water quality management program staff training

Civil & Environmental Consultants, Inc.

Water Quality Management Program

Staff Training


• Why is this change necessary?Why is this change necessary?• ProgrProgram rationaleam rationale• Describe new BMPsDescribe new BMPs• Plans review processPlans review process• Operation and Maintenance PlanOperation and Maintenance Plan• Design examplesDesign examples

AgendaAgenda


• 6 Minimum Control Measures6 Minimum Control Measures• Post construction storm water quality Post construction storm water quality

treatmenttreatment• “…“…treat storm water to the maximum treat storm water to the maximum

extent practicable…”extent practicable…”• All new developments and All new developments and

redevelopments disturbing 1+ acresredevelopments disturbing 1+ acres

NPDES Phase 2 regulations:NPDES Phase 2 regulations:


Steps Taken to Date:Steps Taken to Date:

• Ordinance with post construction languageOrdinance with post construction language• BMP storm water stakeholder groupBMP storm water stakeholder group• BMP Manual revisedBMP Manual revised• Ordinance revisedOrdinance revised• Developed plan review and permitting Developed plan review and permitting

processesprocesses• TrainingTraining


ScheduleSchedule

• Effective date = March 31Effective date = March 31• If plan has been platted and has approved If plan has been platted and has approved

SWMP, no additional storm water quality SWMP, no additional storm water quality treatment required.treatment required.


About the program…About the program…


Program rationaleProgram rationale

• Step 1: Define “Maximum Extent Step 1: Define “Maximum Extent Practicable” (MEP) for Bowling Green.Practicable” (MEP) for Bowling Green.

• Step 2: Establish how much treatment is Step 2: Establish how much treatment is enough.enough.

• Step 3: Develop a “doable” program.Step 3: Develop a “doable” program.


Identify pollutant of concern (303d lists, TMDLs)Identify pollutant of concern (303d lists, TMDLs) Establish pollutant load reduction goalEstablish pollutant load reduction goal

– Based upon accepted research, other communitiesBased upon accepted research, other communities– No need to reinvent the wheel…No need to reinvent the wheel…

Develop design features and practices that work Develop design features and practices that work for the Cityfor the City– Treatment volume based on impervious surfacesTreatment volume based on impervious surfaces– Consider local limitations (karst, groundwater table)Consider local limitations (karst, groundwater table)

How the City DefinesHow the City Defines MEP: MEP:


• Sediment or total suspended solids (TSS)Sediment or total suspended solids (TSS)• Available BMP researchAvailable BMP research• Many other programs using TSS as Many other programs using TSS as

pollutant of concernpollutant of concern• KYR10000 – references 80% TSS KYR10000 – references 80% TSS

reductionreduction• Sediment is no. 1 pollutant in nationSediment is no. 1 pollutant in nation

Pollutant of ConcernPollutant of Concern


Impervious CoverImpervious Cover

• TSS loading is higher from impervious TSS loading is higher from impervious covercover

• Impervious cover…Impervious cover…


Roads

Parking

Buildings

Sidewalks

Driveways


Establish treatment goals/limitsEstablish treatment goals/limits• Water Quality Treatment required for sites that disturb 1 ac or Water Quality Treatment required for sites that disturb 1 ac or

more AND add 10,000ftmore AND add 10,000ft2 2 or more new impervious surfacesor more new impervious surfaces

• WQv WQv = [(= [(P RvP Rv)()(AA)]/12)]/12

• Where,Where,• WQv WQv is the water quality treatment volume (ac-ft)is the water quality treatment volume (ac-ft)• P P is the average rainfall in inches, (in the case of Bowling Green, is is the average rainfall in inches, (in the case of Bowling Green, is

1.1 inches);1.1 inches);• Rv Rv is the volumetric runoff coefficient, which is:is the volumetric runoff coefficient, which is:• Rv Rv = 0.05 + 0.009(= 0.05 + 0.009(II), where I is the percent impervious cover;), where I is the percent impervious cover;• and and A A is the area in acresis the area in acres

• Set treatment goal based upon pollutant of concern…Set treatment goal based upon pollutant of concern…


A “Doable” ProgramA “Doable” Program

• Presumptive program:Presumptive program:– IF you IF you designdesign as described in BMP Manual as described in BMP Manual– IF you IF you installinstall per the approved plans per the approved plans– ANDAND– IF you IF you maintainmaintain the BMP per the Operation & the BMP per the Operation &

Maintenance PlanMaintenance Plan– THENTHEN– You are in compliance.You are in compliance.

• Discharge influent/effluent testing not required Discharge influent/effluent testing not required (for now…)(for now…)


BBestest MManagement anagement PPracticesractices

• Mitigate storm water Mitigate storm water quality and quantity quality and quantity damages from damages from developmentdevelopment

Wetlands Wet Ponds Dry Ponds

Bioretention areas

Water quality swales

Infiltration trench

Sand filter Water quality units

Manufactured devices


PondsPonds

• Dry pondsDry ponds– Outlet Outlet

structurestructure– Dry storage Dry storage

areaarea– 60% TSS 60% TSS

reductionreduction


PondsPonds

• Wet pondsWet ponds– Outlet Outlet

structurestructure– Permanent Permanent

poolpool– 80% TSS 80% TSS

reduction reduction


PondsPonds

• VariationsVariations– MicropoolMicropool– Extended Extended

detentiondetention– Multiple pondsMultiple ponds– Pocket pondsPocket ponds


WetlandsWetlands

• Outlet structureOutlet structure• Shallow wet Shallow wet

treatment areatreatment area• Upland dry storageUpland dry storage• Plants are keyPlants are key• Length of flow Length of flow

(residence time) key(residence time) key• 75% TSS reduction75% TSS reduction


Bioretention areasBioretention areas

• Outlet structureOutlet structure– Small storm & large Small storm & large

stormsstorms• Dry treatment areaDry treatment area

– Depressed planting Depressed planting areaarea

– Specific soilsSpecific soils– Under drainUnder drain

• 80% TSS reduction80% TSS reduction


Open Channel SystemsOpen Channel Systems• Simple outlet Simple outlet

systemsystem• Treatment areaTreatment area• Dry Dry

– good in most all land good in most all land use applicationsuse applications

– Underdrain systemUnderdrain system• Wet Wet

– Not well accepted in Not well accepted in residentialresidential

– Long wetlandLong wetland


Sand filtersSand filters

• Many variationsMany variations• Best suited for Best suited for

non-residentialnon-residential• Typically Typically

undergroundunderground• Must receive Must receive

drainage from only drainage from only impervious impervious surfacessurfaces


Infiltration trenchesInfiltration trenches

• Limited application Limited application due to karst due to karst topographytopography


Manufactured BMPsManufactured BMPs

• Treatment mechanisms different Treatment mechanisms different from non-manufactured BMPsfrom non-manufactured BMPs

• Must provide 3Must provide 3rdrd party testing to party testing to verify pollutant removal to get verify pollutant removal to get approved for useapproved for use

• Nashville has similar program – will Nashville has similar program – will use Nashville’s list of approved use Nashville’s list of approved BMPs and reduction capabilitiesBMPs and reduction capabilities


Summary tableSummary table


WQMPsWQMPs

• Trigger: 1 ac or more disturbance and Trigger: 1 ac or more disturbance and 10,000 ft2 new impervious surfaces10,000 ft2 new impervious surfaces– Or part of a larger common plan of Or part of a larger common plan of

developmentdevelopment

• DPW is point of contact for info on WQMPDPW is point of contact for info on WQMP– P&Z will have checklists and general infoP&Z will have checklists and general info


Conservation SubdivisionConservation Subdivision

• WQMP = WQMP = – Clearly defined clearing limitsClearly defined clearing limits– Total impervious surfaces for development Total impervious surfaces for development

cannot exceed 15%cannot exceed 15%– Minimum lot sizes – 1 acreMinimum lot sizes – 1 acre– Disconnected roof drainsDisconnected roof drains– Stabilized sinkhole basinsStabilized sinkhole basins

• No additional WQ treatment requiredNo additional WQ treatment required


Hot Spot LandusesHot Spot Landuses

• Pretreatment required for following landuses:Pretreatment required for following landuses:1.1. Automotive Fueling FacilitiesAutomotive Fueling Facilities2.2. Automotive Repair FacilitiesAutomotive Repair Facilities3.3. Restaurants with grease collection and disposalRestaurants with grease collection and disposal4.4. Other landuses as determined to have a high Other landuses as determined to have a high

potential of pollutant discharge into the MS4 as potential of pollutant discharge into the MS4 as determined by the City Engineerdetermined by the City Engineer

• Typically, oil grease separators, hydrodynamic Typically, oil grease separators, hydrodynamic separators, etc.separators, etc.


Asbuilt CertificationAsbuilt Certification

• Need to verify Need to verify – That BMP was installed per That BMP was installed per

approved plansapproved plans– That WQv treatment goals That WQv treatment goals

being metbeing met• Engineer and surveyorEngineer and surveyor• Asbuilt must be approved Asbuilt must be approved

before:before:– Bonds released (S/D)Bonds released (S/D)– CO issued (non-S/D)CO issued (non-S/D)


MaintenanceMaintenance

• City to maintain BMPs in City to maintain BMPs in – residential areasresidential areas– on public ROWs on public ROWs

• Landowner to maintain all other BMPsLandowner to maintain all other BMPs• All BMPsAll BMPs

– O&M PlanO&M Plan– Routine inspectionsRoutine inspections– Annual inspection certificationAnnual inspection certification


O&M PlanO&M Plan

• Includes the following:Includes the following:– BMP Maintenance AgreementBMP Maintenance Agreement

• Privately owned BMPs onlyPrivately owned BMPs only

– BMP location mapBMP location map– BMP schematics BMP schematics – BMP maintenance and inspection templatesBMP maintenance and inspection templates– Annual BMP report templateAnnual BMP report template

• Recorded with the deedRecorded with the deed• Privately owned BMPs onlyPrivately owned BMPs only

O&M PlanO&M PlanLashlee LandingsLashlee Landings

- Agreement- Agreement- Location map- Location map- Schematics- Schematics

- Inspection checklists- Inspection checklists


Detention Pond

Bioretention #1

Bioretention #2

Drainage Easement

Access Easement

Drainage Easement

BMP Location MapBMP Location Map


BMP SchematicsBMP Schematics

18” storage

2.5’ planting media

6” #57 stone

4” perforated plastic pipe

Geotextile fabric

Redbud, 10’ O.CDaylilies, 2’ O.C.


BMP SchematicsBMP Schematics


Storm Water Bioretention Area Inspection Checklist for BMP Owners Site name: ___________________________________________________________________________________ BMP Number: _________________________________________________________________________________ Owner Change since last inspection? Y N Owner Name__________________________________________________________________________________ Address______________________________________________________________________________________ Phone Number ___________________________ Location: ____________________________________________ Inspection Date: ______________________________________ Time:__________________________________ Inspector: ___________________________________________________________________________________ Weather Conditions:____________________________________________________________________________ Was flow observed: If so, what was the appearance of the water (i.e. color, sheen, estimated flow rate, etc.)? ____________________________________________________________________________________________

Maintenance Item

Insp

ecte

d?

(Yes

/No)

Ma

inten

ance

ne

eded

? (Y

es/N

o)

Comments

Treatment area (Inspect after major storm events) 1. Evidence of drainage (Is water ponding less than 24 hrs after rain event?) 2. Signs of erosion noted (in contributing watershed or in bioretention area?) 3. Mulch condition – thin or decomposing? 4. Sediment deposits noted in treatment area? 5. Vegetation condition 6. Overflow spillway in good condition? 7. Other (describe)

Note: If any inspection items were checked “yes” for maintenance needed, list maintenance actions and dates completed below.

Maintenance Action Needed Date

Du

e

Com

-pl

eted

? Y/

N

Inspector signature: ____________________________________________________________________________

City of Bowling Green

Storm Water Contact Information: 270-393-3628

BMP Inspection ChecklistsBMP Inspection Checklists


Residential Example: Residential Example: Lashlee LandingLashlee Landing


Site Data - 51 SingleFamily LotsArea = 38 ac.

Impervious Area = 13.8 ac 36% 3 ac in roadway and driveways, 10.8 ac in roof tops

WQv=[(P Rv)(A)]/12Rv = Rv = 0.05 + 0.009(I)WQv = [1.1*(0.05+0.009*36)*38]/12 = 1.30 ac-ft

Scenario 1:Wet pond = 80% TSSDA1, DA2, DA3 routed to pond

1

21

12211

)...(

)...(%

n n

n nn

AAA

ATSSATSSATSSTSS

Single Drainage AreaSingle Drainage Area


Site Data - 51 SingleFamily LotsArea = 38 ac.

Impervious Area = 13.8 ac 36% 3 ac in roadway and driveways, 10.8 ac in roof tops2 drainage basinsEach has to treat WQv; weighted TSS reduction goalDrainage Area (DA) 1Area = 7.6 ac.Imp Area = 2.25 ac; I = 2.25/7.6 = 30.0%Drainage Area (DA) 2Area = 30.4 ac.Imp Area = 11.55 ac; I = 11.55/30.4 = 38.0%

WQv=[(P Rv)(A)]/12Rv = Rv = 0.05 + 0.009(I)

DA1 Rv = 0.05 + 0.009(30) = 0.32WQv = [(1.1*0.32)*7.6]/12 = 0.22 ac-ftDA2 Multiple Drainage AreasMultiple Drainage AreasRv = 0.05+0.009(38) = 0.39WQv = [(1.1*0.39)*30.4]/12 =1.09 ac-ft


DA1 Rv = 0.05 + 0.009(30) = 0.32WQv = [(1.1*0.32)*7.6]/12 = 0.22 ac-ft- 2 Dry WQ Swales- provides 0.11 ac-ft of WQv in each- Dry WQ Swales = 90% TSS reduction

DA2Rv = 0.05+0.009(38) = 0.39WQv = [(1.1*0.39)*30.4]/12 =1.09 ac-ft- Wet pond- provides 1.09 ac-ft of WQv- TSS reduction = 80%

%TSS = (7.6*90)+(30.4*80)/38ac = 82% TSS

Therefore, site okayMultiple Drainage AreasMultiple Drainage Areas


Treatment TrainTreatment Train• When one BMP discharges into anotherWhen one BMP discharges into another• Discharge from upstream BMP will be “clean” so Discharge from upstream BMP will be “clean” so

downstream BMP TSS reduction will be less effectivedownstream BMP TSS reduction will be less effective

Bioretention80% TSS

Dry Detention60% TSSFlow Flow

TSS reduction = 80+60 – (80x60)/100 = 92%

100)( BABATSStrain


Scenario 2:DA1 =

Dry detention = 60% TSS

DA1 = 10ac @60% TSS

DA2 = 15ac @80% TSS then 60% (treatment train)

DA3 = 13 ac @90% TSS

DA1DA1

DA2DA2

Bioretention areas to dry

detention

Dry Swales

TSStotal = ([10ac x 60] + [15ac x 92] + [13ac x 90]) / 38 = 82.8% TSS

DA2 %TSS reduction

= 80+60 – (80x60)/100 = 92%


Commercial Example:Commercial Example:Creekwood VillageCreekwood Village


Creekwood Village S/DCreekwood Village S/D• Multi-familyMulti-family• Dry regional detention Dry regional detention

facilityfacility• Goal - Regional WQMP:Goal - Regional WQMP:

– Provide regional WQ Provide regional WQ BMPsBMPs

– Establish builtout Establish builtout imperviousness per lotimperviousness per lot

• Problem:Problem:– Assume 15 acres, 40 Assume 15 acres, 40

lots w/80% lots w/80% imperviousness per lot, imperviousness per lot, 1500 linear ft of 1500 linear ft of roadway.roadway.

– What is WQv?What is WQv?– What BMPs might What BMPs might

work?work?– Where?Where?


Lots 6 and 7Lots 6 and 7

• Regional WQMPRegional WQMP– Review against Review against

restrictionsrestrictions– If above restrictions, If above restrictions,

require additional on require additional on lot treatmentlot treatment

• Individual WQMPIndividual WQMP– Develop WQMPs as Develop WQMPs as

unit (lots 6-7) or unit (lots 6-7) or separatelyseparately


Dry Pond

Bioretention #1

Bioretention #2

Drainage Easement

Drainage EasementAccess

Easement

Problem:Lot 7 – 0.67 ac total, 25% impervious cover

Lot 6 – 1.1 ac total, 23% impervious cover

Problem:

What is the WQv?

Does this WQMP meet the TSS reduction goal if developed as one WQMP?


Questions and DiscussionQuestions and Discussion

water quality management program staff training

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