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DESIGN STANDARDDS-6 WASTEWATER

TABLE OF CONTENTS

DS-6.1 General ..............................................................................................................1

DS-6.2 Minimum Requirements ......................................................................................1

DS-6.3 Regional Council Requirements .........................................................................1

DS-6.4 Design ................................................................................................................2

DS-6.5 Conveyance - Wastewater System .....................................................................3

DS-6.6 Collection .........................................................................................................13

DS-6.7 Further Considerations .....................................................................................17

DS-6.8 Wastewater Treatment Design .........................................................................18

DS-6.9 Wastewater Pump Stations ..............................................................................19

DS-6.10 Private Pump Stations ....................................................................................22

DS-6.11 Receiving Reticulation ....................................................................................22

DS-6.12 Rising Mains ...................................................................................................22

DS-6.13 Pump Station Layout ......................................................................................23

DS-6.14 Fittings and Materials .....................................................................................24

DS-6.15 Pump Station Services ...................................................................................24

DS-6 WASTEWATER

Updated 01/07/2014 Page 1

DS-6.1 General

The primary goal of a wastewater drainage system is to convey wastewater from urban areasto the Council wastewater treatment plants. The management of wastewater has a functionalrole in the urban and rural environments and also has important cultural, ecological andenvironmental implications. The core design principals of a wastewater system must becarefully managed in order to avoid problems relating to public health and pollution of waterbodies. If the wastewater system is managed in this way, the impact on the safety of the publicand the environment is less.

Understanding the implications of the future land use and its design elements, such as theextent of effluent disposal is important and shall be taken into account.

DS-6.2 Minimum Requirements

Designs shall provide for a wastewater system that:

a) Complies with the operative City Plan and Infrastructure Development Code (IDC).

b) Is designed to acceptable urban design, landscaping and engineering standards.

c) Minimises, isolate or eliminates health and safety hazards during both its construction andits use.

d) Minimises, isolates or eliminates any adverse ecological and environmental effects.

e) The wastewater system shall be located in areas that are geotechnically suitable for thesystem proposed.

Note: Where confirmation of this requirement is not clear a certification statement from aCategory 1 Geo-Professional may be required.

DS-6.3 Regional Council Requirements

Areas not served by a Council owned piped reticulation system (rural and mostrural/residential areas) shall comply with the Bay of Plenty Regional Council On Site EffluentTreatment Regional Plan either as a permitted or discretionary activity. Other factors such asodour and air pollution shall also be considered.

Internal reticulation to sewage treatment and effluent disposal systems shall be installed inaccordance with the New Zealand Building Code and the Bay of Plenty Regional CouncilRegional Plan for On Site Effluent Treatment.

Soakholes for the disposal of septic tank effluent are not a permitted activity in terms of theBay of Plenty Regional Council Regional Plan.

Contact the Bay of Plenty Regional Council for more information.

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Page 2 Updated 01/07/2014

DS-6.4 Design

The following shall apply:

a) Unless otherwise approved by Council, the design of the wastewater system shall be inaccordance with the IDC but may be supplemented by the documents noted in DS-6 ApxA.1 General.

b) A computer modelling system approved by Council may also be utilised.

Detailed design shall be required at the time of Development Works Approval. Where noDevelopment Works Approval is required, Council approval shall be obtained at a timerequired by Council and before the construction of the system.

DS-6.4.1 Calculation of Flows


a) Wastewater flows are a function of water consumption, infiltration and direct entry ofstormwater, which in turn are a function of the age of the system and the quality ofmaintenance. The wastewater system shall be designed to eliminate intrusion ofstormwater & groundwater.

b) Where part or all of the catchment is serviced or will be serviced by a trunk main to beconstructed at a later date, Council may agree to this area being excluded from thecalculation. The flow from all portions of the upper catchment within the Tauranga Cityboundary shall be calculated assuming full development to the zones potential.

c) In residential areas, the wastewater system shall be designed and constructed usingthe following parameters:

i) Population density of 50 people/ha.

ii) Average dry weather flow of 210L/person/day and a dry weather diurnal peakfactor of 2.5.

iii) Dilution/infiltration factor of 2 for wet weather.

iv) Peak hourly flow 0.61 L/sec/ha.

d) For design populations of 1000 people or more, a reduced peaking factor may bediscussed and agreed with Council.

e) In industrial or commercial areas, the wastewater system shall be designed using adischarge rate of 0.7 L/sec/hectare.

Note: These figures include both normal wastewater and trade wastes and include apeaking factor of 5 times average daily water flow (ADWF).

i) Notwithstanding the above, provision for trade waste shall be made byarrangement with the Council and shall be subject to the provisions of theappropriate Trade Waste Bylaw.

The industry type will not necessarily coincide with the zoning classificationshown in the City Plan, but the zoning, particularly where effluent discharge is aperformance standard, may be used to indicate the minimum design flow wheremore detailed information is not available.

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ii) It may be desirable to provide additional capacity if the developer wishes towiden the range of industries to be located in a development area. However thecapacity of the existing receiving facility may be a controlling factor and the finaldecision will rest with Council.

iii) The design of wastewater disposal systems for "wet" industries (very heavywater users) shall be based on the specific requirements for that industry.

f) For commercial flows refer to DS-1 - Apx A.1 General.

DS-6.4.2 Hydraulic Design


a) The hydraulic design of the system shall be designed such that maximum design flowscan be accommodated without surcharging the pipe network.

b) The hydraulic design of wastewater pipelines shall be based on tables for the hydraulicdesign of sewers and pipelines or on graphs or other representation of the samemethods based on the Colebrook White or Manning's Formulae.

c) The pipe roughness coefficient Ks used in the design shall be as shown in NZS4404Table 5.2.

Table 1: Wastewater Pipe Roughness Coefficients

Material Colebrook Whiteco-efficient

Mannings Roughnessco-efficient

PVC-U 0.6 0.011PE 0.6 0.011GRP 0.6 0.011Cement Lining 1.5 0.012PE or Epoxy Lining 0.6 0.011

DS-6.4.3 Maximum Velocity

Maximum velocity flow shall be 3.0m/sec (peak wet weather flow pipe full).

Where a steep grade that will cause a velocity greater than that specified is unavoidable,refer to the Water Services Association of Australia : Sewerage Code of Australia : WSA02 – 2002 for precautions and design procedures.

DS-6.5 Conveyance - Wastewater System

The wastewater system shall be a piped reticulation system.

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DS-6.5.1 Piped Reticulation

The piped reticulation system shall be designed to the following minimum requirements:

a) It must comply with DS-1 - Appendix A.1 General.

b) Reticulation mains shall be no smaller than 150mmØ.

c) Trunk mains shall be ³ 225mmØ.

d) The minimum pipe size for connections or laterals shall be as follows:

1 or 2 independent dwelling unitsMore than 2 independent dwelling unitsCommercial and industrial lotsReticulation servicing residential lotsCarriageway crossings

– 100mmØ– 150mmØ– 150mmØ– 150mmØ– 150mmØ

e) Under no circumstances shall the pipe size be reduced on any downstream section.

f) Manholes are required at each:

i) Intersection of pipes (except for junctions between mains and laterals).

ii) Change of grade (except where vertical curves are used).

iii) Change of direction (except where horizontal curves are used).

iv) Combination of changes of pipe direction and grade (except where compoundcurves are used).

v) Change of pipe size.

vi) Change of invert level.

vii) Change of material (except for repair/maintenance locations).

viii) Discharge of a pressure main into a gravity system.

ix) Permanent or temporary end of a pipe system.

g) Each branch line (excluding connections) shall join the main line at a manholejunction.

h) In potentially unstable ground or where special protection is required, the pipeline shallbe specifically designed including the choice of materials.

DS-6.5.2 Reticulation Layout


a) The alignment of wastewater reticulation shall be laid out to follow the road pattern andeither:

i) Be located clear of the carriageway.

ii) Be located clear of wheel tracks if within the carriageway.

b) Where this is not possible or practical, the main may be located:

i) On public land with approval from Council.

DS-6 WASTEWATER


ii) Within private property parallel to and located between 1m and 1.5m from thefront, rear and/or side boundaries provided it avoids affecting futuredevelopment options available within the lot.

iii) On the low side of lots that have a cross-fall of more than 1.5m.

iv) Drainage reserves outside the 50 year return period storm event (2%AEP) area.

c) Where the only option for location of reticulation is within the carriageway, thereticulation shall be located in the centre of the driving lane & designed to support an8.2 tonne design axle load.

d) Horizontal curved pipes shall only be used only where approved by Council. Designstandards for curved pipes can be found in Water Services Association of Australia :Sewerage Code of Australia : WSA 02 - 2002.

e) Vertical curves may be specified where circumstances provide a significant saving orwhere maintenance structures would be unsuitable or inconvenient. The curvaturelimitations for vertical curves can be found in the Water Services Association ofAustralia : Sewerage Code of Australia : WSA 02 - 2002.

f) Where an existing reticulation system exists, provision must be made for connectioninto this.

g) Where the reticulation is within a private way, right-of-way, or joint-owned access lotthe reticulation shall be located outside the logical wheel track alignment.

DS-6.5.2.1 Close Proximity Rules

T653 T654


a) Buildings or structures to be constructed close to a main or lateral/connectionshall comply with the requirements of T653 and T654. Where dispensation hasbeen granted for a building or structure to be built over a main orlateral/connection, foundations shall be designed by a Chartered ProfessionalEngineer.

b) No enclosed building or structure shall be sited over a manhole or closer than500mm from the outside wall of the manhole structure.

c) No building or concrete slab shall be constructed over a connection point to amain.

d) No buildings shall be constructed over a main if there is a connection closer than1.0m to the building unless the connection is relocated to the satisfaction ofCouncil.

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e) Encroachment of removable, non-permanent structures e.g. carports, decks,fences may be approved by Council when the structure is designed and built suchthat it can be dismantled easily in sections. The removal and re-erection of thesestructures shall be at no cost to Council. Council approval is required in allinstances. Council will assess each application on a case by case basis as thevariables at each site will not always be the same e.g. pipe size, trench details etc.Council may add a record to the property file of any such approval to ensure thatfuture property owners are aware of the approval and Council’s right to have thestructure removed at any time for the purposes of maintenance work, emergencywork or upgrade work.

DS-6.5.3 Minimum Grades for Self-Cleaning


a) The reticulation pipes within the wastewater management system shall be designedand constructed to at least the following minimum grades to achieve self cleansing asshown in DS-6.5.3 Table 2: Minimum Grades for Self-Cleaning.

b) Where the normal velocity and gradient limits cannot possibly be met, Council mayrequire certain additional works to ensure satisfactory operation of the system.

Table 2: Minimum Grades for Self-Cleaning

Trunk or Reticulation MainPipe Size (Ø) Minimum Grade (%)

150mm 0.55225mm 0.33300mm 0.25

Lateral ConnectionPipe Size ( Ø ) Minimum Grade (%)

100mm 1.65150mm 1.2

> 150mm 1.0

DS-6.5.4 Steep Grades

Scour blocks and trench stop configuration shall be detailed on the design drawings andshall be in accordance with the Standard Drawings. Spacing of scour blocks shall be inaccordance with DS-6.5.4 Table 3: Spacing of Scour Blocks.

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Table 3: Spacing of Scour Blocks

Grade % Requirement Spacing (S) (m)15 – 35 Concrete bulkhead S = 100/Grade (%)

>35 Special design Refer to Council

Note: On flat grades where scour is a problem, sand bags are often usedto stabilise the trench backfill.

Where the natural transfer of water from the trench into the surroundingground will not provide sufficient drainage, trench drainage shall beprovided to divert the water.

DS-6.5.5 Cover Over Pipelines


a) In private property:

i) The minimum cover shall be 600mm.ii) If the cover exceed 3m, specific design and approval is required.

iii) The design of cover shall avoid affecting the future development optionsavailable within the lot.

iv) Where the reticulation lines are located in the front yards of lots, the invert levelshall be deep enough so as not to interfere with any future drivewayconstruction.

b) In Road Zones:

i) Pipelines shall achieve 900mm of cover and be designed to support an 8.2tonne design axle load.

c) Where minimum cover cannot be achieved, specific design of pipe and cover isrequired.

DS-6.5.6 Loads on Pipes


a) All pipelines shall be designed to withstand all the likely loads that they may be subjectto.

b) In the first instance, load parameters shall be designed to support an 8.2 tonne designaxle load. Following this:

i) AS/NZS 3725 and AS 2566 shall be used as design guides as applicable.

ii) Any loads relating to backfill techniques, construction traffic, temporary storageof materials and the like shall be incorporated into design parameters andconstruction methodology.

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DS-6.5.7 Concrete Capping of Pipelines

Where minimum cover cannot be achieved, concrete capping may be used taking intoaccount pipe protection and road integrity requirements. Approval from Council is requiredfor the use of concrete capping.

DS-6.5.8 Pipe Materials

Refer to AM-6 Wastewater.

DS-6.5.9 Pipe Joints

All pipelines shall be fully sealed by use of rubber joint rings or welding as appropriateunless otherwise approved by Council.

DS-6.5.10 Pipe Bedding and Backfill

T651


a) Pipe bedding and backfill shall be specifically designed, shown on the detailed designdrawings and submitted to Council for approval.

b) The design shall also include the compaction criteria to be used to certify the backfillhas been compacted to the required compaction standard.

c) All trench backfill under carriageways shall be designed and constructed to achieve forthe required pavement layers strengths for the class of road it is beneath.

DS-6.5.11 Venting


a) The wastewater management system shall be ventilated to minimise the likelihood offoul gases accumulating in the drainage system.

b) In urban developments pipes will normally be adequately ventilated within privateproperty drainage via terminal vent stacks. However there are some situations whereadditional vent stacks may be required. These are:

i) Pumping stations.

ii) Manholes where pumping station rising mains discharge to a gravity pipe.

c) Vents and pump stations shall be located to avoid being a noise or odour nuisance tooccupants of buildings or likely building sites.

DS-6 WASTEWATER


DS-6.5.12 Piped Reticulation Structures


a) This section describes the requirements for structures that may be needed inconveying wastewater through a reticulated system. These are:

i) Manholes.

ii) Rodding Eyes.

iii) Alternative structures as specifically designed.

b) The selection of a suitable location for these structures may influence the pipealignment. Generally a minimum clearance of 1.0m shall be provided clear of theopening around any structure that may allow entry for maintenance or rescueequipment. Council may determine other specific requirements subject to theindividual site’s characteristics.

DS-6.5.12.1 Manholes

T601, T602, T603, T604, T605, T606, T607, T608, T609, T610, T611, T612, T613


a) Manhole spacings shall not exceed 100m. The entire manhole structure shall belocated clear of all boundaries and at the end of all public reticulation mains.

b) The entire manhole structure shall be located clear of all boundaries.

c) Manholes shall be located within Council property or Road Zones as often aspossible. They shall be clear of floodways, stormwater detention areas,stormwater secondary flowpaths and inter-tidal regions.

d) Manholes deeper than 5.0m to the pipe invert and shallow manholes may be usedin certain circumstances subject to the approval of Council. Where a manhole ismore than 5.0m deep it shall:

i) Be specifically designed.

ii) Have access steps installed.

iii) Incorporate clear warning that it is deep.

iv) Have a secure entrance.

v) Require larger diameter chambers and covers.

e) Standard 1050mmØ manhole risers are not suitable where the pipes are eitherlarger than 675mmØ or where multiple pipes enter a manhole causing loss of themanhole wall. Manholes shall be designed to maintain wall integrity in thesecircumstances.

f) Manholes shall not be located within the road carriageway unless approved byCouncil.

g) All manholes shall have an entry safety grill fitted.

h) All standard manholes shall be constructed as detailed on the StandardDrawings.

DS-6 WASTEWATER


DS-6.5.12.2 Manhole Sizing


a) The standard internal diameter of circular manholes is 1050mmØ and thepreferred nominal internal diameters are 1050mmØ, 1200mmØ and 1500mmØ.

b) When considering the appropriate manhole diameter consideration shall be givenby the Designer to the base layout to ensure hydraulic efficiency and adequateworking space in the chamber.

c) Where the effective working space is reduced by internal drop pipes, a largerdiameter may be required.

d) Where there are several inlets, consultation with Council on the layout of thechamber is recommended.

DS-6.5.12.3 Benching


a) Benching shall be provided in the base of each manhole that provides a safeplace to stand for maintenance purposes.

b) Benching shall be close to flat with a cross fall (3H:1V upslope failure zone) intothe manhole pipe system for drainage purposes.

c) Channels shall have a minimum inside radius of 300mm.

DS-6.5.12.4 Internal Falls through Manholes


a) Reticulation pipes:

i) The minimum internal fall through a reticulation channel in a manhole shallbe as outlined in DS-6.5.12.4 Table 4: Minimum Internal Fall Through aManhole.

ii) The maximum benched fall through a manhole shall be 600mm.

iii) Where the outlet diameter at a manhole is greater than the inlet diameter,the minimum fall through the manhole shall be not less than the difference indiameter of two pipes, in which case the pipes shall be aligned soffit to soffit.

iv) For manholes where the maximum internal fall of 600mm across the base ofthe manhole is exceeded due to a large difference between the levels ofincoming and outgoing pipes then internal or external drops shall beprovided as shown in the Standard Drawings.

b) Lateral connections to manholes:

i) The invert of a lateral must connect to the manhole at a level no lower thanthe average of the soffit levels of the main inlet and outlet pipes.

ii) The maximum angle of deflection of lateral into the manhole main channelshall be 90 degrees.

DS-6 WASTEWATER


Table 4: Minimum Internal Fall Through a Manhole

Deflection angle at manhole Degrees(°)

Minimum additionalfall (mm)

0 to 30>30 to 60>60 to120

305080

DS-6.5.12.5 Allowable Deflection Through Manholes

The maximum allowable deflection through a manhole shall be as outlined inDS-6.5.12.5 Table 5: Allowable Deflection Through Manholes.

Table 5: Allowable Deflection Through Manholes

Pipe size (Ø) Maximum deflection (º)

150-300mm150-300mm

Up to 120º for internal fall along manhole channelUp to 150º when using an internal or externaldrop structure

DS-6.5.12.6 Effect of Steep Grades on Manholes

Where a pipe of grade >7 % drains to a manhole, the following precautions shall betaken:

a) Steep grades shall be continuous through the manhole at the same grade.

b) Depth of a manhole to exceed 1.5m to invert for 150mmØ and 225mmØ pipes.

c) Depth of a manhole is to exceed 2.0m deep for 300mmØ pipes.

d) Change of direction at the manhole is not to exceed 45º.

e) No drop junctions or verticals shall be incorporated in a manhole.

f) Inside radius of channel inside a manhole is to be greater than 6 times the pipediameter and benching is to extend 150mm above the top of the inlet pipe.

g) To avoid excessively deep channels within manholes, steep grades (>7 %) shallbe "graded-out" at the design phase where practicable. The design of pipelines ongradients over 7% must be agreed with Council.

h) Benching of channels to ensure that the final platform is parallel with the mainchannel so maintenance workers are able to stand comfortably on a flat surface.The benching shall be sloped towards the channel.

DS-6.5.12.7 Flotation

In areas of high water table, all manholes shall be designed to provide a factor ofsafety against flotation of 1.25.

DS-6 WASTEWATER


DS-6.5.12.8 Access Steps

T603

Manhole steps shall comply with the Standard Drawings and AM-6 Wastewater.Wastewater manhole steps shall be located above the downstream outlet pipe.

DS-6.5.12.9 Covers

T604, T605, T606, T607


a) Manhole covers with a minimum clear opening of 600mm in diameter shall beused.

b) Non-Rock covers must be used on all Level 2 (or primary arterial) roads.

c) Refer to AM-6 Wastewater for manhole cover type.

d) All covers shall be painted with New Zealand Transport Agency (NZTA) Standardapproved "white" road marking paint.

DS-6.5.12.10 Areas Subject to Flooding


a) The top of manholes in areas subject to flooding or located in a stormwatersecondary flowpath shall be raised at least 300mm above the 50 year returnperiod storm event (2%AEP) where practicable. This may require local groundrecontouring to suit.

b) Sealed/watertight access covers may be required where the possibility ofsurcharge exists or the manhole is located:

i) In a hardstand area (e.g. in a carriageway or walkway).

ii) Along a watercourse that is subject to flooding above the level of the cover

iii) In tidal areas or in any location where surface waters could inundate the topof a manhole.

DS-6.5.12.11 Internal and External Drop Manholes

T608, T609


a) All drop connections to new wastewater manholes shall be constructed asdetailed in the Standard Drawings.

b) Internal drop connections will be permitted only by written approval and mayrequire the installation of a 1200mmØ manhole. Internal drop connections may beallowed when working in sand country with potentially high groundwater and aresultant danger to the carriageway exists.

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c) The minimum height for drop connections shall be 600mm.

DS-6.5.12.12 Rodding Eyes

T620, T621


a) A rodding eye shall be required at the ends of some lateral pipes installedbetween a property connection point and the wastewater main.

b) PVC-U bends up to 45° are acceptable.

c) A standard manhole frame and cover shall be installed over the entry point whennot located in a hardstand area. A fire hydrant base and rodding eye cover shallbe used in hardstand areas.

d) All covers must be painted with New Zealand Transport Agency (NZTA) Standardapproved "white" road marking paint.

DS-6.6 Collection

T630, T631, T632, T633, T634

This section describes the requirements for collection of wastewater. These are categorisedas:

a) Property service connections.

b) Alternative collection methods.

DS-6.6.1 Property Service Connections

A connection is the point of union between a property’s private drain and the publicwastewater network. Private drainage generally extends to the property boundary at whichpoint Council accepts responsibility for the downstream pipelines.

DS-6.6.2 Minimum Requirements

Property service connections shall be designed to the following minimum requirements:

a) Each lot shall be served by one service connection.

b) Any individual lot/property connection shall be designed and located to suit theexisting and future development scenarios and where possible sized, located anddesigned to meet the service of the whole property (land parcel), but as a minimum thebuilding platform.

c) Any connections shall be located to service the lowest practical building platform onthe property.

d) The design shall specify the requirements for the property connections including planlocation, lot contours and invert level at property boundary or junction with the main asapplicable.

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DS-6.6.3 Private Drainage

Generally all wastewater pipes installed between a building and the connection point toCouncil’s wastewater network are private assets. The Building Act requires that a BuildingConsent shall be obtained for their installation or alteration and that this work must only becarried out only by a registered drainlayer.


a) Further approval must also be obtained from Council before these drains may beconnected to the wastewater network. Application for this shall be on Council's WaterSupply / Drainage / Vehicle Crossing Connection Application Form.

b) All connections to Council infrastructure shall be carried out only by a CouncilLicensed Contractor.

DS-6.6.4 Connection Locations

Connections shall be:

a) Clear of obstructions, e.g. trees, tree roots, paved areas.

b) Easily accessible for future maintenance.

c) Clear of any known future developments, e.g. swimming pools or driveways.d) For infill subdivisions, particularly where upgrading of existing 100mmØ connections in

sound condition and at reasonable grades would be impractical, up to four dwellingunits may be connected subject to Council approval.

DS-6.6.5 Connection Depth

T630, T631


a) Connection depths shall be set to drain the whole serviced area recognising thefollowing factors:

i) Any connection points shall have a minimum cover of 600mm and be no deeperthan 1.5m. (Deeper connections may be installed in some circumstances butonly with the prior approval of Council).

ii) Surface level at plumbing fixtures of buildings (existing or proposed).

iii) Depth to invert of pipe at plumbing fixture or intermediate points.

iv) Invert of public main at junction point.

v) Allowance for crossing other services.

vi) Allowance for minimum gradients of laterals and private drainage.

vii) Lateral junctions installed at minimum of 45° (vertical) to main.

b) The designed invert level at the connection shall be no higher than the lowestcalculated level consistent with these factors.

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DS-6.6.6 Installation of Connections

T630, T631, T632, T633, T634


a) The end of each connection pipe shall be sealed with a solvent-welded cap paintedred if the connection does not occur immediately.

b) Where the inspection is servicing a property containing multiple residential units then asurface-accessible inspection chamber such as a manhole, rodding eye or otherCouncil approved structure shall be installed.

c) Each connection point shall be marked with a 50mm x 50mm timber stake paintedwhite which shall extend from the invert to a minimum of 300mm above finishedground level. A red marker tape labelled "sewer" shall be attached to the connectionpipe, brought up and tied to the top of the stake.

DS-6.6.7 Connection Destinations

Each service connection shall connect to one of the following points of discharge. Themechanisms are listed in order of preference.

Where the main is within the property boundary a separate connection shall be provided toeach lot.

a) Connections to wastewater mains greater than 5.0m deep will not be approved. Inthese cases a high-level wastewater main will need to be constructed.

b) Connections to trunk mains will generally not be approved by Council.

DS-6.6.8 Lateral Configurations

T637, T638, T639, T640, T641, T642

To provide a service connection to each lot, a minimum 100mmØ line shall be extendedfrom the main reticulation system to terminate within the property boundary at a minimumdistance of 1.0m from the front and side boundaries whether created by cross-lease, unittitle or fee-simple subdivision.

These connections shall also form part of the public system to the site boundary and bebrought up to within 1.2m of the final ground surface level.

In addition the following shall apply:

a) For a lateral providing a service connection for 1 lot connecting to a manhole refer toT637.

b) For a lateral providing a service connection for 2-6 lots connecting to a manhole referto T638.

c) For a lateral providing a service connection for 1 lot connecting to a main refer to T639.d) For a lateral providing a service connection for 2 lots connecting to a main refer to

T640.

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e) Where lateral is over 50m long or the number of connections exceeds 6 lots, normalwastewater reticulation conditions apply.

f) Where practicable and where the connection is within 5m of a manhole the connectionshall be to the manhole.

g) Where the main is within the property boundary a separate connection shall beprovided to each lot.

h) All connections directly to the main shall be made using factory made fittings.

i) For major land use development where significant privately owned reticulation works(i.e. not being vested with Council) are being constructed and are connecting intoCouncil infrastructure, all works shall be designed and constructed in accordance withthe IDC requirements, however the reticulation will remain private.

DS-6.6.9 Infill Subdivision – 3 Lots or Less (Excludes Existing Lot)

It is recognised that infill subdivisions require flexibility in their reticulation layout.However, normal trade practices and standards are needed to ensure that the desiredservice life is achieved.

a) Reticulation of infill subdivisions shall comply with the following criteria:

i) Drainage within the parent lot shall remain private and be protected by anappropriate easement.

ii) Drainage lines shall be separated at the point of connection to the Council’sreticulation system and remain separate for each lot unless specific approval isgained from Council.

iii) Infill subdivisions shall be reticulated on a site-by-site basis.

iv) For minor infill subdivision type works, all private drainage works shall beconstructed in accordance with the NZ Building Code regulations.

b) Infill subdivisions shall be reticulated on a site by site basis to the approval of Council.

c) Lateral connections shall be constructed or upgraded in accordance with the IDC. Thislateral can be vested in Council and provide each lot with the same standard ofindividual connection as new ‘greenfields’ lots.

d) Where this is considered impractical or unnecessary, the Consent Holder may makeapplication to Council for the lateral to remain private within an appropriate easement.However common private drains are not encouraged so as to alleviate the friction thatsometimes occurs between neighbours when shared services are involved.

e) Drainage lines shall be separated at the point of connection to Council’s reticulationsystem and remain separate for each lot unless specific approval is granted byCouncil. Where the main is within a neighbour's property, the new junction may beinstalled immediately within the property being subdivided.

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DS-6.6.10 Multi-Unit Properties (Such as Apartment Buildings and BodyCorporate Developments)

a) For multiple occupancies (unit title, cross lease or company lease) service of the wholeproperty shall be achieved by providing a single point of connection to the wastewatersystem. Connection of the individual units is by joint service pipes owned andmaintained by the body corporate, tenants in common or the company as the casemay require. In this instance the whole of the multiple occupancy shall be regarded asa single lot. All drainage within the development boundary would be private.

b) Alternatively, if authorised by Council, developers may have the option of providingdrainage facilities to individual titles or tenements in new developments by extendingthe public line into the lot and providing a separate lateral/connection to each unit. If soall internal drainage shall be in accordance with the IDC. Easements shall be createdat Council’s discretion and to Council standards.

c) Where multi-unit developments are proposed, a single 150mmØ lateral/connection willbe required. Multi-unit developments will generally be required to upgrade existinglaterals if less than 150mmØ. The connection shall include a surface-accessibleinspection chamber or manhole immediately inside the boundary.

DS-6.6.11 Commercial and Industrial Connections


a) All commercial and industrial lots shall be provided with a wastewater connection.

b) Pollutants and contamination issues shall be identified and managed to thesatisfaction of Council though the Building Consent Process.

DS-6.6.12 Connection to Existing Council Reticulation

Approval shall be obtained from Council before connection can be made to thewastewater network. Application for this shall be on Council's Water Supply / Drainage /Vehicle Crossing Connection Application Form.

All connections to Council infrastructure shall be carried out only by a Council LicensedContractor.

DS-6.7 Further Considerations

The following shall also be considered as part of the design process:

a) DS-6.7.1 Trenchless Technology

b) DS-6.7.2 Access Requirements

c) DS-6.7.3 Easements

d) DS-6.7.4 Rural and Rural-Residential Zones

DS-6 WASTEWATER


DS-6.7.1 Trenchless Technology

Trenchless technology may be preferred or required for alignments passing through orunder:

a) Environmentally sensitive areas.

b) Built-up or congested areas to minimise disruption and reinstatement.

c) Railway and major road crossings.

d) Significant vegetation.

e) Vehicular crossings.

Refer to CS-13 Trenchless Technology for information on trenchless technologyinstallation.

DS-6.7.2 Access Requirements

Where any assets are being created as part of a wastewater system that is to bemaintained by Council, legal and practical access shall be provided for maintenance. Forthe purpose of this standard provision legal and practical access shall be a minimum of a4m wide access width containing a 3m wide access path constructed to an all weatherstandard able to carry an 8.2 tonne design axle load.

DS-6.7.3 Easements

Discussion with Council regarding easements is recommended early in the design phase.

An easement in gross will be required where a structure, pipe or other asset that forms partof the wastewater / stormwater / water supply system is to be vested in or maintained byCouncil and is located within land not vested in Council or a Reserve.

An easement in gross may not be required where the structure, pipe or other asset is:

a) Located within 1.5m of a property boundary.

b) A wastewater pipeline less than 150mm in diameter

All easements shall allow for right of access for practical maintenance.

DS-6.7.4 Rural and Rural-Residential Zones

Refer to DS-6.3 Regional Council Requirements.

DS-6.8 Wastewater Treatment Design

These are to be specifically designed and approved by Council. Discussions with Council shallbe undertaken during the design phase.

DS-6 WASTEWATER


DS-6.9 Wastewater Pump Stations

T660, T661, T662, T663, T664, T665, T666, T667, T668, T669, T670, T671, T672, T673,T674, T675, T676, T677, T678, T679, T680, T681, T682, T683

Wastewater pump stations convey wastewater from developed areas where natural landformand gradients do not allow for a gravity system to be used. It is important that’s factorsaffecting a pump station’s operation are understood as the effect of an overflow on thesurrounding area and/or watercourses is unacceptable due to important cultural, ecologicaland environmental implications as well as public health and pollution issues.

Detailed design shall be required at the time of Infrastructure Development Works Approval.Where no Infrastructure Development Works Approval is required Council approval shall beobtained at a time required by Council and before the construction of the system.

DS-6.9.1 Calculation of Flows


a) The pump station shall be sized to accommodate pumped flows from the totalforeseeable contributing catchment.

b) Each pump shall be sized such that the duty pump is capable of pumping themaximum design peak flow, calculated in accordance with DS-6.4.1 Calculation ofFlows.

DS-6.9.2 Freeboard

The pump station finished lid levels shall be located no less than 300mm above the 100year return period storm event (1%AEP) flood level.

DS-6.9.3 Wet Well and Storage Chamber

T660, T661, T662, T663, T664, T665, T666, T667, T668, T669


a) These shall be as specified in the Standard Drawings.

b) Pump stations and vents shall be located to avoid being a noise or odour nuisance tooccupants of buildings or likely building sites.

c) Wet wells and storage chambers shall be designed to accommodate all anticipatedloadings and safely accommodate all maintenance and operations vehicles andpersonnel.

d) The wet well operational volume (volume between duty pump start and stop level)shall be designed at full catchment average dry weather inflow to limit pump starts to amaximum of 15 an hour based on the following formula:

Operational Volume (litres) = 900 x Q N

DS-6 WASTEWATER


Q = Pumping Rate (l/s)N = Number of starts per hourOperational depth shall be a minimum of 1.5mmeasured from the invert of the inlet pipe.

e) The design and construction of the wet and storage well foundations shall ensure thatno more than 10mm effective long term total or differential settlement of the completedstructure occurs and a factor of safety of 1.25 against flotation is obtained. Effects onadjoining infrastructure must be considered.

f) A geotechnical investigation report may be required by Council at the time of theapplication for Resource Consent or the development plan approval.

g) In determining the appropriate wet well diameter the minimum clearance betweenindividual pumps and side clearances shall comply with the manufacturer’srecommendations.

h) A minimum clearance of 100mm all round the well shall be provided at the lid entrance.

i) Where a separate well is considered necessary to accommodate emergency storagevolume it shall be designed to direct all flow to the outlet point and be self cleansing.

j) A hinged entry safety grill shall be fitted immediately under the wet well chamber lids.

DS-6.9.4 Pump Station Inlet Pipe


a) The invert level of the gravity inlet pipe and emergency storage well shall be aminimum of 100mm above the standby pump start level to prevent surcharge of thesystem during normal operation.

b) Only one gravity pipe may discharge into the wet well and must include an isolationvalve. Where multiple inflows occur they must discharge to a receiving manhole, theninto the wet well.

DS-6.9.5 Pump Selection

a) In calculating the system head losses the effects of all bends and fittings beyond thepump discharge bend shall be allowed for, together with rising main friction losses.Calculations of friction loss shall be carried out based on roughness ‘Ks’ values of1.5mm and 0.5mm to ensure that the selected pump is capable of operating over thisrange of duty points. (Colebrook White formula). Where the discharge is to anexisting rising main, the head shall be calculated to include the operating head in theexisting rising main. Council approval is required for any discharge into an existingrising main.

b) The system static head shall be based on the difference in level between the flange ofthe pump discharge bend and the highest point on the rising main system.

c) The pump and rising main selection shall ensure the minimum velocity in the risingmain is 1.0m/sec and the maximum 2.0m/sec (at peak design discharge rate).

DS-6 WASTEWATER


d) In selecting pumps the operating conditions shall correspond as closely as possiblewith the point of maximum pump efficiency. However final pump selection must beapproved by the Council to facilitate some standardisation of pump model and impellortype and sizes.

e) Standard pump stations shall include 2 identical submersible Wastewater pumps, oneas a duty pump and the other as a standby. Larger pump stations may requireadditional pumps.

f) The pump type shall be as specified in AM-6 Wastewater.

DS-6.9.6 Impellers

To prevent unnecessary blockage all pumps shall be fitted with an ‘N" impeller approvedby the Council. Where a mini pump station is constructed to service 5 lots or less, somedeparture from the IDC may be acceptable. However, approval is required from Council.

DS-6.9.7 Power Supply

T672, T673, T674, T675, T676, T677, T678, T679, T680, T681, T682, T683

All pumps shall be operated from a three-phase electrical power supply system.

DS-6.9.8 Control and Alarm Levels

Control and alarms levels shall be as outlined in Table 6: Control and Alarm Levels.

Table 6: Control and Alarm Levels

Table 6: Control and Alarm Levels

Control Type Level

Low level alarm set to activate if the water level drops below cut out level formore than 1 minute

Pump stop level minimum submergence level of pumps

Duty pump start level 150mm below incoming wastewater invert level

Standby pump start level 100mm above duty cut-in level

High Level Alarm 100mm above stand-by cut-in level

Critical Alarm 100mm below spill level

DS-6 WASTEWATER


DS-6.9.9 Emergency Storage


a) A total of 9 hours emergency storage must be provided upstream of the pumpingstation. This volume may include the upstream pipelines and manholes in calculatingstorage design but only after approval has been received from Council.

b) Specifically designed emergency storage chambers may be required to supplementthe volume provided by the collection system.

DS-6.10 Private Pump Stations

Smaller pump stations serving no more than 6 residential lots/dwellings are permissible.These pump stations shall:

a) Remain in private ownership

b) Be managed by a Body Corporate, Incorporated Society or other similar suitableownership/management structure

c) Be located on private property

d) Not be vested in Council

e) Be designed, constructed, operated & maintained to prohibit the general public coming intodirect contact with wastewater.

f) Not allow intrusion of stormwater & groundwater

g) Provide for a minimum of 9 hours onsite emergency storage based on the average dryweather flow, measured between the first stage alarm level & the point of overflow.Storage shall be in a designed chamber.

h) Be located in areas that are geotechnically suitable for the system proposed. Thisrequires that no more than 10mm of settlement from the completed structure can occur &a safety factor of 1.25 against flotation is achieved.

i) The design life for the pump station plant shall be: 50 years except for electrical &mechanical components which shall have a minimum of 15 years & telemetry equipment aminimum of 10 years.

DS-6.11 Receiving Reticulation

The gravity pipeline system to which the station discharges shall be designed toaccommodate the discharge of the duty pump operating in combination with the peak wet-weather flow from the adjoining gravity network.

DS-6.12 Rising Mains

T670


DS-6 WASTEWATER


a) Only PE80 or PE100 pipes conforming to AS/NZS 4130 shall be used for rising mains.The required minimum pressure rating for a rising main shall be PN 10. Higher ratedpipes may be necessary. Other materials may be considered by Council.

b) Pipe selection shall take into account a 100 year service life and include derating due tooperating temperature and derating due to 107 cycles of cyclic water hammer load causingpressure swings from 1.5P to 0.5P.

c) A safety factor of not less than 1.25 shall also be included to determine the pipe pressureclass.

d) PE fittings fabricated from pipes shall be derated due to stress concentrations in thefabricated fittings. Manufacturer's recommendations shall be strictly followed with regardto the extent of derating required for each type of fabricated fitting.

e) Wherever possible, the rising main shall be designed on a positive gradient avoiding highand low points, therefore minimising the need for air release and scour valves.

f) PE pipes shall not be used for pipe bridges or within tunnels that are not backfilled unlessthe pipe is adequately anchored against flotation and thermal movement.

g) To accommodate all out of balance forces on the main its installation and design shall besimilar to that of a water main incorporating suitable anchorage at all changes of direction.

h) Rising mains shall be installed with "sewer" marker tape laid continuously 200mm abovethe rising main. The tape shall include a metallic wire that can be detected from thesurface.

i) Where any section of a rising main is installed by trenchless technology, tracer wire shallbe strapped to the pipe and fixed thereto by using a minimum of 2 complete wraps of50mm wide heavy duty adhesive tape at a maximum of 3.0m intervals. Wire traces shallbe continuous to allow an electrical current. Rising mains shall discharge into a receivingmanhole in accordance with the detail on the Standard Drawings.

j) Rising mains shall be a minimum of 76mm ID.

DS-6.13 Pump Station Layout

T660

The Council’s typical wastewater pumping station layout details are shown on the StandardDrawings. Alternative layouts or prefabricated stations may be considered for approval on acase by case basis.

Pump stations shall be located on a separate lot solely for that purpose and be provided with apermanent access. An adequate turning area shall be incorporated adjoining the station wetwell and control cabinet to accommodate light commercial maintenance vehicles, unlessimmediate access to the roadway is possible. Control cabinets shall not be situated close tocarriageways in a position where it may be damaged by out of control vehicles.

In addition to the land required to construct a pump station, wet well and valve chamber, anarea of 5.0m x 5.0m shall also be made available to accommodate a biofilter either at the timeof construction or in the future.

DS-6 WASTEWATER


DS-6.13.1 Secondary Storage Well

Where a secondary storage well is to be provided in addition to the pump wet well it shallbe positioned near the valve chamber to allow ready access.

DS-6.13.2 Receiving Manhole

The manhole immediately upstream of a pump station shall be a minimum of 1200mmØ.

DS-6.14 Fittings and Materials

Refer to AM-6 Wastewater.

DS-6.15 Pump Station Services

Pump stations require water supply and electrical services for operation.

DS-6.15.1 Water Supply

T671


a) All pump stations shall be provided with a water supply connection through a standard25mm Council metered water connection and include a 25mm supply to a standardfemale Camlock hose connection located within, or directly outside the backflowpreventer cabinet.

b) A second 25mm water supply connection (including 240 volt solenoid valve) shall beinstalled within the backflow preventer cabinet to facilitate supply to provide for awashdown sprayer be installed within the pump station wet well. For this purpose a25mm (ID) MDPE pipe shall also be installed from the solenoid valve into the wet wellwith sufficient pipe to reach the centre of the well.

c) The water supply shall be protected by a reduced pressure zone 25mm backflowpreventer to comply with AS/NZ 2845.1:1998 and in accordance with DS-7 WaterSupply. This shall be located adjacent to the station and at least 300mm aboveground level.

DS-6.15.2 Electrical Supply

T672, T673, T674, T675, T676, T677, T678, T679, T680, T681, T682

Each pump station shall be fitted with a standard on site electrical control system andalarm/operational data system. These shall be compatible with the Council’s standardsystem. A copy of the standard details for these works is provided in the StandardDrawings.

DS-6 WASTEWATER


DS-6.15.3 Telemetry

An electrical on-site telemetry system, assembled and installed in accordance with theCouncil’s standard specification shall be required.

DS-6.15.4 Access Requirements

Refer to DS-6.7.2 Access Requirements.

DS-6 WASTEWATER


DS-6 - Appendix AAssociated Standards

DS-6 - Appendix A.1 General

The latest revision or operative version of the following standards shall be used inconjunction with the IDC:

a) Council documentation:

i) City Plan

ii) TCC Trade Waste Bylaw

b) New Zealand Standards:

i) AS/NZS 1252:1996 High-strength Steel Bolts with Associated Nuts andWashers for Structural Engineering

ii) AS/NZS 1254:2002 PVC Pipes and Fittings for Stormwater and Surface WaterApplications

iii) AS/NZS 1260:2009 PVC-U Pipes and Fittings for Drain, Waste and VentApplication

iv) AS/NZS 1477:2006 PVC Pipes and Fittings for Pressure Applications

v) AS 1579:1993 Spiral Welded Steel

vi) AS 1646.1:2000 Seal Rings

vii) AS 1657:1992 Fixed Platforms, Walkways, Stairways and Ladders. Design,Construction and Installation

viii) AS/NZS 2280:2004 Ductile Iron Pipes and Fittings

ix) AS/NZS 2544:1995 Grey Iron Pressure Fittings

x) AS/NZS 2566 Buried Flexible Pipelines

xi) AS/NZS 2845.1:1995 Water Supply – Backflow Prevention Devices – Materials,Design and Performance Requirements

xii) NZS 3114:1987 Specification for Concrete Surface Finishes

xiii) AS/NZS 3725:2007 Design for Installation of Buried Concrete Pipes

xiv) AS 3996 Vehicle Loading (Covers)

xv) AS/NZS 4058:2007 Precast Concrete Pipes (Pressure and non-pressure)

xvi) AS 4087 Facing and Drilling of Flanges

xvii) AS/NZS 4130:2009 Polyethylene (PE) Pipes for Pressure Applications

xviii) AS/NZS 4131:2003 Polyethylene (PE) Compounds for Pressure Pipes andFittings

xix) AS/NZS 4158:2003 Thermal-bonded Polymeric Coatings on Valves and Fittingsfor Water Industry Purposes

DS-6 WASTEWATER


xx) NZS 4402:1986 Methods of Testing Soils for Civil Engineering Purposes

xxi) NZS 4404:2010 Land Development and Subdivision Infrastructure

xxii) AS/NZS 4441:2008 Oriented PVC (PVC-O) Pipes for Pressure Applications

xxiii) NZS 4442:1988 Welded Steel Pipes and Fittings for water, sewage and mediumpressure gas

xxiv) AS/NZS 4765:2007 Modified PVC (PVC-M) Pipes for Pressure Applications

xxv) AS/NZS 5065:2005 Polyethylene and Polypropylene and Fittings for Drainageand Sewerage Applications

xxvi) NZS/BS 5163:1986 Specification for Predominantly Key-Operated Cast IronGate Valves for Waterworks Purposes

xxvii) BS EN 124 Vehicle Loading (Covers)

xxviii) NZTA M/7 Roadmarking Paints

c) Other reference material:

i) Resource Management Act 1991

ii) New Zealand Building Act

iii) New Zealand Health and Safety in Employment Act 1992

iv) Bay of Plenty Regional Council On-Site Effluent Treatment – Regional Plan

v) Sewerage Code of Australia WSA 02-002

vi) New Zealand Ministry for the Environment Climate Change Effects and ImpactsAssessment Publication 2008.

vii) New Zealand Department of Labour Approved Code of Practice for Safety inExcavation and Shafts for Foundations – April 2000

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