift from a source-by-source andpollutant-by-pollutant approach to more holisticwater-based strategies. Under the watershed(ie whole catchment area) approach, equalemphasis is placed on protecting healthywaters and restoring those that are impaired.This new approach also included theinvolvement of stakeholder groups in thedevelopment and implementation of strategiesfor improving and maintaining state waterquality and other environmental goals.

Congress amended the CWA in 1987 toestablish the non-point source managementprogramme. This section deals with a range ofactivities including technical assistance,financial assistance, education, training,technology transfer, demonstration projects andmonitoring to assess the success of specificnon-point source implementation projects.

In April 2000, the EPA and the states joinedtogether to form a new state and EPA Non-

Point Source Partnership to identify, prioritiseand provide resolutions to non-point sourceproblems.The states and the EPA haveestablished eight work groups to focus onnon-point source topic areas:

• watershed planning and implementation• rural non-point sources• urban non-point sources• non-point source grants management• non-point source capacity building and

funding• information transfer and outreach• non-point source results• non-point source monitoring.

It is anticipated that the information andproducts emerging from these eight groupsshould assist the individual states to moreeffectively implement their non-point sourcemanagement programmes.

2.1.1.3 Total maximum daily load (TMDL)

The precise way in which the requirements ofthe CWA are implemented at site level is viathe definition of TMDLs for any impairedwater bodies. A TMDL is a calculation of themaximum amount of a pollutant that a waterbody can receive and still meet pre-definedwater quality standards, and an allocation ofthat amount to the source of pollutantscausing the impairment.

The typical steps for developing a TMDLinclude4:

• identify linkages between water qualityproblems and pollutant sources

• estimate total acceptable loading rate thatachieves water quality standards

• allocate acceptable loading rates between sources

• package the TMDL for EPA approval.

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4 USEPA Office of Water Nonpoint source control Branch, Washington (2005). Handbook for developing watershed plans to restore and protect our waters. EPA

841-B-05-005. Draft October.

The most common reported impairments are:metals (19%), pathogens (13%), nutrients(9%) and sediment (8%).

The CWA section 303 establishes the waterquality standards and TMDL programmes. Thejustification for which was that over 40% ofassessed waters in the US still do not meetthe water quality standards states, territoriesand authorised tribes have set for them. Thisamounts to over 20,000 individual riversegments, lakes and estuaries. Theseimpaired waters include approximately300,000 miles of rivers and shorelines andapproximately 5 million acres of lakes pollutedmostly by sediments, excess nutrients andharmful micro-organisms. An overwhelmingmajority of the population – 218 million – livewithin 10 miles of these impaired waters.

Under section 303(d) of the 1972 CWA,states, territories and authorised tribes arerequired to develop lists of impaired waters.These impaired waters are those that do notmeet the water quality standards that states,territories and authorised tribes have set for

them, even after point sources of pollutionhave installed the minimum required levels ofpollution control technology. The law requiresthat these jurisdictions establish priorityrankings for waters on the lists and developTMDLs for these waters.

A TMDL specifies the maximum amount of apollutant that a water body can receive andstill meet water quality standards, andallocates pollutant loadings among point andnon-point pollutant sources. By law, the EPAmust approve lists and TMDLs established bystates, territories and authorised tribes. If astate, territory or authorised tribe submissionis inadequate, the EPA must establish the listor the TMDL. The EPA issued regulations in1985 and 1992 that implement section 303(d)of the CWA – the TMDL provisions.

Local water quality standards are thereforeset by states, territories and authorised tribes.These identify the uses for each water body,for example, drinking water supply, contactrecreation (swimming) and aquatic lifesupport (fishing), and also the relevant

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Water body TMDL pollutantWater qualitytarget

Naturalallocation

TMDL goalTargetedbeneficial uses

A. Hiddenwoodwatershed,Walworth CountySouth Dakota(February 1999)

Accumulatedsediment

Increase/maintainlake storagecapacity by 53 acres

94% of loadingattributable tonatural background

5% decrease insediment loadsfrom watershed

Immersionrecreation; limitedcontact recreation;warm water semi-permanent fish lifepropagationTotal phosphorus Increased visitor

days/camp siteuse; decreasedincidence of winterfish kills

95% of loadingattributable tonatural background

2% decrease intotal phosphorusloads fromwatershed

B. Hunt Riverwatershed RhodeIsland (February2001)

Fecal coliforms Shall not exceed ageometric meanvalue of 20 FC/100 ml and notmore than 10% ofthe samples shallexceed a value of200 FC/100 ml.

Natural backgroundloads from wildlife,especially geese,and other sourcesare thought tomake up asignificant portionof the total fecalcoliform load in theHunt Riverwatershed. Preciselevels areunknown.

Between zero and99% loadreduction in FCdepending on thesource and currentinput loading.

A source of publicdrinking watersupply, primary andsecondary contactrecreationalactivities, and fishand wildlife habitat.

Table 2.1 Examples of TMDLs from EPA website (http://www.epa.gov/owow/tmdl/examples/)

scientific criteria to support that use. Thecalculation must include a margin of safety toensure that the water body can be used forthe purposes the state has designated. Thecalculation must also account for seasonalvariation in water quality. Examples areillustrated in Table 2.1.

Example A in Table 2.1 illustrates the use of‘blanket’ reductions in solids loads andphosphorous across a catchment, for whichthe TMDL is related to a specific percentagereduction in concentrations of dischargedpollutants. Whereas example B shows amuch more detailed application with assignedreductions in inputs to each of thecontributory sources. In the latter example,there are five major sources of fecal coliformbacteria in the Hunt River watershed. Theseinclude stormwater runoff from highways andresidential/commercial areas, a dairy farm,pigeons roosting under a highway, a horsefarm and resident waterfowl, domestic pets,and wildlife. The largest dry weather sourcesof bacteria are the dairy farm, pigeonsroosting under the highway overpass,domestic pets, resident waterfowl and otherwildlife. The largest wet weather source ofbacteria to the watershed is stormwaterrunoff. Although other sources are significantduring wet weather, stormwater runoff has agreater cumulative impact in the watershed.There are clear difficulties in reaching eitherof the targets presented in each example. Inexample B, the EPA provides suggestions forBMPs, as illustrated in Table 2.2.

Table 2.2 Examples of BMPs suggested to achieve theTMDLs for example B in Table 2.1

Specific guidance is also provided in theregulatory guidance on the public outreachprogramme. For Example B, this should beaimed at informing and educating residents inthe watershed about the sources of bacteriain streams and ways to eliminate or reducethese sources. The local towns would beresponsible for carrying out this programme.The public outreach programme in the HuntRiver watershed should focus on educatingthe public about the negative water qualityimpacts that resident waterfowl can have,and the potential health risks associated withencouraging the presence of these waterfowlin local ponds, impoundments and on lawnareas. Additionally, educational informationshould be distributed concerning theimportance of proper maintenance and petwaste clean-up.

While TMDLs have been required by the CWAsince 1972, states, territories, authorised tribesand the EPA had not developed many untilrecently. This led to citizen organisationsbringing legal actions against the EPA seekingthe listing of waters and development ofTMDLs. To date, there have been some 40such legal actions in 38 states. The EPA isunder court order or consent decrees in manystates to ensure that TMDLs are established,either by the state or by the EPA.

In an effort to speed US progress towardachieving water quality standards andimproving the TMDL programme, the EPAbegan a comprehensive evaluation of EPAand the states’ implementation of its CWAsection 303(d) responsibilities in 1996. TheEPA convened a committee under the FederalAdvisory Committee Act, which issued itsrecommendations in 1998. These were usedto guide the development of proposedchanges to the TMDL regulations, which theEPA consulted on and published the final ruleon in July 2000. However, Congress added a‘rider’ to one of their appropriations bills thatprohibited the EPA from spending money in2000 and 2001 to implement the new rule.

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Recommended BMP Responsible entity

Discourage the presence ofresident waterfowl

Residents and propertyowners, towns of NorthKingstown and EastGreenwich

Structural stormwatermanagement BMP(s)

Town of North Kingstown

Agricultural BMPs, includinga waste storage structure,roof runoff management.

Farm owner

The current rule remains in effect until 30 days after Congress permits the EPA toimplement the new rule. TMDLs continue tobe developed and completed under thecurrent rule as required by the 1972 law andmany court orders. The regulations thatcurrently apply are those that were issued in1985 and amended in 1992.5 Theseregulations mandate that states, territoriesand authorised tribes list impaired andthreatened waters and develop TMDLs.

For more information, see the EPA TMDLweb site: (http://www.epa.gov/owow/tmdl/)

2.1.2 Institutional arrangements,regulations and standards, planningsystems and master planning

2.1.2.1. Adoption (permitting)

As authorised by the CWA, the NationalPollutant Discharge Elimination System(NPDES) permit programme controls waterpollution by regulating point sources thatdischarge pollutants into waters of the US.Point sources are discrete conveyances such aspipes or man-made ditches. Individual homesthat are connected to a municipal system, thatuse a septic system or do not have a surfacedischarge, do not need an NPDES permit.However, industrial, municipal and otherfacilities must obtain permits if their dischargesgo directly to surface waters. In most cases,the NPDES permit programme is administeredby authorised state governments.6 Since itsintroduction in 1972, the NPDES permitprogramme has been responsible for significantimprovements to water quality.

2.1.2.2 State and tribal programmeauthorisation status

States, tribes and territories are authorisedthrough a process that is defined by the

CWA. States that want to be authorised toadminister the NPDES programme submit aletter to the EPA from the Governorrequesting review and approval. The EPA thendetermines whether the package is completewithin 30 days of receipt. Within 90 days ofreceipt the EPA renders a decision to approveor disapprove the programme. The time forreview may be extended by agreement.

The NPDES programme7 consists of variouscomponents, including:

• NPDES base programme for municipal andindustrial trial facilities

• federal facilities• general permitting• pre-treatment programme• biosolids.

A state may receive authorisation for one ormore of the NPDES programme components.For example, if the state had not receivedauthorisation for federal facilities, the EPAwould continue to issue permits to federalfacilities (eg military bases, national parks,federal lands etc).

The process of authorisation includes a publicreview and comment period and a publichearing. If the EPA disapproves theprogramme, it remains the permittingauthority for that state, tribe or territory. If theprogramme is approved, the state assumespermitting authority in lieu of the EPA. Allnew permit applications would then besubmitted to the state agency for NPDESpermit issuance. Even after a state receivesNPDES authorisation, the EPA continues toissue NPDES permits on tribal lands (if thetribe is not administering its own approvedNPDES programme). The current status ofeach state is given in Table 2.1.

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5 40 CFR Part 130, section 130.7

6 http://cfpub.epa.gov/npdes/statestats.cfm).

7 http://cfpub.epa.gov/npdes/index.cfm

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StateApproved stateNPDES permit

programme

Approved toregulate federal

facilities

Approved state pre-treatmentprogramme

Approved general permits

programme

Approved biosolids (sludge)

programmeAlabama � � � �AlaskaAmerican SamoaArizona � � � � �Arkansas � � � �California � � � �Colorado � �Connecticut � � � �Delaware � �District of ColumbiaFlorida � � � �Georgia � � � �GuamHawaii � � � �IdahoIllinois � � �Indiana � � �Iowa � � � �Johnston AtollKansas � � �Kentucky � � � �Louisiana � � � �Maine � � � �Maryland � � � �MassachusettsMichigan � � � �Midway IslandMinnesota � � � �Mississippi � � � �Missouri � � � �Montana � � �Nebraska � � � �Nevada � � �New HampshireNew Jersey � � � �New MexicoNew York � � �North Carolina � � � �North Dakota � � � �Northern Mariana IslandsOhio � � � � �Oklahoma � � � � �Oregon � � � �Pennsylvania � � �Puerto RicoRhode Island � � � �South Carolina � � � �South Dakota � � � � �Tennessee � � � �Texas � � � � �Trust TerritoriesUtah � � � � �Vermont � � �Virgin Islands �Virginia � � � �Wake IslandWashington � � �West Virginia � � � �Wisconsin � � � � �Wyoming � � �

Exhibit 2.1 National Pollutant Discharge Elimination System (NPDES) – status of US states

There are certain omissions in Table 2.1. Forexample, Massachusetts Water ResourcesAuthority (MWRA) controls all discharges andmaintains systems in the Greater Boston area,but does not have approved regulatory authority.

2.1.2.3 Issuing of permits

The control of stormwater in the US dependsultimately on the appropriateness of the localmunicipality within the regulatory system.Whilst the granting of permits is delegatedfrom the EPA to state level, this is oftenfurther delegated downwards. In general, thisusually reflects the population of the area. Forexample, major cities such as New York orBoston would have their own role in the formof the authorities that are responsible tocontrol stormwater. Where populations areless dense, this authority would beadministered at county level, and in sparselypopulated areas would probably be retainedat state level.

Whilst the CWA is an overarching federal pieceof legislation, there is a major variation in thedischarge of its operation. The EPA providesadvice on the drafting of ‘state ordinances’ andthese are discussed further in the section onmaintenance (2.3.4). Ultimately, it is the ‘stateordinance’ delegated to the appropriateauthority that underpins the granting of thestormwater permits.

There is also a major variation in the way thatstormwater regulations are enforced. Thecoastal states have a much wider appreciationof environmental issues and this has generallybeen focused in the local environment owing todirect and obvious impacts. Examples of theseare pollution of beaches, degradation ofstreams and rivers, and the effect on wildlife(eg Chesapeake Bay, Boston).

Whilst it would appear that the regulationsare disjointed – some states have still notachieved phase I of the CWA, let alonestarted working towards phase II, which has a

delivery date of 2008 – this is in some waysunderstandable. Each state can have widelydifferent approaches to the control ofstormwater discharges and very often this iscaused by extreme variations in climate,culture, city layout and demographics.

For instance, Los Angeles city is a hugeconurbation (approximately 20 million people)and has little in the way of public parks andgreen areas. The stormwater runoff ispredominantly from roof and road areas.Hence, polluted sediments washed off thesurface are carried by the storm sewersdirectly to the sea where it pollutes thebathing waters and beaches. Hence the LosAngeles approach is to trap sediments.Examples of this are shown in themaintenance section (2.3). Much of this workhas been undertaken as a result of courtcases where the failure to achieve the limitson TMDLs has resulted in litigation.

However, there has been a sea change inattitude of the Los Angeles (and California)area. One of the biggest sustainabledevelopments is taking place at Playa Vistawhere more than 1,000 acres of land is beingdeveloped with major features for the controlof stormwater. These features range fromwater recycling to the avoidance of pollutionusing BMPs and LIDs.

In contrast to Los Angeles, the standards andregulations enforced in Washington state areconsiderably different. The biggest city isSeattle and the regulatory requirements ofstormwater control and the administration ofthese is strictly enforced. New developmentssuch as High Point utilise many techniques inthe treatment of stormwater, includingporous surfacing, bio-remediation swales andmajor ponds. In addition, they are engaged inmajor retrofitting exercises where bio-remediation swales are being introduced intoexisting neighbourhoods (SEA streets).

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In summary, it is apparent that the regulatorypractices from state to state are variable, butin general they are appropriate to the localewhich they serve. Certain states, such asWashington and Oregon, perform to a veryhigh standard and are the benchmarks forsustainable systems, whereas other statesdo not perform so highly, such as Texas.

Provided the construction of the stormwatersystems receives the appropriate permits,then these will be adopted by themunicipality, county or state.

2.1.2.4 Municipal permitting process

Any project that involves a new or change-of-use of property, construction or renovation, orother building and design elements, usuallyrequires a permit from the Department ofPlanning and Development (DPD) of themunicipality specific to the developmentlocation. The DPD administers constructionand land use or zoning regulations for thedevelopment of all construction works withinthe limits of the municipality. Permits must beobtained prior to any works being carried out.There are two major types of permit issuedby the respective DPD and these cover landuse and construction and they may be appliedfor separately or together.

These permits are to assure that all structuresmeet the zoning requirements and complywith all environmental regulations includingstate acts and local plans and programmes.The construction related permits providereviews of the required structural and safetyelements and will determine whether anyadditional permits or a drainage review arerequired. Construction related permits includebuilding, demolition and the re-grading of land.Other required permits are related to internalconstruction such as electrical wiring andplumbing, as well as those for working onpublic highways.

Zoning plans, stormwater and other relateddesign manuals, permit application forms andchecklists are available from municipalities inboth printed and digital formats via theirrespective websites (eg http://www.epa.gov/npdes/authorisation).

2.1.2.5 Drainage review

A drainage review is required when anyproposed project is subject to a developmentpermit or approval, and the project:

• would result in 220 metres squared (2,000feet squared) or more of impervious surface

• would involve 780 metres squared (7,000feet squared) or more of land disturbingactivity

• would construct or modify a drainage pipeor ditch that is 300 mm or more in size, orwhich receives surface and stormwaterrunoff from a drainage pipe or ditch

• is within or adjacent to a flood hazard areaas defined in the municipality codes

• is located within a critical drainage area• is a re-development project with a budget

of $100,000 (approx. £53,000), or• is a re-development project on a site where

the total of the new plus the replacedimpervious surface area is 550 metressquared (5,000 feet squared) or more

There are four drainage review typesintended to evaluate the drainagerequirements related to the project size,location, type and the anticipated impacts tothe local and regional surface water system:

• small project drainage review • targeted drainage review • full drainage review• large project drainage review.

Every project that requires a drainage reviewmust meet the core requirements that arelaid down in the surface water designmanual developed by/for each localauthorised regulator.

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The core requirements include analysis of the following:

• discharge at the natural location• off-site analysis• flow control• conveyance systems• erosion and sedimentation control plan• maintenance and operation• financial guarantees• water quality.

In addition to the core requirements, thereare also special requirements that may applyto a proposed project. These are documentedin the municipalities’ surface water designmanual and relate to:

• area specific requirements• floodplain and flood way delineation• flood protection facilities• source control• oil control.

2.1.2.6 Master drainage plan process andcomponents

Planning as early as possible is the key toestablishing a good project plan and toensuring an understanding of the applicantand local authority needs and requirements.As part of the permitting process, a masterdrainage plan (MDP) is required. This generallyfollows a sequential 10-step process for urbandevelopment proposals. An urban planneddevelopment (UPD) permit gives broadapproval of the overall site plan, projectphasing and development standards that areto be applied to all future developments onthe site, together with conditions that willmitigate any impacts upon the environment,public facilities and services. The planidentifies the particular locations, uses anddensity of proposed development.

The UPD permit becomes the mechanism bywhich the development is implemented and

establishes conditions that are to be compliedwith by all subsequent land use approvals.The necessary requirements to mitigate anyadverse impacts that are related to surfacewater management would be included withinthe UPD permit conditions of approval.

The recommended sequence of events todevelop MDPs is as follows:

1) Pre-application meeting with localauthority engineers

2) Preliminary application submission3) MDP and baseline studies scoping4) Preliminary draft MDP (conceptual

drainage plan)5) Draft MDP6) Recommended MDP7) Hearing examiner process8) MDP finalisation 9) Construction monitoring10) Post-development monitoring

The above process, if correctly followed,promotes dialogue between the applicant andthe local authority that will provide advice andapproval for each stage of the process, thuslimiting time delays and costs. The purpose ofthe post-development monitoring is todetermine whether the level of protectionanticipated in the master drainage plan hasbeen achieved.

In addition to tracking the efficacy of themitigation measures, post-developmentmonitoring can be a useful tool for decreasinguncertainty with respect to resourcemanagement issues and allowing the potentialfor modification of the regulations and policies.The approach is ideally suited to addressuncertainty, when potential impacts may onlybe qualitatively estimated and the magnitudeof the impact is unknown. This process allowsfor adjustments to be made, which may bestructural and/or procedural, that will improveperformance and mitigation measures.

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2.1.2.7 Public engagement (outreach)

The stakeholder groups that need to beengaged vary depending on the local issues orproblems. A stormwater public educationprogramme (SPEP) is a requirement under theCWA and implements activities that are mostlikely to reach the identified target groups.Wherever possible, outreach activities aredeveloped in order to reach residents toinfluence their behaviour as they engage inactivities related to the target pollutants.

Messages for most target audiencesconcentrate on simple ‘how-to’ tips forpreventing pollution and are generallypollution specific, for example, identifying theharm of target pollutants on the communityor neighbourhood and tips to prevent orreduce consequent stormwater pollution.

The target pollutants for the SPEP areidentified in the NPDES permits.The NPDES permit, which includes therequirement for the implementation of aneducation programme, generally has thefollowing three main goals:

• increase knowledge and awareness• change behaviour• reach a diverse audience.

The SPEP is a pollutant specific outreacheffort designed to reach the polluters orpotential polluters through a variety of outletswith similar messages to ensure exposureand to increase behaviour change. Within thisintegrated programme each activity ismutually supportive by building a network ofpublic education and reaching many targetaudiences with pollution prevention tips.

The target pollutants for the SPEP areidentified in the NPDES permit requirements.These include the following topic areas. Thisinformation is provided to the general publicand associated industries free of charge viaprinted leaflets and internet:

• Trash (litter) – main target areas arerestaurants and customers of fast foodoutlets

• Indicator bacteria – advice to owners ofpets – including horses – and septic sewersystems

• Nutrients – advice to gardeners andowners of pets and septic sewer systems

• Pesticides – advice to pet owners,gardeners and DIY enthusiasts

• Hydrocarbons – most municipalities havea used oil recycling programme. DIYmechanics and the motor repair trade areboth targeted.

2.1.3 Champions and sources ofassistance

It is important to appoint or engagechampions for stormwater innovations to besuccessful. Champions are, or become,leaders that can help spread the word andsupport innovative surface water drainagesystems. Strong champions are needed andthese are particularly important in the keystakeholder groups, which include theenvironmental organisations. It is importantfor the nominated or self appointedchampions to have good knowledge andunderstanding of the issues and to ensureintegration across disparate groups to createa strong commonality of purpose. Where practicable, the ‘adoption’ bycommunities or stakeholders of stormwaterfacilities, such as ponds, is an opportunitythat needs to be exploited to ensure longterm success.

There is a need for the right champions withgood knowledge to be engaged in theprocess to assist in the selection of the mostsustainable solutions, and to ensure thewater quality and other performance aspects,including flooding, are appropriately joined up.

Innovative funding schemes can be useful inpromoting and raising awareness andencouraging stakeholder engagement,

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including champions. One example of a‘champion’ organisation is the Center forWatershed Protection (CWP). The CWP wasfounded in 1992 and is classified as a not-for-profit organisation. It is dedicated toprotecting and restoring watersheds (ie rivercatchments) through effective land and watermanagement. It is considered to be theforemost authority in the development,application and dissemination of stormwaterand watershed protection managementtechniques. It provides practitioners with realworld solutions and believes that individuals,particularly within local governments andwatershed groups, hold the key to protectingand restoring watersheds.

The centre undertakes and translatesresearch mainly produced by others intopractical tools so that the non-technicalpublic, as well as experts, can understandand act upon the emerging guidance andrecommendations. Activities are aligned tofive main programme areas:

• research• practice• implementation• learning• education and outreach.

The development of BMPs and guidance fordesign and use by the centre have assistedmunicipalities in meeting the EPArequirements to minimise stormwaterpollution entering water bodies by thereviewing of existing codes and thedevelopment of new manuals and bestpractice guidance.

The centre is financed from a number ofsources, which include federal funds from theEPA and the undertaking of contract work forprivate consultants and local authorities (citiesand municipalities). Outputs from researchare turned into applicable and accessibleguidance manuals and handbooks, and thisinformation is also provided via its website,

where extensive resources are available freeof charge. The centre currently has 21 staffthat have produced over 30 manuals andreports relating to urban watershed protectionand restoration, developed extensiveresources for the EPA and has conductedover 350 training workshops over the past 10 years.

The centre provides local governments,environmental groups and watershedorganisations around the country with thetechnical skills to help protect and restorerivers, streams and lakes. This is done via amulti-disciplinary strategy to watershedprotection, which includes research,developing watershed managementpractices, encouraging watershed planningand implementation, fostering learning, and building the capacity of local watershed organisations.

Stormwater management is an essential partof the work undertaken by the centre since ithas recognised that untreated watersdischarging to the environment present oneof the greatest threats to water quality.

2.2 Treatment and management of

urban stormwater runoff

Many cities across the US are looking forcreative ways to treat and manage theirstormwater. Different approaches are used ifthe stormwater is included in a newdevelopment or exists as runoff from alreadydeveloped urban areas.

2.2.1 Best management practices (BMP)

The USEPA defines two types of BMP thatare used to reduce the threat of stormwaterrunoff pollution from construction anddevelopment in urbanising areas: (i) non-structural or source control BMPs, and (ii)structural or treatment BMPs. A recent listof types of non-structural BMPs is given in

25


Table 2.3 and structural BMPs in Table 2.4.8

LID is considered as a combination of bothnon-structural and structural BMP.

Non-structural controls that rely more onnatural approaches – with limited construction– seek to minimise runoff or the introductionof pollutants. Structural controls involve‘engineering principles’, designed to providetemporary storage or treatment of runoff intheir delivery.

Table 2.3 Non-structural BMPs for urban stormwaterrunoff

Table 2.4 Structural or treatment best managementpractices for urban stormwater

2.2.2 Low impact development (LID)

The US goal of an LID is to mimic site pre-development hydrology by using designtechniques that maintain the originalinfiltration, filtering, storage, evaporation,recharge and detention of runoff as close tothe original condition as possible. Techniquesare based on the premise that stormwatermanagement should not be seen asstormwater disposal. Traditional techniquesconvey, manage and treat stormwater inlarge, costly end-of-pipe facilities (regional)located at the bottom of drainage areas,whereas LID addresses stormwater throughsmall, cost-effective landscape featureslocated ideally at the house plot level.

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Majorcategories

Structural BMPs

Ponds Dry retention ponds.Dry-extended detention ponds.Wet (retention) ponds.

Stormwaterwetlands

Constructed wetlands.

Vegetativebiofilters

Grass swales (wet/dry).Filter strips/buffer.Bioretention cells.

Infiltrationpractices

Infiltration trench.Infiltration basin.Porous pavement.

Sand and organicfilters

Surface sand filter.Perimeter filter.Media filter.Underground filter.

Technologyoptions and other

Water quality inlets.Multi-chambered treatment train.Vortex separation/continuous deflectionsystems.

8 Water Environment Federation (WEF) and ASCE. (1998) Urban Runoff Quality Management. ISBN 1-57278-039-8. WEF, Alexandria, VA.

Majorcategories

Non-structural practice

Public education Public education and outreach

Planning andmanagement

Better site design.Vegetation controls.Reduction/disconnection of impervious areas.Green-roofs (also a structural control).LID (combination of non-structural andstructural).

Materialsmanagement

Alternative product substitution.Housekeeping practices.

Street/storm drainmaintenance

Street cleaning.Catchbasin cleaning.Storm drain flushing.Road and bridge maintenance.BMP maintenance.Storm channel and creek maintenance.

Spill preventionand clean up

Above ground tank spill control.Vehicle spill control.

Illegal dumpingand controls

Illegal dumping controls.Storm drain stencilling (labelling).Household hazardous waste collection.Used oil recycling.

Illicit connectioncontrol

Illicit connection prevention.Illicit connection – detection and removal.Leaking sanitary sewer and septic tank control.

Stormwater reuse Landscape watering.Toilet flushing.Cooling water.Aesthetic and recreation ponds.

These landscape features, also known as LIDintegrated management practices (IMP)9, are the building blocks of LID. Almost allcomponents of the urban environment havethe potential to serve as an IMP. This includesopen space, rooftops, streetscapes, parkingareas and pedestrian areas. LID is a versatileapproach that can be applied equally well tonew development, urban retrofits, andredevelopment and regeneration projects.Utilisation of LID practices can eliminate theneed for centralised BMP facilities.

In the mid 1980s LID was pioneered to helpPrince George’s County, Maryland, to addressthe growing economic and environmentallimitations of conventional stormwatermanagement practices.

LID allows for greater development potentialwith less environmental impacts through theuse of smarter designs and advancedtechnologies that achieve a better balancebetween conservation, growth, ecosystemprotection and public health, andconsequently quality of life.

Bioretention is seen as either a BMP facility(Table 2.3) or one of the many LID techniquesthat are available. Others include permeablepaving, the use of street planters and swalesand the disconnection of roof water downspouts. An LID site will incorporate a widerange of techniques that are designed tocontrol pollutants, reduce runoff volume,manage runoff timing and address a numberof other ecological concerns.

LID has numerous benefits and advantagesover conventional stormwater management.It is a more environmentally soundtechnology and a more economicallysustainable approach to addressing theadverse impacts of urbanisation. Bymanaging runoff close to its source throughintelligent site design, LID can enhance thelocal environment, protect public health, and

improve and enhance visual amenity includingthe possibility of reducing project costs. To besuccessful, stormwater managementprogrammes require that a wide array ofcomplex and challenging ecosystem andhuman health protection goals be addressed.

Many of these goals are not, and cannot, bemet by conventional stormwatermanagement technology. Communities arestruggling with the economic reality offunding the ageing and ever-expandingstormwater infrastructure. The challenge ofhow to restore stream quality in watershedsthat have already been densely developed isdaunting. Simply relying on imperviousreduction and/or conventional detentionponds to address these issues is not feasible,practical or sustainable. LID provides the keyin its emphasis on controlling or at leastminimising the changes to the localhydrologic cycle or regime.

LIDs (or should these be re-named low impactdesigns?) are utilised to address a wide rangeof wet weather flow issues. These includecombined sewer overflows (CSOs), NPDESstormwater phase II permits, TMDL permits,non-point source programme goals, and otherwater quality standards. The agenciesresponsible for permitting can use LID as amodel to facilitate more cost-effective,ecologically sound development practices.Developers can achieve greater projectsuccess and cost savings through theintelligent use of LID, and designers can applythese techniques for innovative, educational,and more aesthetically pleasing sites.

A common concern is that LID-based projectswill be more expensive because they couldrequire higher design and construction costsand a longer period to receive projectapproval. This may or may not be true and willto a great extent depend upon the experienceof the project consultants and contractors,and how receptive local government officials

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9 Field R., Sullivan E. (Ed.) (2003) Wet weather flow in the watershed. Lewis pub. 1-56676-916-7. p281

are to innovative practices. Additional LIDcost concerns include the potential forgreater expense owing to the increased landtake and landscaping requirements. Costs arevery site specific and each project will beunique and be based on the site’s soilconditions, topography, existing vegetation,land availability etc.

Despite these issues, experience in the UShas indicated that LID still saves money overconventional approaches through reducedinfrastructure and site preparation work. Casestudies and pilot programmes indicate thatthere is a 25-30% reduction in costsassociated with site development that useLID techniques. These savings are achievedby reductions in clearing, grading, pipes,ponds, inlets, kerbs and paving. By carefuldesign, infrastructure reduction can realisesavings that can enable developers to addvalue-enhancing features to the property oreven to recover more developable spacesince there will be no requirement to utiliseland for a stormwater pond.

Many LID techniques have nothing to dowith, nor can they be, significantly influencedby the behaviour of the property owner.These include basic subdivision andinfrastructure design features such asreducing the use of pipes, ponds, kerbs andgutters; maintaining recharge areas, bufferzones, and drainage courses; using infiltrationswales, grading strategies, and open drainagesystems; reducing impervious surfaces anddisconnecting those that must be used; andconserving open space.

The long-term success of LIDs has muchmore to do with the knowledge, skills andcreativity of the site designers than what theproperty owner does or doesn’t do. However,the key factor in the success of LID is toensure that the landscape practices (such asrain gardens) are attractive and perceived bythe property owner as adding value to theproperty. If these LID practices are viewed as

assets, the primary motivation for their long-term maintenance is that of property ownersprotecting their vested economic interests.

Additionally, experience has shown thateducational efforts can successfully promoteactive public engagement in protectingwaterways by the simple act of peoplemaintaining their properties. Appropriate LIDsite source controls should significantlyreduce maintenance burdens for propertyowners and municipalities (local authorities).The techniques are simple, need no specialequipment or high costs to maintain, andencourage property owners to be responsiblefor the impacts associated with their land.

For preserving stream integrity, experiencehas demonstrated the importance of astormwater system that specificallyaddresses the more frequent or micro-stormsthat can and do occur on a regular basis. Byusing decentralised site-based sourcecontrols, LID uses the stormwater from thesemore frequent events as a resource and is aneffective ecosystem approach. Additionally, ifthe full suite of LID controls and site designpractices is creatively used, LID is capable ofautomatically controlling the higher returnperiod storms through its primary strategy ofrestoring the built area’s natural rainfall-runoffrelationship. The more techniques that areapplied, the closer to the undevelopedhydrologic function the catchment willbecome, and where there are known floodingproblems, a hybrid approach may be required.

Although the term LID can be loosely defined(much like sustainable development), theappropriate definition of LID is distinct andshould not be confused with otherstormwater management and developmentstrategies. LID seeks to design the builtenvironment to remain a functioning part ofan ecosystem rather than exist apart from it.

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The approach relies more upon smarter andadvanced technologies than it does onconservation and growth management and isnot to be regarded as a land use controlstrategy. LID is a balanced approach and is anadvanced, ecologically-based landdevelopment technology that seeks to betterintegrate the built environment with thenatural environment. LID principles andpractices allow the developed site to maintainits predevelopment watershed and ecologicalfunctions. LID provides technological tools toplan and engineer any type of urban site tomaintain or restore a watershed’s hydrologicand ecological functions.

The LID approach includes five basic tools:

• encourage conservation measures• promote impact minimisation techniques

such as impervious surface reduction• provide for strategic runoff timing by

slowing flow using the landscape• use an array of integrated management

practices to reduce and cleanse runoff• advocate pollution prevention measures to

reduce the introduction of pollutants to theenvironment.

LID is relatively simple and can be veryeffective, therefore the long- and short-termcosts and benefits are advantageous. Insteadof large investments in complex and costlycentralised conveyance and treatmentinfrastructure, it allows for the integration oftreatment and management measures intourban site features. The promotion ofsustainable development techniques may alsoattract financial incentives in the form of freeconsultations and application fee discounts.

2.2.3 Examples of application

2.2.3.1 SMURFF

Stormwater and urban runoff is consideredthe number one source of pollution in SantaMonica Bay, California. The Santa Monica

Urban Runoff Recycling Facility, otherwiseknown as the SMURRF, is an example of howto deal with polluted stormwater and urbanrunoff to protect coastal waters and isillustrated in Exhibit 2.2.

The project to overcome the stormwaterpollution issues was instigated by the city ofSanta Monica, which also provided fundingtogether with contributions from the city ofLos Angeles, the State Water ResourcesControl Board, Metropolitan Water District andFederal funds. The SMURFF project is the firstfacility of its kind in the US. This state-of-the-art facility treats dry weather runoff water as aresult of runoff from excessive irrigation, spills,construction sites, swimming pool draining,car washing, the washing down of pavedareas and some wet weather runoff thatcurrently discharges directly into Santa MonicaBay through storm drains. Prior to theconstruction of the facility, pollutants such asoil and animal waste or anything that finds itsway onto a surface exposed to runoff weredischarged into the bay.

An average of 2,300 cubic metres (approx500,000 gallons) per day of urban runoffgenerated in parts of the cities of SantaMonica and Los Angeles are treated byconventional and advanced treatment systemsat SMURRF. The runoff water is diverted fromthe city’s two main storm drains into SMURRFand treated to remove pollutants such as trash,sediment, oil, grease and pathogens.

Treatment processes include:

• coarse and fine screening to remove trashand debris

• dissolved air flotation to remove oil and grease

• degritting systems to remove sand and grit• micro-filtration to remove turbidity• ultra-violet radiation to kill pathogens.

Once treated, the water is safe for alllandscape irrigation and dual-plumbed

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30


Exhibit 2.2 The SMURFF unit in LA city designed to engage public interest in stormwater management

systems (that is, buildings plumbed to acceptrecycled water for the flushing of toilets) asprescribed by the California Department ofHealth Services. The treated water meets therequirements as laid down by the city of LosAngeles and the county of California and isused for highway landscaping along the SantaMonica freeway, city of Santa Monica parks,cemeteries and school grounds.

As outlined in Section 2.1.2.6, dealing withstormwater pollution in the last decade hasincluded education and the motivating ofindividuals and businesses to reduce theirsurface water runoff contributions. As part ofthe out-reach requirements, the SMURFFfacility at Santa Monica is open to the publicand has been designed with education in mind,having an elevated walkway that descendsfrom one end of the site to the other. Visitorshave a complete view of all of the equipmentand processes that are used to purify the urbanrunoff. The siting of the equipment and thetechnology used has been considered equallywith the need to make the process of runofftreatment understandable to visitors. Theequipment is arranged in sequential order andoriented towards the viewer so that any visitorscan follow the technology and the processvisually. Each piece of equipment is placed on aprominent base and raised to an appropriateviewing level. In several locations the watermoving through the system has been exposedto the open air to allow the process to beclearly seen by visitors.

2.2.3.2 Downspout disconnection

In several cities of the US that have acombined sewer network, a downspoutdisconnection programme is considered to bea key part of the effort to reduce combinedsewer overflows (CSO). This disconnectionreduces the overflow within the sewersystem, which in turn helps alleviate thepollution of rivers, lakes and the ocean.Overloading of the system can also causeflooding, particularly in basements.

Examples of this were seen in Boston,Massachusetts and Portland, Oregon. TheEnvironmental Services department inPortland, Oregon, encourages homeowners todisconnect their downspouts from the sewersystem in targeted neighbourhoods. Not alldownspouts can be safely disconnected andonly those homeowners in targeted areaswho have received written permission can bereimbursed for disconnecting.

Printed leaflets and on-line informationprovides the homeowner with informationrelating to the rationale behind the project,current targeted areas, consent applicationforms and a ‘do-it-yourself’ guide. Informationis provided on creative landscapingtechniques that can be employed to managethe runoff water safely and effectively.

The municipality will pay the homeowner todisconnect provided that the work has beenconsented and the works approved. The oneoff lump sum payment is currently around $50(approx £27) per downspout disconnected,plus an annual charge reduction. This acts asan incentive for the homeowner to participatein this scheme. The local authority will alsoundertake this work free of charge, as aconsequence the homeowner will not receivethe one-off payment.

Around 44,000 homeowners in the city ofPortland, Oregon, have disconnected theirdownspouts, which has resulted in theremoval of approximately one billion gallons(4.5 million cubic metres) from the combinedsewer system annually.

2.3 Stormwater control, operation and

maintenance

The expense of maintaining most stormwaterBMPs is relatively small compared with theoriginal construction cost. Too frequently,however, BMP maintenance is notundertaken, particularly when it is privatelyowned. Improper maintenance decreases the

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efficiency of BMPs and can also detract fromthe aesthetic value of the installation. Theoperation and maintenanceguidance/mandate within a stormwaterordinance can ensure that designs facilitateeasy maintenance and that regularmaintenance activities are completed.

The maintenance of stormwater BMPsincludes the elements of design, routinemaintenance, and inspections. Stormwaterordinance terminology regarding themaintenance of erosion control measureswould differ slightly from a sediment anderosion control ordinance owing to the short-term nature of these measures. In addition, itis important to note that elements such as theprocess of applying for a permit would beincluded in more comprehensive sedimentand erosion control or stormwater ordinances.

2.3.1 Legal issues

Many communities across the US are facingchallenges associated with natural resourcedegradation due to rapid growth anddevelopment. Local governments need tohave legal authorities in place to shapedevelopment and to protect resources. TheEPA helps local governments by providing theinformation necessary to develop effectiveresource protection ordinances.

The EPA includes model ordinances to serveas a template for those charged with makingdecisions at state or county level concerninggrowth and environmental protection. Foreach model ordinance there are several real-life examples of ordinances used by local andstate governments around the nation. Theordinances address matters that are oftenforgotten in many local codes, includingaquatic buffers, erosion and sediment control,open space development, stormwater controloperation and maintenance, illicit discharges,and post construction controls. There is also amiscellaneous category containing ordinancesthat do not fit into these categories.

In addition, there are materials that supportparticular ordinances, such as maintenanceagreements and inspection checklists.

Some important elements of effectivestormwater operation and maintenanceordinance terminology are the specification ofa specific entity responsible for long-termmaintenance and reference to regularinspection visits. The ordinance should alsoaddress design guidelines that can help easethe maintenance burden, such as theinclusion of maintenance easements.Although language that legally requiresoperation and maintenance of stormwaterBMPs is important, there might be a disjointbetween the ordinance language and whathappens ‘on the ground.’ The informationprovided in support of the ordinance, such asmaintenance agreements and inspectionchecklists, is as important as the ordinance toensure that stormwater BMPs performefficiently over time.

2.3.2 Observations on operation andmaintenance

The authority charged with issuing theNPDES permit is also automaticallyresponsible for the maintenance of thesystem, be it municipality, county or statelevel. Construction is a major factor in thesuccessful implementation of the structuresand regular inspections during thedevelopment are an important feature.Funding of the process is discussed further insection 2.3.4.

The public are also involved in themaintenance of BMPs. In Seattle, for example,the SEA streets project requires directinvolvement from the public. Although theconstruction is of a very high standard and thesystems are low maintenance with carefullyselected vegetation and plants, lowmaintenance does not mean ‘no maintenance’.

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The natural drainage systems are maintainedby the city and in this the municipalityundertake to:

• check and clean the structures periodically• maintain plants as required to ensure

effective storm drainage systemperformance

• perform other unscheduled maintenanceas required due to unforeseencircumstances such as damage fromstorms or accidents etc

• look after the underground drainage sewernetwork to cope with the natural drainagesystems.

In the majority of cases infiltration isexpected to take place within 24 hours of astorm occurring. If after three days thesystem has not drained down a maintenanceresponse is triggered from the city. The cityhas a ‘no ditch filling’ law which means thatshould a resident decide to fill in their ditch,the city authorities will return to re-excavateand replace it at the resident’s expense.

It was noticeable that there is relatively highaffluence in the areas in Seattle where the SEAstreets have been retrofitted. This also indicatesa reasonable standard of education andcommunity interest, which helps with publicengagement with environmental concerns.Maintenance processes in the heavily built-up

Los Angeles areas are considerably different.Sediment entrapment facilities are the mostused and the mission witnessed the annualcleaning of one such process.

As can be seen from the exhibits, the cleaningrequired considerable plant and manpower.Safety was clearly less of a consideration thanin the UK – notice the lack of hard hats andsafety harnesses, as well as lack of interest inthe protection of bystanders.

However, despite over-manning, this was onlyan annual operation. Hence, despite itsapparent over-use of manpower andquestionable safety procedures, one couldnot question its effectiveness or the amountof pollutants that had been removed by thedevice. In the right context therefore, this is a

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Exhibit 2.3 Maintenance and cleaning

Exhibit 2.4 Maintenance and cleaning

procedure (and use of proprietary equipment)that is appropriate and worthwhile.

The mission made several visits toorganisations with direct responsibility forboth stormwater management and themaintenance of BMPs. At times theviewpoint expressed in the office was not sokeenly observed in practice.

Whilst there are wonderful examples ofdesign, construction, maintenance andcontrol, such as in Portland, Oregon, andSeattle, there were occasions when the siteexperience did not bear out the enthusiasticoratory of the municipal officers. One suchexample was where the key points of themaintenance crews were prioritised as safety,function and aesthetics.

The location of Exhibit 2.5 has beendeliberately withheld. Note the steeplysloping sides of these ponds, making egressdifficult when any water is present in thestructure. The control structures were of poordesign and this one was blocked by leaves.There seemed little consideration for how thecontrol is cleared should it become blocked.The site is also protected by a small fencethat is very easy to climb over.

The same authority indicated that fourdrownings had occurred in the past year inponds where there had been no fences.

The optimum solution was seen to be plasticcovered chain link fences 42 inches high. Thefact that the BMP was poorly designed andconstructed and therefore necessitated afence seemed lost. The same individualscongratulated themselves on the fact thatbecause of their experience they knew moreabout the design and operation of BMPs thanthe consultants submitting designs formunicipal approval!

However, despite the negatives, one cannotcriticise the enthusiasm of the officers toimprove the environment by controllingstormwater run-off and removing pollutants. Itis important to learn from poor design andconstruction as well as good.

2.3.3 Public engagement

Public engagement was a recurring theme ofall locations visited in the US. This will befurther discussed under funding issues, butthe role of the general public in successfulimplementation of BMPs and LIDs cannot be overestimated.

The public are aware that effective control ofstormwater can be of major importance totheir lives and environment. Direct citizeninvolvement on managing boards for waterresources and drainage improvesengagement and commitment. Strong driverssuch as the high awareness of environmentalimpacts on Chesapeake Bay and itshistorically poor condition due to pollutinginputs has promoted an awareness of thefinancial implications to local livelihoods, andcan deliver support for innovative surfacewater solutions.

In the Boston area the public are aware of theneed to keep groundwater levels high. A dammaintains groundwater levels and protectsthe wooden piles that support much of thecity of Boston from drying out. This has aknock-on effect of ‘backing up’ the drainagesystems in Cambridge (Harvard) County,

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Exhibit 2.5 Example of poor maintenance

Massachusetts, and causes flooding ofbasements, which owing to the veryexpensive land costs have become convertedliving quarters. The public in Cambridge,Massachusetts, have become very supportiveof the innovative use of stormwater, as theyrealise the direct impact and consequence.

It was made clear that water qualityimprovements (of the combined seweragesystem) and innovation has led to a majoreconomic boom around the harbour (>$1 billion) and a general increase in cityproperty values.

In Seattle, community and local ‘stakeholder’adoption of stormwater facilities is a majorbuy-in and opportunity.

2.3.3.1 Getting the message across

Public facilities (such as Sea Life Centers),with special links to stormwater are verystrong vehicles for raising awareness. School

education is another example. It was evidentthat public engagement was theresponsibility of an individual within each ofthe organisations visited, the sole purpose ofwhich was to ensure that education in manyforms was effective.

There were few locations where a BMP ornatural drainage system did not have a signtelling the public exactly what it was and itspurpose. This even extended to thedevelopment of viewing platforms andwalkways around the SMURFF UVstormwater treatment plant at ‘Muscle Beach’in Los Angeles, described in Section 2.2.3.1(See Exhibit 2.6).

Professionals living in local neighbourhoodsbelieved it was their public duty to informtheir communities of any new facilities forstormwater management.

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Exhibit 2.6 Signageexplaining purposeof natural drainagesystems

2.3.4 Maintenance and adoption of

stormwater facilities in US

practice: utility types and delivery

mechanisms

Most stormwater control mechanisms arefunded from what is termed the ‘generalfund’. This can be apportioned at state, countyor municipal level. In the same way that theresponsibilities are delegated in regard toadoption and maintenance, so also are thefunding mechanisms. In the US, local taxes, inaddition to state and federal taxes, can bemade in a number of ways, such as localtaxes paid over the counter on all purchases.This varies from state to state, with highpurchase taxes in some states and none inothers. For example, Portland, Oregon, has nolocal purchase taxes and revenue is raiseddirectly from home owners and companies.

Funding for stormwater is set at a level that ismost appropriate for the successfulmanagement and delivery of the process.Whilst the above are fairly general in theapplication of funding mechanisms, thefollowing are examples of variations.

2.3.4.1 Seattle, Washington

This city has achieved an apparentappropriate balance in terms ofapportionment of responsibility forstormwater management. The stormwaterbudget is calculated directly from contributingroof area and plot size. This presumes thatthe amount of water landing on a roof isdirectly proportional to the use requirementfor stormwater disposal. Hence charges aredirectly apportioned. This seems simple toapply and equitable.

2.3.4.2 Massachusetts Water ResourceAuthority (MWRA)

MWRA in Boston has a high degree ofautonomy, but as it has to raise capital. Amajor concern is credit rating; hence it has to

be seen to be efficient and open tostakeholders. Stormwater is the responsibilityof the local communities in Massachusetts,but MWRA can design, maintain, constructand operate these. Some communities do notundertake their stormwater responsibilitieswith sufficient diligence and in cases wherethis happens MWRA will intervene.

In Boston all other utilities (than stormwater)have to pay for their own re-routing whenstorm sewer facilities are built. This indicatesthe hierarchy of the varying utilities and thepriority assigned to stormwater management.

Because of its autonomy, MWRA has beenable to consider a more integrated approachto stormwater management in the city andsurrounding area. Accurate stormwater mapsare essential for planning, and MWRA hasshown that limited investment in relation toensuring good understanding of stormwatersystems and hydraulic performance – whenwell planned and targeted – can produce bigbenefits. MWRA has backtracked from a largescale storage CSO management solution ($1.3 billion in 1993). It now prefers theprovision of a large number of smallerdispersed projects locally targeted anddelivered at much lower cost. ($835 million attoday’s prices). These solutions are seen to bemore flexible and involve new storage,stormwater disconnections and otherapproaches, even in densely populated areas.

MWRA has established sustainable successin rainfall runoff control by combining sourcecontrol, LID, in situ control and central control.It has also successfully negotiated multi-tasking with its employees to lower costs. Ithas embraced new technology and utilisesroving crews without demarcation.

2.3.4.3 Los Angeles

The city and state of Los Angeles have acombined population larger than mostcountries. The city has developed in the

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coastal plain below the mountains and coversa vast urban ‘sprawl’ with huge demographicand cultural spreads. The most endearinggeographical feature of the city (apart fromthe weather) is its beaches on the westcoast. However, the beaches are underenormous environmental strain fromstormwater runoff pollution. The stormwatercarries a high sediment load which contains avariety of gross pollutants including: largeorganic litter, smaller granular solids, heavymetals and hydrocarbons; faecal and othercoliform bacteria from human and animalactivity within the catchments.

The continuing degradation in the environmentled the population to demand a clean up(litigation) and it was decided that water qualityimprovements amounting to some $0.5 billionof expenditure were necessary. A two thirdsmajority was required to create this law and itwas carried by over 70% of the citizens byselling it as a ‘bond issue’ rather than as a newtax. The expenditure budget has been brokendown as follows:

• rivers, lakes, beaches, $250 millionbays and ocean water protection projects

• water conservation, $75 milliondrinking water and source protection

• flood water reduction, $100 millionriver and neighbourhood parks

• stormwater capture, $75 millionclean-up and re-use

$500 million

By raising this in the form of a bond, themoney is ring-fenced and ensures that noneof the funding on water quality can besiphoned off to other projects.

2.3.4.4 Construction bond

A feature of BMP and LID funding is the useof up-front construction bonds in some areasof the US, such as Baltimore County,Maryland. A bond is paid to the permittingauthority equivalent to the cost ofconstruction of the BMP to ensure that theconstruction regulations and standards arerigorously applied. If the standards are notproperly applied, the permitting authority hasthe power to retain this money to put rightany substandard work. This power ensuresthat the developer is careful duringconstruction and may also include such thingsas a tree protection policy, as in Seattle,Washington state.

2.3.4.5 Research and development (R&D)

Investment in R&D in the area of stormwatermanagement in the US appears substantialand this benefits the public domain. R&D is afederal funded initiative and there appears tobe no shortage of funding, although USEPAbudgets are subject to political whims andhence are reduced when administrations areanti-environment. Most software andstormwater manuals are freely available andare extensively peer reviewed to ensureconsistency on a national level. The modelsdeveloped are both comprehensive in scopeand detail. Of particular relevance is the‘SUSTAIN’ tool (system for urban stormwatertreatment and analysis integration) for BMPselection and cost optimisation, which isunder development by the EPA. It is expectedto become a main decision support tool forstormwater management in the US whenreleased in 2008.10

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10 Lai F. –h et al. (2003). Development of a decision-support framework for placement of BMPs in urban watersheds. In: National TMDL Science and Policy

Speciality Conference, Chicago Il. WEF.

2.3.4.6 Public engagement

The role of the public has been discussedwith regard to adoption and maintenanceissues in Section 2.3.3 and, in particular, itsrole in funding the Los Angeles stormwatermanagement programme. Public awarenessinitiatives and the public role in funding is akey aspect in stormwater management inthe US.

It is apparent that direct citizen involvement instormwater management boards improvesengagement and commitment, and thisincludes the allocation of funds. InMassachusetts local communities decideindividually if tariffs should be rising, decliningor fixed for both water and sewage. This hasresulted in communities in the MWRA areacompeting with each other to be moreefficient and water, sewage and stormwaterare locally politically-controlled functionswithin the community. Hence, politicians areseen as accountable for efficient services.

Further gearing of public engagementincentives to companies and retailers isanother way of supplementing expenditureand raising awareness (eg in tree plantingsubsidies). Promoting innovative fundingschemes also enhances awareness andengagement.

2.4 Performance and design of the

systems used

The mission visited the EPA Office ofResearch and Development, UrbanWatershed Branch in Edison, New Jersey. TheEPA staff gave a comprehensive series ofpresentations covering BMP R&D, includingswales, green roofs, design guides, BMPplacement, design tools and creek restoration(Appendix C4). Further information aboutperformance was provided by Eric Streckerand Wayne Huber in Portland, Oregon(Appendix C10).

2.4.1 Overall effectiveness for health,safety, environmental quality andamenity in the US

There are a large number of BMPs to choosefrom. The USEPA menu11 lists some 130separate BMPs. These are categorised intothe six minimum requirements, elementsfrom each of the six categories must beincluded to comply with the NPDESstormwater phase II regulations:

1 Public education and outreach2 Public involvement and participation3 Illicit discharge detection and elimination4 Construction site stormwater runoff control5 Post-construction stormwater management

in new development and redevelopment6 Pollution prevention/good housekeeping for

municipal operations.

New BMPs are continually being developedespecially in the first two areas above.

Some estimates indicate that pollutant loadreductions of 25-40% will occur whereNPDES permitted stormwater managementprogrammes are fully implemented. However,full implementation does not occureverywhere because of resource limitations.Evidence suggests that in some instancescompliance may build up gradually with time,taking a decade or so to reach 90%.

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Exhibit 2.7 EPA best management practice researchand development in New Jersey

11 USEPA (2003). National menu of best management practices for stormwater Phase II. http://cfpub.epa.gov/npdes/stormwater/swphases.cfm

Enforcement also increases compliance butrequires resources. Compliance should bebetter where there are impaired water bodiesand TMDLs are required for outfalls, withassigned maximum waste loads. Even if astormwater outfall is not subject to anNPDES permit it may still be addressed undera TMDL load allocation if the receiving waterrequires a TMDL.

Coastal zones are also subject to the coastalzone reauthorisation amendments (CZAR),Section 6217 regulations. This specifiesadditional stormwater regulations for coastalareas. For new developments the post-construction TSS load must remain at re-construction levels or at least an 80%reduction on annual TSS loads in stormwaterrunoff following completion and sitestabilisation. This is often the mainrequirement in BMP selection for coastalsites. Typically the 80% reduction can only beachieved using a treatment train of BMPs.

Of all the BMP options, only a few aresuitable for stormwater quantity control.These include the various pond options andwetlands. These are usually provided asregional control measures. Other BMPs canhelp reduce peak flows but, for example,bioretention, infiltration systems etc do notdeal very well with high volumes and thus donot provide flood protection for longer returnperiod storms. However, they are useful forreducing the erosion impacts on receivingwaters. Some systems aid groundwaterrecharge, with the BMP database showingthat vegetative filter strips and dry detentionponds can add some 30% of inflow volumesto groundwater.

Stormwater reuse is promoted in many of thedriest states. In Florida, uses include: golfcourse irrigation; toilet flushing; and industry.Retention BMPs are generally the mostuseful for these purposes.

Pollutant removal is now probably the mostimportant use for BMPs in the US. TheNPDES regulations specify pollutantreduction ‘to the maximum extentpracticable’. A lot of information is presentedabout pollutant removal efficiency of BMPs,but this is not readily transferable from onesite to another. Hence BMP selection basedon removal efficiency is not likely to produceexpected results. There are a number offactors that influence structural BMP pollutantremoval efficiency:

• active pollutant removal mechanisms, suchas sedimentation

• BMP design characteristics as selectedand used for the particular application

• influent pollutant removal properties andconcentrations, such as particle sizedistributions

• conditions within the BMP, such asdissolved oxygen levels.

Although the presentation and selection ofBMPs using percentage pollutant removal iswidely criticised, there is as yet noalternative approach, although the observedfinal effluent quality is an approach promoted as an alternative. Table 2.5illustrates the performance of thecommonest structural BMPs.

Non-structural BMPs primarily removepollutants by source reduction through betterpersonal decisions. However, theireffectiveness is difficult to assess, althoughdynamic and participatory activities willproduce better results than passive measuressuch as advertising.

The other major non-structural BMP that can bevery effective is I/I detection and reduction(Section 2.7.3). It was reported that in Waynecounty, some 1,000 kg of solids wereprevented from entering the stormwatersystem over a period of four years by I/I elimination.

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Construction site controls are essential andwell developed in the US (section 2.6). Thesetypically reduce solids inputs to thestormwater system by up to 85%.

The reliability of particular BMPs is importantwhen considering their use, as this can alsorelate to maintenance needs. Certain BMPssuch as ponds need regular cleaning in orderto maintain their performance.

Effectiveness in terms of social, health andamenity considerations will dictate whetheror not a BMP can be used and where.Important factors are:

• mosquito breeding• provision of wildlife habitats• other community acceptance factors

º safety issues

º aesthetics.

Open water bodies are the most significantfor mosquito risks and the link to West Nilevirus has made this issue more importantrecently. Under-performing infiltration systemswhere standing water is visible are typicallyvisited after 72 hours and the top soil layerreplaced to improve infiltration capacity.

Safety is a major issue and is viewed as apriority in many regulatory areas. Risk ofdrowning in open water bodies is addressed, forexample, by permanent fencing around ponds inMaryland. However, in Los Angeles city thevery large gully inlets in highways (up to 6metres long and with openings some 300 mmwide) and in use for almost a century did notappear to cause concern for drowning risks.

Many of the BMPs visited in the mission wereaesthetically attractive; however, some werenot, particularly the fenced dry and wet pondsin Maryland. In Seattle and Portland, Oregonthe SEA streets and rain gardens wereattractive, although the latter did collect litter.Aesthetic value requires maintenance if it is tobe sustained. None of the visited sites hadBMPs that in themselves provided amenityvalue, such as water sports or other recreation.

2.4.2 Examples of technologies (newand retrofit) and testing

The following sections provide examples ofthe technologies seen during the mission.There are many others available and thoseillustrated are not presented as necessarilythe best technologies.

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BMP Percentage removal

TSS TP TN NOx Metals

Dry extended detention pond 61 19 31 9 26-54

Wet retention pond 68±10 (min -33to max 99)

55±7 (12 to 91)

32±11 (-12 to 85)

34±21 (-85 to 97)

26-65 (-97 to 96)

Infiltration trench 75 60-70 55-60 – 85-90

Porous pavement 82-95 65 80-85 – 98-99

Bioretention 80 65-87 49 15-16 43-97

Sand or organic media filter 66-95 4-51 44-47 -95 to 22 34-88

Stormwater wetland 71±35 56±35 19±29 40±68 0-57

Grassed swale 38±31 (-100 to 99)

14±23 (-100 to 99)

14±41(-100 to 99)

13±31 (-100 to 99)

9-62 (-100 to 99)

Vegetated filter strip 54-84 -25 to 40 20 -27 to 20 -16 to 55

Table 2.5 Range of percentage pollutant removals using certain structural BMPs1

2.4.2.1 Bioremediation as a sustainabledrainage BMP

The mission viewed a number ofbioremediation examples during the sitevisits, principally in Baltimore, Portland,Oregon, and Seattle. These structuresincluded bio-swales, eco-roofs (green-roofs),bio-detention basins, street planters and raingardens. In many instances these wereaesthetically incorporated into the urbanlandscape. Their role and performance is notonly directed towards improving surfacewater quality; they also serve to attenuateand control the quantity of runoff.

Bioremediation is a ‘natural’ surface watercleansing method utilising the biological andbiochemical processes available from flora(fungi, plants, trees etc) to remove levels ofcontamination associated with urbanpollution, diffuse or otherwise.Bioremediation has been successfully used inthe clean up of American brownfield sites.Certain plants have the ability and toleranceto take up high concentrations of toxicchemicals, including hydrocarbons, and incertain instances processing some of thesechemicals to less toxic derivatives. The samenatural cleansing principles can be applied assource control treatment to the polluted loadof surface water runoff sources. A typicalbioswale will provide 30-80% pollutantremoval, including reductions in total

suspended solids, total phosphorous, totalnitrogen, floating trash, heavy metals,biological oxygen demand, bacteria, greases,oils and turbidity. These systems are suitablefor compliance with the CWA to cleansurface water runoff to specified TMDL levels.

2.4.2.2 Low Impact Development (LID) inBaltimore, Maryland

LID techniques were the initial focus of themission, by way of the meeting and site visitswith Baltimore County Department ofEnvironmental Protection and ResourceManagement at its Towson office. Surfacewater management has been a key issue inMaryland since the mid 1970s withcommitment at all administrative levels, soBMP technologies and public engagementissues are well advanced. The key driver forimprovement and change has beenenvironmental, with strong media pressure toclean up Chesapeake Bay.

At the LID sites visited the vast majority ofBMPs viewed were natural bioremediationstructures such as detention basins and filterstrips incorporated into landscaping. In termsof the natural BMPs viewed in Baltimore, thetechniques observed by the mission inPortland, Oregon, and Seattle may havegreater value in terms of relevance andinnovation to the UK as they were smallerscale and many were retrofitted into denseurban areas.

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Exhibit 2.8 Bioremediation

Exhibit 2.9 Bioremediation filter strip and detention basin

2.4.2.3 Bioremediation filter strip anddetention basin

Key BMP design parameters from Baltimoreclaim to use a single 1% return period designstorm, over a 24-hour duration with intensitypeaks. Freeboard for storage systems isbetween one and two feet (0.3-0.64 metres).Treating surface water quality is as importantas controlling quantity in accordance with theCWA. There was some debate with regard tothe long-term effectiveness of infiltrationtechniques and many of the BMPs werefitted with sacrificial sand filter layers (typically600 mm thick).

Sample collection during some of the NPDESMS4 phase I permits required a grab and acomposite sample to assess compliance. A grab sample was normally taken during the first 30 minutes of discharge, and a flow-weighted composite sample for the entiretime of discharge. The initial grab sample was used for the analysis of the ‘first flusheffect,’ assuming that most of the pollutantsare discharged during the first period ofrunoff. The composite sample was obtainedwith aliquots collected about every 15-20minutes for at least three hours, or until theevent ended.12

A recurring technical theme across many ofthe US meetings from the mission (Baltimore,EPA, Hydro International Conference,Professor John Sansalone), was that the firstflush theory, which presumes that themajority of pollutants are washed from urbansurfaces in the first stages of runoff, is flawedas flushes can be observed, but are notpredictable in terms of flush load or timingwithin a storm event.12 Hence, techniques forquality control should not be based on thepresumption that these flushes occur at thestart of storm events. Evidence suggests thattypically the first 5 mm of rainfall-runoff is

insignificant in terms of total pollutant loading.It was recommended that for design purposesof surface water BMPs, runoff should beevaluated not in terms of the discredited ‘first-flush’ but rather as a series of a ‘pulsed-flushprofiles’ for pollutant loading.

All natural BMPs are inspected at least onceevery three years and Baltimore County ownsand maintains the majority of the structures. Asthe mission went on to learn from the USEPAOffice of Research and Development UrbanWatershed Branch in Edison New Jersey thefollowing best practice guidelines for increaseddetention are also valuable to note:

• typical detention basin design provisionshould be a minimum six hours of storagetime for the first 0.5 inches (12 mm) of runoff

• longer retention times of 24-48 hours arerequired for the effective treatment ofsurface water runoff

• outlet controls need to be properly sized;they are typically designed for peakdischarge, but they should be installed(new build or retrofit) to slowly releasesmaller storm events that would otherwisepass through with little or no attenuation.

Exhibit 2.10 Detention basin landscaped into publicopen space

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12 Maestre, A., Pitt, R. E., Williamson D. “Nonparametric statistical tests comparing first flush with composite samples from the NPDES Phase 1 municipal

stormwater monitoring data.” Stormwater and Urban Water Systems Modeling. In: Models and Applications to Urban Water Systems, Vol. 12 (edited by W.

James). CHI. Guelph, Ontario, pp. 317-338. 2004

Another recurring theme, which was firstencountered in Baltimore, was a levy on theamount of impermeable area within theboundary of a property and contributing tothe storm drainage system – domestic,commercial or industrial. As surface waterrunoff from infill and micro development isbecoming a significant issue in the UK, thisimpermeable area charge has great potential.With the levy of a surface water charge thereis an opportunity to offer a discount forreducing the amount of impermeable areaand consequently the amount of surfacewater runoff being positively drained.

Exhibit 2.11 The importance of trees

Some of Maryland’s ‘soft’ BMP techniques areworthy of note. For example, the importance offlora for bioremediation and mature trees forevapotranspiration was another crucial BMPtheme repeated in a number of places.Baltimore has successfully employed thefollowing two techniques. The first isestablishing protected ‘forest buffer’ zones,especially around creeks where water quality isimproved. Maryland itself has a mandatoryforest conservation act and restoration hasbeen very successful leading to increasedforestation and buffer zones. The second wasthe ‘Growing Home Campaign’ that affordedhome owners a $5 (£3) tree voucher from thecounty and fostered greater public awareness.This initiative was backed by a further $5 (£3)discount from the retailer, leaving the

homeowner to find the $15 (£8) shortfall for atree. The campaign was a great success and itis worth noting that the county viewed theinitiative as raising $20 (£11) capital expenditureper dwelling and not spending $5 (£3).

A follow-up meeting at the Center forWatershed Protection in Ellicott City served tounderline many of the technology messagesreceived from the previous day with thecounty. The value and contribution of treeswithin a watershed was reiterated as avaluable process in the treatment train ofrainfall, interception, evapotranspiration,infiltration (refer to the centre’s ‘UrbanWatershed Forestry Manual, Methods forIncreasing Forest Cover in a Watershed). Interms of BMP design for infiltrationtechniques, the following were recommended:

• use a conservative infiltration rate• infiltrate shallow depths in small areas

close to source• understand future land use• control construction operations, both in

terms of residual compaction and poorquality control

• use two levels of pre-treatment• do not use a bottom liner• restrict the amount of impermeable area

draining to an infiltration device to limitedrealistic levels

• set a realistic design life in accordancewith each structure type.

2.4.2.4 ‘Smart sponge’ advancedtechnology in Norwalk, Connecticut

‘Smart sponge’ is a proprietary advancedpolymer technology that removes pollutantsfrom surface water runoff and holds potentialfor use in the UK as the WFD is implementedand the water industry strives to meet the2015 water quality requirements. Patented byAbTech Industries based in Scottsdale,Arizona, the technology claims to have aunique molecular structure based oninnovative polymer technologies that are

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chemically selective to hydrocarbons.Traditional absorbent technology whensaturated often leaks oils and other pollutantsback into the water if mishandled. However,this technology fully encapsulates recoveredhydrocarbons, resulting in a substantially moreeffective response that prevents leaching.

There are other similar advanced polymerproducts being marketed in the US, however,smart sponge is claimed to be unique in thatits porous structure allows water to passthrough it and not simply pass over thesurface area. This porosity affords a greaterlevel of performance towards contaminantcapture. It is also capable of removing oil fromwater, thereby successfully removing sheen.In addition, it remains buoyant in calm oragitated water, permitting it to remain in placeuntil fully saturated and resulting in no wastedproduct. Once oil is absorbed, the pollutantsare transformed into a stable solid, providing a‘closed-loop’ solution to water pollution.

As this technology has evolved, a ‘smartsponge plus’ has been developed that isclaimed to incorporate an anti-microbial agentstructure that captures harmful bacteria(including Escherichia coli and otherpathogens) frequently found in stormwaterand other water streams. In this product ananti-microbial agent is bound to theproprietary polymers, thereby modifying theirsurface and adding microbiostatic featureswhile maintaining their oil absorbingcapabilities. A patent is pending on thisproduct in the US. The presence of bacteria insurface water runoff is a serious problem inthe US that poses significant health risks andincreasingly results in the contamination ofwater bodies. In Europe and the UK, bathingwaters are subject to strict bacteriologicalstandards and such removal techniques maybe useful. Water quality standards for bacteriaare very strictly monitored in most coastalareas and small increases in bacteria countscan trigger US beach closures.

Exhibit 2.12 AbTech’s ‘Smart sponge’ demonstration tothe mission

AbTech believes that this breakthrough ishighly significant in the surface water market.However, in the US there is a tendency formanufacturers to claim that their stormwatercontrol products can solve a wide variety ofpollution problems. Independent third partyresearch and testing to accredit performancehas traditionally been undertaken in the US byNSF International as part of stormwatertreatment technology verification testing(ETV), but funding for this is a significantburden on some smaller companies.Nonetheless, independent verification ofperformance is an advantage to all newtechnologies and one approach is to useeffective R&D from studies in the field, suchas the smart sponge performance evaluationsunderway in Norwalk and Los Angelesdescribed below. With the impending WFD, UK industry should be looking toemulate this to evaluate the long-termviability of such technologies.

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Smart sponge advanced polymer technologycan be pre-installed or retrofitted into a rangeof applications. These are usually non-mechanical in the US, although theinstallation is also used in a range of waterindustry proprietary products. The followingapplications may have UK potential:

• ‘ultra-urban filter’ is a proprietary insertfitted into urban catchpits (basins or gullies)that serve to both collect trash/sedimentand filter surface water runoff. Thisapplication may not be feasible in the UK,as our catchpits are much smaller thanthose found in the US. A single point, end-of-pipe application, perhaps coupled withanother proprietary product, may well bethe solution for the UK

• ‘passive skimmers’ remove pollutants andoil sheen in catch basins, sumps andproprietary separators

• ‘line skimmers’ encapsulate hydrocarbonsand oil sheen in non-confined water flowssuch as ponds, streams, clarifying wellsand marinas

• ‘bilge skimmers’ control hydrocarboncontamination that occurs from the normaloperation of boats and marinas. As the UKinland waterways industry is viewed as akey WFD stakeholder, such technologymay be very applicable to itsenvironmental targets.

Exhibit 2.13 Sustainable drainage BMPs protecting theNorwalk River

The mission visited the Norwalk storm drainfilter project. The project is funded via an EPAgrant of $397,000 (£215,000) with some localadditional support. It is a collaborative projectbetween the EPA, City of Norwalk, AbTechIndustries, Longo & Longo and The LongIsland Soundkeeper (an environmentaleducation and advocacy organisation). Otherproject partners are the Maritime Aquarium(one of the largest attractions in Connecticut)and the Norwalk River Watershed Initiative(since 1995 a unique partnership of sevenwatershed towns to address local waterquality). The key project driver is to improvethe quality of surface water draining from thewatershed and into the Norwalk River,Norwalk Harbor and Long Island Sound.

The mission team was shown an example ofthe AbTech trash baskets and smart spongeultra-urban filter inserts installed into the 275 storm drain catchpits (gullies) in thewatershed, adjacent to the Aquarium anddraining out to the Norwalk River; the basketinsert was raised onto the sidewalk forinspection. All of the other catchpits in thevicinity also contained the AbTech dual filtersystem. This is a dual filter system becausethe proprietary collar and basket collects alltrash entering the catchpit, while the smartsponge insert filters the surface water runoff,permanently adsorbing harmful pollutants.

Exhibit 2.14 AbTech’s ultra-urban catchpit insert

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The 275 unit installation is claimed to be aunique project involving private and publicbodies, including the local aquarium, whichserves to incorporate considerable publicengagement. It has also included contrastingcatchments without the filtered outlets forcomparison. There is a 12-month monitoringperiod to assess improvement in runoff quality,with a target removal of hydrocarbons, a rangeof bacteria (including Escherichia coli), totalsuspended solids, heavy metals and trash. Ofthe 275 trash screen collectors cleaned andweighed, 10 are taken away to be analysed forcontaminants; it is estimated that there will be50 lbs (23 kg) of trash per drain per annum.Locally, dredging in the Norwalk River has asignificant cost associated with sludgedisposal, so a reduction in dredged volumes iseconomically valuable. The catchment hassome 84,000 people and 27 square miles (70 square kilometres). Modification costs areunder $1,000 (£540) per catchpit in total. An effective and proactive maintenanceprogramme will always be a key issue; theseinlets should be cleaned once a year, butpotentially once in three years is consideredmore likely, which may compromise thesystem performance.

The EPA has included AbTech’s ultra-urbanfilter product incorporating smart spongetechnology in the BMP listing under federalenvironmental guidelines that apply to localand state legislators.

The spent smart sponge is either disposed ofto landfill or burnt as a fuel source in the US. Apotential problem for UK application is theclassification of the spent product; it is likely tobe classified as special waste, making UKdisposal costs potentially prohibitive. Inaddition, with tighter UK emissions control,incineration may not be a feasible option.Coupled with the lack of third partyperformance accreditation, there are seeminglyintractable barriers to UK implementation,despite the technology having great potentialfor improving surface water runoff quality.

Smart sponge has been available in the UKfor sometime through licence holders SourceControl Systems. The industry’s keystakeholders may need to collectively adopt apioneering, pragmatic approach if the UK is torealise the benefits that these advancedtechnologies may yield. During theGeoSyntec workshop in Portland, Oregon(Strecker and Huber), it was stated that thesetypes of proprietary products are expected to‘do-all’ and that isn’t really fair; because thereis no ‘silver bullet’, but as a component in aneffective treatment train, they do have a keyrole to play.

2.4.2.5 Up-Flo filter technology inPortland, Maine

The mission visited a stormwater conferencehosted at the American headquarters of UKbased company Hydro International, inPortland, Maine. Hydro offers innovativeproducts for the cost effective control andtreatment of stormwater and wastewater,and the visit included a tour of its PortlandR&D and testing facilities specifically tocoincide with this mission.

The main focus of the Hydro visit was its Up-Flo filter, which is claimed to be a novelsolution for managing pollutant loaded surfacewater runoff. This proprietary product ismarketed as the first high-rate, modular,upflow filtration system and bespoke designto meet stringent treatment regulations. Thecompact surface water treatment traincapabilities were developed through extensivefull-scale laboratory and field-testing, CFDmodelling, and more than 30 years of stormwater treatment research byHydro. The unique modular design – smallfootprint, upward flow path and drain-downmechanism – distinguish the Up-Flo filter fromconventional radial or down-flow stormwaterfiltration devices. The system adopts atreatment train concept by integrating highlyefficient screening, sedimentation andfiltration technologies to eliminate the need for

46


multiple treatment devices. The companyclaims that this treatment train design,together with its high treatment capacity andeasily retrofitted components make the Up-Flofilter the most economic filtration deviceavailable for stormwater treatment.

Exhibit 2.15 Hydro’s Up-Flo filter during field pilottesting and verification

Hydro’s laboratory and field data from pilotstudies have indicated that the Up-Flo filterhas a total suspended solids (TSS) removalefficiency of over 90%. These data arecurrently being independently confirmedunder the protocols of the USEPAEnvironmental Technology VerificationProgram. The applications for removing grossdebris, fine sediments, metals, organics andnutrients from stormwater runoff areimmediate and widespread. A highly efficient,highly adaptable and low maintenanceproprietary BMP such as the Up-Flo filtercould potentially provide significant levels ofeconomic surface water treatment both in theUS and in the UK to help meet the stringentwater quality requirements of the WFD.

2.4.2.6 The green streets of Portland,Oregon

Portland’s green streets were very much a‘watershed’ destination for the mission in

terms of evaluating the implementation of LID.The City of Portland, Oregon, receives anaverage annual rainfall of 37 inches (940 mm)that generates some 10 billion gallons (~45 billion litres) of urban surface water runoffper year. Not only does this runoff lift and washpollutants from a raft of urban impermeablesurfaces, but it also engulfs the sewerageinfrastructure, increasing the number of CSOspills. In fact, the detrimental environmentalimpact on the local Willamette River fromfrequent CSO spills in the past wasconsiderable. This has been a key local driverfor not only extensive ‘big pipe’ sewerageimprovements, but also the widespreadimplementation of contemporary sustainabledrainage techniques and significant publicengagement. This LID is known locally as‘green streets.’ By encompassing these naturalsustainable drainage techniques, theenvironmental message from the city ofPortland, Oregon, remains: ’working for cleanrivers, healthy watersheds and a liveablesustainable community.’

Exhibit 2.16 An impressively vegetated green streeteco-roof

Working from the highest level down, thegreen streets’ BMPs include vegetated roofsystems in the form of eco-roofs and roofgardens. Utilising the benefits ofbioremediation, an eco-roof is a compositestructure comprising proprietarywaterproofing overlaid with an optionaldrainage layer, a natural layer (growing

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medium) and finished with a vegetative cover.The vegetation is not just limited to grass,which seems to be a common UKmisconception. The mission visited exampleswhich utilised a range of plant species thatwere not only very performance effective, butwere also aesthetically pleasing. Typically eco-roofs may be planted with up to 10 differentspecies for performance and optimumsurvivability, with variety also helping tomaintain aesthetically pleasing, continualblooming flora as long as possible.

Exhibit 2.17 Various species of plants aids survivabilityand enhances aesthetics

As well as bioremediation, eco-roofs will alsocool roof temperatures during summer (andhence reduce air conditioning usage), insulateduring winter (reducing heating costs), and are

effective evapotranspiration devices; theperformance range is 10-100% precipitationremoval (from runoff) dependent uponantecedent conditions and seasonal changes.This is a BMP often mooted in the UK butrarely used because of concerns over cost,longevity, roof maintenance etc, some of whichmay be unfounded. Maybe an economicinducement needs to be introduced. Forexample in Portland, Oregon, if a green roof isconstructed on a commercial building, localplanning conditions may permit an additionalfloor (storey) to be added. The use andperformance of vegetated roof systems oncommercial buildings in Portland, Oregon,emphasises the potential of the technique as akey link in the surface water management train.

Downpipe disconnection is a very simpleBMP technique, either as new build orretrofit, and has been around as a drainageoption for quite a while. While there are manyolder UK downpipes connected to a sewer,the vast majority of these are connected to abespoke surface water sewer. However, inmany instances these downpipes connect toa combined system, which in turn leads toincreased CSO spills downstream. Surfacewater sewer connected downpipes addpollutant loading and flood risk that stressesreceiving water systems and will need to bebetter controlled to meet the requirements ofthe WFD. Strategic downpipe disconnectionis a valid BMP that reduces the amount ofsurface water runoff positively drained, andexamples were seen in Boston,Massachusetts and Portland, Oregon.

With a surface water charging system basedon the amount of impermeable area connectedto the drains, the city of Portland, Oregon,offers a discounting system for a reduction ofthis impermeable area through retrofitdownpipe disconnection of about $50 (£27) perdownpipe, a one off payment plus an annualreduction in charges. Homeowners are evenencouraged to ‘do-it-yourself’, and there issignificant public engagement to educate and

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get the message across in a comprehensiblemanner. This includes a number of clear andinformative leaflets and brochures that not onlyexplain how to disconnect, but also promotethe benefits, not only for the wider Portlandenvironment, but also to the property itself.Indeed, many residents proudly displaydownpipe disconnection message boards intheir gardens and it is clear that because ofinformative promotional marketing many of thegeneral public have subscribed to this initiativeand ‘disconnected’.

With over 47,000 properties either completelyor partially disconnected in Portland, Oregon,the reduction of surface water flows reachingthe sewerage network is substantial, withpositive environmental benefits for theWillamette River. This BMP also has great UKpotential, either for new build or retrofit.Nonetheless, surface water overland flowsneed to be controlled, for example, in terms

of freezing in pedestrian areas. With a climatenot too dissimilar to the UK’s, Portland,Oregon, has managed this effectively. Thestormwater source control systems weredesigned for two year return period storms,with excess flows passing into the mainsewer network. These systems were alsotested using a fire hydrant up to an equivalentof 25 year event, with a volume reduction of82% and 81% in peak flow.

The City of Portland, Oregon, is very proud ofits ‘green streets’ and rightly so. Owing to anunderstanding of the detrimentalenvironmental effects of surface water as aresult of runoff pollutants and CSO spills,Portland is constructing ‘sustainable streets’around the city to mitigate the effects. Greenstreets use BMPs to mimic the natural siteconditions by managing surface water runoffin a sustainable manner in terms of bothquality and quantity. The BMPs used includeporous pavings, bio-swales, bio-detentionbasins, street planters, rain gardens and areall aesthetically incorporated into the urbanlandscape. In terms of BMP performancetowards controlling surface water runoffquantity, these utilise attenuation, infiltrationand evapotranspiration. In terms of improvingrunoff quality the processes includebioremediation and natural filtration. There is astrong apparent aesthetic value of suchlandscape in the urban environment.

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Exhibit 2.18 A rainwater downpipe draining to an openlandscaped surface water box

Exhibit 2.19 Downpipe disconnection is simple, costeffective and it works

Exhibit 2.20 A green streets planter incorporated intothe urban landscape

There is a comprehensive public engagementand marketing campaign towards educationassociated with the green streets project.There is even a ‘stormwater cycling’ tour mapavailable, where cyclists are given asuggested route to visit a portfolio of localBMPs including eco-roofs, bio-swales,planters, rain gardens and ‘naturescaping’(landscaping with native plants that requireless water and no fertilisers or pesticides). A well marketed example of a successfulgreen street is NE Siskiyou; traffic calmingkerb extensions into the carriageway (toreduce the street to one lane at one end) areinfilled with soft landscaping and convertedinto mini bio-detention basins for controlledquantity and improved quality of surfacewater runoff. The street runoff enters theplanter via gaps in the kerbs and is attenuatedand naturally treated before infiltrating orevaporating; there is no positive sewerconnection, as a key driver is to reduce flowsinto a nearby combined sewer. Costing only areported $15,000 (£8,100) to construct, the

long term maintenance issues were resolvedas a result of positive public engagement;local residents maintaining the planters asthey add amenity and economic value to thegreen street they live in. There is a clearlesson to be learned for the UK from this USsuccess story.

Exhibit 2.21 An inlet to the street planter and noteintegration with pavement

2.4.2.7 SEA streets in Seattle, Washington

The Seattle street edge alternatives (SEA)streets were a similar use of BMPtechnologies to achieve LID to those seen inPortland, Oregon. The SEA streets’technologies include bio-swales, bio-detentionbasins, street planters, rain gardens andporous pavements, and are aestheticallyincorporated into the urban landscape. Theirrole and performance is not only directedtowards improving surface water quality; theyalso serve to attenuate and control thequantity of runoff. The main drivers for thesustainable drainage approach are to improvethe quality of the Puget Sound, Elliot Bay andSeattle’s many creeks by reducing thenumber of CSO spills and improving theoverall quality of surface water runoff.

With an average annual rainfall of 39 inches(990 mm) and a climate not dissimilar to theUK’s, the application of BMPs in Seattle heldgreat interest for the mission. One of the keyreasons for the terminology ‘street edgealternatives’ and a marked difference with

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Portland, Oregon’s green streets, is that theseBMPs are not only designed to drain thehighway and pavement, but the whole urbansub-catchment behind it, including the dwelling.This means that while Seattle does not havesuch a sizeable downpipe disconnectionprogramme as Portland, Oregon’s (neither doesit have a surface water charge based onimpermeable area; although it is beingconsidered), it is a key BMP. Many of theresidential downpipes are not connected into abelow ground system from new, and simplydrain to ground, or overland to the street edgeBMP during high levels of precipitation.Downpipe disconnection is also undertaken asa retrofit on combined sewers when a newsurface water sewer is constructed.

Exhibit 2.22 A SEA street bio-swale edged withporous road and pavement

The mission visited two SEA street sites; thefirst was the High Point new-builddevelopment employing an extensive use ofbio-swales, traditional (grass lined) swales,porous paving and disconnected downpipes.Interesting permanent signage informed:‘Natural Drainage. Natural plants and grasseson gently sloped parkways cleanse rainwaterfrom streets and sidewalks.’ With the quantity

and quality source control largely managed atthe street edge in the surface watermanagement train, site control was providedin the form of a balancing pond, as each trainof swales had a high level overflow system toa below ground surface water sewer. Fromthe High Point balancing pond the controlledand cleansed outflow drains to theLongfellow Creek. As with the majority of USdevelopments seen during the mission, thecompleted High Point developmentpermissible surface water discharge was theequivalent pre-development greenfield rate.

Once again, the importance of mature treesto the general environment and the surfacewater management train were evident inSeattle. This included ‘tree protection fences’that were effective exclusion zones for thecritical root zone around any mature trees onconstruction sites. The signage on the fencingalso carried an appraised tree value as awarning of a resultant fine should the tree bedamaged. These valuations were always inthe $1,000s (£550+). Another very importantconstruction issue that was being effectivelymanaged at High Point was silt control ofexposed soil areas. This can be a majorsource of pollution during precipitation if notcontrolled, as heavy downstream siltation canoccur as a consequence. Mitigation measuresobserved included covering exposed soilareas between construction activities andblocking inlets and outlets to prevent themovement of silt.

The second site at the Broadview Green Gridwas a well established 15-block housingdevelopment example of SEA streets. Itshowed no signs of redundancy as a result ofpoor maintenance, despite the majority of theBMPs being street edge bio-swales, althoughthe Seattle Public Utility (SPU) does carry outregular light maintenance and inspection. Thewhole SEA streets catchment, includingViewlands and Carkeek Cascades, drains tothe nearby Piper’s Creek. While each residentis not compelled to maintain their street edge

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BMP (although they cannot infill or remove),the majority do and have turned them intovery aesthetically pleasing landscapefeatures. Again, the importance of publicengagement and the education process wasclear. Due to local health concerns regardingmosquito breeding in still waters, any streetedge BMP that does not drain-down withinthree days (there is a five day breeding cyclefor mosquitoes), is excavated and thefiltration layer replaced.

Exhibit 2.24 A well established SEA streets landscape;drainage BMPs perfectly integrated

Part of the success of SEA streets can becredited to public engagement and

awareness campaigns. For example, the SPUCreek Steward Program seeks communityvolunteers to become stewards for the careand upkeep of the local creek. Whilsteducating the community with the benefits tothe environment from healthy river andenvironmental systems, this also includes theimpact of surface water runoff from localhouses and businesses within the catchmentand promotes changes that can improve thequality of water draining from a property.Established Creek Stewards can even applyfor city of Seattle grants to further improvethe local watershed.

Exhibit 2.25 A typical bio-swale located in a residentialgarden

2.4.2.8 Application of proprietarytechniques in Los Angeles,California

The city of Los Angeles not only has aproblem with the quality of surface waterrunoff, but at times also experiences majorimpacts regarding trash pollution on itsjustifiably prized beaches. Whenever there issignificant rainfall the volume of trash that iswashed into the sea via the Los Angeles

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Exhibit 2.23 A familiar grass lined bio-swale

River (which has a daily TMDL) is substantial.Much of this trash is subsequently washedonto the resort and highly used recreationalbeaches, which can result in closures forhealth and safety precaution. As well beingunsightly and a significant polluter, trash-induced beach closures impact upon thetourist industry and hence the local economy.The mission visited two sites in Santa Monicawhere proprietary techniques are beingimplemented to address the problem.

Exhibit 2.26 The mission visiting the AbTech LosAngeles field study

‘The city of Los Angeles field study on smartsponge,’ is in the Santa Monica Bay area andincorporates the advanced polymertechnology discussed in Section 2.4.2.4.Essentially the same reasoning for thetechnology and a similar application to theNorwalk project, there is a greater emphasisin LA on the capture of trash. A trial fieldstudy, fully funded by AbTech Industries, isbeing undertaken in collaboration with thecity of Los Angeles (CLA). The surface waterdischarges into Santa Monica Bay, which hasgradually been cleaned up since the early1980s through the CWA and strongenvironmental groups (litigation) providingpublic engagement, including the SantaMonica Baykeeper and Heal the Bay.

Exhibit 2.27 A line of ultra-urban filter inserts in an LAcatchpit

The mission team was shown examples ofthe trash baskets and smart sponge ultra-urban filter inserts installed into 80 stormdrain catchpits (gullies) in the watershedaround Thornton Avenue and draining toSanta Monica Bay. CLA officials accompaniedthe mission during the visit and confirmedthat independent testing was being carriedout to verify the performance of the units.The results from this trial will be available inaround twelve months, althoughunfortunately they will not be published andwill be used only internally for CLA purposes.Income for the Bay clean-up was confirmedas bond funds paid for by property taxes,with an average estimated tax increase on a$350,000 (£190,000) home of $35/year(£19/year) for a period of 24 years. Theexpenditure breakdown is shown in Section2.3.4.3. Project funds can be used for projectplanning, design, advertisement, bid andaward, construction, constructionmanagement and inspection. There are alsobusiness improvement districts (BID) wherecompanies are eligible for tax relief to assistin the clean-up.

Another proprietary technique demonstratedin Santa Monica was the CDS Technologies‘continuous deflective separationhydrodynamic separator’ (CDS unit), installedand maintained by the city of Los Angeles.These separators can be installed in-line oroff-line, depending on the hydraulics, and canalso be end-of-pipe solutions. The CDS unit

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was installed on the main storm drain withinone chamber and the configuration meetsmultiple engineering objectives by combiningboth treatment and bypass capabilities in onestructure. By utilising the CDS patentedscreening technology which is claimed to benon-blocking, the unit ensures removal ofboth fine and suspended solids along with oil,grease, trash and debris. The sump is animportant design feature of the CDS unit, asthe sumps prevent scour because depositedmaterial is not stored within the treatmentflow path.

The entrapment of hydrocarbons within theunit is effected by a secondary technology;advanced polymers similar to the AbTechproduct range. With a relatively smallfootprint, this system can be incorporatedinto new build projects or retrofitted intoexisting stormwater collection systems. Thereare no moving parts to maintain or replaceand the unit requires cleaning out byemptying at least once a year, which willrequire plant such as a crane and jetvac.

The conclusions and observations drawnfrom this part of the mission, from the

Norwalk demonstration site and HydroInternational visit are that proprietarytechniques have their place, but thesesystems require independent accreditation tobe widely accepted and they should not beexpected to perform too many ‘multi-tasks’.

There did appear to be mixed approaches topublic engagement in the places visited. Forexample, trying to influence behaviour for litterand pollutant sources in parts of Los Angeles.There was some evidence of this withwarning signage well distributed around theneighbourhood. However, the significantlyhigh number of homeless ‘street-dwellers’ inthe city exacerbated the source of the trashproblem due to bin raking. Also, the city onlyrequires commercial areas to have trash bins,which means they are noticeably absentelsewhere. An effective method of sourcecontrol to reduce trash could be to providemore bins on the streets and engage thepublic in using them responsibly. There werebetter examples, such as the SMURFF project(see Section 2.2.3.1) and the plebiscite for thestormwater bond. Efforts at greater publicengagement with stormwater managementmay yield further improvements.

2.5 Design and selection of systems

Few watershed management practicessimultaneously reduce pollutant loads,conserve natural areas, save money andincrease property values. Fortunately, suchpractices have been developed. By designingand selecting the best stormwatermanagement techniques that suit the siteand environmental characteristics, the overallsite design aims can be achieved through theimplementation of appropriate BMPs, LIDsand traditional piped drainage methods.

The design manuals and guidancedemonstrated during the mission varied incontent, style, level of guidance or specificcriteria to be achieved. A brief summary ofthe manuals that were encountered during

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Exhibit 2.28 Essential cyclic maintenance on a CDSTechnologies installation; removing LA’s trash

the visits is provided in the followingsections. Overall, the Center for WatershedProtection provided the most comprehensiveset of resources for stormwater managementplanning, design and delivery.

2.5.1 Center for Watershed Protection,Ellicott City

The Center for Watershed Protection (CWP)provides a range of resources relating todesign. The development of BMPs andguidance for design and use by the centrehave assisted municipalities in meeting theEPA requirements to minimise stormwaterpollution entering water bodies by reviewingexisting codes and the development of newmanuals and best practice guidance.Stormwater management is an essential partof the work undertaken by the centre since itis recognised that untreated watersdischarging to the environment present oneof the greatest threats to water quality.

The CWP provides local authorities,environmental groups and watershedorganisations around the country with thetechnical skills to help protect and restorerivers, streams and lakes. This is done via amulti-disciplinary strategy to watershedprotection, which includes conductingresearch, developing watershed managementpractices, encouraging watershed planningand implementation, fostering learning, andbuilding the capacity of local watershedorganisations. The CWP website hasresources for the drainage engineer andprovides an abundance of informationregarding not only design criteria, but alsorelating to NPDES.

Whilst at the CWP a meeting took place withNeil Weinstein from the Low ImpactDevelopment Center. He has recentlyproduced a disconnection guide, published byWERF/IWA.13

2.5.1.1 Urban sub-watershed restorationmanual (http://www.cwp.org)

This composite manual provides a frameworkfor small urban watershed restoration,comprising 11 individual manuals that includeassessment methods and design tools forriparian and upland watershed restoration.

Exhibit 2.29 Examples of guidance from CWP manualfor urban sub-watershed restoration manual

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13 Weinstein N. et al (2006). Decentralized Stormwater Controls for Urban Retrofit and Combined Sewer Overflow

The Low Impact Development Center, Inc. MD 20705, USA. IWA Publishing. ISBN 1-84339-748-x

2.5.2 Baltimore County, Maryland(http://www.mde.state.md.us)

The CWP features in the design standardsimposed by Baltimore County as it helped thestate to write the stormwater design manualcurrently in use.

Maryland has a comprehensive stormwaterdesign manual available on the internet. Thebasic principle of the manual relates to theexperience that the state has gained sincethe 1980s. Title 4, subtitle 2 of theEnvironment Article Annotated Code ofMaryland states that ‘…the management ofstormwater runoff is necessary to reducestream channel erosion, pollution, siltationand sedimentation and local flooding, all ofwhich have an adverse impact on the waterand land resources of Maryland.’ Earlyprogrammes focused on addressing thisarticle primarily by controlling runoff increasesand mitigating water quality degradationassociated with new development.

The counties and municipalities in Marylandhave been responsible for the administrationof effective stormwater managementprogrammes that ‘…maintain afterdevelopment, as nearly as possible thepredevelopment characteristics…’ Thelocalities have performed well in establishingMaryland as a national leader in stormwatermanagement technology. Maryland hasexperience of tens of thousands of BMPsthat have been constructed to achieve therequirements of the article mandate. It isalso fortunate as it has a relatively wealthy community.

However, the experience gained sinceMaryland’s stormwater statute was enactedhas allowed it to identify necessaryimprovements and revealed a need to refocusthe approach to fulfil the original intent of thisessential water pollution control programme.Increased emphasis on water quality,resource protection needs, increased BMP

maintenance costs, and identifiedshortcomings in Maryland’s programme haveall contributed to basic philosophical changesregarding stormwater management. Theupdated ‘Maryland stormwater designmanual’ was produced in an effort toincorporate the significant experiences gainedby the state’s stormwater community andaccommodates much needed improvementsfor managing urban runoff.

The design standards and environmentalincentives provided in the manual have beendeveloped with the aim of producing bettermethods and advancing the science ofmanaging stormwater by relying less onsingle BMPs for all development projects andmore on mimicking existing hydrologythrough total site design policies. This issimilar to the current philosophy in the UKwhere the ‘treatment train’ approach isfrequently recommended. Additionally, thedesign standards have been developed toensure that inherent philosophical changeshould produce smaller, less obtrusivefacilities that are more aesthetic and lessburdensome on those responsible for long-term maintenance and performance.

The main purpose of the manual is threefold:

• to protect the waters of the state fromadverse impacts of urban stormwater runoff

• to provide design guidance on the mosteffective structural and non-structuralBMPs for development sites

• to improve the quality of BMPs that areconstructed in the state, specifically withregard to performance, longevity, safety,ease of maintenance, communityacceptance and environmental benefit.

The ‘general performance standards’ outlinedin the manual specify criteria used to createrunoff control options that would performequally well. The BMPs contained in themanual are by no means exclusive. The state

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of Maryland actively encourages thedevelopment of innovative practices that meetthe intent of Maryland’s stormwatermanagement law and can perform accordingto the standards in the design manual.

One interesting fact that is in contrast to thecurrent UK philosophy concerns theconsideration of retrofit on redevelopment/regeneration of brownfield sites. The state hasa policy to actively encourage theredevelopment of brownfield land. Whilecertainly recommending the BMPs listedwithin the manual, it is emphasised that theseBMPs may not be appropriate forredevelopment areas where site size isconstrained, and existing infrastructureprevents the use of conventional BMPtechnology. Therefore, redevelopment projectsare not necessarily required to meet thedesign standards and performance criteriaestablished in the manual.

The state of Maryland has developed 14 performance standards that must be met atdevelopment sites to prevent adverse impactsof stormwater runoff. These standards apply toany construction activity disturbing 5,000 ormore square feet (465 square metres) of earth.However, the following development activitiesare exempt from these performance standardsin Maryland:

• additions or modifications to existing singlefamily structures

• developments that do not disturb morethan 5,000 square feet (465 squaremetres) of land

• agricultural land management activities.

The following performance standards areoutlined in the manual and must beaddressed at all sites where stormwatermanagement is required:

• standard no. 1 site designs shall minimisethe generation of stormwater andmaximise pervious areas for stormwatertreatment

• standard no. 2 stormwater runoffgenerated from development anddischarged directly into a jurisdictionalwetland or waters of the state of Marylandshall be adequately treated

• standard no. 3 annual groundwaterrecharge rates shall be maintained bypromoting infiltration through the use ofstructural and non-structural methods. At aminimum, the annual recharge from post-development site conditions shall mimicthe annual recharge from pre-developmentsite conditions

• standard no. 4 water quality managementshall be provided through the use ofstructural and/or non-structural practices

• standard no. 5 structural BMPs used fornew development shall be designed toremove 80% of the average annual postdevelopment total suspended solids load(TSS) and 40% of the average annual post-development total phosphorous load (TP).It is presumed that a BMP complies withthis performance standard if it is:

º sized to capture the prescribed waterquality volume (WQv)

º designed according to the specificperformance criteria outlined in this manual

º constructed properly

º maintained regularly• standard no. 6 on the eastern shore (a

specific area of the state of Maryland), thepost development peak discharge rate shallnot exceed the pre-development peakdischarge rate for the two-year frequencystorm event. On the western shore, localauthorities may require that the post-development ten-year peak discharge doesnot exceed the pre-development peakdischarge if the channel protection storagevolume (Cpv) is provided (see standard No. 7). In addition, safe conveyance of the100-year storm event through stormwatermanagement practices shall be provided

• standard no. 7 to protect stream channelsfrom degradation, Cpv shall be provided by 12-24 hours of extended detention storagefor the one-year storm event. Cpv shall not

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be provided on the eastern shore unless theappropriate approval authority deems it isnecessary on a case-by-case basis

• standard no. 8 stormwater discharges to critical areas with sensitive resources egcold water fisheries, shellfish beds,swimming beaches, recharge areas, watersupply reservoirs, Chesapeake Bay CriticalArea may be subject to additionalperformance criteria or may need to utiliseor restrict certain BMPs

• standard no. 9 all BMPs shall have anenforceable operation and maintenanceagreement to ensure the system functionsas designed

• standard no. 10 every BMP shall have an acceptable form of water quality pre-treatment

• standard no. 11 redevelopment, defined asany construction, alteration or improvementexceeding 5,000 square feet (465 squaremetres) of land disturbance on sites whereexisting land use is commercial, industrial,institutional or multi-family residential, isgoverned by special stormwater sizingcriteria depending on the amount ofincrease or decrease in impervious areacreated by the redevelopment

• standard no. 12 certain industrial sites arerequired to prepare and implement astormwater pollution prevention plan andfile a notice of intent (NOI) under theprovisions of Maryland’s stormwaterNPDES general permit. The requirementsfor preparing and implementing astormwater pollution prevention plan aredescribed in the general discharge permitavailable from MDE and guidance can befound in the USEPA document entitled,‘Stormwater Management for IndustrialActivities, Developing Pollution PreventionPlans and Best Management Practices’(1992). The stormwater pollution preventionplan requirement applies to both existingand new industrial sites

• standard no. 13 stormwater dischargesfrom land uses or activities with higherpotential for pollutant loadings, defined ashotspots, may require the use of specific

structural BMPs and pollution preventionpractices. In addition, stormwater from ahotspot land use may not be infiltratedwithout proper pre-treatment

• standard no. 14 in Maryland, localgovernments are usually responsible formost stormwater management reviewauthority. Therefore, prior to design,applicants should always consult with theirlocal reviewing agency to determine if theyare subject to additional stormwater designrequirements. In addition, certain earthdisturbances may require NPDESconstruction general permit coverage fromMaryland state.

The six groups of acceptable BMPs that canbe used to meet recharge and water qualityvolume sizing criteria in the state ofMaryland are:

• stormwater ponds• stormwater wetlands• infiltration practices• filtering systems• open channel practices• non-structural practices.

Specific performance criteria and guidelinesfor the design of five groups of structuralBMPs are outlined in the manual. Theperformance criteria for each group of BMPsare based on six factors:

• general feasibility• conveyance• pre-treatment• treatment geometry• landscaping• maintenance.

The manual also provides the user with aselection section that outlines the best BMPsfor a specific site based on environmental andother site characteristics. This section hasbeen designed so that the reader can use thetables in a step-wise fashion to identify themost appropriate BMP or group of practicesto use at a site.

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2.5.3 Seattle – Washington state designcriteria (http://www.ecy.wa.gov/programs/wq/stormwater/manual.html)

The stormwater management advocated inthe Washington state stormwater manualinvolves careful application of site designprinciples; construction techniques to preventerosion and the discharge of sediments andother pollutants; source controls to keeppollutants out of stormwater; flow controlfacilities to reduce discharge flow rates; andtreatment facilities to reduce pollutants. Thecurrent version was updated in 2005following a public review draft prepared andpresented at three public workshops. Ecologystaff reviewed public comments andincorporated many of those comments intothe final document.

The application of specific design standardsand minimum technical requirements that anystormwater management facility (includingBMPs) should achieve are outlined within themanual. The manual specifies a number of flowdiagrams to guide the user to specific technicalrequirements that the developer should achievefor new development and redevelopment.

The retrofit design requirements stipulated byWashington state differ from those stipulatedby Maryland state. Seattle requiresredevelopment land to include appropriateBMPs. Compliance is required regardless ofthe type of redevelopment, and regardless ofwhether or not a permit is required.

A maintenance manual is available on theSeattle SEA streets. This will not bediscussed in detail in this section as the focusis on design manuals and selection criteria.

2.5.4 Portland, Oregon(http://www.portlandonline.com/bes/index.cfm?c=35117)

The purpose of the stormwater managementmanual developed by Portland, Oregon is toprovide stormwater management principlesand techniques that help preserve or mimicthe natural hydrologic cycle, minimise sewersystem problems and achieve water qualitygoals. The manual provides developers anddesign professionals with specificrequirements for reducing the impacts ofincreased stormwater runoff flow quantityand pollution resulting from newdevelopment and redevelopment.

The requirements of stormwatermanagement apply to all projects within thecity of Portland, whether public or private:

• projects of any size are required to complywith stormwater destination/ disposalrequirements as identified in the manual.Specific facility designs that meet theserequirements are presented throughout

• all projects developing or redeveloping over500 square feet (55 square metres) ofimpervious surface, or existing propertiesproposing new stormwater discharges off-site, are required to comply with pollutionreduction and flow control requirementspresented in the manual. Specific facilitydesigns that meet the stipulatedrequirements are outlined in the manual

• all projects constructing destination/disposal, pollution reduction or flow controlfacilities are also required to comply withoperations and maintenance requirements

• projects that are classified as high riskbecause of certain site characteristics oractivities must comply with the sourcecontrol requirements identified.

The manual is easy to use as it provides a flowchart for the navigation of projects of all sizesand types. It also takes a number of exampleprojects step-by-step.

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Stormwater destination/disposal hierarchymust be used to determine the ultimatedischarge point for stormwater from adevelopment site. The hierarchy is set up toprotect watershed health and mimic pre-developed hydrologic conditions by requiringon-site infiltration wherever practicable. Thisalso serves to protect the capacity ofdownstream infrastructure and minimise theoccurrence of combined sewer overflows andbasement sewer backups in the combinedsewer system. The hierarchy is also intendedto protect groundwater resources by limitingthe use of infiltration in some cases. It requiresinfiltration at the ground surface wherepracticable, and pollution reduction where it isnot. Where on-site infiltration is not practicable,the hierarchy dictates the use of off-site storm-only systems for stormwater discharge iffeasible, before discharge to combinationsewer systems can be considered.

At the meeting with Eric Strecker and WayneHuber in Portland, Oregon, a new design guidewas introduced, published by WERF and IWA:‘Critical Assessment of Stormwater Treatmentand Selection Issues’14, based on two researchprojects: ‘Development of a BMP evaluationmethodology for highway applications’ fundedby the US National Cooperative HighwayResearch programme; and ‘Critical assessmentof stormwater pollution control selectionissues’ funded by WERF.

2.5.5 Education of the key stakeholdergroups

Selection of a BMP or LID is influenced by theability of the stakeholders to use or maintainthe systems; hence education and capacitybuilding are key elements in the CWA.

The primary goals of education in relation tostormwater in the US includes: increasingcommunity awareness; preserving localwater resources; and gradually changing user

behaviours to reduce the amount ofpollutants from stormwater runoff. Educationprogrammes may focus outreach on a singlebehaviour on a broad basis, or concentratetheir efforts at the sub-watershed level. Themost effective education programmes focuson key pollutants or behaviours, carefullytarget their audiences, and survey residentsto understand their attitudes before designingeducation campaigns.

The CWP website provides free materialproviding technical guidance and help togenerate project and training ides for smallwatershed organisations (primarily localresidents and commercial/retailestablishments). The website also provides freematerial that may be used in educating localstakeholders on the impacts of watershedrelated behaviours and the usefulness of BMPand LID techniques to manage stormwater.

The CWP material is used to targethomeowners to help strengthen educationprograms; specifically a series of HomeownerAssociation slideshows on suburban impactsto water resources is available. The centrealso encouraged the local paper to publishrelated articles, and initiated demonstrationprojects to educate watershed residents onvoluntary ‘back yard’ practices to minimiseresidential impacts.

2.6 Construction

2.6.1 Introduction

The typical levels of earth disturbance thatoccur during land development aresubstantial; hence the construction process iswidely identified as a critical time for theprevention of siltation and pollution due tostormwater runoff from sites underdevelopment. Traditional constructiontechniques involve levelling the site andinstalling the primary stormwater drainage as

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14 Strecker E. (2006) IWA publishing, January ISBN: 1843397412

one of the first priorities, thus utilising thedrainage to stabilise the site for construction.In an ideal situation the primary drainagewould be constructed at the end of thedevelopment with a temporary or secondarydrainage system installed to service the siteduring the construction process, however, thefinancial sense of this relies on predicting thecost of a clean up of the primary drainagesystem caused by bad management practice(BaMP) during the construction process.

During the mission each of the cities andstates visited had, and were expected toadminister, construction site stormwaterrunoff preventative measures. On the whole,the US has identified the need to legislate inthis area and developed regulations to allowthe enforcement and management ofconstruction site pollution in general. Thefollowing sections provide an overview of thefindings in this area.

2.6.2 Rigorous controls – constructionsite regulation

With the introduction of the CWA came thebasic overriding, though not limiting,regulations for construction site runoff. Thesefundamental controls on construction activityare channelled through the EPA WaterPermits Division and administered throughthe NPDES. Obtaining a permit requirescontrol of stormwater discharges associatedwith industrial activities, which includesconstruction activities, thus limiting anynegative impact on the environment. Landdevelopers/construction site operators areexpected to adhere to a set of preventativemeasures aimed at reducing construction siteerosion and the discharge of contaminatedconstruction site runoff.

The NPDES was introduced as a federalregulation so that the US as a whole wasrequired to act on the problems created byconstruction site discharges. Prior to this,certain states already had in place state laws

that required land developers to control theirconstruction site discharges. These lawscome with the requirement of a soil erosionand sediment control plan approved from thelocal soil conservation district (SCD),representing the approval process.

The visit to the county of Baltimore and its‘Department of Environmental Protection andResearch Management’ (DEPRM) offeredperhaps the best example of the controls andstructure in place for construction sitesediment and erosion control, including thepracticalities of enforcing the laws, along withfinancial aspects. Along with and prior to theNPDES permit system, the state of Maryland,and subsequently the county of Baltimore, haddeveloped a separate ‘sediment control law’(passed in 1970) which requires the approval ofan ‘erosion/sediment control and stormwatermanagement plan’ before the issuing of abuilding permit and any grading permit. Thiswas seen by the county and others to besomewhat innovative compared withelsewhere in the US. It is worth noting that thecounty of Baltimore is well funded due to therelative affluence of its citizens and as suchmay not represent a majority view, although itprovides a good example of what is possible.

2.6.3 Inspection and enforcement

Enforcement of the regulations relating toconstruction site runoff is primarily subjectto resources the controlling body hasavailable to carry out inspections. In practicalterms the NPDES requires that a developerwishing to disturb more than 5 acres (2hectares) of land has to apply for a NPDESpermit. The developer will need todemonstrate that an approved soil erosionand sediment control plan is in place alongwith records showing that a weeklyinspection of erosion and sediment controls,plus an inspection the day after any stormevent, has been carried out. They will also beexpected to keep a record of anysubsequent maintenance.

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Where a developer is found to be incontravention of its NPDES generalconstruction permit, or has disturbed earth aspart of a construction activity withoutnotification of intent, it can be prosecutedunder federal law and specifically the CWA.Additionally, if a developer is found to be incontravention of the governing environmentalregulations of the relevant state it is liable forany number of penalties which can rangefrom the following:

• issue of a correction notice• shut down of the site either in its entirety or

in the specific location of any infringement• wide ranging fines: eg Seattle has

examples of contractors being fined inexcess of $1 million (£550,000) for notcontrolling solids runoff during construction

• prosecution penalties for contravention ofthe NPDES permit and the CWA can rangein severity from a maximum fine of $2,500(£1,350) per day and/or imprisonment fornot more then one year for negligence, toa fine of $25,000 (£13,500) and/orimprisonment for a maximum of 15 years.

2.6.4 Fees and discounts

Fees are generally payable for permits suchas an NPDES general construction permit,grading permits, etc, but will vary dependingon the state regulations as to how or if theymanifest themselves. For example, inBaltimore there is a one-time application feeto pay based on the size of the planneddisturbance. This is described as a ‘gradingsecurity’ based on a rate of five cents persquare foot, (3p/0.1 square metre), up to amaximum of $30,000 (£16,275). The size ofthe planned disturbance is provided by thedeveloper upon submission of a notice ofintent, from which the authorising engineerwill decide the fee payable. It is possible toget a discount on the up-front fees payable inMaryland by demonstrating that certaincriteria can be met, such as the intention toconvert a construction BMP such as a

sediment pond into the primary drainageBMP once construction is complete. Anotherimportant consideration is that reduction ofconstruction site pollution in the naturalenvironment can be the cost-effectivealternative to cleaning up the environmentpost construction.

The overriding impression is that fees are usedto control the construction practices ofcontractors, with the onus put on thecontractor/developer to ensure thatdevelopment sites are as environmentallyfriendly as possible, thus enabling thecontractor to limit the up-front financial burdenplaced upon it. The effectiveness of this typeof incentive to a developer is hard todetermine from the visit, but from the sitesvisited and general observations, some of themore obvious control methods adopted bycontractors are highly visible and in abundance.

2.6.5 Effective contractors –construction process

The process involved in acquiring all permits andpermissions to construct will vary from state tostate and city to city. The process for BaltimoreCounty is shown.

2.6.5.1 Baltimore – Maryland

• The first step is to have the relevantstormwater management plan and erosionand sediment control plan approval in place.This plan is a requirement wheredevelopments will disturb land greater then50,000 square feet (4,645 square metres),or move more then 100 cubic yards (76cubic metres) of fill material. Theaforementioned plans will require theapproval of soil conservation districts (SCD)and any other affected parties (such asutilities etc).

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• A grading plan, a sediment and erosioncontrol plan, stormwater pollutionprevention plan etc are produced andsubmitted for approval.

• Financial securities are paid up-front ofapprovals and issuing of permits.

• If an area greater then five acres (twohectares) is going to be disturbed then anNPDES permit will be required and anotice of intent needs to be submittedwith a fee.

• Before the construction can begin a pre-construction meeting will be conductedwith all of the parties involved, including arepresentative of the community.

• The developer may then be required to putin place the sediment control measuresand have them inspected before the permitis issued. Sediment control is required tobe carried out by a trained contractor.

• Once construction activity is finished andthe site has been ‘finally stabilised’, thedeveloper will have to issue a notice oftermination and must have or be imminentlyremoving all temporary control measures.

• Only once the site has been inspected andapproved will the stormwater/gradingbonded security be released. A suitableamount is kept back to cover anyunconformities as a leverage to make surethe work is finished to a satisfactorystandard. The money that is held back willbe used to carry out any remedialmeasures that the contractor/developerfails to carry out. A certain amount willthen be kept for a year after the site isapproved as a maintenance bond.

2.6.6 Good construction practice (GCP)

The example of Baltimore County (2.6.5.1)showed how a formal structure is in place toapply and enforce the regulations relating toconstruction site stormwater runoff. Seattle,Washington state, provides an equivalentexample of a practical application where arange of controls has been applied to aconstruction site; a new housing estate thathad been constructed entirely utilisingBMP/LID drainage.

During the tour of the site in Seattle (alongwith observations from other visits) themission delegates were provided withexamples of construction practices gearedtowards reducing contamination of theenvironment and the primary drainagesystem, which are summarised below:

• covering recently disturbed soil during astorm event to alleviate the eroding effectof stormwater flowing across its surface

• laying turf over areas instead of seedingthe ground and waiting for it to growstabilises areas of soil quickly, as opposedto seeding. There are obvious costimplications to this but if the intention is toturf the area (landscaping traditionally beingthe last job), then planning as early aspossible will provide soil erosion protectionat no extra cost

• suitable biodegradable geotextiles can belaid on regraded areas where they canprovide support and binding for the soil,growing plants and seeds

• construction of a temporary sedimentbasin or underground storage structure onsite to receive construction sitestormwater for silt settlement andattenuation of flow. This can then beconverted into a permanent feature orremoved post-construction

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• managing the regrading of the site duringthe construction process to reduceexposed areas that are susceptible toerosion during storm events. Also knownas construction sequencing, this was veryevident in that large blocks of the Seattledevelopment were completed, withconstruction elsewhere still at an earlystage on other parts of the site

• the use of silt fences to alleviatestormwater runoff is a simple but relativelyeffective way to contain sediment on thesite. Silt fences are a minimumrequirement of the NPDES permit andwere perhaps the most visible of controlmeasures present on the construction sitesvisited. This was because of their ubiquityand location around defined constructionsite perimeters

Exhibit 2.30 Silt fences in use

• covering and protection through thediversion of stormwater away fromsensitive drainage features that could bebadly affected by siltation, andcontaminated stormwater such as porouspavements, biofilters, swales etc

• the use of filtration baffles in front ofcatchbasins and access points that leadinto piped drainage systems provideprotection from silt. A variation observed inSeattle was a silt sack installed incatchbasins to provide a primitive form ofsilt filtering device

Exhibit 2.31 Covering and protection

Exhibit 2.32 Filtration baffles

• using contractors with required training inthe area of construction site pollutionmanagement termed as ‘responsiblepersonnel.’ This was a common themehighlighted in Baltimore and Seattle where itwas a requirement for a qualified contractorto install the sediment and erosion controlson site. In the county of Maryland, theMaryland Department of the Environmentoffers a training course entitled ‘responsiblepersonnel training for erosion and sedimentcontrol’ to contractors in order to meetthese requirements

• the addition of mulch amongst recentlyconstructed drainage features or recentlydisturbed soil provides a certain amount ofsoil stabilisation, although it lacksrobustness. This is the practice of laying acarpet of loose clippings, typicallybiodegradable waste products (eg straw)over the top of the surface

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Exhibit 2.33 Protecting established trees

• the practice of protecting established treesand their roots by giving them a price whichwill be payable as a fine if they are removedillegally. Signs are prominently displayed onthe construction site at each of the specifictrees warning against accidental removaland discouraging intentional or unintentionalremoval by providing a sense of worth(expressed in $) to the existing environmentthrough education.

There are many more techniques available foruse on construction sites which were notdirectly observed during the mission. Furtherinformation can be found on the internet onthe EPA web-site (www.epa.gov) or theindividual states or municipality websites.

2.6.7 Construction – summary

To ensure the effective reduction inconstruction site pollution within the US, theFederal Government and State Governmentshave created legislation that provides aminimum requirement to mitigate anypotential pollution and erosion created byconstruction site stormwater runoff. Alongsidethe regulatory aspects there are welldeveloped systems of control and inspection,financing, incentives, permitting and penalties,all aimed at encouraging compliance by theuse of stormwater management techniquesidentified as being effective means of silt anderosion prevention.

Notwithstanding the above, it must beacknowledged that the mission did not havethe opportunity to engage with contractors ordevelopers to ascertain the views of theconstruction industry in controllingconstruction site runoff. Nonetheless,although these views are largely missing it isclear that there is a tangible required anddemonstrable effort by all parties to addressthe problems associated with constructionsite stormwater runoff. Despite theundoubted problems in applying the practicalsolutions associated with construction sitestormwater runoff, it is still fair to say that thefirst steps have been taken on a metaphoricalroad that is undoubtedly having, and willcontinue to have, a positive effect on theenvironment that the American public live in.

2.7 Monitoring of performance

There are two important aspects here; onerelates to compliance monitoring and theperformance of BMPs and LIDS, the other tothe continuing performance of stormwaterdrainage systems in relation to the wastewatersystem as a whole. The latter requires anunderstanding of the unwanted inputs to thesesystems, known as I/I in the US.

2.7.1 Introduction

Stormwater standards in the US are generallydelivered using technologies that are‘deemed to comply’ with pollutant removalefficiencies, but in reality it is almostimpossible in many cases to design systemsdeterministically to achieve these standards.

US stormwater regulations have sixminimum operational requirements forcompliance/permitting:

• public education outreach – to raiseawareness and support

• public involvement – to meet notificationrequirements

• illicit discharge detection and elimination –remove cross connections

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• construction erosion control – for newdevelopment and redevelopment

• post–construction management – must bereviewed for compliance

• pollution prevention – municipally ownedBMP maintenance schedule.

It was clear from the visits that theimplementation of an effective SUDS/BMPmonitoring programme, whether pre-, post-,or during construction, is not astraightforward task. A one-size-fits-allapproach is very unlikely to succeed owing tothe widely varying techniques and methodsadopted in designing, installing andmaintaining a project.

The term BMP tends to group together amassively varying range of techniques, fromsource control approaches such as streetsweeping and green-roofs (Exhibit 2.34), localschemes incorporating proprietary devices(Exhibit 2.35) for treatment and control,swales, bio-retention areas, through to largeregional structures such as large detentionponds, each with their own peculiarities,technical difficulties and challenges (Tables 2.3and 2.4).

Exhibit 2.34 Green-roof in Portland, Oregon

Coupled with this wide range of BMP options(which is growing), the large variations inweather patterns, geography, land use etc.across the US complicates the problems of

monitoring even further. If a BMP monitoringprogramme is to be effective, it must dealwith this variability to produce reliable andmeaningful information.

With all these difficulties to overcome it isunderstandable why a US GovernmentAdvisory Committee produced a report in200215 on current monitoring practices in theUS, noting that data gaps are prevalent and‘particularly serious for non-point sources’.

Monitoring data from the EPA compliancewith the NPDES requirements programmehave been included in some databases. TheCDM national stormwater quality databaseincluded 816 NPDES storm events in adatabase that includes approximately 3,100total events. The Rouge River National WetWeather Demonstration Program office inDetroit included its NPDES data in itsdatabase. Recently, the EPA granted theUniversity of Alabama and the CWPprotection funding to collect and evaluateNPDES MS4 municipal stormwater permits.By the end of 2002 this project had collected3,757 storm events from 66 agencies andmunicipalities in 17 states. This databaseincludes geographic and seasonal informationthat can be useful for various analyses.

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Exhibit 2.35 Proprietary Up-Flo filter system fromHydro International

15 United States Environmental Protection Agency (U.S. EPA). Environmental monitoring and assessment program – research strategy. EPA 620/R-02/002. – July 2002

2.7.2 Main findings relating tomonitoring and compliance

It is evident that any performance monitoringprocedures currently in place relating toinvestigations, studies and complianceevaluation can vary greatly from state to state.The success or efficiency of monitoringsystems can rely, in many instances, althoughnot exclusively, on issues such as the presenceof a ‘champion’ or ‘champions’ within therelevant organisation with the right knowledgeand experience (Section 2.1.3), or on theexistence of dedicated funding allocatedspecifically to deal with stormwater issues.

A typical example of the disparity in approachbetween one state and another and howindividual states deal with stormwater indifferent ways, is highlighted for LA, Californiawhere the main approach is to obtain widerimprovements in stormwater qualitymanagement is through additionalrequirements imposed on redevelopmentprojects. The assumption is that over timethis approach will lead to the entirestormwater system being improved.

In California, the Department of Transportationcarried out a $30-40 million (£16-24 million)study on BMP performance and found thatthe performance of these systems wasinadequate. The major effort in terms ofstormwater for these projects was reallyfocused on the ‘during construction phase’.

It is widely accepted in some states that it isessential to control catchment sedimentduring construction upstream (which may notbe within their personal jurisdiction) and thereare excellent examples of sediment controlduring construction, which crosses municipaland management boundaries.

Another example of monitoring relevant to aparticular state or city is in Baltimore Countywhere the municipality does not maintain‘underground structures’, ie storage

chambers etc, but they do monitorperformance using remote cameras. Also, allprivate stormwater facilities are inspectedevery three years. These must have agreedmaintenance rules when built (stated in theNPDES permit) with the plans beingequivalent to a contract between the countyand the developer.

Some other counties in the state of Marylandhave made sure all stormwater facilities areprivately owned and maintained. Maryland as astate seems to be ahead of the rest of the USin a lot of respects, and environmental concernis strong amongst the public due to awarenessof the need to clean up Chesapeake Bay, as ithas an impact on the tourism and leisureindustries. High levels of taxation evoke publicinterest and the population of Maryland isgenerally quite wealthy.

In the US there is local state interpretation offederal watershed protection requirements (inmany ways equivalent to member states inthe EU and the WFD). Individual states thenpass standards to communities forcompliance (the state generally produces astormwater manual). It is evident that somestates and communities are not dealing withthis. Phase II compliance of the CWA isrequired by 2008, but many states have noteven achieved phase I compliance as yet

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Exhibit 2.36 Sediment control on a construction site inPortland, Oregon

(See Table 2.1). There are some excellentexamples of stormwater manuals withincertain states and municipalities, but thecontent and structure varies a great deal fromone manual to the next. A good source ofmany such manuals can be found on thewebsite created and maintained by the CWP(http://www.stormwatercenter.net/). Anothergood example is the ‘stormwatermanagement manual for western Washington’(http://www.ecy.wa.gov/biblio/ 0510029.html).

Many types of monitoring exist, such as pre-BMP monitoring to establish design,implementation monitoring and performancecompliance monitoring. It would appear thatuntil recently the most prevalent type takingplace was the pre-BMP during the designevaluation stage. However, there does seemto have been a steady increase, in manyareas of the US in compliance monitoring.

There are many examples of proprietarysystems available in the US with varyingranges of data relating to performance. CFDmodelling is a very effective method forassessing the performance of settlingsystems, but should be linked to pilot studies.It is clear that the development of anyproduct leading to satisfactory up-takerequires a number of steps to be followedfrom laboratory through to pilot testing, andfinally field scale and independent verification.An illustration of such data and examples ofsystems that have followed this route can befound on the Department of Ecology forWashington state website(http://www.ecy.wa.gov/programs/wq/stormwater/newtech/). Evaluation of a range ofemerging stormwater treatment technologiesis covered detailing the use level categoriesfor a list of proprietary systems currentlyavailable in the US for which satisfactory datahas been provided and subsequentlyapproved by the Department of Ecology.

Various methods exist for monitoring BMPeffectiveness including input/output sampling,

before/after sampling, and upstream/downstream monitoring. Errors andineffective data are often prevalent becauseof incorrect flow measurements and samplecollection problems. For example, automaticsampling was found to be ineffective forassessment of stormwater control systemsas large and whole cross-sectional samplingis required. Some BMPs do not have clearlydefined inflow and/or outflow (vegetated filterstrips and green-roofs, for example), whichpresents great difficulties in collectingmeaningful representative samples and data.However, it was shown that these barrierscan often be overcome in some instances ifthe desire or need is strong enough.

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Exhibit 2.37 Hydro International’s Up-Flo systemduring on-site pilot testing and ETV verification by PennState University

Exhibit 2.38 Monitoring equipment on demonstrationgreen-roof site in Portland, Oregon

The USEPA and ASCE’s Urban WaterResources Research Council has compiled a national stormwater bestmanagement practices database(http://www.bmpdatabase.org/), the purposeof which is to develop a more useful set ofdata on the effectiveness of individual BMPsused to reduce pollutant discharges fromurban development. A review of theinformation contained in this database as wellas the data that is required is useful todetermine precisely what information shouldbe collected as well as how.

Care must be taken, however, whenconsidering the use of data collectedelsewhere, particularly relating to anydifferences that may lead to incorrectconclusions (eg weather, geography, sourcesof pollutants). Assumptions that certain

pollutants are associated with certainsediment fractions may lead to errors.

Another example of effective monitoring is inthe city of Seattle where inspectors visit sitesto check compliance and occupancycertificates are not issued if the system doesnot meet the requirements. There is someconcern at the moment that this process cantake too long, but work is being carried out tostreamline and speed up certificate issuing.

Post-construction monitoring is also seen asessential to show compliance in order toavoid litigation, amongst other things, and it isvital that this type of monitoring should bebuilt into the system and considered duringthe design phase. It would seem thatmonitoring can be either visual or detailed butnot prescriptive. It is also recognised thatsome methods for field performanceevaluation are expensive and only effectivewith very great care.

Exhibit 2.39 Runoff reduction data from Seattle’s SEAstreet monitoring scheme

A great deal of post-construction monitoring,particularly with proprietary systems, tends totake place during the planned maintenanceprogramme activities (provided they havebeen instigated in the first place). If a deviceis being cleaned or emptied at set intervals,

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this is the ideal time to carry out any ongoingmonitoring requirements, whether simplyvisual or using more detailed sampling.

Despite the prevalence of pre-BMPmonitoring, many areas remain whereperformance is poorly understood, such asstormwater pollution from agricultural run-off,despite the fact that this is known to beimportant particularly for backgroundconcentrations in urban area watercourse(Section 2.1.1.3).

A recently published report produced for TheNational Cooperative Highway ResearchProgram, Transportation Research Board andNational Research Council16 focuses onimproving the scientific and technicalknowledge base for the selection of BMPspredominantly for highways projects, and onthe improvement of the decision-makingprocess through a better understanding ofBMP performance and application. The reportrecommends that drainage engineers shoulduse fundamental unit operation and process(UOP) principles to guide their selection oftreatment systems for control of stormwaterwith UOP selection based on specifictargeted pollutants, as opposed to the ‘one-

size-fits-all’ with typical BMP performancedata. It is also recommended that guidanceand requirements for stormwater BMPsbased upon UOP approaches are combinedwith empirical approaches based onperformance databases. Simple design rulesbased, for example, upon a 24-hourprecipitation analysis for sizing andconsidering all BMPs equally will not producedesigns meeting water quality goals. There isevidence to suggest that 80% of US BMPshave delivered less than desired results.

Infiltration systems in general may not berobust in a lot of cases due to clogging,groundwater contamination or poorconstruction. However, if they can be linkedbetter to groundwater recharge, with qualitycontrol, they may be useful. Moreinvestigations may be needed to ensureinfiltration performance problems are not dueto bad construction and/or maintenanceneeds. It is clear, however, that infiltrationBMPs have a place if properly engineered(and constructed) and used appropriately – butgenerally not on a large scale (BaltimoreCounty experience). Pre-treatment is anessential component (particularly for sedimentremoval) of infiltration in the treatment train.This is also true for storage systems.

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Exhibit 2.40 Temporary monitoring equipment in placeat SEA Street development

Exhibit 2.41 The captured contents of a CDS separatorprior to annual clean-out

16 Project 25-20(01) – Evaluation of Best Management Practices and Low Impact Development for Highway Runoff Control.

http://web.engr.oregonstate.edu/~huberw/25-20/March06Final/ResearchReport/FinalReport3-13-06.pdf

There needs to be more recognition about thelimitations of knowledge and the complexitiesrelated to rainfall-runoff and diffuse pollutionprocesses. Acknowledgment of theuncertainties should be made explicit inregulation and the delivery of solutions.

2.7.3 Illicit discharge and infiltration (I/I)

In the US the terminology for I/I is slightlydifferent to that of the UK. The term I/I in theUK normally refers to ‘inflow and infiltration’.Nevertheless, they are essentially identical,refering to flows that are entering the sewerwhich should not really be there.

In the US the presence of I/I is generallytargeted at illicit discharges into storm sewersas most sewer systems are separate, notcombined. The CWP, in conjunction with Robert Pitt, University of Alabama, hasdeveloped a ‘guidance manual for programdevelopment and technical assessments’,which deals directly with illicit dischargedetection and elimination. Some of the textbelow is taken directly from thiscomprehensive document and illustrates theimportance of this in a holistic strategytowards a ‘sustainable’ drainage system. Itwould appear axiomatic that unless theeffects of unwanted discharges are removedfrom drainage systems, it will be impossibleto achieve a sustainable solution.Unfortunately this is often not tackled ineither the US or UK.

Provision of the CWA requires NPDES permitsfor stormwater discharges. Section 402requires that permits for municipal separatestorm sewers include a requirement toeffectively prohibit problematic non-stormwaterdischarges into storm sewers. Emphasis isplaced on the elimination of inappropriateconnections to urban storm drains. Thisrequires affected agencies to identify andlocate sources of non-stormwater dischargesinto storm drains so that they may instituteappropriate actions for their elimination.

Detection and eliminating these illicitdischarges involves complex work that makesit hard to establish a rigid prescription as tohow to ‘hunt down’ and correct all illicitconnections. Frequently there is no singleapproach to take, but rather a variety of waysto get from detection to elimination. Localknowledge and available resources can playsignificant roles in determining which path totake. At the very least, communities need tosystematically understand and characterisetheir stream, conveyance and storm sewerinfrastructure systems. When illicit dischargesare identified, these need to be removed. Theprocess needs to be ongoing and theeffectiveness of a programme should improvewith time. In fact, well-coordinatedprogrammes can benefit from and contributeto other community-wide water resources-based programmes, such as public education,stormwater management, stream restorationand pollution prevention.

2.7.3.1 I/I programme at MWRA

The mission team saw an example ofinfiltration management that deliveredexcellent results for the overall managementof the wastewater system at the MWRA inBoston. The city of Boston resembles anumber of UK cities in its arrangement ofsewer systems. Boston relies on an oldcombined sewer system serving a central citypopulation of around one million with spursthat emanate out dendritically to the smallertownships that serve the outer lying areasand swell the total population to around twomillion. The trunk sewers which serve theouter lying communities can be up to 20 miles (33 km) long.

The Greater Boston system is subject tocontinuous flow monitoring at strategicpositions in the network. This provides realvalue to the operation of the sewer network.

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For example:

• any new illicit discharge is immediatelypicked up as it registers a change at lowflows during night time. This enables MWRAto track it down and remedy it fairly quickly

• the effects of gradual downspoutdisconnection can be observed over time,providing clear evidence of its value

• the hydraulic computer models used(Infoworks) can be honed to a higher degreeof accuracy (calibrated), thereby bettertargeting capital expenditure on the networkin a more strategic and holistic way

• it targets and improves maintenanceefficiency.

The use of the targeted flow monitoring andmetering (of both water and wastewatersystems) has resulted in water usage beingreduced from 340 million gallons per day to120 million gallons per day, which is the sameas 1911 despite a much larger population.

2.7.3.2 I/I programmes – relevance to the UK

Many sewer network systems in the UK aresubject to major inflow and infiltrationproblems. This is often seen as ‘just one ofthose things’ and it is therefore not allottedsufficient relevance. It seems incongruous toembark on the construction of bigger andbigger carrying sewers and storage structureswithout tackling the problems of gettingunwanted water in its many guises (storm,groundwater infiltration, rivers and streams,leaking potable water etc) out of the system.The presence of I/I and its detection andremoval should be part of any ‘sustainable’holistic solution for UK drainage systems.

There is growing evidence of attempts atintegrated management of wastewatersystems and examples of these include theholistic approach being undertaken inGlasgow. Here ‘communities need tosystematically understand and characterise

their stream, conveyance and storm sewerinfrastructure systems’. In Cardiff there hasbeen a 12 month monitoring programme onkey sewers in the network to help understandhow these Victorian systems actually work.

Programmes such as these should beextended and continuous, as the MWRA hasshown that the results can be valuable for acomparatively limited investment.

The IDDE programmes of the US concentrategenerally (Boston excepted) on illicitdischarges into storm sewers whilst theproblems in the UK are centred on combinedsystems. Nevertheless, much of thedetection and elimination is of the same typeof water, eg groundwater, leaky pipes etc.Hence a number of the proceduresrecommended in the CWP guidance manualare equally applicable to the UK.

2.8 Integrated management and

stormwater as a resource

During the mission there was little evidencethat significant interest existed in the use ofstormwater as a resource, although the moreenlightened, like John Sansalone, did indicatethat there was an urgent need to start toconsider stormwater as a resource. Directuse and reuse are recognised LIDs andBMPs, although so far mainly recommendedfor external uses. The limited evidence ofstormwater reuse was probably because inthe areas visited, perhaps with the exceptionof LA city, there is no apparent water stress.Also possibly because there is very littleinterest in the US in the future potentialimplications for climate change. Although inthe LEED (leadership in energy andenvironmental design) programme of the USGreen Building Council, rainwater harvestingplays a part in achieving building performanceaccreditation (http://www.usgbc.org/DisplayPage.aspx?CategoryID=19). This hassome equivalence to the UK ‘Code forsustainable homes’

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There were examples of direct water use for‘rain gardens’ in Portland, Oregon and ingarden watering using the treatedstormwater from the SMURFF device in LA,but this had notices warning the public thatthe irrigation water was potentially hazardous(See Exhibit 2.42).

There were no examples of any explicitattempts at integrated water management bythose visited.

Rainwater planters are regularly used in thecity of Portland, Oregon, to managedisconnected flows. Exhibit 2.43 illustratesthe use of rainwater planters and also theemphasis on public education.

Exhibit 2.43 Public information notice board providinginformation regarding roadside rainwater planters,Portland, Oregon

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Exhibit 2.42 Re-used stormwater from the SMURFF in LA for irrigation carries a health warning

Other examples of using rainwater at sourceinclude the use of rainwater in public areas tocreate communal recreational areas. Thisexample (Exhibit 2.44) in Portland, Oregon, isa feature at the local university. The rainwaterhere is also recycled and used to flush toilets.

Exhibit 2.44 Use of rainwater recycling to createrecreational areas in Portland, Oregon

At present annual water use in Portland,Oregon, is approximately 23 billion gallons(100 billion litres) and the annual yearly rainfallis approximately 91 billion gallons (400 billionlitres). Stormwater reuse is not widely usedin Portland, but is now starting to be exploredas an option, although there are majordifficulties in charging for services if the take-up rate is high because of the current form ofinstitutional arrangements for charging forwater supply, sewage and stormwater. Asmall direct water use project has beeninstalled at the University of Oregon where‘treated’ stormwater is used to flush toilets.Installation of this system was however,strongly opposed by certain regulators and bythe city’s plumbers.

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The mission produced a list of conclusions foreach day of the visit. These have beencollated and grouped into generic categoriesin the following sections.

3.1 Drivers, reasons and motives

• The drivers and motives for adoptingparticular stormwater managementpractices such as BMPs need to beunderstood if novel approaches are to beutilised. In the US, implementation sincethe CWA has often stemmed fromenvironmentalists and the legal systemthat provides the means for citizens, NGOsand other interested parties to bringprosecutions against federal, state andother organisations where they areperceived not to be fulfilling their statutoryduties. Environmentalists concerned withthe obviously poor condition of many USwaters have been able to readily mountlegal action to force those responsible toaddress the problems by enforcing therequirements of the CWA, such as definingthe water bodies that are impaired within aparticular area. In LA, local environmentalgroups and the state both carry out testsat bathing beaches and can close them ifthe water is of poor quality. The success inimplementing the CWA has been despite along history of central government notbeing amenable to funding environmentalimprovements.

• There is a view from some of those visitedthat the environmental lobbyists are lessinterested in the actual outcome orresolution of impaired water bodyproblems than in the process of litigation.Much of this activity by theenvironmentalists is also not as well-

informed as it should be. Nonetheless,there are still states in the US, such asTexas, where the CWA has not beenimplemented. There is also a problemcaused by the threat of enforcement andlitigation, which can lead to over-regulationand delays in implementation ofimprovements.

• Similar attempts at prosecution of any ofthe various parties involved in stormwatermanagement in the UK cannot beenvisaged, owing to problems of obtainingsuitable evidence, the opacity of theservices provided and the relative secrecyand complexity of UK governance andinstitutional systems compared with thosein the US.

• On a more local level, citizens and localagencies such as Baltimore County arehighly conscious of the condition of itsmore prominent water bodies, such as inthe Chesapeake Bay. Elsewhere, thecitizens of LA city were prepared to payhigher (bond) taxes to improve the qualityof their beaches. Whilst clean-up presentsa challenge, it can also be an opportunityto ensure that all stakeholders buy-in to theneed for additional resources and specialmeasures for dealing with stormwater.

• In the Boston area high property and landvalues have forced people to convertbasements to habitation and this hashighlighted the problems of flooding risk.This has resulted in increased buy-in byproperty owners and dwellers. In theadjacent township of Cambridge,Massachusetts, the challenges facing thestormwater managers relate to sustainedhigh river levels, which are maintained to

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3 CONCLUSIONS AND LESSONS FROM US STORMWATER MANAGEMENT

PRACTICES

ensure submergence of the timber pilessupporting much of the city of Boston. Thisleads to frequent urban flooding and, as aconsequence, community pressure to dealwith the problems. Although many of theoptions selected to deal with the problemsinvolve new in-sewer storage, utilisation ofgreen-roof BMPs is expected to result inup to 100% reduction in local runoffvolumes in selected areas.

• A major lesson for the UK is the need todetermine and build on local drivers (issuesand motives) when trying to implementinnovative stormwater measures such asSUDS in the UK. It is unfortunate that theWFD does not appear to offer the sameflexibility as the CWA in itsimplementation, particularly in relation topriority substances. Local needs andmeasures may therefore become ‘lost’ inEuropean or UK nationally defined policiesand standards. In the US, regulations thatspan across states possibly fit more easilythan in Europe, as US culture is morecoherent. What is different in the US isthat local wealth and community attitudesdetermine to what standards, and how theCWA, NPDES and TMDLs, will bedelivered via definition of impairment ofwater bodies and subsequent funding. Forexample, in LA city there were some 166water bodies initially identified as‘impaired’, ie not suitable for intended use.Although the WFD requires a proper cost-benefit assessment to determine whetheror not particular measures are required.This in principle is similar to the position inthe US. In the UK, a proper application ofthe WFD’s river basin managementapproach by all stakeholders should avoidunrealistic standard setting and lack ofcommunity engagement, and ensurelocally determined and appropriatesolutions to stormwater management thatare affordable.

• The knock-on benefits of improving waterquality should not be underestimated. Theeconomic benefits accruing from the cleanup of Boston Harbor are estimated at some$1 billion (£550 million). These benefits havemade the major investments required forthe clean-up more palatable. Engagementof the public by direct involvement in theMWRA board and in determining chargesfor sewage and stormwater managementhas also ensured better community buy-inand public acceptance. This contrasts withthe UK, where there is no direct publicinvolvement or accountability of the mainstakeholder groups; a major factor in publicdisinterest in wastewater management.

• Climate change is not as yet a driver in theUS, in contrast with the UK where it isused perhaps too often as a ‘threat’ to thepublic. None of the design approachesused for BMPs reported any considerationof climate change over the typical 30-yearlifetime expected, with even Strecker andHuber indicating that this was not amaterial consideration in their use of 20 or more years of continuous rainfallrecords for simulating storm drainagesystems performance.

• Plumbing codes make the direct use ofstormwater very difficult in Portland,Oregon. Hence direct use of stormwater isnot significant. Although the relatively highrainfall does not make this a main driver atthe moment, it may become important inthe future.

3.2 Institutions, regulations and

stakeholders

• Strong champions are needed in the keystakeholder groups if innovative and moresustainable management of stormwater isto be implemented. These championsmust have good knowledge and welldeveloped plans. By selection, the visitmet a number of champions in the EPA,municipal and stormwater utilities,

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consultants and academics. In addition tochampions, better integration across allstakeholder groups and a strongercommonality of purpose in delivery ofinnovative stormwater management needsto be in place.

• In England and Wales, the loss of asewerage agency function by localauthorities and the loss of experiencedengineering staff has resulted in thembeing less capable of dealing withstormwater issues. A typical local authoritywill now only have highway engineers who are often inexperienced or too focusedon the delivery of safe road transport to beinterested in both the quality and quantitymanagement of stormwater within acatchment perspective. This may lead toproblems in the future when the WFD is being implemented as it will beimportant to ensure that highway drainageis properly integrated.

• From US experience it is apparent that aseparate stormwater utility can bebeneficial for managing longer termmaintenance of facilities. Evidence fromthe visit also indicated that, despitedecades of use, there is insufficientcapacity in the US consulting andcontracting service sector to design andimplement innovative BMP systems. Thesituation in the UK is similar, although witha shorter history of use of BMP typesystems. Current design and constructionservice capacity for innovative stormwatersystems would be inadequate if thesesystems were to become morewidespread in the near future. This lack ofcapacity is also in part responsible for alack of take-up of SUDS due to the inabilityof consultants and others to assume anadvocacy role for their use.

• Where there are a range of stakeholdersinvolved in stormwater management,agreements need to be clear and robust.

These may be between (adjacent)municipalities, those responsible forstormwater system construction andstormwater maintenance serviceproviders. Where stormwater managementis required across watersheds andmunicipal or state areas, this can becomeof major importance. For example, LA cityofficials reported that a recent change inengineering leadership in the adjacentcounty has resulted in a renouncing ofprevious agreements on cross-jurisdictionmanagement of stormwater that willcompromise in-city measures.

• Where practicable, community andstakeholder ‘adoption’ of stormwaterfacilities can raise awareness ofenvironmental systems and help promotecitizenship and strengthen communities.This was apparent in most places visited.However, community willingness to adoptis by no means universal in the US, withevidence that individuals and communitieshave not been willing to take on BMPmaintenance responsibilities. This wasevident for individual sites in Seattle and inBoston, where MWRA may have tointervene when some of these wide rangeand number of types of local communitiesin Massachusetts responsible forstormwater do not take their stormwatermanagement duties seriously.

• The structure and way in which stormwaterutilities operate is significant in terms of theservices delivered and interaction withstakeholders. MWRA in Boston is a publicbody that has a high degree of autonomy. Italso has to raise capital for investment andone of its main concerns is its credit rating.As a consequence it wishes to beperceived by all stakeholders as efficientand ‘open’ in terms of performance.Regulation of the MWRA is statecontrolled, although there is strong directcitizen involvement. There may be someanalogy in the way in which MWRA and

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Scottish Water operate, although the latterdoes not have to deal with the wide rangeof constituent stormwater service providersthat exist in Massachusetts.

• Although there are already a number of‘trade-related’ bodies involved instormwater in the US, such as AWWARF,WEFTEC etc, there is still a need for astormwater trade group to help withtechnology development and acceptability.

• There are a number of barriers to utilisationof innovative stormwater managementsystems in the UK. Partnering is needed toproperly understand the issues and solvethe problems. In addition, understandingneeds to be improved as to theuncertainties and limitations of knowledgein relation to stormwater, stormwatermanagement and what is realistic. Industryand regulators are often averse to utilisingnew knowledge where this is perceived asbeing ‘too academic’ – even where it mayimprove practice with often very simplechanges. There is also a danger thateducators (at all levels, especiallyprofessional) focus too much on traditional(engineering) solutions. To resolve thisrequires flexibility combined with ‘fairness’in regulation, capacity building (education),and possibly institutional change toencourage greater innovation.

• The CWA states: ‘develop and implementa stormwater management plan to reducethe discharge of pollutants to the‘maximum extent practicable’. Hence, therequirements and definition of TMDLs areopen to widespread and uncoordinatedinterpretation resulting in differentiatedstandards across the US. This has led theUSEPA to criticise certain local regulatorsfor poor implementation. However, incertain states there is a view that somequality requirements have become tooonerous, particularly those related tobacteriological and pathogenic indicators.

• Multi-disciplinary teams are required todeliver BMP and SUDS approaches tostormwater management in order toensure proper account of the social,economic and environmental aspects. Thismeans the involvement of planners,landscape architects and others is neededto properly fit the more ‘natural’ systemsinto the urban landscape.

• In many areas of the US, stormwatercharges are based on the extent of thedirectly connected impervious area to thestormwater system, although in others (LAcity), charges are based on propertyvalues. The former has allowed a variety oftypes of service provider to develop andalso for these service providers to utilisedifferential charging systems, rebates,provide support for disconnections and/ordevelop innovative management systems.The current institutional arrangements inthe UK militate against this type ofapproach. Although potentially feasible fornew-build, in England and Wales therewould be too many risks to both the EA,local authorities and the sewerageundertaker if existing stormwater systemdisconnection was encouraged. The EAand local authorities would be concernedabout increased or transferred flood risk,whereas the sewerage undertakers wouldbe concerned about both the loss ofrevenue and also the potential undersection 106 for subsequent propertyreconnection to the main sewer network.

3.3 Development planning, funding

and control of stormwater

• In the US there is local state interpretationof federal watershed protectionrequirements (equivalent to EU and WFD) –the state then passes standards tocommunities for compliance (usuallyproducing a manual). For example, inCalifornia the main planning baseline is the‘basin plan’, which designates the beneficial

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uses of waters. Some states/communitiesare not yet complying with this approach.Phase II compliance of the CWA is requiredby 2008 although many states (eg Texas)have not yet implemented phase I. It wassuggested in LA that the main objective isto ‘address’ the ‘pollutants of concern’identified in the TMDLs – not necessarily toeffectively deal with them. Most proposalshave been accepted when the developershave followed the guidance in the manualsand problems have been overcome bynegotiation and refinement throughpartnership. Nonetheless, somestormwater management implementationdoes not follow the best practice specifiedin these manuals, but may nevertheless be accepted.

• In Massachusetts, the MWRA has re-planned the original large scale storagesolution to manage CSOs (estimated as$1.3 billion (£700 million) in 1993). Thereare now a larger number of smallerdispersed projects (approx 100) underway.These are locally targeted, incremental andcome at a much lower cost ($835 million(£450 million) at 2006 prices). Thesesolutions involve new storage,disconnections and other local solution-based approaches and are seen to bemore flexible and open to modificationfollowing experience in use. The solutionsare also being used in the densest urbanareas. Evidence from Portland, Oregon,suggests that downspout disconnectionsare not effective in all areas and may notbe usable owing to a lack of suitablealternative outlets for the stormwater. Inaddition, most urban areas in the US havemore open space than most conurbationsin the UK. Hence, a key issue in the UK isthe space to locate open ‘natural’structures such as BMPs. Ascontemporary UK planning requirements(PPS3) demand ever denser housing,sometimes in direct conflict to otherrequirements for development and floodrisk planning (PPS25), the premium on

developable land area grows and theavailability of ‘soft areas’ to implementnatural BMPs reduces. The solution is abalanced urban landform approachdeveloped by using a contemporarytoolbox of drainage techniques. Thisincludes both natural and proprietary BMPsand also piped systems. More R&D isneeded in this area to determine underwhat circumstances there would besufficient and robust benefits arising fromthe summation of lots of small responsessuch as widespread disconnections.

• A growing problem in the UK is infill andmicro development, which lead to‘creeping’ increases in surface waterrunoff. Downpipe disconnection is beingused extensively in the US and may be asimple and effective way of not onlymitigating the impact, but also reversingthe increasing flows. However,disconnections should only be undertakenfollowing flood risk assessments inaccordance with standards such as PPS25.Without a surface water impermeable areacharge, and hence the ability to offerincentives and discounts for disconnection,the UK stakeholder take-up may be lesssignificant than in Portland, Oregon. Inaddition, the section 106 right to connectcould mean that previously disconnecteddownpipes could be subsequentlyreconnected in future. This risk could beoffset by implementing a similar chargingsystem to the US in the UK, although itmay not be attractive to the sewerageundertakers due to loss of revenue fromthe disconnected stormwater inputs.

• The most enlightened stormwater serviceproviders in the US believe the rightapproach is to manage the problem andnot simply meet regulations. This conformsto the approach taken in the UK, althoughthere are instances where problems ‘fallbetween’ more than one main stakeholder.Where each stakeholder is moreconcerned with operating within strict

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legislative boundaries then problems canremain unresolved. Examples includewhether or not a covered watercourse isactually a ‘sewer’.

• Retrofit disconnection of stormwater, viadownpipes or other inputs being removedfrom main sewerage networks, is animportant option in the US for themanagement of CSOs. However, preciseapplication and maintenance ofdisconnected stormwater systems in theUS appears to be very variable, with certainmunicipal agencies assuming responsibility(eg Portland, Oregon) and others expectinglocal property owners to assumeresponsibility (eg Seattle). Disconnectionhas however, been shown to be acceptableand effective at removing stormwater fromthe system providing disconnection waterdoes not discharge across pavements.

• Retained bond payments bydevelopers/contractors for stormwaterfacilities prior to beginning BMPconstruction can be very effective atensuring that specified standards areachieved during and after construction. In Seattle, one developer was recentlyfined around $1 million (£550,000) forcontravening construction controls onstormwater pollution and all work on the site was stopped until the problemwas rectified.

• In many places the stakeholdersresponsible for enforcing developmentregulations are not the same as thosedrawing up the specification or planningstructure for stormwater managementsystems. In Baltimore County thesefunctions are carried out by separate teamsthat nonetheless have established closeworking relationships. In the UK, buildingregulatory functions are typically carried outby different agents from those drawing upplanning specifications (eg LDFs in England)or those with professional expertise in

drainage, such as local authority engineersor the EA. Under current building inspectionregimes in England and Wales there havebeen problems with stormwater systemsonce constructed. There is a need for better inspection processes with betterqualified inspectors for stormwater assets,linked in future to the new ‘Code forsustainable homes’.

• To be effective, any utilisation ofsustainable drainage systems must include appropriate cooperation betweenall of the functions of regulation, buildingcontrol and planning. This may also requirebetter training of those responsible forbuilding control.

• There are similarities in the delivery of USwatershed management plans and whatwill be needed for the WFD in the UK.Conditions in LA: population, land valuesand rainfall variability resemble thesouthern parts of the UK, where lessonsfrom LA may be applicable, particularly withregard to conditions under future climatechange. States, counties and cities in theUS have the ability to deliver a more joined-up approach than in the UK as they havemore responsibility for the various parts ofthe water cycle (although these vary state-to-state and between communities), whichis unlike England and Wales, whereresponsibilities are fragmented and moredifficult to coordinate. Of particularimportance will be better linking of theplanning framework to stormwatermanagement earlier in the developmentprocess. This has been recognised in‘Making space for water’ and with moreformalised and effective cooperationbetween the principal stakeholders shouldbecome more effective in the future.

• Land use management is the key tostormwater management within a basinperspective. Creating landscape can assistthe disposal of stormwater and in the US

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redevelopment has to include newlandscape in most cities. For newdevelopments the CWP in Marylandsuggests that the primary scale forstormwater management should be at thelocal level, rather than the larger catchmentscale (ie 50 square kilometres not 250square kilometres). Smaller scaleapproaches work better in engagingcommunities and can be used collectivelyto deliver solutions on a larger scale.

• In some areas of the US problems arisewhere different standards are used forpotentially adoptable BMPs compared withprivately operated and maintainedsystems. Because of this, BaltimoreCounty stipulates identical standards forboth private systems and those intendedto be adopted. In England and Wales,differing standards apply for privatestormwater systems (Parts G/H buildingregulations) and for adoptable systems(Sewers for adoption). The latter does notinclude SUDS systems although there isan EA SUDS for adoption document.

• In many stormwater service provisions inthe US the separation of the stormwatercharge from that for other water streamsprovides new opportunities for institutionalarrangements and imaginative fund raisingand investment via the clearly earmarkedspecific revenue stream. However, in anumber of areas there are problems withcharging for sewage where the sewagearises from direct stormwater use, asthere is no metered water consumption.Such an arrangement may be worthconsidering in the UK, although theinstitutional arrangements in England andWales may preclude it.

• Arrangements with other key stakeholdersare important. For example, a historicalagreement does not allow Portland,Oregon, to charge the transportationdepartment and main highways agency forstormwater management.

• The whole catchment should be managed(eg regionally). In some instances it maybe more effective to invest in managingthe downstream watercourse into whichstormwater is discharged, rather than inrefinements to the BMPs in the upstreamcatchments. This approach is only feasiblewhere the major stakeholders can agreeand budgets can be allocated appropriately.In the UK, it is probable that the WFD willprevent this approach being taken.

• In the US it is essential to get publicsupport for new taxes. Raising specificrevenue to manage stormwater requirespublic plebiscite with a 70% approval in LAcity. Re-packaging the message as ‘bond-raising’ instead of ‘tax’, led to a successfulvote for water quality improvements in LAcity (79% in favour of $500 million(£270 million)). This income is to be raisedas $100 (£55) per year added to eachproperty tax for 20 years, but spent in thenext 10 years. Perhaps better differentiationof water, stormwater and sewage chargescould help to engage the UK public indealing with the stormwater challenges.

• The vision for improving stormwatermanagement in California is toincrementally ensure improvements instormwater systems throughredevelopment projects, which it isassumed over time will eventually lead tothe entire stormwater system beingimproved. State grants are typicallyinadequate for what the state expects tobe done. This is being achieved by passingcosts on to developers and requiringstormwater permits for developmentprojects that disturb one acre or more ofland. Such an approach can only be takenwhere the timescales are open-endedenough to accommodate prolonged clean-up over time.

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3.4 BMP planning, forms and

performance

• Sustainable success in rainfall-runoff controlwill require a combination of source control,LID, in situ control and central control. Evenin the US there is inconsistency in usage ofthe terms for stormwater managementsystems. Evidence has been provided thatin some instances BMPs are considered aspart of LID, and in other instances LIDs areconsidered a form of BMP. Confusingly,there are also LID integrated managementpractices, which are a component of theLID approach. Despite the unfortunateterminology used in the UK, SUDS, whichare not a priori necessarily ‘sustainable’,there is a strong case for a single term.Views were expressed in the US that insome instances there needs to be a littleless ‘religion’ and more science in LIDs.When viewed within a wider planningcontext, SUDS, BMPs and otherstormwater management approaches maybe considered to be but one part of adesign process that includes all aspects ofwater within the planning process. Becauseof this, Australia and much of the Far Eastuse the term ‘water sensitive urban design’(WSUD) which means all aspects of waterwithin the planning process. WSUDencompasses both LID and BMP as well asSUDS concepts. There is therefore still aneed for a clearer definition of terms,ideally internationally. The IWA urbandrainage glossary, published in 2004,includes definitions for BMPs, and sourcecontrols, but does not mention LID, SUDSor WSUD.

• Although much of the emphasis instormwater control in the US is on qualitymanagement, with LID concepts assistingsignificantly the management of smallerstorms, it is possible that these may notbe as effective for larger runoff events. It istherefore recognised that flow-durationcontrol is important for downstream

watercourse erosion prevention. Muchdesign now uses long-term continuoussimulation, which makes it easily possibleto analyse flow-duration and control theimpact on receiving waters.

• There is a gradual transition in assessmentof performance by regulators that steadilybecome interested in increasing numbersof pollutants (although this is not anapplication of the precautionary principle),with the main interest in impairment ofwater use. There are reportedly irreduciblebackground concentrations (eg Cd 3 μg/l) indiffuse stormwater runoff in the US.Regulations require there to be zero litter instormwater discharges in Los Angeles by2013. This is another example of unrealistictargets given the multiple (diffuse) inputsof litter to the stormwater systems.Paralleling this, the WFD priority hazardoussubstances directive to remove all tracesof certain defined substances is alsounrealistic, and de minimis levels for thesesubstances need to be defined.

• Notwithstanding the difficulties that arisein defining these de minimis levels, thereis a need for environmental requirementsto be both prescriptive and performancebased, ie there should be fixed emissionlimits for acute, toxic and bioaccumulativesubstances, whereas substances that maybe assimilable more readily in receivingwatercourses should be managed by thesetting of local standards. This is theapproach taken in defining TMDLs in theUS. However, stormwater standards in theUS are delivered using technologies thatare ‘deemed to comply’ by achievingdefined pollutant removal efficiencies.Currently it is virtually impossible to designthese systems deterministically to achievedefined quality standards.

• Responding to current and future driverswill require flexible and adaptable solutionsthat may not be apparent with current

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knowledge. Therefore a range of types(portfolio) of solution should be utilised,some of which may include piped orsewered systems. There is no ‘magicbullet’ solution that can deal with allchallenges now and in the future. Solutionsshould also include non-structural as wellas structural solutions, which may crossboundaries between the main stakeholdergroups under current UK institutional andregulatory regimes.

• Investments need to be made in the mostappropriate part of the system to achievethe most efficient and effective outcomefor stormwater management, irrespectiveof which stakeholder has the primaryresponsibility. There is also a need to betterengage the public and wider community,although considerable difficulty exists as tohow best to do this in the UK. However,this is a major aspiration of the current‘Making space for water’ initiative.

• There is a perceived priority order forstormwater management in the regulatoryareas where there is long experience inimplementing the requirements of theCWA. These are: public safety, followed byutility, then aesthetic benefits. For thisreason certain areas, such as BaltimoreCounty, utilise permanent fencing aroundopen water BMPs.

• There is considerable reliance in the US onexperts as they are considered to beeffective as overview project or watershedmanagers. Hence the CWP is playing amajor role in delivering effectivestormwater management across the US.This has shown that strong guidance viaclear manuals for professional and otherstakeholder use and good practice areneeded, often with experts acting as theinterface between research andpractitioners. Manuals and guidance etcshould show examples and illustratechoices, but should not limit innovation. It

is not clear whether or not CIRIA (whichmay be the UK equivalent to the CWP) isindependent enough to deliver thisfunction and whether UK guidance isactually being provided at the appropriatelevels and format for each of thestakeholder groups.

• There is variability in use of types of BMP,for example, in Portland, Oregon, largedetention basins or wetlands are notpromoted, whereas they are usedextensively in other parts of the US.Experience in Maryland has shown thaton-line (on-stream) storage systems arenot easy to maintain in terms of sedimentremoval and offline, in terms of thestream, are preferred (these would still beon-line as part of the drainage system).

• US experience has shown that funding forstormwater management should be at thelevel and location at which it is mostappropriately managed and delivered. Itshould not be fixed so that the serviceprovider is constrained to deliver particulartypes of solution. The sewerageundertakers in the UK cannot utilisesustainable drainage systems as these arenot legally definable as ‘sewers’.

• Although much quoted, the first flushconcept is not good. It has been shown inUS (and French) studies not to bestatistically valid for smaller particulatesand other pollutants. This is becauseflushes may not occur at all, or occurthroughout the storm in ‘pulses’. However,evidence from LA city suggests that theremay be first flushes of larger ‘trash’ litter.Notwithstanding, in Massachusetts thefirst flush concept is used to control finersediments based on retention of half aninch (12 mm) of rain (runoff). In BritishColumbia and many other places in the US,stormwater pollution control standards arebased on the capture by BMPs of 90% ofrunoff for a one year storm. The precise

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stormwater storage volume neededdepends on the wetted surface area andalso on the nature of the surface (grasstype etc) as this will control the likelypollutants. In the UK, capture is typically ofthe first 5 mm of rainfall-runoff which isinadequate by US standards. UKapproaches should be modified to achieveat least 25 mm capture if the expectedWFD water quality standards are to bemet in the future.

• Regulators such as the EPA investsubstantially in R&D in the US and thisclearly benefits the public domain; theoutcomes are open, transparent and freelyavailable, with key software and manualsbeing extensively peer reviewed. This is aclear route to consistency on a nationalscale. The situation in the UK is verydifferent. Commercialisation has led tosecrecy, opacity and the exclusion of keystakeholders from access to information,guidance and support for implementingsustainable drainage systems. The lack ofpeer review of key UK computationalmodels and secrecy about the processesused in the models stifles effective debateand scrutiny and leads to poor usage andunquestioning belief in outputs bymodellers who do not understand theprocesses used in the computer models.Ironically, the US is arguably the mostcommercial country in the world, and yetaccess to information in this area is muchmore readily available than it is in the UK.

• In Baltimore County there are sixoperational requirements in relation tostormwater management:

º public education outreach

º public involvement

º illicit discharge detection and elimination

º construction erosion control

º post-construction maintenance

º pollution prevention.

• Demonstration projects are important andalso facilitate access by others for dialogueand in-depth contact with those alreadyusing or responsible for them. Trying andtesting stormwater innovations isimportant as this provides opportunities tolearn by doing and even from mistakes.Prior to applying regulatory controls todevelopment proposals, municipalities andother regulators should firstly manage theirown premises’ stormwater problems todemonstrate good practice. In order to dothis an accurate storm sewer map of anyexisting system is essential. As part of thisapproach it is important to implementquick-wins in a staged stormwatermanagement improvement programme.The MWRA has illustrated this approach bymaking staged and initially limited but welltargeted investment in stormwatermanagement, producing large economicbenefits and convincing stakeholders toprovide further resources and support toimplement further improvements.

• The use of traffic calming areas in streetsfor stormwater management is growing inthe US (also in Australia). There could bemore imaginative use of the space in trafficcalming measures in the UK to includestormwater facilities, such as streetgardens. However, even in the US there isonly limited cooperation between highwayand traffic managers and those responsiblefor overall stormwater management. Thisoften restricts usage of the mostappropriate solutions.

• The utilisation of typical BMPs in the USwill have a greater effect on stormwaterquality rather than on controlling quantity interms of flood risk.

• There are problems of application of BMPsand LIDs in some areas due to tradesmenand trade associations. Plumbers, forexample, in California. This may bebecause of the need to re-train or of

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perceptions of increased costs of thesesystems. There may also be correctlyperceived grounds to question the safetyof certain BMP systems, particularly thosethat recycle or make direct domestic useof stormwater. There are examples in theUS where BMP solutions have beenshown to be cheaper in terms of capitalinvestment than pipes. A BMP system inDavis, California was installed at less costthan the equivalent piped system and hasreportedly performed well for 30 years.

• Bioprocesses are important for qualityrelated performance, and plants and treesare considered essential for effectiveBMPs across the US.

3.5 BMP construction and

maintenance issues

• The impact of practices and constructionon the community needs to be addressedand taken seriously into account.

• Ownership and maintenance of the above-ground BMPs is another key UK issue. Thiswas not entirely resolved across many ofthe similar US sites visited because insome areas municipal responsibility isassumed, whereas elsewhere it is left tothe developer or property owners.However, in the US, barriers such asresponsibility for maintenance did notappear to prevent these systems beingused as maintenance responsibility wasdeemed resolvable. It was contended thatmany of these street BMPs are onlymarginally more expensive to maintainthan a standard landscape feature and thebenefits of having the BMP performancefar outweighs the small cost increase. Asplanning deems it essential to incorporatelandscape features in UK development andmodern urban streetscapes, many of thesefeatures could multi-task using sustainabledrainage BMPs.

Construction methodologies for BMPs are stilla problem in many parts of the US. However,they are essential in controlling catchmentsediment during construction. The US hassophisticated and very detailed techniques tocontrol construction sediment runoff and planshave to be certified by the SCS.

• There is a tendency to only use reactivemaintenance in the UK, but there is a needto see proactive maintenance as perfectlyvalid within the whole life performance ofthe BMP.

• BMP construction. In Boston the otherutilities have to pay for their own re-routingwhen storm sewer facilities are built.

• Effective, planned and accepted maintenancestrategies are essential within a whole-lifecosts framework. There is a critical linkbetween operation and maintenance.

• Post-construction monitoring is essentialand designed into the system.

• In Portland, Oregon, maintenancearrangements are inconsistent and tackledcase by case.

• Random policing of continuity ofdownspout disconnections is made inPortland, Oregon, (not clear what happensif these are reconnected) – tax reductionsaccompany disconnections.

• Householders are responsible for themaintenance of stormwater structureswhere these are on the sidewalk up to theroadway, although the city will step inwhere necessary.

• Maintenance for BMPs is really identical towhat it would be if these were a landscapefeature anyway (parks and landscapedepartments in the UK could becomeresponsible for the quality control of BMPs,but flood control may be too important atthis time to leave it to these groups, but thiscapacity could be built).

• Below ground solutions are ‘out of sight,out of mind’; above ground it is (usually)obvious when maintenance is needed.

• Portland, Oregon, is not too worried aboutmaintenance and is keen to ‘get systems

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in’ in the expectation that it will work outas communities seem to be morecommitted to engaging in this.

• Maintenance by property owners is morelikely where this influences property values– however, where BMPs are considered tobe aesthetically or otherwise unappealingthese may be abused.

• The classification of pollutants removedfrom stormwater as ‘hazardous’ makestheir removal less attractive as the ‘newowner’ then has a difficult job of disposingof them.

• Of 1,000 CDS units in the ground insouthern California, only some 30% arebeing properly maintained.

• There is no definitive agreement onmaintenance responsibilities and payments– LA County is adopting more of these toensure compliance is achieved bymaintaining and using developer commutedsums and units built on public land.

3.6 Performance of BMPs

• More BMP performance data needs to beroutinely collected and the monitoring andmaintenance systems should be designedinto these systems. Predictions ofpollutant loads and hence removalefficiency require highly site-specificempirical data fractionated for modelcalibration. However, methods for fieldperformance evaluation of BMPs areexpensive and only effective with verygreat care. Automatic sampling is oftenineffective for the assessment ofstormwater control systems as large andwhole cross-sectional sampling is required.Pilot scale testing of BMPs is preferredwhere possible, rather than full-scaletesting due to the controllability of theparameters and the large number of stormevents required at full scale.

• Flood risk management in the US typicallycontrols 25 year events and also some 100year events – there is a similar perspective

for pollution control, although pollution fromthe smaller more frequent events may bethe most significant. It is not clear how theexcess flow is managed. Using typical USdesign rules, BMPs can only be effective atimproving water quality for smaller andmore frequent events. However, designshould be based on flow volume and masstransport simultaneously.

• Transport and pollutant yield in runoff canbe characterised by either flow limited(zero order) or mass limited (first order)resulting in significantly differing volumetriccriteria for the design of controllingstructural BMPs. When using treatmenttrains, ‘daisy-chaining BMPs’, it is wrong toassume a similar performance at each stepof the train as for a single unit process, asthis will over-predict the performance.Water quality modelling for the design ofBMPs should be long-term continuoussimulation in order to account properly forthe various storage elements.

• As foul flushes cannot be defined a priori –as they may or may not exist underdifferent circumstances – there is a needto improve regulations or standards thatinclude the need to capture the ‘first flush’.Percentage pollutant removal is not asensible design standard, although it isinvariably specified in the TMDL; the use ofan EIA or equivalent based approach ismore sensible.

• Many of the lessons, tools and solutionsfrom experiences gained in the longhistory of wastewater treatment are notreadily transferable to stormwater – forexample, the effectiveness of end-of-pipecompared with distributed systems (see3.6.1). Also, for the management ofresiduals as this will become a big industryfor stormwater management in the future.Even in the US, treatment processes formanaging particular pollutants instormwater have not yet been developed.

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• More recognition is needed of thelimitations of knowledge about stormwatersystem performance and the complexitiesrelated to rainfall-runoff and diffusepollution processes. A tacitacknowledgement of the uncertaintiesneeds to be made explicit in regulation and delivery of solutions.

• There is a need for more engineereddevelopment of structural BMPs, withdesign and operation that should be openand transparent and that includes betterand independent testing and verification ofperformance of components. Proprietarysystems (widgets17) do have a place wherethey are targeted in terms of particularpollutants or process, but cannot beexpected to do too many things.Certification for conditional use (with a viewto future unconditional use) has to beapplied for each proprietary system fromstormwater regulators. Unfortunately in theUS manufacturers of these systems believethat they are forced into mis-representingperformance as users want a ‘magic-bullet’device that will remove all pollutants.Certified equipment is often substituted bysimilar but inferior sources (cowboys andgarage manufactured) that is cheaper, butdoes not perform adequately. Users needto be better informed to make them realisethat this is not realistic and to understandhow complex the stormwater managementarea is. In the UK it is most likely that thetake-up of ‘widgets’ can be more easilyeffected at the ‘end-of-pipes’/single pointsthan at inlets, as is being done in LA city.The visit to the trash screen near the beachin LA showed how devices located at theends-of-pipes can localise maintenance.

• Encouraging evapotranspiration is typicallyan under-rated means of stormwatermanagement. As a first step it is importantto manage the ‘sponge’ (soil and flora)before anything else. Soils should also be

engineered to manage key nutrients suchas phosphorus. As nitrogen is very difficultto remove from stormwater, there is aneed to use plants in every above-groundstructural BMP.

• Some 80% of US BMPs studied havedelivered less than desired results. Forexample, CalTrans undertook a $30-40 million(£16-24 million) study on BMP performanceand did not find satisfactory performance.However, the major effort in terms ofstormwater management for highways isfocused on the ‘during construction phase’. Alot of schemes, such as road widening, areexempt from stormwater regulations.

3.6.1 Infiltration systems

• Infiltration systems have their place ifproperly engineered (and constructed) andused appropriately – but not at large scale,as they may suffer from clogging. However,there is a need for more investigations toensure infiltration performance problemsare not because of bad construction and/ormaintenance needs. It is possible to returnthe effectiveness of infiltration pavementsto almost 100% by both vacuuming and sonication.

• If infiltration systems can be better linkedto groundwater recharge, with qualitycontrol, they may be useful in waterstressed areas. In Oregon, state regulatorsare concerned about the polluting impactsof stormwater on groundwater and haverequired special permits for any newinfiltrating BMPs. There is little knowledgeabout the adsorption processes that occurin media or soils in infiltrating systems,although these are the key to dealing withmetal removal from stormwater.

• Pre-treatment is an essential component(sediment removal) before infiltration in thetreatment train and it frequently may be

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17 Water Integrated Device Giving Effective Treatment (Bob Pitt)

achieved using buffer strips. Engineered‘smart’ media are required in infiltrationsystems in order to remove both metalsand nutrients as the use of natural mediasuch as sand is ineffective. Althoughstormwater infiltration systems may have alot to learn from water treatmentexperience and research. There is a rangeof smart media or infiltrating surfaces nowbeginning to emerge, such as cementitiouspermeable pavement (CPP). However, untilthese are taken up by manufacturers theyare not likely to be widely available oreconomic to use.

3.6.2 Storage systems

• Storage is one of the most common formsof BMP and can be very effective at bothquantity and quality control. Ponds in seriesare better than a single pond of the samesurface area, but the removal performanceefficiency of each pond is not the same asfor a single pond alone. Unfortunately,some BMPs are simply ‘HIGS’ –holes-in-ground that are not maintained or performaccording to design. Unless effectivecontrols of sediments in inflows toconstructed wetlands are utilised, thenfacilities can become depositories forhazardous pollutants. Pre-treatment is anessential component (sediment removalusing, eg a sediment trap prior to largescale storage. Hydraulic loading appears tobe the only controlling factor for solidsremoval in ponds and planted wetlands.

• Retention times need to be at least 24-48hours, preferably 72 hours. Pond sizeshould be able to cope with 90% of theannual storm. When assessingperformance conductivity appears to be agood correlator of pond quality parametervariability. There is a byelaw requirement inCambridge, Massachusetts, for developersto store between the two and 25 yearstorm and also to provide 25%impermeability. In this example, and

elsewhere, multiple outlets are needed toensure appropriate capture and release ofdifferent types of event. The city ofCambridge, Massachusetts, has developeddemonstration examples of how to bestmanage stormwater (to be applied as anexample to the new police headquarters)and shown as part of therecommendations for use by developers.

• Steel corrugated pipes should not be usedto store stormwater unless the frequencyof their replacement is built intomaintenance programmes.

• The maintenance of ponds in whichdeposited sediments are removed typicallyhas no effect on stormwater sedimentremoval efficiency. Sediment removal doesimprove COD concentrations as most CODloads seem to be as a result ofdecomposing leaves, depending upon theseason. Classification of residual arisings isan important consideration in the ability toutilise innovative approaches tostormwater management – as disposalmay be costly and difficult.

• CFD modelling is very effective at assessingthe performance of settling systems, butshould be linked to pilot studies.

3.6.3 Green-roofs, trees, street gardensand inlets

• Green-roofs can be very effective, with arunoff coefficient of 0.1 likely from a greenroof compared with 0.9 from aconventional roof. Green roofs can alsosignificantly improve water quality andbenefit the usage of energy over the life ofa building through helping cooling in thesummer and heating in the winter. Otherbenefits accruing to users of green-roofsinclude a gain in planning benefits, such asan allowance to construct an extra storeyon buildings in Portland, Oregon, where agreen-roof has been used.

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• Some of the demonstration approaches inCambridge, Massachusetts, are innovative,particularly in showing how effectivegreen-roof storage can be. These use acombination of both green-roof surface andon-roof storage.

• Stormwater planters and water gardendesign can be effective and these systemshave been well developed in Portland,Oregon. Trees older than 10 years are veryeffective at managing stormwater quantityand quality. However, Portland street gardensystems are not viable in areas where thereis pressure on car parking on streets.

3.6.4 Other BMPs, stormwatermanagement and related issues

• There appears to be promising proprietarysystems for a range of pollutants, includingfor inlet controls for solids and bacteria;however, there is as yet insufficientindependent evidence to confirm this.Product development and take-up requires athree stage process: lab-pilot-field scale andindependent verification. Because of thisvarious full-scale trials are underway acrossthe US, partly funded by manufacturers andpartly by regulators to assess theeffectiveness of a range of types of system.

• As yet there are too few US applications togive credibility to the new generation of Up-Flow filter technology to UK applications.

• In Massachusetts, plumbing codes nowrequire low flush toilets. There is also arequirement to modify these and ensurethat there is no risk of backflow siphonagewhen there is major building refurbishment.

3.6.5 Non-structural BMPs

• Effective public and stakeholderengagement is the most important aspectof non-structural BMPs (see 3.8). This isrecognised as an essential component of

the CWA which seems to be much clearerin this regard than the WFD.

• The lesson that non-asset basedapproaches (non-structural) can be moreeffective than building yet more assetsneeds to be emphasised for UKapplications. Current institutional boundariesalso need to be addressed to make the useof these systems more viable. For example,a series of small contributory schemes maybe as effective as and more sustainablethan one single large additional asset.

• Control at source is the most effectiveBMP and as part of this a new generationof US street cleaning machines can nowremove up to 80% of all sediment particlesize fractions.

3.7 Sewer related issues

• There are similar issues in the US as in theUK related to a mixture of combinedsewerage (mainly in the denser urbanconurbations) and separate stormwater andsanitary sewerage. CSO control is asimportant for the combined sewers in theUS as it is in the UK. They have similarproblems related to separate stormwatercontrol, although there are additionalproblems in the US because of overflowson sanitary sewers (these are not dealt within this report). Infiltration and inflow (I/I) is amajor problem across the US and it isextensive in all types of sewerage system.This includes not only infiltration, but wrongconnections between storm and sanitarysystems. For example, I/I is typically 50-60% of the flow even in notional sanitarysewers in the MWRA area.

• The continuous measurement of flow insewer networks is considered essential to:(a) understand performance and I/I; (b)target and improve maintenance efficiency;(c) optimise performance; and (d) allowproper calibration of computer models

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(quality modelling is not done, except forreceiving water coliforms FCs/EC). In theMWRA area charges are based onmeasured sanitary sewage flow. There is asubstantial I/I control programme workingright across the catchment in Boston (withthe remotest areas being some 20 miles(33 km) away from the city centre).

• Any new developments in the MWRA areawhich will add additional flows to thesanitary sewer network have to providecompensatory reductions elsewhere in thenetwork of between 3-15 times theproposed new inputs.

• Studies in Cambridge, Massachusetts, byMWH have shown that rain caught incatchbasins can be used locally toeffectively flush sanitary sewers to keepthem clean of sediment. Daily in-sewerflushes can also control fats, oils andgreases in sanitary sewers.

• There has been a number of large sewerstorage tunnels proposed to deal with CSOproblems. For example, the ‘big pipe’ inPortland, Oregon. This is, however, nowsmaller than first envisaged due to theeffectiveness of a stormwaterdisconnection programme. However,despite evidence that the ‘big-pipe’ may nolonger be needed longer-term, it is goingahead anyway because of the shorttimescale for implementation of the CSOclean-up programme (2011).

• One innovative proposal in Portland,Oregon, is that during dry weather it maybe useful to divert separate stormwaterfrom ‘nuisance flows’ (such as baseflowfrom irrigation and other domestic inputs,which is up to 150 gallons/house per day)into the sanitary system, which will havespare capacity and hence allow these flowsto be treated.

3.8 Public engagement

• Gearing of public engagement fiscalincentives from stormwater serviceproviders to also include retailers can helpsupplement expenditure and also raiseawareness. For example, from targeted treeplanting subsidies for householders linkedto discounts from retail outlets in Portland,Oregon. In the UK, subsidies for rain waterbarrels from sewerage undertakersexperience high levels of uptake, but cannotcope with demand at times of drought.

• Innovative funding schemes can be usefulin promoting awareness and engagementand there should be more national subsidyoptions for engaging householders instormwater management. Unfortunately,the enhanced capital allowance (ECA)scheme applies only to industry. More UK government efforts via subsidies, grant schemes and other means arerequired, along the same lines as energyefficiency promotion.

• School education is a major opportunity toraise awareness in stormwatermanagement. Sea Life Centers andequivalent public facilities, with speciallinks to stormwater as at Norwalk, are verystrong vehicles for raising awareness,engagement and thence improving waterquality in coastal areas through educationand encouraging more willingness to payfor better stormwater facilities.Unfortunately, in the UK the nationalcurriculum may be a constraint to usingthese approaches to improve awarenessand responsibility in schools.

• Across the US, direct citizen involvement inmanaging boards for stormwater utilitiesimproves community engagement andcommitment. For example, inMassachusetts local communities decideindividually if tariffs should be rising,declining or fixed for both water and

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sewage. Communities in MWRA competedwith each other to be more efficient andwater, sewage and stormwater werepolitically controlled functions within thecommunity. Hence politicians are seen asaccountable for inefficient services.

• Public choice about expenditure onstormwater management is part of decisionmaking in Cambridge, Massachusetts. Thehigh proportion of intellectuals living in thecity are strongly engaged in the decisionmaking processes and their views need tobe taken into account. The use ofprofessionals living locally (eg architects) indesign details can help keep the localcommunity on board with new facilities forstormwater management.

• In LA city, community representatives havealso been directly involved in determiningwhere the funds raised by the stormwaterbond should be spent; although there issome concern that the funds raised will bemisappropriated for uses other thanstormwater improvements. Unlike the US,the distance of UK consumers ofstormwater services from decision makingprocesses is a major barrier to their effectiveengagement and better stormwatermanagement. It is unlikely that the newCCW will be able to bridge this gap.

• Unlike the UK there is no public warningsystem for flooding risk in Cambridge,Massachusetts, despite frequent (one-to-two year) flooding.

• Metering of sewage from connectedcommunities into the wastewaternetworks operated by MWRA is universaland encourages the control of I/I bycommunities themselves. This is despitethere being no reduction in charges formore efficient households, as capitalinvestments in the sewerage andstormwater networks needs to be repaidover 25 years. In the same area, waterusage of 340 million gallons (1,530 Ml) per

day has been reduced by 120 milliongallons (540 Ml) per day as part of adistribution system leak detectionprogramme (also an I/I programme). Thishas resulted in water usage returning to1911 levels despite an increase inpopulation in the Boston area.

• Effective engagement is also required withthe service deliverers and in MWRA,employees have embraced newtechnology and multi-tasking with rovingcrews with no job demarcation.

• The most effective ways ofcommunicating with the public in relationto stormwater systems have to beappropriate and directly relate lifestyleimprovements and recreational benefits tocosts and investments.

• Stormwater disconnection incentives needto be communicated effectively andpitched at a level to make theseworthwhile to householders. In Portland,Oregon, total stormwater charges (whichare separately billed) can be reduced by athird by disconnections. Public awarenesscan be heightened about water systems ingeneral with specific campaigns aimed at,for example, disconnections. The use ofposted ‘my stormwater is disconnected’signs on property as seen in Portland, canencourage wider community take-up.

• Changing existing stormwater systems tothose that are more effective andsustainable takes a long time, and keepingcommunication working for such longperiods can be challenging. ‘Public agencies’have a duty to ensure proper stories are toldto ensure continuing support over lengthyperiods of change. This also requires trust inthese agencies by service users. Continuingmessages using permanent displays atstormwater treatment facilities can be usedto promote and maintain public awarenessby making these a public feature, asillustrated by the SMURFF facility in LA city.

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3.9 Sources of diffuse pollution

• Stormwater pollution arising fromagriculture is poorly understood in the US,although it is known to be important. Thedifficulties of controlling diffuse pollutionarising from agricultural runoff are similar inthe US to the UK and there are no obvioussolutions to deal with this.

• In urban areas the majority of pollutantsare transported by the most frequent butsmallest storms with less than one yearreturn period. 75-80% of all pollutantsoccur in only one-tenth to two-tenths of aninch (2.5–5 mm) of runoff. The mainsources of problematic pollutants that findtheir way into stormwater runoff are fromolder neighbourhoods and where carsowned by the poorest inhabitants dripmost oil. Other problem areas includewhere there are vehicle stop-startmovements, eg supermarket car parks.

• Diffuse pollution can arise from watersolubility of building materials such as the copper pipes used in domesticplumbing. These materials should be inertto water solubility.

• Property owners and users may beirresponsible in their domestic use ofpesticides.

• In LA city there is a huge homelesscommunity that creates a lot of trash inparticular areas. Because of this ‘bin-raking’,the city cannot provide trash bins as rubbishis thrown all around the streets; hence theyare only being provided in commercialareas. Street sweeping and gully cleaningoccurs once a week and cars parked in theway are fined. Current strategy formanaging litter and trash enteringstormwater systems is in tackling high trashareas first and intensively, sometimeshourly. This is in addition to extensive trialsusing catchbasin inlet screens.

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4 RELEVANCE TO UK PRACTICE

4.1 Water Framework Directive (WFD)

and other standards

The CWA has a number of similarities to WFD.However, the CWA has now been around for 30years with a target of final phase IIimplementation of 2008. The WFD encapsulatesa lot of similar concepts to the CWA, but WFDimplementation is expected over a muchshorter time frame (approximately 10 years fromnow). In addition, the CWA is delivered throughan NPDES system and specified TMDLs,whereas the WFD is expected to result in a so-far undefined ‘good ecological status’ for waterbodies. The latter also requires the 100%removal of certain priority hazardous substancessuch as cadmium and nickel.

Many of the water quality standards that areenforced in the UK, such as the urban wastewater treatment directive (UWWTD) havefocused on the quality issues relating tofoul/combined sewer pollution. Surface waterhas not been subject to the same degree ofquality control. Apart from the imposition ofpetrol/oil interceptors when high levels ofpollution are expected, there is little to be foundin the form of treatment other than in Scotlandwhere there has been a greater interest intreating stormwater. It is often the case thatsurface water runoff arrives untreated at thewatercourse or into tidal waters. The USevidence shows that wet weather runoff cancontain high levels of contaminants and oftenthe most persistent and bioaccumulativesubstances such as heavy metals. Treatment inthe US can take many forms, such as bio-swales, filter media and bespoke commercialdevices. Unfortunately, the standards set forTMDLs, for example, may not be easily appliedor realistic as illustrated in the extract from theEPA website in table 2.1.

Some of the requirements to removepollutants from stormwater can be overlyonerous. This is true of both the CWA andWFD. There is a need to be cautious whenexpecting the removal of ‘all’ (no de minimisconcentrations) of a certain pollutant such ascadmium or nickel as these, and other prioritysubstances, are naturally occurring in theenvironment, come from sources other thanwastewater emissions and in any case, totalremoval from stormwater is actually notpossible with current technologies (see alsoHouse of Lords inquiry report on WaterManagement, June 2006).

Additional difficulties relate to monitoring andcompliance testing. It is clear that full scalesampling requirements to ensure compliancecan be substantial and hence costly. There isa need to be realistic in the approaches taken;solutions should be provided to satisfy valuefor money, as well as environmental concerns and not just arbitrarily set ‘technical’ standards.

4.2 Institutional similarities

The biggest difference in issuing permitsbetween the US and UK is in the use ofNPDES. In the US the issuer of the NPDESwill generally be the organisation chargedwith adoption and maintenance. It istherefore in its own interest to get thestructures constructed well and to regulatethese appropriately. Where managementcompanies have been used, the legalframeworks controlling them have to be verytight to ensure that responsibilities are clearlydefined. The use of stormwater managementcompanies is now emerging in the UK – suchas the ‘Green Belt Company’, but this canonly be described as ‘early days’.

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In the US there is a wide variety ofresponsible bodies for managing stormwaterand delivering the requirements of the CWA.The Federal and municipal sectors are heavilyinvolved in regulation and delivery of goodpractices and even in managing stormwatersystems. This diversity has both good and badaspects. It is good in that municipal deliveryseems to be very effective at stakeholderengagement and promotion of individualresponsibility. Disadvantages include the lackof consistency between stormwater serviceprovision and lack of nationally agreed designand operational standards. In the UK it wouldappear that in many cases the mostappropriate and responsible body for theadoption and maintenance of SUDS is thesewerage undertaker. However, delegatingpowers to others such as local authoritiescould be considered, particularly in largetowns and cities. Alternatively, separatestormwater management utilities/companiescould be established.

The closest example to the UK modelwitnessed in the US was the MWRA,although this is entirely state owned.However, there are many differences in theway it operates, the most important of whichis its direct funding from taxes and chargesbased on measured sewage flow rates; witheach municipal area being responsible for itsown sewage and stormwater systems up tothe point of connection. Other majoradvantages are that citizens have directinvolvement in funding decisions and theorganisation is non- profit making.

4.3 Stormwater Profile and Public

Engagement

The revision of PPG25/PPS25 and theconsultation and delivery of ‘Making space forwater’ are probably the biggest incentives sofar in England and Wales to engage the widerstakeholder community in an understandingof surface water runoff, climate change andtheir place in the planning and development

process. The development of flood maps andtheir effect on insurance premiums has alsohelped concentrate thinking; however, theserelate to main rivers and coastal flooding andare of less significance for local pluvialflooding of the type caused by stormwater.

Much of the planning guidance onPPG25/PPS25 relates to the precautionaryprinciple and great weight is given to floodingaspects and the control of flood water.Unfortunately, the implementation of the floodmaps can be over-zealous by officers whohave little experience or knowledge of thedevelopment process. It has been known fordevelopers to be asked by planners (and theEA) to specify exactly which SUDS device willbe implemented before site investigation andsoil conditions are known. The developer canfeel hampered by this approach and oftenreverts to known parameters with less riskand uncertainty such as pipes andunderground tanks. This is often not thesustainable answer and perhaps there needsto be a ‘commitment’ toward appropriateSUDS techniques and understanding of floodrisk at the planning stage, rather then focusingtoo much on ‘exact’ engineering design.

There needs to be a certain amount ofmutual trust on the part of planners (and theEA) and designers/developers and this couldbe accounted for within the text of theplanning approval. EA is looking to remedysome of these difficulties by improving thetraining on SUDS to its officers and this is tobe commended.

4.4 Planning and the water company

perspective in England and Wales

Typically, UK planning documents and policieshave not accounted sufficiently for theimportance of water within developments,although this is now changing with RSS,LDFs, the SEA and WFD directives.Nonetheless, problems still remain includingthe growth in hard surfaces that occurs due

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to creeping urbanisation – in which lawns areconverted to driveways and patios.

As sewerage undertakers the watercompanies in England and Wales have a role inthe planning process, but this generallyextends only to whether there is sufficientsewer capacity. ‘Right to connect’ undersection 106 is a big issue militating against theuse of SUDS systems and water companiesquite often have to rely on the buildingregulations to force developers away fromconnecting surface water into their sewers. Inany case, it is then possible for future propertyowners to subsequently invoke section 106 todisconnect a SUDS system and connect intothe sewer network if so wished.

The ‘definition of sewer’ also precludesadoption of many types of natural drainagesystems as the sewerage undertaker onlyhas a right to adopt a ‘sewer’ which has aproper outfall.

Primary legislation is required to enable watercompanies in England and Wales to properlyfund SUDS so that they can arrange adoptionand maintenance standards. The Seattle modelis an excellent example of stormwater funding.The only other alternative in a lot of cases isthe use of ‘management companies’ – but thisis not ideal because of wider legal difficultiesand problems of long-term ownership.

There are known difficulties with off-siteponds with legislation relating to groundwaterinfiltration. This makes adoption andmaintenance very difficult. Until thegovernment acknowledges and addresses theproblems associated with the legislationthere will be continuing problems in relationto the types of system that can be built. As itis likely that SUDS may be the only way inwhich WFD compliance can be achieved inthe future, these problems need to beaddressed with some urgency.

‘One size does not fit all’ and the currentplethora of organisations responsible forstormwater (as recognised in making space forwater) require greater freedom to developcooperation, appropriate and agreed standards,and also raise and allocate revenueappropriately to deliver the best solutions. Inorder to do this the organisations need to beheld more accountable to their stakeholders.One way of doing this is by direct engagementof the public in the decision making boards toensure transparency and clarity.

4.5 Redefining UK sustainable

drainage

The precise terminology relating to sustainabledrainage systems varies around the world.There is even confusion in the US betweenBMP and LID. In the UK there has been abelief for some time that the term ‘SUDS’ isconfusing, misused and potentially redundant.It has for too long conjured up a misplacedbelief that all SUDS should be a ‘natural BMP’,but this is inaccurate. The contemporarybalance for a surface water management trainmust surely lie in a toolbox of sustainabledrainage techniques that includes both naturaland proprietary BMPs as well as pipedsystems where appropriate, set within theconcept of LID. The sustainable drainagemission to the US has only served to reinforcethis view and ‘sustainable drainage BMPs’ may be a more appropriate definition,incorporating natural, proprietary and traditionaldrainage techniques.

It is also clear that the selection ofcontemporary sustainable drainagetechniques goes beyond the key definitiontenets of quality, quantity and amenity,although all three are all still authentic andvalid. The US mission underscored theimportance of construction and maintenancetowards successful implementation andlongevity; and there is an overriding need tounderstand the whole life costing ofsustainable drainage BMP selection for the

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UK water industry (see Anglo-US project‘Performance and Whole Life Costs of BestManagement Practices and SustainableUrban Drainage Systems’ (05/WW/03/6)). Ifan analysis of this ideology, including theimportance of applying whole life costingresults in an oversized concrete pipe with aflow control as the preferred solution for agiven context and set of implementationparameters, then that by definition isnonetheless a ‘sustainable drainage system’.

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5 TOP 10 CONCLUSIONS AND RECOMMENDATIONS

These are selected as those of most potentialsignificance to the UK and in many casesreinforce what is already known.

5.1 Conclusions

Drivers/reasons

1 The perceived need to clean up theenvironment, reflected in increasinglystringent environmental legislation andregulation as specified respectively in theCWA and the WFD, is the main driver fortackling stormwater in the US and UKrespectively. In the US, flooding andclimate change are not as significantdrivers as they are in the UK. In addition tothe threat of prosecution, a significant USdriver for the better management ofstormwater is also the nature and use ofthe water body being discharged into (egocean, fishing water, stream and amenityuse), and the resultant negative impactfrom pollutants on every day lives. Peoplerecognise the benefits of living in acleaner, healthier environment.

Technology

2 Novel and more flexible approaches tostormwater management are becomingmore important for addressing the driversdescribed above in the most sustainableway possible. The technologies to do this(such as BMPs, LIDs, SUDS andassociated software and IT tools) are stillemerging and developing an understandingof whole life performance. New ideas andversatile systems that will assist withparticular applications in the UK areneeded, such as high density housing,retrofitting to resolve existing problems

and to meet the requirements of the WFD.Compared with the US, the UK has greaterchallenges as to how stormwater can bemanaged due to limited space, particularlyin urban environments.

3 Proprietary systems are providing solutionsfor dealing with particular water quality orquantity problems. However, because ofthe way in which the industry is regulatedin the US, manufacturers are beingencouraged to make unrealistic claims withregards to the efficacy of proprietarysystems. Although these systems areeffective when applied appropriately andcan provide some valuable solutions forremoving contaminants, there is noevidence that there is a ‘magic bullet’device that can provide all of the treatmentneeds in a single unit.

Disconnection/stormwater removal

4 US experience has shown that theincremental and localised small-scalemanagement of stormwater, such as:evapotranspiration techniques; green-roofs;bioremediation, water gardens and/ordisconnecting existing inputs to majordrainage systems, does collectively providesignificant benefits to managing local anddownstream water quality and quantity.These approaches can also provide otherbenefits such as local irrigation oropportunities for reuse as well asenhancing local amenity. In the UK, it islikely that stormwater disconnections(retrofit) as part of a portfolio of approacheswill become increasingly important (if notessential) to meet the requirements of theWFD, as disconnections could potentiallyreduce both discharge volumes and

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remove significant pollutants fromdischarges into natural water bodies.

Funding

5 It is apparent from US practice that thereare considerable benefits from providinggreater incentives for the use ofinnovative stormwater managementtechniques. These are most effectivewhen the stormwater costs are clearlyidentifiable within charging schemes.Incentives include charges (and discounts)based on directly connected imperviousareas that include hard standing,highways and roads. Clearly identifiablecosts and discounts or rebateopportunities can aid in engaging each ofthe stakeholders, including public,property owners, professionals and otherutilities and service providers.

6 In many areas of the US, separatestormwater utilities (municipal or private)deliver a service associated with a definedincome stream as above. These utilitiesalso raise awareness of stormwater, helpidentify the better opportunities forinnovative management and moreeffectively engage all stakeholder groups.There are clear advantages of suchutilities; however, they need to be properlypositioned within an integrated watermanagement and planning system.

7 Whole life performance and costing ofstormwater systems is needed to includeconstruction, maintenance and theselection of the most appropriatesustainable drainage systems (this mayinclude piped systems). Ensuring effectivedesign and construction is challengingeven in the US. The lodging of developerbonds (refunded on satisfactorycompletion) with the regulatory authoritiesbefore construction can ensure that gooddesigns and construction are delivered.

Public and other stakeholders

8 In the US the CWA makes clearrecommendations about education andcommunity participation. There is a needto build capacity (knowledge andcompetence) within the stakeholdercommunities and also to helpstakeholders understand and acceptinnovatory approaches and technologieswhich may include the need for certainindividuals or stakeholder groups toassume a more responsible role. Thereare a number of excellent examples in theUS including publications andprogrammes offered by the CWP.Engagement is the key to gaining bothmomentum and support and should beclear and concise and at an appropriatelevel to each stakeholder community(including regulators and legislators).

Planning, regulation, adoption andmaintenance

9 The US regulatory framework –comprising CWA-NPDES-TMDL –definition that is devolved and locallydetermined appears to offer a flexibleapproach to the management ofstormwater within context and region.With the future challenges of climate andenvironmental regulations, institutionaland regulatory approaches need to be asflexible and adaptable as possible in orderto be able to respond better to theuncertainties of stormwater managementin the future. This includes ensuring thatstormwater management is appropriatelyprioritised within town planningprocedures, with flexibility for locallydetermined priorities and solutions.

10 There is a wide variety of approaches tothe adoption and maintenance of BMPsand LIDs in the US, from municipalresponsibility to individual householders.Within a particular regulatory area there is

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a tendency to utilise one single approach,for example, in Baltimore County BMPsare almost entirely municipally managed,with inspectors assessing the few thatare private. It is apparent that stormwatersystems should be adopted and managedby a single appropriate agency(organisation or individual) within a localcontext. This may be a separatestormwater utility (See 6 above).

5.2 Recommendations in relation to

more effective future stormwater

management in the UK

1 It is essential to understand current andfuture drivers affecting stormwatermanagement and plan for them. Wherepossible, the implementation of the drivers(eg the WFD, Daughter Directive on PriorityHazardous Substances and consequentimpacts) should be influenced as they willhave major implications for stormwaterdrainage systems in the UK. It will also beessential to consider stormwatermanagement systems as one part of thewater cycle and manage stormwaterappropriately within an integrated context,and as a key part of the planning processbased on, for example, the LID approach inthe US or the WSUD approach in Australia.

2 Notwithstanding recent efforts in the UK,there is a need to invest more indeveloping and evaluating theperformance of sustainable drainagesystems via clearly defined andscientifically robust long-term monitoring.Protocols for monitoring from US studiesand guidance will help to defineinvestigation programmes. This willrequire significant investment and shouldbe recognised by regulators and others asessential for the development of long-term and sustainable stormwatermanagement systems. However, careshould be exercised so that theimplementation of innovative stormwater

controls is not delayed unduly in thepursuit of certainty, ie risk assessmentevaluations should be used in thedecision making processes.

3 There are a number of innovativeproprietary systems that deal withspecific aspects of stormwater problems.It is recommended that these systemsshould only be used where theirperformance is proven by pilot and/or full-scale testing. Further development ofnew devices is needed to addressparticular challenges, such as controllingbacteria and pathogens and as muchsupport as possible should be given topromising emerging technologies.

4 There is a need to better understand theeffectiveness of dispersed solutions to themanagement of stormwater in the UKcontext. Particularly the position of,barriers to, incentives for, andeffectiveness of, the various disconnectionoptions utilised in the US and elsewhere.Costs, risks and institutional barriers needto be considered within a whole systemperformance context. Cross-regulatory andinstitutional barriers arising due to themixed management responsibility forstormwater in England and Wales need tobe exposed and eliminated wherestormwater disconnection is identified asthe best option.

5 An identifiable separatesurface/stormwater charge should beapparent to bill payers in the same waythat sewage and water charges arecurrently identified. Alternatives availablefor stormwater system users to, forexample: disconnect; reuse; fit green-roofs; use alternative lawn fertilisers etc,should be made clear in informationavailable from the EA, sewerageundertakers and others such as the CCW.This should be accompanied by clearindications of the financial support and

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benefits (rebates and also benefits otherthan financial, such as waiving certainplanning restrictions), available foralternatives, along with educationalprogrammes aimed at enablinghouseholders, facilities managers andothers to take a more active role in localstormwater management. As the latterwill not be in the interests of thesewerage undertakers in England andWales (see recommendation 6) because itwill lead to a reduction in income, Ofwatwill need to review the incentives to theundertakers to promote these changes tocurrent practice.

6 Although there is a risk of furtherfragmentation of the responsibilities forwater management, the establishment ofseparate stormwater utilities may beuseful in the UK. These have been shownto be very effective at ensuring theimportance of stormwater in planning andmanagement systems is given a highpriority and also overcomes the problemsassociated with the responsibility foradoption and long-term maintenance.Such utilities may be attractive to existingsewerage undertakers if ‘natural’sustainable drainage systems can bedefined as assets, as this can increasethe benefit to the water companies inEngland and Wales.

7 The limited experience of sustainabledrainage systems in the UK means thatbetter arrangements need to be in placeto ensure good design and construction.This requires a whole life performanceperspective and the education andtraining of all stakeholders, especiallyplanners and building control officers. Inaddition, schemes, such as that inBaltimore in which up-front bonds have tobe lodged prior to construction should beconsidered in order to ensure that thesesystems are properly constructed. Thismay necessitate the establishment of

specialist sustainable drainage inspectors(this may be a service offered byestablished consultants as it is unlikely tobe a local authority capability), who mayalso be trained in other stormwatermanagement aspects such as local floodrisk management advice to householdersand property managers.

8 The capacity to understand and dealeffectively with stormwater within virtuallyall stakeholder communities in the UK islimited. This is also true even in the US(although the CWA recognises andformalises the need for stakeholdereducation). With the changing drivers (andeven current ones such as the WFD), thisis no longer going to be acceptable in theUK. A more concerted and robustapproach to the engagement andeducation of all stakeholders is essential inorder to build the capacity to deal with thefuture challenges. Currently the EA hasassumed the role of educating andbuilding capacity in England and Wales todeal with stormwater amongst certainstakeholder groups. This has to bewidened into a consistent nationalprogramme to include all the keystakeholders and all agencies engaged inany aspect of stormwater management.There is a clear need for a cross-institutionstakeholder engagement and capacitybuilding initiative; however, this is currentlyimpossible due to the inflexibility andintractability of the existing regulatory andinstitutional arrangements that arerestraining the opportunities for innovativestormwater management in the UK.

9 Currently the place of stormwater (andwater) within formal UK planningprocesses is not considered to be veryimportant, although in England variousPPS (eg 11, 12, 25) are bringing waterrelated matters more to the fore.However, other planning guidance(particularly PPS 3) is making the

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implementation of sustainable drainagesystems more difficult due to therequirement for high density development.In view of the future uncertainties fromclimate change and impacts from currentlegislation (WFD in particular), stormwatermanagement will need to take a morecentral role in all aspects of planning. Inaddition, the regulatory system will needto become more flexible and adaptable tonew knowledge, for example recognisingthe need for regionally based buildingregulation, including more performancerelated standards rather than prescriptivespecifications for design details.

10 The case for a single agency to assumeresponsibility for all aspects ofstormwater management is strong. Thisagency would facilitate SUDS adoption(and maintenance) and should alsoinclude responsibilities for flood riskmanagement. This would have theadvantage that one single agency wouldreceive payment for the delivery andmaintenance of the required infrastructureincluding public education andcommunication. Any agency in this roleshould not be constrained by the need tomaintain and own assets, but rather to beable to operate across the whole range ofstructural and non-structural approachesto stormwater management, supportingother stakeholders where appropriate.

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Prof Richard Ashley

University of Sheffield and Pennine WaterGroup (mission leader)[email protected]

Richard is Profeesor of Urban Water atSheffield University and Managing Director ofthe Pennine Water Group (PWG) which is aspecialist centre for water and wastewaterresearch. He is responsible for overall groupoperation, high-level R&D across the variousareas of water management: wastewater;stormwater; and water supply.

University of Sheffield and Pennine WaterGroup (PWG)www.shef.ac.uk/p/pwg

The PWG is a multi-disciplinary specialistcentre for water and wastewater research,and is one of only four such internationalcentres of excellence in water research in theUK. The PWG’s primary mission is to developimproved procedures and support systemsfor the more sustainable management ofwater services, assets and their interactions.

Ian Pallett

British Water (mission manager)[email protected]

Ian is the Technical Director at British Water.He coordinates members’ activities viaindustry focus groups within the TechnicalForum. The Forum facilitates the preparationof industry technical standards, best practiceguidance and information documents andindustry participation in the development andapplication of sound environmental policies.

British Waterwww.britishwater.co.uk

British Water is the lead association for theUK water and wastewater industryrepresenting all areas of the supply chainincluding contractors, consultants,manufacturers, equipment suppliers, andmany specialist service providers. It lobbiesgovernment, regulators and major customersand provides vital information on home andoverseas water and wastewater markets.

David Schofield

[email protected]

David was nominated by Arup as a WaterEngineering Skills Network Champion fordrainage and sewerage, providing technicalexpertise to a wide range of Arup projects.He has over 20 years’ infrastructure andwater engineering experience, includingextensive work on master-planning, analysing,reporting, rehabilitating, designing andconstructing sustainable drainage systems(SUDS) on foul and surface water networks.

Arupwww.arup.com

Founded in 1946, Arup is a professionalengineering consultancy providing worldwidetechnical solutions. Arup’s project portfolioincludes the following key tenets; localknowledge and global expertise, creativebusiness solutions, project creation andmanagement, multidisciplinary design andplanning and engineering consultancy.

Appendix AMISSION DELEGATE DETAILS

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Richard Munden

Copa [email protected]

Richard is the Business Development Director for Copa Limited, part of the CDSgroup. He has been in the water industrysince 1989 and was responsible for thecommercial introduction of the submergedaerated filter (SAF) for sewage treatment insmall communities.

Copa Limitedwww.copa.co.uk

Copa Limited is the European division of CDSTechnologies, a multi disciplined companyoffering a comprehensive range of products,wastewater treatment technologies andprocesses along with storm watermanagement solutions for attenuation, flowcontrol and storm water overflow treatment.The products are focused on the municipalwater treatment market.

Alan Rafelt

Environment [email protected]

Alan is the Regional Strategic andDevelopment Planning Team Leader withinthe Flood Risk Management Function of theEnvironment Agency. His principleresponsibility is to lead the regional team toproduce, develop, and maintain a long-termand integrated plan for sustainable flood riskmanagement with a three to 50 year horizon.

Environment Agencywww.environment-agency.gov.uk

The Environment Agency is the principalenvironmental regulator in England and Wales.It was established in April 1996, and is theleading public organisation for protecting andenhancing the environment in England andWales. The Agency’s vision for theenvironment is ‘a better place for people andwildlife for present and for future generations’.

Alex Stephenson

Hydro [email protected]

As Director of the UK Stormwater Division,Alex is responsible for the day-to-day running of the business based in the headoffice in Clevedon, Somerset, and liaisesclosely with the Wastewater division basedin Ely, Cambridgeshire. Alex is also currentlythe convenor of the British Water SUDSFocus Group.

Hydro Internationalwww.hydro-international.co.uk

Hydro International plc provides innovativeproducts for the cost effective control andtreatment of water. The group has developedtechnologies to control stormwater, combinedsewer overflows and municipal wastewaterand, in recent years, has developedconsiderable expertise in computational fluiddynamics (CFD) simulation.

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Stuart Ramella

Polypipe [email protected]

Stuart manages set research anddevelopment projects, which predominantlyinvolves the design and development of newproducts from beginning to end. Stuart hasalso had involvement in SUDS development,not only within Polypipe, but also throughinvolvement with the CIRIA working group fordocument providing guidance sustainabledrainage systems.

Polypipe Civilswww.polypipecivils.co.uk

Polypipe Civils Ltd belongs to the PolypipeGroup of companies, which is one of thelargest plastics manufacturers in Europe withproducts predominantly aimed at theconstruction/building industries. PolypipeCivils Ltd manufactures and supplies productsinto the civil engineering, construction,utilities and agricultural industries.

Kate Zabatis

United Utilities North [email protected]

Kate is responsible for developingwastewater network policies and strategiesand ensuring that all regional wastewaternetwork expenditure projects are in line withthese strategies. She represents thecompany on issues such as SUDS, first timesewerage and contaminated surface waters.Kate also delivers the company’s response tonational consultations such as ‘privatesewers’ and ‘sustainable drainage systems’.

United Utilities North West (Subsidiary of UU Plc)www.unitedutilities.com

United Utilities manages and operates theregulated electricity distribution and water andwastewater networks in north west England(UUNW). United Utilities PLC also owns twosupport services businesses: United UtilitiesContract Solutions and Vertex. Thesebusinesses supply infrastructure managementand business process management in theprovision of service to others.

Jeremy Jones

Welsh [email protected]

Jeremy Jones is a specialist in the field ofsewer and stormwater networks andtreatment. He provides specialist advice onthe implementation of SUDS and has beendeveloping guidelines and procedures fortackling the key issues of adoption andmaintenance. Jeremy is the Secretary of theSUDS Working Party for Wales.

Welsh Waterwww.dwrcymru.com

Welsh Water (DCWW) is a company thatsupplies drinking water and wastewaterservices to most of Wales and western partsof England. It is the only utility company notowned by shareholders, being wholly ownedby Glas Cymru, a single purpose companythat exists only to provide better valueservices to Welsh Water’s customers. It istop of the Government’s ‘OverallPerformance Assessment’.

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Appendix BHOST ORGANISATIONS AND ACKNOWLEDGMENTS

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Date Location/activity Contact Report responsibility

13 March Baltimore CountySite visits

Al Wirth Supervisor, Storm Water Engineering DEPRM [email protected]

Steven Stewart Natural Resource Manager Watershed Management and [email protected]

Scott PorterBaltimore County DEPRM [email protected]

Tom Vidmar Baltimore County DEPRM [email protected]

Dave Outen Baltimore County DEPRM [email protected]

RichardAshley

14 March Ellicott City, Maryland1. Center for Watershed Protection

Jennifer Zielinksi [email protected]

Tom [email protected]

RichardAshley

2. Low Impact Development Center Neil [email protected]

AlanRafelt

15 March Edison, New JerseyUSEPA Wet Weather Center Urban WatershedManagement Branch National RiskManagement Research Laboratory

Richard Field [email protected]

AlanRafelt

Norwalk, ConnecticutSite visit to Abtech smart sponge

Rodolpho B ManzoneExecutive Vice President Chief Technology [email protected]

Graham Martin-Loat Source Control [email protected]

DavidSchofield

16 March Portland, MaineHydro International conference – The ChangingFace of the Stormwater Industry

Prof Bob AndohHydro International [email protected]

AlexStephenson

17 March Boston MWRA Dennis DohertyJacobs Civil Inc [email protected]

Frederick A LaskeyExecutive Director Massachusetts Water Resources [email protected]

Michael J HornbrookChief Operating Officer Massachusetts Water Resources [email protected]

Jeremy JonesKate Zabatis

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Date Location/activity Contact Report responsibility

18 March BostonMorning seminar on John Sansalone’s work onsurface drainage in Florida and elsewhere

John Sansalone

Associate Professor Dept of Environmental [email protected]

Richard Munden

20 March Portland, OregonMorning seminar on regulations and raingardens at Portland City offices, Bureau ofEnvironmental Sciences. Afternoon site visits arranged to ecobuildingsand other sites. Evening working dinner.

Tom Liptan

Landscape Architect City of Portland’s Bureau of Environmental [email protected]

John Gardiner

Suri Futures [email protected]

Dean Marriot

Director of Environmental [email protected]

StuartRamella

21 March Portland, OregonWest Coast applications of LID

Eric Strecker

GeoSyntec [email protected]

Wayne Huber

University of Oregon [email protected]

DavidSchofield

22 March Seattle City CouncilSEA streets

Tracey Tackett

Senior Civil Engineer Seattle Public Utilities Drainage/Wastewaterand Solids Waste Engineering Division [email protected]

Mara Rogers

Seattle Public Utilities [email protected]

Jeremy JonesKate Zabatis

23 March Los AngelesSite visits to see small and large stormsystems being cleaned out. Then session with municipal engineer onmaintenance issues and afternoon workshopon six areas of interest.

Richard Munden

Business Development DirectorCopa [email protected]

Barry Febey

CDS Technologies [email protected]

Mark Cuneo

CDS Technologies [email protected]

Richard Munden

24 March Los AngelesCity of Los Angeles officials and roadwaydrainage.Abtech – roadway catchpit inserts and smartsponge.

Rodolfo B Manzone

AbTech [email protected]

Duane E Cook

AbTech Industries [email protected]

DavidSchofield

Appendix CVISIT REPORTS

C1 Baltimore County Council Offices,

Towson, Baltimore County Dept of

Environmental Protection and

Resource Management, Maryland.

(http://www.co.ba.md.us/Agencies/environment/)

Visited: Steve Stewart (watershed protection,monitoring and management), Tom Vidmar(Deputy Director), Scott Porter (stormwateroperations/capital and maintenance), Al Wirth(stormwater management planning), DonOuten (policy, education, research, GIS andcommunity links).

Date: 13 March 2006

Purpose: To discuss and review (with sitevisits) drivers, delivery and current regulatoryframework for BMPs, delivery of NPDES andTMDL programmes, performance, design andmaintenance of BMPs and associated issues.

Information provided

There were no formal presentations;information was provided via dialoguebetween the mission and BCC staff. A visitwas made to Owings Mills’ high-densitydevelopment.

Summary

Baltimore County is the third largest county inMaryland and nearly surrounds the city ofBaltimore; 90% of the population is served bypublic water and sewers and drainage passesto the Chesapeake Bay. Baltimore County is acorporate and political body which performsall local government functions. Since the mid1970s it has focused development within anurban growth boundary. Today, more than

85% of citizens live inside the growthboundary on one third of the land. Theoutlying areas have been zoned to protectagriculture, reservoirs, and forests. BCCDepartment of Environmental Protection andResource Management (DEPRM) is theenvironmental focus for the county. It hasdeveloped an active programme for streamrestoration (using Rosgen-based naturalchannel design) and stormwater BMPs.Restoration is driven by the more than 85%of development which pre-dated theenvironmental controls which were enactedafter the 1980s. DEPRM has an educationalspecialist devoted to working withbusinesses, citizen organisations and homeowners to provide education aboutalternatives for the use of non-structuralBMPs. They have promoted the state ofMaryland’s Green Schools programme andhave more certified green schools than anyother county. The provision of water andtreatment of wastewater are theresponsibility of the city, and the county paysfor these services under a long-standingintergovernmental arrangement enactedunder law. Under recent state law changes,stormwater requirements for newdevelopment now require five dischargevolumes to be accommodated (recharge,stream channel protection etc). BCC is a largeinvestor in watershed planning ($2 million(£1.1 million) in local funds to complete plansfor nine of 14 major watersheds). It conductswater quality modelling (SWMM) for pollutantrunoff and channel stability assessments andhas completed close to 30 stream restorationprojects, restoring more than 53,000 linearfeet (1,346 metres) of streams at more than$12 million (£6.5 million) investment. Many of these projects also incorporate stormwater improvements.

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The CWP is located in Ellicott City (seeseparate visit report) and has helped the stateto write the stormwater design manual. BCCowns most stormwater structures, whereasother counties in MD want to thrustresponsibility onto the homeowners. BCCconsiders this problematic. In 2002Montgomery County took ownership of1,400 previously privately-owned structuresas it was resulting in unreliable management.A developer wanting to build 30 houses onland between two communities wouldnormally have to show a concept plan to thecommunities that shows the general locationof any stormwater structures. However, theBaltimore County Code 1 states that thisshould also include preliminary hydrologiccomputations, type, size and location ofstructures, and verification of a suitableoutfall. The outfall is crucial – the generalpublic do not want a pipe pointing straight attheir house. BCC looks at the existingdrainage patterns on the site, and tries toencourage sheet flow to a wetland or the useof buffers to spread the flow. For the last 28years there has been an attempt in the regionto get stormwater utilities to deal withgovernance and to fund maintenance foroverall stormwater problems. These utilitiesexist all over the US except in Maryland,where only Montgomery County hasauthored a statute. Baltimore Countycurrently builds the bill for inspection andmaintenance into the rest of the watershedprogramme that the citizens pay for in taxes.

Conclusions and observations

• Chesapeake Bay ‘critical area’ designationand high public awareness are seen as themain drivers for getting politicians tointroduce legislation and the public to bemore interested in stormwater (quality).

• Wetland buffers, tree (re)forestation usedto improve stream protection.

• Strong and well-developed controls onconstruction site runoff based on longexperience of application.

• Priority for stormwater management is safety> function > aesthetics for maintenance. Thestate owns some 800 stormwater facilitiesand this will rise to 1,500 or so shortly. Thereare some 1,500-1,600 privately operatedstormwater facilities. The county approvessome 300-400 stormwater plan submissionseach year out of a total of 1,500.

• All private stormwater facilities are inspectedevery three years by Baltimore County.These must have agreed maintenance ruleswhen built (stated in NPDES permit).

• State of Maryland manual sets out qualitystandards, specifying the type of BMP toachieve standard – using a ‘deemed tosatisfy’ approach. Currently, 80% removalof TSS and 40% of P.

• Capital costs of BMPs planned in adevelopment are held up front by thecounty, then only returned to the developeronce ‘signed-off’ as built and after one yearof post-construction.

• Zoning regulations restrict creepingurbanisation in housing areas.

• Detailed development controls are used forstormwater where there is more than5,000 square feet (465 square metres) of development.

• Typical designs from consultants areinadequate and because of the longexperience in Baltimore County, theengineers have more extensiveknowledge and hence are better able tojudge (in)effectiveness of plans. BaltimoreCounty engineers have delegated damsafety endorsement from US Corps ofEngineers.

• Maryland County sees advantages inmaintaining – as control and land ownershipare seen as beneficially long-term.

• The site grading plan is the baseline – thisis the maintenance of land form and layoutto retain natural drainage characteristics asfar as practicable.

• Stream erosion and sediment control is amajor objective (was two year returnperiod, Al Wirth thinks this should changeto one year) and is regulated by the Soil

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Conservation Service (SCS) for constructionphase (also responsible for farm plans).

• Public awareness and behaviour is seen asessential in delivering an environmentalimprovement programme. Lots ofinitiatives: green schools; growing home($10 (£6) toward new tree, with $5 (£3)payback from county to retailer).

• Most developments become maintainedby the county – and the developer candecide that the Home OwnersAssociations will be responsible. Noreductions in taxes where stormwater isprivately managed and standards ofconstruction must be identical to thoseadopted by the county.

• Baltimore County use 42 inch (1 metre)high chain link plastic covered fences.Margins typically slope at 3:1.

• Original state specifications stated thatinfiltration should be the first option.Problems were found with fine sedimentclogging, and now infiltration is rarely used.Many early systems had no overflows orbypasses when blocked. Most facilitiesnow use offline ponds.

• Largest facilities have 2 feet (610 mm) offreeboard for 100 year event and use roadsas flow paths.

• Ten watershed management plans havebeen set up considering quality impacts anderosion of streams. Channel plans to takeincreased flows, but with natural form. Latest project is Gwyms Falls with130 possible projects ($30 million (£16million) estimate).

• So far these plans have not focused onTMDLs and need to be revised. Non-structural options seen as essential indelivery with strong community involvement.

• Some problems with convincingcommunities – eg West Nile virus has ledto the shelving of plans for shallowmarshes in one community.

• Now getting money into communityWatershed Associations to help deliver on-the-ground solutions. This includes lots ofnew media outputs to change behaviour.

Visit to Owings Mills development

Owings Mills is one of Baltimore County’sdesignated growth areas with a population ofmore than 20,000 located within the fast-growing northwest section of BaltimoreCounty, less than half an hour’s drive fromthe city. The median household income isabove state average as is the median housevalue. Hispanic race population percentage isabove state average. Building density is fromfive and a half-up-to-16 units/acre. There is alot of green space between the clustereddevelopments, some of which comprisesstormwater ponds (mainly dry). See below.

Exhibit C.1 Owings Mills – apartment developmentswith detention pond in foreground

Exhibit C.2 Owings Mills – pond serving a retail andoffice cluster

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C2 Center for Watershed Protection

(CWP), Ellicott City, Maryland

Visited: Dr Jennifer Zielinski (ProgrammeDirector) and Professor Tom Schueler (Directorof Watershed Research and Practice).

Date: 14 March 2006

Purpose: The CWP is one of the mainchampions for stormwater managementwithin the context of watershed protectionand has been responsible for a number ofmanuals and guidance documents now usedacross the US. The aim of the visit was to tapinto this expertise and experience.

Summary

Jennifer made presentations and Tomparticipated in discussion. Founded in 1992,the CWP is a non-profit corporation thatprovides local governments, activists andwatershed organisations around the countrywith the technical tools for protectingstreams, lakes and rivers. The centre hasdeveloped and disseminated a multi-disciplinary strategy to watershed protectionthat encompasses watershed planning,watershed restoration, stormwatermanagement, watershed research, better sitedesign, education and outreach, andwatershed training. The centre is supportedby five major revenue sources: state andfederal grants, contracts with localgovernments, subscription and publicationsales, workshop fees, and privatefoundations. Annual revenue climbed from$77,362 (£42,000) in 1993 to more than $1 million (£550,000) for the fiscal year 2001.The centre operates with a very low overheadrate; nearly 95% of all income is used directlyfor programme expenses. The centre hasproduced many of the design manuals (forLID and BMPs) and good practice guides formany states/counties/cities across the US(http://www.cwp.org/index.html).

The CWP’s main goal is to translate R&Doutcomes into practical tools. Majorprogrammes include ‘American Forests’ – tobetter use cover in urban landscapes. TheCWP has produced an urban sub-watershed(small catchment) manual and 11 manualswith all the details of watershed restoration (ie enhancing catchments). The CWP is mainlyconcerned with monitoring not modelling.Recommended scale of working is sub-catchment size of 100 square miles or lessand preferably with one key stakeholder onlyat circa 20 square mile size. This gives bettercommunity engagement. The best examplesof stormwater separation are in Milwaukee(USEPA mandated drivers) and to some extentPortland, Oregon. Most of the on-site facilitiesin Maryland are now inspected annually byspecialist contractors that report to themunicipality. There are complex and variablejurisdictions in the US for financingstormwater facilities. Andy Reece of AMEChas produced a recent report on this. Ingeneral property fees are based on amount ofconnected impervious area. Highway drainageis managed in each state and requires aUSEPA permit. Many states suffer as thereare few competent BMP constructionorganisations or designers. In the 1980s therewas an apparent 50% failure of infiltrationfacilities; however, since then smaller(distributed) systems are used that functionbetter. The CWP believes that it is impossibleto meaningfully measure pollutant removal ininfiltration systems and also that the perceived‘first flush’ does not always occur. Frommonitoring it has been possible to establishthat the typical treatment volume is from 0.9-1.5 inches (23-38 mm) of rainfall. Mostgood research has been done at the very localand detailed level, and recently good work hasbeen carried out on bioretention. The CWPhas developed methods to deal with local‘hotspot’ problems. Most failures result fromisolated extreme events like spillages. Eachstate sets its own standards in response tothe CWA. USEPA did not want to overburdensmall communities; hence some of them are

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not complying. Some 15-20 US states havestrong programmes, with the rest takingbetween five-10 more years. Many stateshave set up separate stormwater utilitieswhich operate identically to any other utilityand raise revenue.


• The CWP is not involved in brownfieldsites, although there are majordevelopments on these.

• Maryland as a state seems to be ahead ofthe rest of the US in many respects due tothe unique driver. Environmental concern isstrong due to awareness of ChesapeakeBay. High levels of taxation evoke publicinterest and the population is generallyquite wealthy.

• Watershed areas are some 100 squaremiles and sub watersheds are circa 20square miles and the latter are the primaryplanning level for stormwater.

• Separate systems have existed since the1900s, but in the city of Baltimore thereare now decay problems and a lot of I/I inthe combined systems.

• Septic systems are a big problem in theChesapeake Bay area as their locations arelargely unknown.

• In five to 10 years it is expected that CWAstandards will apply across the US.

• Limited numbers of consultants arecapable of designing BMPs properly, ordevelopers of constructing them.

• A lot of BMPs have been installed anddetails not recorded.

• Citizens rejected the responsibility to adoptand maintain ponds in Baltimore County

• The community was more interested inpaying a stormwater charge to getBaltimore County to do the maintenance.

• Proprietary systems – no definitivestandards to judge and lack of supportingdata to demonstrate performance.

• Quality standards in MD relate to‘presumed compliance’ and are based onadvisory standards at federal level.

Exhibit C.3 Examples of CWP activity

C3 Low Impact Development

(LID Center)

Visited: Neil Weinstein (at the office of theCWP, Ellicott City)

Date: 14 March 2006

Purpose: To discuss and be appraised of thetechniques currently available for inclusionwithin designs for LIDs and review theirapplicability to the UK.

Outline of information provided • Extensive discussion over lunch• Location of websites

Summary This report is the result of a lunchtimediscussion followed by research on return tothe UK.

The LID Center was established to developand provide information to individuals andorganisations dedicated to protecting theenvironment and water resources throughproper site design techniques. Neil Weinsteinis the Executive Director and one of thefounders of the LID Center, which is a non-profit research organisation based inMaryland dedicated to the advancement ofLID technology.

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Neil is one of the pioneers of LID and hashelped create the initial planning, design andanalysis tools that are the basis of LIDstrategies. He and his team have worked todevelop stormwater policies and strategies atthe national and local levels through research,development and policy analysis. The LIDCenter works on projects in many differentareas, which includes design, ordinancedevelopment, outreach and master planning.clients have included the American Society ofEngineers, USEPA, Federal Governmentdepartments as well as numerouscommunity watershed organisations.The centre also works closely with the CWP,the EPA and various academic institutions.


• The LID approach includes five basic tools:

º encourage conservation measures

º promote impact minimisationtechniques such as impervious surfacereduction

º provide for strategic runoff timing byslowing flow using the landscape

º use an array of integrated managementpractices to reduce and cleanse runoff

º advocate pollution prevention measuresto reduce the introduction of pollutantsto the environment.

• LID techniques are relatively simple and effective and address stormwater atits source.

• LID has numerous benefits andadvantages over conventional stormwatermanagement approaches since it is basedon more environmentally sound technologyand a more economically sustainableapproach to addressing the adverseimpacts of urbanisation.

• LID is flexible and offers a wide variety ofstructural and non-structural techniques toprovide for both runoff quality andquantity benefits.

• LID works in highly urbanised constrained areas, as well environmentallysensitive sites.

• The key distinction of LID from other moreconventional strategies is that it isessentially an ecosystem-based approach,and seeks to design the built environmentto remain a functioning part of anecosystem rather than exist apart from it.

• Opportunities to apply LID principles andpractices are practically infinite since anyfeature of the urban landscape can bemodified to manage runoff and reduce therisk of pollution.

• It is a comprehensive multi-systemsapproach that has built-in redundancy,which reduces the possibility of failure.

• By managing rainfall runoff as close to itssource through intelligent site design, LIDcan enhance the local environment, protectpublic health, and improve visual amenityand reduce infrastructure costs.

• Most conventional techniques will requirean off-site sewer to collect the stormwaterfrom the on-site system, resulting inadditional project costs for theenhancement of downstream sewers asthe urban areas expand.

• LID techniques have been used to addressa wide range of wet weather flow issues,including Combined Sewer Overflows(CSO), NPDES stormwater phase IIpermits, TMDL permits, non-point sourceprogramme goals, and other water qualitystandards.

• Case studies and pilot programmes haveshown that as a result of employing LIDtechniques on residential developmentscapital costs can be reduced by around 25to 30%.

• The techniques also provide additionalbenefits, such as groundwater rechargeand cleaner watercourses, but they alsoincrease the urban forest, reduce theurban heat island, improve air quality,reduce thermal stream pollution andenhance the visual amenity.

• LID practices such as rain gardens canusually be designed as part of thedevelopment’s open space, without anyloss of developable area.

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• The key factor in the success of LID is toensure that the landscape practices (suchas rain gardens) are attractive andperceived by the property owner as addingvalue to their property.

• LID practices are viewed as assets andthe primary motivation for their long-term maintenance success is that ofproperty owners protecting their vestedeconomic interests.

• LID maintenance burdens for propertyowners and local governments are simpleand do not require specialised equipment.

• To assist in the preservation of streamintegrity, experience has demonstrated theimportance of a stormwater managementsystem that specifically addresses thefrequent micro-storms that occur on aregular basis (weekly or monthly).

• LID techniques can be successfully utilisedin both retrofit and brown-fielddevelopment areas.

Websites• http://www.lowimpactdevelopment.org/

announce.htm• http://www.larch.umd.edu/LIDSITE/

judgin.htm• http://www.psat.wa.gov/Programs/LID.htm• http://www.toolbase.org/techinv/

techDetails.aspx?technologyID=223• http://www.nrdc.org/water/pollution/

storm/chap12.asp Exhibit C.4 Retrofit street edge alternatives (SEA) in Seattle

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C4 US Environmental Protection

Agency, Urban Watershed

Management Branch

Visited: EPA staff included: Richard Field(chair and host) and Dennis Lai, Mike Borst,Tom O’Connor and Scott Struck (presenters).

Date: 15 March 2006

Location: Edison, New Jerseyhttp://www.epa.gov/ednnrmrl/

Purpose: To be appraised of the work beingundertaken by the staff of the Office ofResearch and Development at the NationalRisk Management Laboratory.

Outline of information provided• Presentations on the current work related

to stormwater management• Tour of the laboratory• CD containing presentations

Summary

The EPA leads the nations’ environmentalscience, research, education and assessmentefforts and works to develop and enforceregulations that implement environmental lawsenacted by congress. It advances educationalefforts to develop an environmentally consciousand responsible public and to inspire personalresponsibility in caring for the environment.

In recent years, approximately half of the EPA’sbudget has provided financial support to stateenvironmental and research programmes.It is responsible for setting national standardsfor a variety of environmental programmesand has the power to delegate theseresponsibilities to the various states andmunicipalities for the issuing of permits andfor monitoring and enforcing compliance.

The UK team was informed of the researchand studies that are currently being managedby the Urban Watershed management team,which included the following:

Dennis Lai:• Framework for the placement of BMPs in

urban watersheds to protect source watersand meet water quality goals.

• Sanitary sewer overflow analysis andplanning toolbox (SSOAP)

• System for urban stormwater treatmentand analysis and integration (SUSTAIN)

Michael Borst:• BMP performance: pilot-scale evaluation of

wet ponds and constructed wetlands forsolids reduction

• Pilot-scale evaluation of swale designs (testrig to be constructed at the laboratory)

Tom O’Connor:• Stormwater best practice

management guide• Performance monitoring of a BMP pond

on Staten Island• Green-roof research

Scott Struck:

• Accotink Creek (City of Fairfax) RestorationProject: stream restoration techniques

Conclusions

• Methodologies and decision support toolsare required to help develop, evaluate,select and place BMPs in urban watershedsbased on both sound science and aconsideration of costs and effectiveness.

• Currently, the typical detention basindesign provides for six-hour storage timefor the first half inch (12 mm) of rainfall.Evidence has shown that longer retentiontimes of between 24 and 48 hours areneeded to treat stormwater runoff.

• Pond outlet controls need to be designed(and retrofitted where necessary) to slowlyrelease smaller storms (higher frequency)

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that may pass through the system withlittle or no attenuation.

• The incorporation of accessible and securemonitoring facilities should be incorporatedinto the BMP design.

• The collection and collation of long-termdata sets will assist in better site design.

• Leaves from trees appear to be a majorcontributor to chemical oxygen demand.

• Pond maintenance regimes can adverselyaffect the chemical oxygen demand.

• The treatment capabilities of BMPs, and in particular ponds, may vary from seasonto season.

• There is a preference for actual data, suchas rainfall, as opposed to a simulation ofthe hydrograph. Hence the need to ensurethat monitoring is incorporated in themaintenance requirements.

• Watercourse restoration and theimplementation of appropriate BMPs canassist the resolution of short and long termflow problems and provide an acceptableflow regime to achieve dynamic equilibrium.

• There is currently little knowledge on theperformance capabilities of swales to dealwith water quality issues; however, it isgenerally accepted, and this is mainlyanecdotal evidence, that swales greatlyassist in the reduction of run-off volumeand may provide between 60% and 99%particulate reduction.

• The EPA is increasingly advocating the useof swales as an alternative to gutter and kerbdrainage as part of the designs for LIDs.

• The US Department of Transport’sexpenditure on swale and pond systems ishuge, but the performance results areregarded as being vague. These systemswere originally designed and installed toremove water from the highway as quicklyas possible for driver safety reasons.

• Green-roofs have numerous benefits and include:

º the control and management ofstormwater

º reduction in the urban ‘heat island’ effect

º provision of additional and in somecases diverse habitat

º reduction in energy costs associatedwith heating and cooling

º can be more visually attractive.

Website• http://www.epa.gov/ednnrmrl/

Exhibit C.5 Examples of activities undertaken by the CWP

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C5 Site visit to AbTech smart sponge

Organisation visitedAbTech Industries (Scottsdale, Arizona).Source Control Systems (UK).City of Norwalk (Connecticut).

Location: Norwalk ‘Storm Drain Filter Project’site visit to the Maritime Aquarium andfollow-up meeting at city of Norwalk TownHall, Norwalk, Connecticut.

Date: 15 March 2006

Purpose: Evaluate the US advanced polymertechnique (smart sponge) for cleaning surfacewater runoff with the manufacturer (AbTech)and project promoter (City of Norwalk). Thistechnique may be significant for future use bythe UK water industry for improving surfacewater runoff quality, in accordance with therequirements of the WFD.

Details of persons met:• Rodolfo Manzone – Executive Vice

President of AbTech Industries• Graham Martin-Loat – Director of Source

Control Systems• Sal Longo – Contractor and Connecticut

distributor of smart sponge• Michael Yeostock – City of Norwalk

Senior Engineer.

Information provided:• The Norwalk Storm Drain Filter Project –

presentation and accompanying handoutsby AbTech Industries

• The Norwalk Storm Drain Filter Project –local information booklet by the city of Norwalk.

Site visit to the Maritime Aquarium

The project is funded via an EPA grant of $397, 000 (£215,000) with some local additionalsupport. It is a collaborative project between theEPA, City of Norwalk, AbTech Industries, Longo& Longo and The Long Island Soundkeeper

(an environmental education and advocacyorganisation). Other project partners are theMaritime Aquarium (one of the largestattractions in Connecticut) and the NorwalkRiver Watershed Initiative (since 1995 a uniquepartnership of seven watershed towns toaddress local water quality). The key projectdriver is to improve the quality of surface waterdraining from the watershed and into theNorwalk River, Norwalk Harbor and Long Island Sound.

The mission team was shown an example ofone of the AbTech trash baskets and smartsponge ‘ultra-urban’ filter inserts installed into275 storm drain catchpits (gullies) in thewatershed, adjacent to the aquarium anddraining out to the Norwalk River; the basketinsert was raised onto the sidewalk forinspection. It was noted that all of the othercatchpits in the vicinity also contained theAbTech dual filter system. It is a dual filtersystem because the proprietary collar andbasket collects all trash entering the catchpitwhile the smart sponge insert filters thesurface water runoff, permanently taking outharmful pollutants.

Presentation and discussion (at the Norwalk City Hall):• www.abtechindustries.com• www.sourcecontrol.co.uk• ‘The Norwalk Storm Drain Filter Project’: a

unique project involving private and publicbodies, including the Aquarium. Involvedretrofitting 275 storm drains with smartsponge and included contrasting areaswithout the filtered outlets for comparison.

• There was a 12 month monitoring periodto assess improvement in runoff quality.Includes target removal of hydrocarbons, arange of bacteria (including Escherichiacoli), total suspended solids, heavy metalsand trash.

• Of the 275 trash screen collectors cleanedand weighed, 10 are taken away to beanalysed for contaminants. Estimated 50lbs of trash per drain per annum.

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• Dredging has a significant cost associated with sludge disposal, so areduction is valuable.

• The project is aiming for 90% hydrocarbonremoval and 80% bacteria.

• AbTech smart sponge technology is now ata 10 year evolution and the ‘popcorn’ canbe manufactured into any shape or form. Itis both porous and buoyant and usesabsorption techniques to chemically selectcontaminants into the inner part of itsstructure. Standard capability is the captureof hydrocarbons, trash and sediment. Itcan absorb up to five times its own weightin contaminants. A recent upgrade haspermitted the capture of some bacteriaand the future capture of heavy metals isa possibility.

• There has been EPA collaboration in theNorwalk project.

• There is no release of by-products eitherduring or after pollutant capture from thesponge. Typical lifespan is two-to-threeyears, dependent upon the amount ofpollutants captured; at this time thesponge is saturated and must be changed(‘jellification’). Other usage has includedsports socks and medical gowns becauseof its anti-bacterial properties.

• This is a dynamic treatment of SW runoff.Bacteria capture efficiency varies, but it canbe up to 75%. AbTech is now in generationfour of smart sponge. Hydrocarbon captureis up to 95-97%. Development of theadvanced polymer technique continues andthe intention is for heavy metal capture.There will be a slight loss of hydraulicperformance at each inlet from the 10-15%reduction in area.

• SCS commented that it has six UK testsites. ‘Real world’ applications for the UKare essential, as is the classification for thespent sponge; special waste? If specialwaste, the disposal costs may beprohibitive. Disposal may include landfill orincineration as a fuel. Another UKapplication may be in landfills.

• Maintenance will always be an issue; inlets

should be cleaned once a year, but once inthree more likely, when the spongereaches saturation.

• The catchment has some 84,000 peopleand 27 square miles. Modification costs are under $1,000 (£550) per gully,total for all infrastructure.

Conclusions

• A separate stormwater utility is beneficial formanaging longer term maintenance. Alsoperhaps for installation and construction.

• Sea Life Centers and equivalent publicfacilities are very strong vehicles forimproving water quality in coastal areasthrough education.

• Agreements between municipalities,maintenance companies and contractorsneed to be clear and robust.

• Community and stakeholder ‘adoption’ of stormwater facilities is a major buy-inand opportunity.

• School education is a major opportunity –in the UK the national curriculum may be a constraint to improving awarenessand responsibility.

• Classification of residual arisings is animportant consideration in the ability toutilise innovative approaches tostormwater management.

• Non-asset based approaches (non-structural) can be more effective thanbuilding yet more assets. A series of smallcontributory schemes may be as effectiveas and more sustainable than one singlelarge additional asset.

• There is too much reactive maintenance inthe UK. It needs to see proactivemaintenance as perfectly valid withinwhole life performance.

• There appears to be promising proprietarysystems for both inlet and single-pointoutlet controls for solids and bacteria.However, additional independent evidenceto confirm this would be useful.

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Exhibit C.6 AbTech’s ultra-urban catchpit insert

Exhibit C.6 AbTech’s ‘smart sponge’ demonstration tothe mission team

C6 Hydro International conference –

The Changing Face of the

Stormwater Industry

Visited: See Below

Location: Portland, Maine

Date: 16 March 2006

Purpose: This conference was intended toprovide knowledge and offer a greaterunderstanding of the stormwater industry inthe US by bringing together regulators,consultants and academics to discuss thechanging state of stormwater management.

Outline and programme for the day

• Welcome – Steve Hides, CEO andPresident, Hydro International

• ‘Sustainable stormwater management –an international perspective’ – ProfRichard Ashley, Professor of Urban Water,University of Sheffield and MD, PennineWater Group

• ‘Stormwater treatment at critical sourceareas’ – Robert Pitt, PE, PhD, University ofAlabama

• ‘Implementation of stormwatertreatment standards modellingprogram’ – Jim Bachhuber, PH, EarthTech

• ‘History and future of technologyverification programs’ – Tom Stevens andPat Davison, NSF International

• ‘Choosing appropriate stormwatertreatment practices considerations forengineers, planners and regulators’ –Richard A Claytor, Jr, PE, Principal, HorsleyWitten Group

• ‘Regulatory driven developments inproprietary stormwater treatmentdevices’ – Dr Robert Andoh, Director ofInnovation, Lisa Glennon, US Research andDevelopment Manager, Hydro International

• Hydro International R&D facility tour

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Summary

Copies of all the presentations/papers can beviewed/downloaded at:http://www.hydrointernational.biz/us/docs/downloadpage.php

During the day it was demonstrated that thedrivers for stormwater management need tobe fully understood to be effective and thatchampions within the industry should belooked for and encouraged.

A good example of a USEPA funded projectwas showing how the development ofstormwater treatment control devices usingfilter media and a multi chamber treatmenttrain approach resulted in thecommercialisation of Hydro’s Up-Flo filtersystem, which is currently being evaluatedwithin the ETV programme. Extensive mediaresearch by Bob Pitt was also presented indetail showing all the early work that wascarried out to develop the Up-Flo filter.

Experiences with the EPA’s ETV programmewere explained as well as some of thedifficulties encountered with field testingprocedures and how difficult it can be inachieving meaningful results in uncontrolledconditions. It was also explained that cautionneeds to be exercised especially whenobtaining data in the field using automaticsamplers and measuring devices.

A guided tour of the R&D facilities showedthe in-house testing equipment available anddemonstrated a lab based unit of the Up-Flosystem used to verify the performance of thevarious filter media, as well as allowingongoing development work to be carried out.

Conclusions

• The six minimum requirements of USstormwater regulations are: 1) publiceducation outreach; 2) public involvement;3) illicit discharge detection and

elimination; 4) construction erosion control,5) post-construction maintenance; and 6)pollution prevention.

• Innovative funding schemes can be useful in promoting awareness andengagement and there should morenational subsidy options.

• There needs to be more performance data collected routinely and monitoring and maintenance systems should bedesigned in.

• Irreducible concentrations, eg Cd 3μl mayexist in stormwater.

• Majority of pollutants are transported insmallest storms.

• The impact of practices on the community needs to be addressed andtaken seriously.

• Older and poorer cars drip most oil, andstopping/starting in supermarket, drive-instore car parks, for example, leads tohigh pollutants.

• Methods for field performance evaluationare expensive and only effective with verygreat care.

• Whilst there are some good proprietarysystems available on the market and thereare many cases where products can beused successfully, especially in conjunctionwith other devices, they should not beforced by the market to being sold as allthings to all people.

Exhibit C.8 Hydro International’s R&D facility –Portland, Maine

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Exhibit C.9 The Up-Flo filter system from HydroInternational

C7 MWRA Boston

Visited: Fred Laskey (Executive Director)MWRA, Michael Hornbrook (Chief OperatingOfficer) MWRA, Massachusetts WaterResources Authority (MWRA), DeardenCambridge City Council, Dennis Doherty(Jacobs Civils Inc)

Date: 17 March 2006

Boston: Population 590,000, land area 48 square miles, water area 41.21 square miles,annual precipitation 41.5 inches (1 metre)

Cambridge: Population 101,000, land area6.43 square miles, water area 0.7 square miles

Purpose: Presentation from MWRA on CSOprogramme in Boston, meeting withCambridge City Council (Department of PublicWorks). Site visits.

Outline of information provided

• Massachusetts Water Resource Authorityfive-year progress report 2000-2004

• ‘The State of Boston Harbor. Mapping theHarbor’s Recovery’ Massachusetts WaterResource Authority 2002

• ‘Your Drinking Water Test Results’Massachusetts Water Resource Authority 2004

• Cambridge Department of Public Works –www.cambridgema.gov/TheWorks/stormwater/index.html

Summary: Massachusetts Water ResourcesAuthority (MWRA)

In order to fulfil its mission of providingquality water and sewerage services to itscommunities, the Massachusetts DistrictCommission (MDC) needed to raise sufficientrevenues to hire adequate staff, properlymaintain plants and equipment, to financemajor capital programmes, and to developoperating budgets that were responsive toexisting and future needs. MWRA wasdeveloped in order to fulfil the goals ofprovision of quality water and sewerageservices to customers. In 1984, legislationwas enacted to create the MWRA, anindependent authority with the ability to raiseits revenues from ratepayers, bond sales andgrants. The primary mission of thedepartment was to modernise the area’swater and sewer systems and clean upBoston Harbor.

Boston Harbor was previously considered oneof the dirtiest harbours in the US. However, in1985 a federal court order set an ambitiousschedule for the newly formed MWRA toplan and construct new sewage treatmentfacilities that would end the discharge ofuntreated and partially treated sewage toBoston Harbor.

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Four major construction projects werecompleted:

• cessation of sewage sludge disposal toriver via new facility development toproduce commercial fertiliser pellets

• a new secondary wastewater treatmentfacility at Deer Island

• a tunnel from Nut Island to Deer IslandTreatment Plant to capture CSO forsecondary treatment

• an outfall diffuser system that dischargestreated effluent 9.5 miles offshore intoMassachusetts Bay.

Harbour water quality improvements in thelast 10 years have led to a major economicboom around the harbour to over $1 billion(£550 million) and a general increase inproperty values.

The final stage of the clean up programmerelates to the removal of CSO discharges tothe Charles River.

Originally CSO resolution was to have onelarge interceptor project. Following detailedplanning that considered sites and effluentissues, 29 smaller projects have beendeveloped and are in the process of beingimplemented. These include sewerseparation, interceptor improvements, newCSO treatment facilities, upgraded CSOtreatment facilities and storage facilities at atotal cost of $747 million (£400 miilion).

The city of Boston has mixed areas ofseparated and combined sewerage systems.MWRA is not responsible for stormwaterdrainage; this is the responsibility of thespecific communities (60 of which make upthe Massachusetts area). At present there isa stormwater disconnection programme infour communities (Boston, Somerville,Cambridge and Chelsea). The success of theCharles River clean up has lead to calls forclean up activity in other areas such as theMystic River. It has been recognised that thelevel of CSO improvements made in this area

will have little impact if the stormwater is notbetter managed as it is causing deterioration.

As a result, municipalities (such asCambridge) have been issued withstormwater permits to ensure that at leastBMP techniques are being implemented toreduce stormwater impact.

All communities barring one are metered toenable easy identification of system I/I andexfiltration. As such, flow instrumentation insewer networks is considered essential to:

• understand performance and I/I• target and improve maintenance efficiency• optimise performance (d) allows calibration

of models (quality modelling is not done,except for the harbour FCs/EC).

I/I control programme works right across thecatchment. Metering of connectedcommunities was universal and not onlyencouraged the control of I/I by communitiesthemselves, but reductions in charges werenot necessarily forthcoming as capital neededto be repaid over 25 years. I/I representstypically 50-60% of flows even in notionallysanitary sewers.

Summary: Cambridge City of Public Works

Cambridge city is the sixth most denselypopulated city in the US. The sewer systemdates to the early nineteenth century and ishome to 15 CSOs, the majority of which siton the north side of the city. The sewersystem is predominantly combined and assuch there is a federal court requirement toaddress sewer separation. Surface watermanagement is also being implemented toresolve the growing number of floodingproblems. This is a result of householdersusing/inhabiting basements due to the risingcosts of land and house prices. Currently,sewer systems manage up to two year stormevents, 10 year storm events can causehighway flooding.

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An MWH consultant provided a presentationon flow controls used to prevent/reduceflooding, sediment controls and LIDs.

Site visits

Numerous sites were visited focusing mainlyon the MWRA’s current programme ofdetention tank, discharge pre-treatment andCSO construction to achieve federalrequirements of Boston Harbor clean up.

Site visits included Prison Point and CottageFarm – new disinfection and dechlorinationfacilities, and Union Park Detention TreatmentFacility, a project to eliminate 20 out of 26discharges by increasing detention capacityand treating flows via screening, disinfectionand dechlorination.

Exhibit C.10 Union Park Detention Treatment Facility

Conclusions

• Direct citizen involvement in managingboards improves engagement andcommitment. Linking lifestyleimprovements and recreational benefits tocosts and investments associated withprojects assisted public approval. Publicchoice about expenditures is part ofdecision making. Use of local professionals(eg architects) in design details can helpkeep the local community on board.

• High property and land values have forcedpeople to convert basements to habitationand has highlighted the problems offlooding risk and increased buy-in.

• Local communities decide individually iftariffs should be rising, declining or fixed.

• Limited investment targeted well canproduce big benefits. There was a retreatfrom a large scale storage solution ($1.3 billion (£700 million) in 1993) to alarger number of smaller disbursedprojects (100) locally targeted, at a muchlower cost of $835 million (£450 million) attoday’s prices. These are seen to be moreflexible and involve new storage,disconnections and other approaches(didn’t mention non-structural).

• The use of instrumentation and meters(such as water meters and hand-heldscanning devices for maintenancepersonnel) has greatly improved efficiency.Metering has led to water usage reductionof 120 million gallons per day. Water usageis now the same as in 1911. All but onecommunity has water metering.

• Flow instrumentation in sewer networks isconsidered essential to: (a) understandperformance and I/I; (b) target and improvemaintenance efficiency; (c) optimiseperformance; and (d) allow calibration ofmodels (quality modelling is not done,except for the harbour FCs/EC).

• Daily in-sewer flushes can control FOGS.• ‘External’ factors are important – such as

the maintenance of high groundwaterlevels to keep the wooden piles submerged– the knock on effect is backing up ofdrainage systems and more sediments.

• Other utilities have to pay for their own re-routing when storm sewer facilities are built.

• Stormwater was the responsibility of thelocal communities, but MWRA could design,maintain, construct and operate these –some communities do not take theirstormwater management duties seriously

• For new developments in the MWRA area,developers that wish to add new flows

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have to provide compensatory reductionselsewhere of between three-15 times theproposed new foul inputs.

• There is no public warning system forflooding risk. Flood risk to control 25 yearevent, but also some 100 year events.

C8 John Sansalone: work on surface

drainage in Florida and elsewhere

Visited: John Sansalone, University of Florida (UoF)

Location: Boston

Date: 18 March 2006

Purpose: To understand the work beingundertaken at UoF on stormwater and where it is focusing its research activities.


• overview of rainfall runoff and historical controls

• coupled quantity and quality issues• aqueous and particulate chemistry• treatment and controls concepts• source control to central control• data and behaviour required at range

of scales• examples and required analysis of

control/treatment• laboratory scale – controlled pilot –

uncontrolled full scale.

Summary

The science and understanding of stormwateris still very much in its infancy and so are thesystems/processes that treat it. There is alsovery little real knowledge or understanding ofthe maintenance and operation of all thesetypes of systems, whichever option is chosen:LID, BMP and proprietary etc. There needs tobe proper management systems in place,

which is generally not the case in US, if unitsare to perform over their working life as originally designed.

Hydrology, chemistry and particulate transportare coupled and complex phenomena. Simplerules of thumb such as ‘first-flush’ are fraughtwith uncertainty. If fact there is probably nosuch event as a first-flush and regulationsbased on it are not going to deliver the desiredeffect of cleaning up diffuse pollution.There are significant challenges in properlysampling any stormwater system. Themethods used are critical and auto-samplingdoes not work. A mass balance is required andthe error should be within 10% otherwise thedata is suspect. The make up of stormwater iscomplex and full analysis is expensive andcomplex. It is important to look at thedissolved and particulate bound pollutants,particularly at a full range of particle sizes fromcolloidal to gross solids. All these issues thenmake the widespread characterisation of sitesand catchment areas impractical, thus theTMDLs are really not appropriate and the 80%reduction required naïve (and unachievable).

Conclusions

• Stormwater is not wastewater. The currentmethods of sampling and analysis, plus theconcepts we retain from our biologicalwaste treatment backgrounds, are veryproblematic for effectively understandingstormwater and all the possible solutions.

• BMPs and LIDs can only really handle smallstorm events, but these smaller storms arethe highest in number and generallytransport the predominance of annualpollutant load.

• The key to success is integrated design andunit operations/processes as well as afundamental knowledge of the loadings.Not all engineered solutions are the same.Properly engineered media andmaintenance of media systems are neededto resolve quality issues. Perlite and sandare of no real use.

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• Many tools and solutions are needed tosolve the stormwater problem. Reuse mustbe considered and planned for, especially inareas where water is scarce. We must dealwith residuals differently than we deal withbiosolids. This combination of tools shouldinclude both classical treatment systems(so-called structural controls) anddevelopment of non-structural controls thathave viable verification schemes. How webuild our infrastructure and the selection ofinfrastructure materials we utilise can be ofpotential benefit in load reduction ofspecific contaminants.

• More development is urgently required.There should be an open design where theoperation and maintenance are transparentwith the systems well documented, testedand verified. The systems should bethought of as unit operations andprocesses that we can build in treatmentmodules or ‘trains’ similar to the packagetreatment concepts and systems.

• There are severe limitations on what weknow about stormwater control andtreatment, which needs to be recognisedand the complexities relating to rainfall run-off acknowledged. These uncertaintiesneed to be explicitly reflected in theregulations so that there is a flexibleapproach to delivering the solutions.

• Reuse and reclamation of stormwater asan integrated part of the urban watersystem is urgently needed.

C9 City of Portland, Oregon – Bureau

of Environmental Services

Organisation visited: Bureau ofEnvironmental Services (BES)http://www.portlandonline.com/bes

Location: City of Portland, Oregon

Date: 20 March 2006

Purpose: Presentation including video anddiscussion with Tom Liptan regarding the City

of Portland’s stormwater management.Question and answers session with TomLiptan and Dean Marriott.

Details of persons met: Tom Liptan –Landscape architect, working as a stormwaterspecialist within the bureau, Dean Marriott –Director of Environmental Services

Information provided: Tom Liptanpresentation of green-roofs, various examplesof promotional and educational material

The BES is a government departmentresponsible for protecting the quality ofsurface and ground waters with specificareas of responsibility in wastewatertreatment and collection, storm-watermanagement, watershed management, CSOprogramme and pollution prevention.

They are located in the City of Portland, whichis located in the state of Oregon and isperhaps the closest we came to finding anequivalent in terms of the weather conditionsin the UK. Average annual rainfall isapproximately 37 inches (939.8 mm) a year.This compares favourably to the north ofEngland, which has an approximate annualrainfall of 37 inches (ref. Met Office-climateaverages – 1971 to 200 and 1961 to 1990)

The City of Portland has approximately half amillion people stretched over an area of 85,000acres, it has approximately 110,000 homes andhas a main river running through it called theWillamette River. The city has a whole range ofBMP types including eco-roofs, indigenousstreet trees, porous pavements, bio-swales/bio-filters, rain gardens, infiltration devices anddownpipe disconnections.

Summary of meeting

• Within Portland it is the responsibility ofthe residents to maintain the sidewalk infront of their property unless it has beenadopted by the city.

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• Very strong public information programmesare run to communicate the work of theES and the stormwater managementprogrammes that are being initiated. Publicinformation is distributed through mailingsand advertising media along witheducational schemes run with schools inconjunction with Ameri-corps.

• Currently the drainage and CSOs empty into the Willamette River causing pollutionand damage to the eco system. This hascaused destruction of salmon habitat alongwith damage to the wildlife causing greatpublic concern; this concern has beenexploited and used as a driver for change.

• The City of Portland has a separate‘stormwater charge’ based on theimpervious area of the site/property/house.This has been in force since-the 1970s andhas recently been updated (April 2006) toinclude a restructured discount schemelimited to a maximum discount of 35% ofthe basic stormwater charge andcalculated on a sliding scale. Large sitescould reasonably expect to save in theorder of $10,000 (£5,500) per annum (inthe region of one third of their total bill) ontheir stormwater charge by implementingthe full range discountable actions.

• Stormwater management is the cheapestof water charges in Portland with the splitbetween water services for an averagefamily being:

• The stormwater management charge forcommercial properties is approximately$8.5 (£4.60) per 100 square feet (9.3 squaremetres) per month.

• It is recognised that transportation plays abig part in stormwater managementproblems and is claimed to provide thesource of 70% of the demands on thestormwater systems and proportionally

high loads of pollutants. It is currentlyrecognised that transportation should becharged accordingly for their stormwatermanagement, but at present no charge iscollected due to a historical agreement.

• The City of Portland has a ‘stormwaterdesign manual’ based on the ‘City Code andCharter’ and ultimately the CWA (1972).

• A legal agreement was signed to clean upthe river by reducing CSO discharge in tothe river by six million gallons a year.

• The City of Portland has developed andpromoted a ‘downpipe disconnection’programme. This enables participants toreceive a fee of $53 (£29) per disconnecteddownpipe, dependant on the participantcarrying out the work. Alternatively, alicensed contractor can be paid by the cityto carry out the disconnections.

• 44,000 homes out of a possible 110,000houses have participated in the program,which has removed over a billion gallons ofroof water per annum from combinedsewer systems.

• Signs advertising a homeowner’sparticipation in the downpipe disconnectionscheme was provided by the bureau ofenvironmental services in an attempt topromote community pride in their efforts.

• The downspout disconnection scheme hasa deadline for completing its objective ofdisconnecting all eligible downspouts from the combined sewer system by 1 December 2011.

• City zoning code 33.510 ‘Planning andZoning’ FAR Bonus: eco-roofs are a bonusoption within the code, which can meanfor every square foot of rooftop garden, abonus of one square foot of additional floorarea is earned, which could equal an extrafloor. The building owner must alsoexecute a covenant with the city tomaintain and continue the facility.

• A resolution was passed in 2005 thatrequires all city buildings to install eco-roofs when re-roofing, where practical.

• As a demonstration project a street hasbeen fitted with what can be termed as astreet garden. The road has been necked in

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Water bill breakdown ($) Cost per month

Stormwater charge 13

Sewer charge 33

Potable water charge 15

at a selected point to provide a drainagefeature (bio-swale) that combines with atraffic calming measure.

• Stormwater reuse is not widely used withinPortland, but is just starting to be explored asan option, although they are unsure how tocharge for services if the take up is high.Annual water use in Portland is approximately23 billion gallons and the annual yearly rainfallis approximately 91 billion gallons.

• As part of the LEED programme, which isequivalent in the UK to the ‘Code forsustainable homes’, rainwater harvestingplays a part in achieving the accreditationlevels. http://www.usgbc.org/DisplayPage.aspx?CategoryID=19

• The use of green-roofs in Portland has raisedconcerns about ground water recharge.

• Two large pipes are being constructed tocarry all the CSO to a sewerage treatmentplant. The pipes are 22 feet (6.7 metres) indiameter and six miles long, and 14 feet(4.3 metres) in diameter and three-and-a-half miles long.

• The cost of the whole CSO abatementprogramme will be met by the rate payerwithout any federal assistance at a cost inthe region of $1.4 billion (latestestimate).The whole programme will takein the region of 20 years to be completed.

• An expressed opinion in hindsight was thatif the work carried out to date in reducingthe inflow of stormwater in to thesewerage facility, then the large pipesmight not have been necessary.

• Four events during the winter period willoverflow from the tunnel withstored/intercepted water being pumpedfrom the pumping station at Swan Islandto treatment at a maximum of 10 milesaway. This has produced concernsregarding the operating and maintenance(O&M) costs of the pipe.

Conclusions

• Demonstration sites with full disseminationof the results promote learning amongstthe community, as well as developers, and

help to alleviate worries surrounding new orunconventional techniques.

• In Portland, maintenance arrangements are inconsistent and tackled on a case-by-case basis.

• Change is a time consuming occupation.Public agencies have a duty to retainsupport through the telling of properstories to ensure continuation of supportduring lengthy periods of change.

• Disconnection incentives need to beworthwhile, communicated effectively, and pitched at a level that is coherent to householders.

• Problems can arise where the enforcers of development regulations are notinvolved in making the specification forstormwater management.

• UK planning documents do not accountsufficiently for the importance ofstormwater. Perhaps it is looked at moreas a waste product then a resource.

• Charges based on the inpermeability of aproperty footprint may be the best basesfrom which to create a stormwaterrevenue stream separate from other waterstreams and start to solve infilldevelopment issues.

• Design manuals should be easily translatedwith the use of examples and casestudies, but should not be done in such away as to stifle innovation.

• It is important to identify the public driversand motives and use them as a basis toimplement a staged programme ofchanges that will achieve quick wins thatdemonstrates effectiveness and a clearroute to goal.

• Bio filters incorporated in the streets servea dual purpose of stormwater treatmentand infiltration as well as acting as a trafficcalming measure. However, they would beimpractical where there is a requirementfor on street car parking.

• The big pipe project is smaller then firstenvisaged due to the effectiveness ofprogrammes such as the downspoutdisconnection programme.

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Visits

During the second part of the visit the teamwas given a guided tour of some of theprojects that the BES had undertaken or beeninvolved with:

Rainwater harvesting – University ofPortland: this building was built to complywith the LEED programme. Part of thedrainage system is used to divert stormwaterthrough bio filters in to storage tanks wherethe water is used to flush toilets on the firstfloor. The scheme was restricted to supplyingwater to the toilets on the first floor due toobjections/reservations from plumbing control.

Green-roof – University of Portlandaccommodation: roof dedicated to an eco-roof and the rooftop installed services.

C10 Eric Strecker, GeoSyntec

Consultants and Wayne Huber,

University of Oregon

Organisation visited: GeoSyntecConsultants.

Location: 55 SW Yamhill Street, Suite 200,Portland, Oregon 97204

Date: 21 March 2006

Purpose: Workshop and discussion regardingthe design and implementation of BMPs and LID.

Details of persons met: Eric Strecker –Principal at GeoSyntec Consultants, WayneHuber – Professor at Oregon State University

Information provided: Design stormmeeting, design standards presentation – E Strecker, Hydrologic regionalisation impactspresentation – W Huber, SWMM5presentation – W Huber.

Presentation by Eric Strecker and discussion

• www.geosyntec.com• The California Project estimated that some

35% of precipitation will evaporate.Greater consideration for UK design of wet BMPs.

• Always use a filter medium or filtrationmedium before infiltration.

• Green-roofs are an excellent medium forevapotranspiration.

• ‘Managing the sponge’; infiltration.• Avoid accidentally introducing diffuse

pollutants (such as zinc) when establishingnatural BMPs (eg preservatives in timber).

• Eric Strecker comments on smart spongeand other such sorbent techniques; ‘Goodfor hydrocarbon removal, especially for aspill or an illegal dump. Not convincedregarding the capture of bacteria or otherpollutants. These types of products areexpected to ‘do-all’ in terms of theirperformance, which isn’t really fair.’

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Exhibit C.11 Green-roof used to provide an amenity forthe residents of a flat

Exhibit C.12 Surburban drainage in an integrated urbanenvironment

• Important to consider long term durabilityand whole life costing for BMPs.

• If there is a well manicured landscape stripavailable, the additional whole lifeoperational maintenance costs are onlymarginally increased if that soft area isactually implemented as a BMP.

• Treatment design should focus on the ‘sizeof storm’ and less on the pollutants.

• Eric Strecker comments on good BMPpractice for design; ‘consider how muchsurface water runoff is prevented and howmuch runoff is treated.’

• Pollutant parameters to consider; physical,biological, chemical and hydraulic.

• Good design and implementation practiceto have a treatment train.

• Do not overlook downstream erosion control.• Wetland BMPs should always be protected

from siltation; install specific BMP/structure upstream to trap silt.

• The outlet structure from a BMP is veryimportant (especially structures such asdetention basins).

• For effective sustainable water quality; EricStrecker’s suggested management train:1 Hydrological source control2 Pollutant source control3 On-site treatment4 Regional treatment5 Watercourse restoration/stabilisation.

• www.bmpdatabase.org – National BMP database.

• Consider using multiple outlets at differentinvert levels for increasing severity stormreturn periods; this will enhance theperformance of the flow control.

• Key American eco-drivers for water qualityimprovements: the northwest and salmon,California and its beaches, Florida and theEverglades. This replicates what was seenand heard in Maryland (Chesapeake Bay)and Boston (harbour).

• The effect of vegetation in BMPs issignificant; improving water quality andproviding some attenuation of flows.

• It is important to implement waterproofingpreventative measures when locatingwater boxes close to buildings.

• www.naturaltreatmentsystem.org

Conclusions

• Evapotranspiration is an under-rated meansof surface water management – managethe ‘sponge’ first before anything else.

• Percentage removal is not a sensibledesign standard – EIA or equivalent basedapproach is much more sensible.

• Treatment training BMPs and assumingsimilar performance at each step will over-predict the performance.

• Water quality modelling should be a long-term continuous simulation in order toaccount properly for the storage elements.

• General diffuse pollution from agriculture ispoorly understood but known to be asignificant problem.

• The approach should be to manage theproblem, not simply meet regulations.

• Flow duration control is important fordownstream watercourse erosion.

• Partnering is needed to properly understandthe issues and solve the problems.

• It is worth considering investment in thedownstream watercourse rather thanrefinements to BMPs.

• The whole catchment/watershed should bemanaged (eg regionally)

• Standards seem to vary significantly fromstate to state. This has led to criticism.

• Bacterial pathogenic indicators areunrealistically onerous in the US.

• Regulatory standards are confusing in theUS because they are so variable.

• Building materials should be inert to water solubility.

• Proprietary products have a place wherethey are targeted in terms of their processand cannot be expected to do too manythings; in the US manufacturers can bealmost forced into misrepresenting theirproducts. The market should not force this misrepresentation.

• Assessment of pre- and post-conditionsusing flood criteria will not show as bigdifferences as when looking at qualityperformance differences.

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• There may be a need for a little ‘lessreligion and more science’ in LIDs.

• Below ground solutions are ‘out-of-sight,out-of-mind’; when above ground it is(usually) apparent when maintenance isneeded (if inspected).

• BMP solutions can be cheaper in terms ofcapital investment than below groundsolutions – one example in the US (Davis,California) quoted where this was true andthe system has continued to perform wellfor 30 years. Whole life costing data isrequired for the UK industry.

• It is now essential for landscape architectsto be part of the design team and ideallyothers such as ecologists and socialscientists.

• Environmental requirements should beboth prescriptive AND performance based.

• There is no ‘silver bullet’ and engineersshould be educated to realise howcomplex this area is.

• A runoff coefficient of 0.1 is likely from agreen-roof compared with 0.9 from aconventional roof.

• Post-project monitoring is essential toshow compliance for/to/from litigation.

• Maintenance for BMPs is not that muchmore onerous than for a landscape featureanyway (local authority departments in theUK could become responsible for the qualitycontrol BMPs, but flood control may be tooimportant to leave to these groups).

• The City of Portland is not too worriedabout maintenance and is keen to ‘getsystems in’ in the expectation that it willwork out – on the principle that it will workout as communities seem to be morecommitted to engaging in this.

• Plants and trees are essential for BMPs;for example, evapotranspiration andnitrogen removal.

• In the US climate change factors have notbeen accounted for.

• Property owners and users may beirresponsible in regard to the use of pesticides.

• Maintenance by property owners is morelikely where this influences propertyvalues. However, where BMPs areconsidered to be aesthetically or otherwiseunappealing these may be ignored.

• Hydraulic models should use long termobserved rainfall records if available.

C11 Seattle City Council/SEA streets

Visit Report: Seattle Public Works, Seattle,Washington

Visited: Tracy Tackett, PE, Senior CivilEngineer, Seattle Public Utilities

Date: 22 March 2006

Purpose: To examine the use of naturaldrainage systems in new developments.To learn processes for retrofitting naturaldrainage systems in existing neighbourhoods.To understand funding issues and publicengagement examples.

Seattle

Seattle is considered one of the mostbeautiful and prestigious places to live andwork in the whole of the US. The city isbounded by the Rocky Mountains to the east,which drop down to Washington Lake, andthe city is sandwiched between the lake andPuget Sound with the impressive OlympiaMountains in focus to the west. Itsclimatology is temperate, with similarseasons and rainfall to the UK.


• Wide ranging discussion on theimplementation, adoption, maintenanceand funding of natural drainage systems.

• Site visits

º High Point, development of new housing

º SEA streets, retrofitting of natural drainagesystems in existing neighbourhoods.

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Summary

At the initial meeting the mission team wasmet by Tracy Tackett who is a key player in theintroduction of (SUDS) in the Seattle area.

It is rather incongruous that a city so focusedtowards the use of sustainable systems andsource control elements in their stormwatersystems should be engaged in such a largeamount of high-rise building.

Over 17 years ago the planning authorities ofSeattle confined the construction of high-risebuildings in downtown Seattle to a limit. It isnow recognised that the high-rise officesallow urbanisation to be confined to a smallarea and, with careful planning andarchitectural control, has produced awonderfully exciting and enhanced view ofthe city – almost Manhattan-esque.

Tracy is an avid believer in the use of naturaldrainage systems. She was able to providethe group with a range of importantinformation and was also able to talk of thefinal detail of the drainage systems. It is clearthat the city is very proud of theirenvironmentally friendly projects.

As with the other local authorities that thegroup met in the US, discussion andengagement with the public was consideredan extremely important issue. The publicworks department does not try to workagainst the public view. They seek to do theopposite. They encourage local participation inthe projects, but should any resident not wishto take part in any project then they are notforced to do so.

Conclusions

Some of the key information is summarisedin the following:

• A development disturbing more than 5,000 square feet (465 square metres) mustuse and provide stormwater treatment.

• The Western Washington State Standardsstipulate that any development greaterthan 10,000 square feet (930 squaremetres) must replicate the pre-development condition for both waterquality and quantity.

• The municipality has the power to close sites if the contractor fails to meetthe required standards in terms ofstormwater runoff.

• It was recognised in certain situations thatpermitting can be slow, but this tended tobe a function of the lack of experience ofthe contractor and the dialogue thatnecessitated between the council and the contractor.

• The budget for stormwater control is $20 million (£11 million) a year. SUDS arenot called BMPs or LIDs in Seattle, theyare known as natural drainage systems.This seems a much more appropriateterminology.

• Each of the natural drainage systemsseeks to trap any storm of six months orless in magnitude. Using this method, theymanage to retain 91% of the annualaverage storm and this is always stored for48 hours to allow for sedimentation orsettlement to take place.

• Washington state has acquired over 50 years of rain data. This data has beenused to develop the Western WashingtonHydrologic Model which is provided freelyon the internet. This hydrologic modelallows continuous simulation which it claimsbrings an accurate understanding of theway in which natural drainage systems aregoing to work. The system is not without itsdrawbacks as it was clear in discussion thatclimate change had not been allowed for.

• The green roads that have been constructedgive up to 91% infiltration and attenuate thestormflows to the pre-developed condition.The green roads include runoff from boththe roads and roofs.

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• Unfortunately the situation is not all rosy. Itwas reported that the transportationdepartment has not been entirely supportiveto this way of thinking. It is estimated thatthe green roads strategy costs around$300,000 (£160,000) per 660 feet (200metres) long block.

• Design costs are high in this type ofconstruction but the municipality feels thatthe design and highly engineered solutionproduces the best solutions and overalloptimum results.

Maintenance

In the majority of cases infiltration isexpected to take place within 24 hours of thestorm. If after three days the system has notdrained down, a maintenance response istriggered from the city. The city has a ‘noditch filling’ law, which means that should aresident decide to fill in his ditch the cityauthorities will return to re-excavate andreplace it at the residents’ expense.

It was noticeable that Seattle in general is anaffluent area and the demographics of thepopulation seemed to be high. This seems tohelp with public engagement with anappreciative environmental concern.

Funding of the projects

The city used to have a flat rate on privateproperties for the funding of stormwater.However, this has now been changed to amethod which employs actual roof areas. Thisseems a fairer way of analysing the costs ofstormwater systems since it relates to theactual impervious area of the property, ieproperties with larger roofs and surface areacontribute a greater amount than those thathave less. The city encourages an incentive todisconnect their stormwater systems and thethree main methods of natural drainage

system being employed are bio-retention,porous pavement and ‘compost mendedlawns’17 (spongified).

Note: The annual average rainfall for Seattle isaround 39 inches, which is similar to manyareas of the UK.

Site Visits

High Point development

The High Point development is a newdevelopment that consists of some 300 acresof land. It is an interesting developmentbecause natural drainage systems have beenplanned in from the development’s earliestconception. The development uses a widerange of natural drainage systems from bio-retention swales and porous car parks toa large retention pond.

The developers and contractors work hard tokeep sediments out of the swales. This isvery important as sediment would quicklyclog up the swales and render themredundant. The swales are carefullyconstructed of specially made soils andplanted with appropriate species that willenable the maximum amount ofevapotranspiration to take place.

The project team has worked around maturetrees whenever possible. Each tree has beenvalued and has been closed off to avoiddamage. If any damage to the tree shouldoccur within 18 months of construction, thiscost will be served on the contractor. Manytrees are planted as part of the project and theproject will see a net increase in the numberof trees. The City of Seattle is aware of thedamage that stormwater run-off can have oncreeks, lakes and ocean waters and thenatural drainage systems meet multiple goalsand have a number of things in common:

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17 Compost mended lawns – A method of changing soil type to create a surface more conducive to absorption of rain water (sometimes referred to as

‘managing the sponge’)

• they meet the public’s expectations formanaging flooding in their neighbourhoods

• they provide an asset to communities byimproving the appearance and function ofthe street right of way

• they provide responsible stewardship ofthe environment

• they meet city, local and stateenvironmental regulations.

How well the bio systems are maintainedaround properties is ultimately up to theresident. The city provides basic maintenanceand the plants used require low service.However ‘low maintenance’ does not mean‘no maintenance’.

SEA streets (green streets)

SEA streets was the city’s first integratednatural drainage system project combiningneighbourhood enhancements with a newstormwater system that reduces run offvolumes from a one block residential area.

These streets direct stormwater throughwide step pools to improve water quality forthe large volumes of runoff for a wide area(serving nearly 50 acres) before it gets toPiper’s Creek.

The Broadview Green Grid project, involving15 city blocks, is almost an entire sub-basin ofthe Piper’s Creek watershed. The citycombines both cascade and SEA streetsprototypes to reduce stormwater pollutionand impact while providing otherneighbourhood improvements like tree coverand traffic calming sidewalks.

Americans love their cars and changing thelook and use of the street right of way willalter the way in which the street is used.After construction, parking will be reducedbut will still exceed the neighbourhood’scurrent use. Street use and parking studiesare conducted for the neighbourhood. Thenew street designs provide adequate parkingalong each block.

Exhibit C.15 Typical Layout prior to SEA streets

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Exhibit C.13 High Point development

Exhibit C.14 Protecting established trees

Exhibit C.16 Post construction of SEA street

The road looks quite different from theoriginal. The wide gravel shoulder that existedhas been eliminated. Parking on the newpaved portion of the street is legal as long asa 10 foot wide lane is maintained for traffic.This means parking is available only on oneside of the street. It will be up to residents toinform visitors and guests of this requirement.Vehicles that need to be parked for longperiods will simply be parked in the driveway.

City law allows parking on the street for up to72 hours; however, the law is only enforcedin response to citizen complaints. Parking ofdetached trailers on the street is never legal.Vehicles wider than 80 inches are prohibitedfrom parking on the street between midnightand 6 am. Residents park trailers and largervehicles on private property.

In summary, it would appear obvious fromthe photographs that this style ofmanagement of runoff represents not only aneffective, but also an aesthetically pleasingway of managing runoff. Although at an earlystage, it would seem that residents are veryhappy with the new arrangements. Aninteresting anecdote was that some of theneighbourhoods that were offered this styleof management refused it. On seeing theresults of the changes made, they have maderepresentation to the city to have their streetsupgraded in this way. They have even offeredto part fund it!

The overall effect on this work has been toclean up the creeks into which thestormwater ultimately flows. There is aprogramme ongoing in conjunction withthese works that is trying to bring salmonback to the rivers and creeks. They havefound that they need to use a Chub salmon,which seem more able to respond to thewaters in the best way.

http://www.ci.seattle.wa.us/util/About_SPU/Drainage_&_Sewer_System/Natural_Drainage_Systems/index.asp

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Exhibit C.17 SEA street bio systems

Exhibit C.18 SEA street bio systems

C12 CDS City of Los Angeles

Visit report: CDS Los Angeles

Date: 23 March 2006

Visited: Host: Mark Cuneo, LA GeneralManager, CDS. CDS is one of the leadingcompanies in US for providing proprietaryhydrodynamic separators and filter systems.Its system is unique in that is has an in buildscreen (patented). www.cdstech.com

Los Angeles (LA): Population of 10 million,high-density, high-land costs, average rain 14 inches (356 mm), which is highly variableand seasonal. It has an area of 4,447 squaremiles, plus 120 miles of coast.

Purpose: To look at some proprietarysystems being maintained, to visit theSMURRF facility and to discuss regulationsand the stormwater market in LA.


• Site visits – beach-front storm separatoroutlets and SMURRF

• Presentations on CDS products

Site visits

1 The clean out of a large hydrodynamicseparator, a PSW70, which is a 7 feet (2.1 metres) diameter by 7 feet tall screencylinder with a lift-out basket on RedondoBeach. This was rated at 26 cubic feet per second (cfs) (736 litres/second)screening capacity.

2 The Pico Kenter Drain diversion was aPSW30 device, 3 feet (0.9 metres) indiameter by 3 feet deep, divertingnuisance flow of up to 3 cfs (85litres/second) from a storm drain to theSMURRF on Santa Monica beach. It actedas a pre-treatment screen.

3 Viewed the SMURRF complex at Santa Monica.

4 Looked at 25 acres (10 hectares) ofwetlands (freshwater marsh) created at theplaya Vista project (1,000 acres (405 hectares) of new development).

Summary

Maintenance seems to be an issue notaddressed by the regulators, and there is noplanned servicing by any of the citydepartments (townships). New developments(disturbing an acre or more) are where thesurface water regulations are being applied,thereby slowly improving the stormwater infra-structure. In many cases, these developmentsare private and even more ‘disconnected’ fromthe maintenance process. However, thecounty does specify where BMPs should beused, and if they were put on public propertythen they would adopt them, with anassociated commuted sum. The cost ofemptying a hydrodynamic device ranges from$850 to $1,700 (£460-£920), depending upontheir size plus the number of rainfall events.Emptying is usually annual.

There were devices for creating dry weatherdiversions from stormwater sewers to thefoul sewers which seem to be an effectivemethod of treating infiltration and ingress. Thefigure being quoted (for I/I) was a 50-150 USgallons/day/house. A number of proprietarysystems were being used to catch trash andsolids: nets, gravity settlement, vortexsystems, bar screens in manholes andpumping chambers. A significant problem isthat watersheds cross municipal boundaries.

The City of LA has very little money allocatedfor the control and quality issues associatedwith stormwater. However, a $500 million(£270 million) bond was raised to be paid for bythe LA residents. It was successful as it wasnot seen as a tax. $12 million (£6.5 million) willbe spent per annum for the next 10 years onreducing trash, 10% of which is maintenance.This is considered a fraction of what is reallyrequired to meet the trash TMDL.

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There are concerns that the bond is stillunder-funding the stormwater needs of LAand the funds raised may not be spenteffectively.

The Santa Monica urban runoff recyclingfacility (SMURRF) is a state-of-the-arttreatment facility for stormwater,http://sannica.org/epwm/smurrf/smurrf.html.The system treats 500,000 US gallons per dayand comprises: a coarse and fine screen toremove trash and debris; a DAF unit toremove oil and grease with a degrittingproduct to remove sand and grit; a micro-filtration unit and finally a UV component. The system cost about $10-12 million (£5.4-6.5 million) and was commissioned in2001. One of its main purposes was toeducate and improve awareness ofstormwater treatment/recycling.

Conclusions

• The main driver for quality seems to berelated to the cleanliness of the beachesand associated tourism income.

• It seems the environmentalists forceaction on stormwater issues by successfullitigation. This is not always the mosteffective way to resolve the problem and isvery confrontational.

• Charging for stormwater is based onproperty values and is included in thesewage charge. Bringing in new taxesrequires a 70% approval of the voters.

• Diverting nuisance flows from stormsewers to treatment works in dry weatherso that they can receive full treatmentseems to make good sense.

• Maintenance is an unresolved issue. CDShas installed approximately 1,000 units inSouthern California and it is estimated thatonly 30% are being maintained.

• SMURRF is very useful for promotingpubic awareness of stormwater issues andits educational value meets some of theobligations of the CWA.

• The target of zero litter in stormwaterdischarges by 2013 is totally unobtainablebecause of the multiple inputs and lack offunding required to achieve it.

• The $500 million (£270 million) bond wasnot seen as tax and was agreed by theratepayers. A possible reason for this isthat it ‘ring fenced’ the money, meaning itwould only be spent on stormwaterimprovements.

• There is a need for the right champions,with good knowledge, to select the bestoptions and to make sure the water qualityand other performance aspects, such asflooding, are appropriately ‘joined up’,especially when they cross functional andmunicipal boundaries.

C.13 AbTech Industries City of

Los Angeles

Organisation visited: AbTech Industries(Scottsdale, Arizona). Department of PublicWorks Watershed Protection, City of LosAngeles (California).

Location: ‘The City of Los Angeles field studyon smart sponge,’ Santa Monica, LosAngeles, California.

Date: 24 March 2006

Purpose: Evaluate US advanced polymertechnique (smart sponge) for cleaning surfacewater runoff with manufacturer (AbTech) andproject promoter (City of LA). This techniquemay be significant for future use by the UKwater industry for improving surface waterrunoff quality, in accordance with therequirements of the WFD.

Details of persons met: Rodolfo Manzone –Executive Vice President, AbTech Industries.Duanne Cook – AbTech Industries.Elvin Yeck – Borough of Sanitation,Department of Public Works WatershedProtection, City of Los Angeles

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Information provided: The Norwalk stormdrain filter project – presentation andaccompanying handout by AbTech Industries. Smart sponge news clips DVD –AbTech Industries.

Site visit to the Santa Monica Bay area

The field study is being funded by AbTechIndustries in collaboration with the City of LosAngeles. The City of Los Angeles has anestimated population of 3.9 million, while LosAngeles County has 10 million. The surfacewater discharges into Santa Monica Bay havegradually been cleaned up since the early1980s through the implementation of theCWA and strong environmental groupsincluding the Santa Monica Baykeeper andHeal the Bay. Trash (a big problem for LA) andpollution still threatens the beach withdamaging closures, so there is still strongsupport for continued improvements. Thisproved to be a good test site for AbTech todemonstrate its smart sponge advancedpolymer technique.

The mission team was shown examples ofthe AbTech trash baskets and smart sponge‘ultra-urban’ filter inserts installed into 80storm drain catchpits (gullies) in thewatershed around Thornton Avenue anddraining out to Santa Monica Bay. It wasnoted that all of the other catchpits in thevicinity also contained the AbTech dual filtersystem. It is a dual filter system because theproprietary collar and basket collects all trashentering the catchpit, while the smart spongeinsert filters the surface water runoff,permanently taking out harmful pollutants.

The project timescale is 12 months.

Presentation and discussion

• www.abtechindustries.com• www.sourcecontrol.co.uk• The visit is to an AbTech funded field study

to retrofit 80 catch basins with trash

baskets and smart sponge. The trashproblem in Santa Monica is medium tolow, dependent upon street sweeping.

• The City of LA is carrying out independenttesting to verify the field work; this will becomplete in 12 months, but will probablynot be published and only used internally.

• AbTech’s advanced polymer smart spongehas elastic behaviour and differs from othersimilar products in that water passesthrough smart sponge to capturepollutants and not over the surface area. Inthis way, the smart sponge advancedpolymer is unique in its porous design.

• Income for the Bay clean-up will be bybond funds paid for by property taxes, withan average estimated tax increase on a$350,000 (£190,000) home of $35 (£19) ayear for 24 years. Project funds can beused for project planning, design,advertisement, bid and award, construction,construction management and inspection.

• The position of the screen in the catchpit(usually on top) is critical and fixed screensare not permitted.

• AbTech offered the field study to the Cityof LA and is meeting all the costs.

• Only commercial areas are required tohave trash bins; this explains the lack ofthem on the sidewalks and why trash issuch a problem. The first line of sourcecontrol could be trash bins. Additionalsocial education would also be good.

• BID (Business Improvement District;companies get a tax relief to assist in theclean up).

• LA has a high percentage of homeless,which contributes greatly to the trash problem.

• Street cleaning should be carried outweekly; but is probably not achieved in reality.

• The LA River has a trash TMDL for theclean up; there are no plans to soften its concrete lining structure with natural surfaces.

• The City of LA has no plans for a surfacewater impermeable area charge.

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• No single proprietary technology can beexpected to solve all the problems. Therehas to be an integrated surface watermanagement train.

Conclusions

• Ownership of stormwater systems andmaintenance is confused and seems to beprimarily based on which municipalorganisation owns the most land in an areaon which the BMPs sit.

• The best approach is to ensure that BMPsare used progressively as areas areredeveloped. No plans for big retrofitsother than screening for litter.

• Water quality samples are taken duringeach rain event (inlet and outlet). The city isalso involved and does bacterial analysis.AbTech Industries is funding the field study.

• The ocean is sampled either side ofoutfalls and 20 yards offshore (someenvironmental groups also do sampling).

• The involvement of environmentalists andlitigation has been both a nuisance and abenefit in driving improvements.

• Adjacent (inland) municipalities in the samewatershed can change their minds aboutstormwater management and do nothing,potentially compromising LA citysuccesses and approaches. Recent changein leadership has led to great difficulties forthe City of LA.

• There are various types of advancedpolymer technologies that ostensibly claimto do the same, but differ. AbTech’s smartsponge has unique characteristics and isprobably the market leader in thisdeveloping technology field.

• Proprietary products are sometimesunfairly expected to do almost everything,although in reality there is no ‘silver bullet’and there has to be an integrated surfacewater management train.

• Certified equipment can be replaced withsimilar but inferior products that do notperform adequately.

• The city sends out questionnaires to thepublic to help decide what solutions areapplied in particular areas.

• The huge LA homeless community createsa lot of trash in particular areas and trashbins will not solve this problem.

• Cross-municipality rivers lead todownstream impacts from othersupstream that don’t behave responsibly.

• As yet, little evidence of advancedtechnology performance research that isacademically peer-reviewed; the view isthat this field study will be internal only forLA city, although some other states’ workhas USEPA collaboration.

• Trash movement may well be related to afirst flush.

Exhibit C.19 The mission visiting the AbTech LosAngeles field study

Exhibit C.20 A line of ultra-urban filter inserts in an LAcatchpit

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Exhibit Page Caption

S.1 6 The team watching filter maintenance on a drain emptying into Los Angeles bay

2.1 20 National Pollutant Discharge Elimination System (NPDES) – status of US states2.2 30 The SMURFF unit in LA city designed to engage public interest in

stormwater management2.3 33 Maintenance and cleaning2.4 30 Maintenance and cleaning2.5 34 Example of poor maintenance2.6 35 Signage explaining purpose of natural drainage systems2.7 38 EPA best management practice research and development in New Jersey2.8 41 Bioremediation2.9 41 Bioremediation filter strip and detention basin2.10 42 Detention basin landscaped into public open space2.11 43 The importance of trees2.12 44 AbTech’s ‘Smart sponge’ demonstration to the mission2.13 45 Sustainable drainage BMPs protecting the Norwalk River2.14 45 AbTech’s ultra-urban catchpit insert2.15 47 Hydro’s Up-Flo filter during field pilot testing and verification2.16 47 An impressively vegetated green street eco-roof2.17 48 Various species of plants aids survivability and enhances aesthetics2.18 49 A rainwater downpipe draining to an open landscaped surface water box2.19 49 Downpipe disconnection is simple, cost effective and it works2.20 50 A green streets planter incorporated into the urban landscape2.21 50 An inlet to the street planter and note integration with pavement2.22 51 A SEA street bio-swale edged with porous road and pavement2.23 52 A familiar grass lined bio-swale2.24 52 A well established SEA streets landscape; drainage BMPs perfectly integrated2.25 52 A typical bio-swale located in a residential garden2.26 53 The mission visiting the AbTech Los Angeles field study2.27 53 A line of ultra-urban filter inserts in an LA catchpit2.28 54 Essential cyclic maintenance on a CDS Technologies installation;

removing LA’s trash2.29 55 Examples of guidance from CWP manual for urban sub-watershed

restoration manual2.30 64 Silt fences in use2.31 64 Covering and protection2.32 64 Filtration baffles2.33 65 Protecting established trees2.34 66 Green-roof in Portland, Oregon2.35 66 Proprietary Up-Flo filter system from Hydro International2.36 67 Sediment control on a construction site in Portland, Oregon

Appendix DLIST OF EXHIBITS

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Exhibit Page Caption

2.37 68 Hydro International’s Up-Flo system during on-site pilot testing and ETVverification by Penn State University

2.38 69 Monitoring equipment on demonstration green-roof site in Portland, Oregon2.39 69 Runoff reduction data from Seattle’s SEA street monitoring scheme2.40 70 Temporary monitoring equipment in place at SEA Street development2.41 70 The captured contents of a CDS separator prior to annual clean-out2.42 73 Re-used stormwater from the SMURFF in LA for irrigation carries a

health warning2.43 73 Public information notice board providing information regarding roadside

rainwater planters, Portland, Oregon2.44 74 Use of rainwater recycling to create recreational areas in Portland, Oregon

C.1 109 Owings Mills – apartment developments with detention pond in foregroundC.2 109 Owings Mills – pond serving a retail and office clusterC.3 111 Examples of CWP activityC.4 113 Retrofit street edge alternatives (SEA) C.5 115 Examples of activities undertaken by the CWP in SeattleC.6 118 AbTech’s ultra-urban catchpit insertC.6 118 AbTech’s ‘smart sponge’ demonstration to the mission teamC.8 119 Hydro International’s R&D Facility – Portland, MaineC.9 120 The Up-Flo filter system from Hydro InternationalC.10 122 Union Park Detention treatment facilityC.11 127 Green-roof used to provide an amenity for the residents of a flatC.12 127 Surburban drainage in an integrated urban environment C.13 132 High Point developmentC.14 132 Protecting established trees C.16 133 Post construction of SEA streetC.17 133 SEA streets bio systemsC.18 133 SEA streets bio systemsC.19 137 The mission visiting the AbTech Los Angeles field studyC.20 137 A line of ultra-urban filter inserts in an LA catchpit

Table 2.1 17 Examples of TMDLs from EPA website (http://www.epa.gov/owow/tmdl/examples/)

Table 2.2 18 Examples of BMPs suggested to achieve the TMDLs for example B in Table 2.1

Table 2.3 26 Non-structural BMPs for urban stormwater runoffTable 2.4 26 Structural or treatment best management practices for urban stormwaterTable 2.5 41 Range of percentage pollutant removals using certain structural BMPs

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Appendix EGLOSSARY

AWWA American Water Works AssociationAWWARF AWWA Research FoundationBMP best management practiceBOD biochemical oxygen demandCC county councilCCW Consumer Council for WaterCFD computational fluid dynamicsCOD chemical oxygen demandCPP cementitious permeable pavementCSO combined sewer overflowCWA Clean Water ActCWP Center for Watershed ProtectionDPD Department of Planning and DevelopmentECA Enhanced Capital Allowance SchemeEA Environment AgencyEIA Environmental Impact AssessmentEPA Environmental Protection AgencyETV Environmental Technology Verification ProgramEU European UnionHIG holes in the groundGIS Geographic Information SystemGCP good construction practiceI&I or I/I inflow and infiltrationIMP integrated management practicesLDF Local Development FrameworkLID Low Impact DevelopmentMWRA Massachusetts Water Resource AuthorityMCTT multi-chambered treatment trainMDP Master Drainage PlanNPDES National Pollutant Discharge Elimination SystemO&M operation and maintenancePPS Planning Policy StatementR&D research and developmentRSS Regional Spatial StrategiesSEA Strategic Environmental AssessmentSEA street street edge alternative streetSMURFF Santa Monica Urban Runoff Recycling FacilitySPEP stormwater public education programmeSUDS sustainable drainage systemSWMM stormwater management modelTMDL total maximum daily loadTSS total suspended solids

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UOP unit operation and processUPD urban planned developmentUSEPA Unites States EPAUWWTD Urban Wastwater Treatment DirectiveWEFTEC Water Environment Federation Technical Exhibition and ConferenceWERF Water Environment Research FoundationWFD Water Framework DirectiveWSUD water sensitive urban designwidget water integrated device giving effective treatment

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Grant for Research and Development – is available through the nine English RegionalDevelopment Agencies. The Grant for Researchand Development provides funds for individualsand SMEs to research and develop technologicallyinnovative products and processes. The grant isonly available in England (the DevolvedAdministrations have their own initiatives).www.dti.gov.uk/r-d/

The Small Firms Loan Guarantee – is a UK-wide, Government-backed scheme that providesguarantees on loans for start-ups and youngbusinesses with viable business propositions.www.dti.gov.uk/sflg/pdfs/sflg_booklet.pdf

Knowledge Transfer Partnerships – enableprivate and public sector research organisations to apply their research knowledge to importantbusiness problems. Specific technology transferprojects are managed, over a period of one tothree years, in partnership with a university,college or research organisation that has expertise relevant to your business.www.ktponline.org.uk/

Knowledge Transfer Networks – aim to improvethe UK’s innovation performance through a singlenational over-arching network in a specific field oftechnology or business application. A KTN aims to encourage active participation of all networkscurrently operating in the field and to establishconnections with networks in other fields thathave common interest. www.dti.gov.uk/ktn/

Collaborative Research and Development –helps industry and research communities worktogether on R&D projects in strategicallyimportant areas of science, engineering andtechnology, from which successful new products,processes and services can emerge.www.dti.gov.uk/crd/

Access to Best Business Practice – is availablethrough the Business Link network. This initiativeaims to ensure UK business has access to bestbusiness practice information for improvedperformance.www.dti.gov.uk/bestpractice/

Support to Implement Best Business Practice

– offers practical, tailored support for small andmedium-sized businesses to implement bestpractice business improvements.www.dti.gov.uk/implementbestpractice/

Finance to Encourage Investment in Selected

Areas of England – is designed to supportbusinesses looking at the possibility of investingin a designated Assisted Area but needingfinancial help to realise their plans, normally in the form of a grant or occasionally a loan.www.dti.gov.uk/regionalinvestment/

Other DTI products that help UK businesses acquire andexploit new technologies

Global Watch Information

Global Watch Online – a unique internet-enabled service delivering immediate andinnovative support to UK companies in theform of fast-breaking worldwide business andtechnology information. The website providesunique coverage of UK, European andinternational research plus businessinitiatives, collaborative programmes andfunding sources.Visit: www.globalwatchservice.com

Global Watch magazine – distributed freewith a circulation of over 50,000, this monthlymagazine features news of overseasgroundbreaking technology, innovation andmanagement best practice to UK companiesand business intermediaries.Contact:[email protected]

Global Watch Missions – enabling teams ofUK experts to investigate innovation and itsimplementation at first hand. The technologyfocused missions allow UK sectors andindividual organisations to gain internationalinsights to guide their own strategies forsuccess.Contact:[email protected]

Global Watch Technology Partnering –providing free, flexible and direct assistancefrom international technology specialists toraise awareness of, and provide access to,technology and collaborative opportunitiesoverseas. Delivered to UK companies by anetwork of 23 International TechnologyPromoters, with some 8,000 currentcontacts, providing support ranging frominformation and referrals to more in-depthassistance with licensing arrangements andtechnology transfer.Contact: [email protected]

For further information on the Global WatchService please visitwww.globalwatchservice.com

The DTI Global Watch Service provides support dedicatedto helping UK businesses improve their competitivenessby identifying and accessing innovative technologies andpractices from overseas.

Printed in the UK on recycled paper with 75% de-inked post-consumer waste content

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