5. sanitary drainage -...

SECTION 5 Code of Practice for Development TAURANGA DISTRICT COUNCIL Sanitary Drainage

Sewer.doc Print Date: May 2002 VERSION 1 R1 Page 5-1

5. SANITARY DRAINAGE

MINIMUM REQUIREMENTS

5.A General 5.A.1 Unless otherwise approved, all allotments within the Tauranga District urban area shall be provided with an individual connection to Council’s sanitary drainage system. For Rural and Rural Residential areas connections to Council’s sanitary drainage will not be provided. (Refer to Section 5.K)

C1 It is recognised that in reticulating infill subdivision that generally each site is unique. Therefore, the reticulation of infill subdivision will be done on a “site by site” basis and to be approved by Council. In general no common private drains will be allowed unless specifically approved by Council. Proposals for each site shall be submitted at the time of the Resource Consent application.

5.A.2 The sanitary drainage system shall be designed to serve the whole of the natural upstream catchment area and shall have a design life of at least 100 years. However, where part or all of the catchment is serviced or will be serviced by a trunk sewer to be constructed at a later date, the Group Manager City Services may agree to this area being excluded from the calculation. The flow from all portions of the upper catchment within the district boundary shall be calculated assuming complete urbanisation except for those areas permanently set aside for recreation reserves.

C2 Where further development, upstream of the work under consideration is provided for in the District Plan or Regional Plan, the Group Manager City Services may require sewer pipelines in the development area to be constructed to the boundaries of the development area.

5.A.3 Hydraulic design of all reticulation shall be such that maximum design flows can be accommodated with no surcharging of pipes or manholes. 5.A.4 The sanitary drainage system shall be designed to inhibit direct stormwater entry into the reticulation system and pumping stations.

In cases where substantial costs are likely to be incurred in providing extended sewer lines that will not serve the development under consideration, the Council may contribute towards these costs on an agreed cost sharing basis, to be negotiated prior to any work commencing.

5.A.5 Where sanitary drainage has been or is to be installed by Council, to serve the natural catchment, contributions on an area basis shall be made in terms of the development impact fees or other agreed cost sharing arrangement.



MEANS OF COMPLIANCE

5.B Design Criteria 5.B.1 Calculation of Flows Sewerage flows are a function of water consumption, infiltration and direct ingress of stormwater, which in turn are a function of the age of the system and the quality of maintenance.

C.3 210 l/d / person is based on 2.7 people/house.

5.B.2 Domestic Flows Domestic sewerage flows can be calculated on the basis of the average dry weather flow of 210 l per day per person, with the population figures based on the district planning scheme forecast. A dilution factor of 2 for wet weather and a peaking factor of 2.5 are recommended. Variable peaking factors may be required by the Group Manager City Services.

Unless otherwise demonstrated as satisfactory, domestic sanitary drainage systems shall be designed to cater for a peak flow of 0.45 litres/second/hectare.

C4 A high peaking factor may be appropriate for a small catchment but too much for a large catchment where peaks are less pronounced. Due allowance needs to be made for the land use.

5.B.3 Industrial Flow and Trade Wastes Where the industrial waste and trade waste flows from a particular industry are known, these shall be used as the basis for the sewer design. When the above information is not available, the following may be used as a design basis:

Industry Type Minimum Design Flow (water usage) (litres/second/ hectare) Light Development 0.4 Medium development 0.7 Heavy development 1.3



The above design flows include both normal sanitary sewage and trade wastes and include peaking factors. Notwithstanding the above, provision for trade waste shall be made by arrangement with the Group Manager City Services and shall be subject to the provisions of the Tauranga District Council Trade Waste Bylaw.

5.B.4 The industry type will not necessarily coincide with the zoning classification shown in the district planning scheme, but the zoning, particularly where effluent discharge is a performance standard, may be used to indicate the minimum design flow where more detailed information is not available.

5.B.5 It may be desirable to provide additional capacity if the owner wishes to widen the range of industries which are to be located in a development area. However, the capacity of the existing receiving facility may be a controlling factor.

The design of sewage disposal systems for “wet” industries (very heavy water uses) is to be based on the specific requirements for that industry.

5.B.6 Hydraulic Design of Pipelines (a) The hydraulic design of sanitary sewer pipelines shall be based on tables for the hydraulic design of stormwater drains, sewers and pipelines, or on graphs or other representation of the same methods, based on the Colebrook White formula.

(b) The pipe roughness coefficients ks used in the design shall be those nominated by or agreed upon with the Group Manager City Services on the basis of commonly adopted modern engineering design practice. For preliminary design purposes it is recommended that ks be assumed to be 1.5mm as an overall coefficient which allows for joints and so on.

(c) The desirable flow velocity in 150mm diameter pipes when full shall normally be not less than 0.65 metre/second (minimum gradient 0.55%) but 0.75 metre/second (minimum gradient 0.72% 1 in 140) shall be the desirable minimum velocity for the upper portions of sanitary sewer systems.

Gradients flatter than 0.55% (1 in 180) for 150mm diameter pipes may be permitted in special cases where no alternative practicable solution exists.



(d) Where the normal velocity and gradient limits as defined by (c) above cannot possibly be complied with, the Group Manager City Services may require certain additional works to ensure satisfactory operation of the system eg. Installation of an approved flushing tank.

C5 In practical terms, unless the catchment exceeds 250 houses, dwelling units or their equivalent, and where no flow from a pumping station is involved, 150 mm diameter pipes laid within the above limits will be adequate without

specific hydraulic design.

5.C Primary System

5.C.1 The levels and locations of all pipes laid for sanitary drainage shall conform with Council’s overall plan for reticulation. Provision must be made for connection into the existing reticulation system.

5.C.2 Subdivision 4 lots or more - Minimum pipe sizes are 150 mm diameter nominal size for reticulation sewers and 100 mm diameter nominal size for laterals. For the purposes of this clause a reticulation sewer is any pipeline terminating with a manhole at its upstream end and a lateral is any public pipeline connecting from the reticulation sewer to an individual allotment. In addition, the following shall apply:

C.6. Clause 5.C..2 relates to the provision of connection for house lots to the public system. It is desirable that the same be used for general infill reticulation. However, there will be many occasions when infill subdivision may need a more flexible system than defined here. Hence Clause 5.C.3.

(a) Lateral with single connection (out of manhole):

• 100mm diameter up to 50m. • Provide rodding eye at end of 100mm diameter pipe for

lengths greater than 25m • Above 50m normal sewerage reticulation standards apply,

(ie. 150mm minimum diameter pipeline with terminating manhole).

• 150mm diameter pipes must be used under all streets.

RE

SSMH

Lot 1

(As required)

5.C.2.(a) Lateral with singleconnection (out of MH)

Lot 2


Sewer.doc Print Date: May 2002 VERSION 1 R1 -5

(b) Lateral with two connections (out of manhole):

• 100mm diameter up to 25m. • Provide rodding eye at end of 100mm diameter pipe. • 150mm diameter lengths 25m up to 50m. • Above 50m normal sewerage reticulation standards apply. • 150mm diameter pipes must be used under all streets.

Lot 2

RE

SSMH

Lot 1

(As required)

5.C.2.(b) Lateral with twoconnections (out of MH)

(c) Lateral with three connections or more (out of manhole):

• Use 150 mm diameter pipe up to 50m. • Provide rodding eye at end of all laterals. • Above 50m normal sewer reticulation standards apply. • 150mm diameter pipes must be used under all streets.

Lot 2

RE

SSMH

5.C.2.(c) Lateral with threeconnections or more (out of MH)

Lot 1

Lot 3(All cases)

(d) Lateral Out of Line Servicing One Allotment: • 100mm diameter up to 25m. • 150mm diameter pipes must be used under all streets. • Rodding eye required where the line passes through an

adjoining lot.

5.C.2.(d) Lateral out of lineservicing one allotment

Lot 2

RE (As required)

Lot 1



(e) Lateral Out of Line Servicing 2 Allotments: • 100mm diameter up to 25m. • Provide rodding eyes at end of all laterals. • 150mm diameter pipes must be used under all streets.

(Typical details of rodding eyes are shown on Drawings S1 and S2). Rodding eyes are not permitted in the road carriageway.

Lot 2

RE (All cases)

Lot 1

5.C.2.(e) Lateral out of lineservicing two allotments

5.C.3 Infill Subdivision 3 lots and less (includes existing Lot) Reticulation of infill subdivisions shall comply with the following criteria : 5.C.3.1 • Infill subdivisions are to be reticulated on a site by site basis to

the approval of the Group Manager Environmental Services. 5.C.3.2 • Where practicable drainage reticulation should be constructed or

upgraded in accordance with the Code of Practice requirements for sanitary services (other than 5.C.3) so that the drains can be declared public and provide each allotment with the same standard of individual connection as new “greenfields” allotments.

5.C.3.3 • Where 5.C.3.2 is considered impractical or unnecessary by, the

Consent Holder and the Group Manager Environmental Services, drainage within the parent lot will remain private and be protected by an appropriate easement.

C7 It is recognised that infill subdivision require flexibility in their reticulation layout. However, normal trade practices and standards still to ensure that the desired service life is still achieved. Common private drains are not encouraged so as to alleviate the friction that sometimes occurs between neighbours when shared services are involved.

Lot 2

Kerb & Channel

Option 1:Easement not required asconnection becomes public

Option 2 : Easement protects privatedrain and connection to Lot 1

Lot 1

Option 2Option 1

(preferred)

Lot 1

Lot 2

Kerb & Channel

ConnectionLot 1

ConnectionLot 2

Aba

ndon

line

Aba

ndon

line



5.C.3.4 • Drainage lines are to be separated at the point of connections to

the Council’s reticulation system and remain separate for each lot unless specific approval is granted by the Group Manager Environmental Services.

5.C.3.5 • All private drainage works to be constructed in accordance with

Building Code regulations. 5.C.3.6 • All private drainage to be constructed by a Registered

Drainlayer.

Lot 2R E

SSMHKerb & Channel

Ease

men

t pro

tect

spr

ivat

e dr

ain

and

conn

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n to

rear

lot

Lot 1

(New)

5.C.4. Where practicable and where connection is to be within 6m of the manhole the connection shall be to the manhole.

6 m

Xü

5.C.5 Where the main line is within 5m of the property boundary a separate connection shall be provided to each allotment (only when the main is in Council reserve, otherwise Section S.C.3.4).

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5 m

5.D Service Connections

5.D.1 The connection provided for each site shall be of a type capable of taking an approved drain pipe of 100mm internal diameter, unless the Group Manager City Services requires a larger size connection. 5.D.2 Where the sanitary sewer line is outside the site to be served by it, a 100mm diameter connection shall be extended to the boundary of the site.

C8 Where the connection will cross more than one site boundary, the prior approval of the Group Manager City Services should be obtained before the installation is made. If the above conditions cannot be met, then a 150 mm diameter branch sewer line will normally be constructed complete with a terminal manhole.

5.D.3 Connections shall be provided to serve each site. In all cases connections shall be finished at a depth to allow the entire site to be serviced allowing a minimum cover of 600mm over the drainage system within the allotment. All lines shall be laid to straight line and grade.



5.D.4 Connections that are deeper than 3.5m below ground level shall be specifically approved by the Group Manager City Services. 5.D.5 For all industrial sites, 150mm diameter connections shall be provided.

5.D.6 Each connection shall be marked by a 50mm x 50mm timber stake with the top painted white ground treated extending from below invert level to 300mm above ground level. A pvc marker tape labelled sewer shall be tied around the end of the connection and brought up to the finished surface level as the trench is backfilled. The location shall be shown on the ‘As Built’ plan.

The ‘As Built’ plans shall also show the distance of the “Y” junction from the nearest downstream manhole.

5.D.7 All connections, whether to reticulation lines or to manholes, shall be sealed with a cap.

5.D.8 All connections to existing main sewers and manholes shall be made by an approved contractor with the consent of the Group Manager City Services at the owner’s expense.

5.D.9 Ramped Risers (a) Unless required otherwise by the Group Manager City Services a ramped riser shall be constructed to bring the connection to within 1.2m of ground level or such level required to service the entire building platform.

(b) Ramped risers shall be constructed as on Drawings S3 and S4.

(c) Where an extended connection is to be taken from a sewer to the boundary of another site, a ramped riser need not be used and the extended connection may be sloped up at the continuous gradient from the sewer to terminate just inside the site to be served, at a sufficient depth at the boundary to drain the building site.



5.D.10 Connections to Deep Lines Where an existing or proposed sewer is more than 5m deep to the top of the pipe, connections shall not be made directly to it, but a new shallower branch sewer shall be laid from a manhole on the deep sewer and connections provided to the site to be served.

Where manholes are located in a stormwater overland flow path, their lid levels shall be above the design flood level for a 2% AEP storm.

5.E Manholes

5.E.1 General Manholes shall normally be provided at each change of direction or gradient, and at each branching sewer, at a spacing of not more than 100m. Precast manholes shall be used wherever practicable. Where manholes are located in a stormwater overland flow path, their lid levels shall be above the design flood level for a 2% AEP storm

C9 Alternative Access System Tauranga District Council along with a number of other Council’s in NZ are reviewing Sewer Maintenance Management systems. Consideration is being given to incorporate parts of the Australian Sewerage Code WSA 02(L) – 1999 especially with respect to use alternative maintenance access system. This would introduce the use of Maintenance shafts instead of manholes in specific designs (refer Appendix D.)

5.E.2 Standard Manholes These are to be circular manholes with a minimum internal diameter of 1050mm. Precast manholes shall consist of centrifugally spun 1050mm diameter concrete pipes to Class “S” standard. They shall have holes cast in the side for step irons.

Cast in situ manholes shall only be used with the approval of the Group Manager City Services and shall be constructed using ordinary grade concrete (17.5 MPa) well vibrated to give maximum density and watertight construction.

Details of standard manholes are shown on Drawing S5. Details of precast, 1050mm diameter manhole lids are shown on Drawings S6 & S7.



The method of jointing the precast sections shall be strictly in accordance with the recommendations of the manufacturer and when using a proprietary joining compound or adhesive, in conformity with the manufacturer’s instructions to provide a watertight structure to the satisfaction of the Group Manager City Services.

5.E.3 Deep Manholes Where manholes are more than 5.0m deep they shall be specifically designed and shall incorporate an intermediate landing platform in order to prevent a free fall of more than 5m as shown on Drawing S8.

5.E.4 Shallow Manholes Shallow manholes to be constructed as is shown on Drawing S9.

5.E.5 Step Irons and Steps All manholes other than shallow manholes shall be provided with approved step irons or steps or ladders in order to give reasonable access. These should normally be of the “dropper” or “safety” type such that a foot will not slide sideways off them. Details of manhole steps and ladders/or are shown on Drawing S10. Step irons are to be galvanised or stainless steel.

5.E.6 Manhole Covers and Frames (a) Manhole covers and frames shall be of a design approved by Council manufactured from a strong and durable material. Standard duty covers are to be used unless otherwise approved by the Group Manager City Services. Typical examples of standard, light duty, and non-rock covers supplied in high quality grey cast-iron, coated with a bituminous protective compound are shown on Drawings S11, S12 and S13.

(b) Manholes shall be constructed so that the manhole cover matches the surrounding surface levels. All covers must be visible and accessible for ease of maintenance. (c) All sanitary sewer manholes covers shall be painted white with road-marking paint.



5.E.7 Drop Connections Unless otherwise specifically approved by the Group Manager City Services, drop connections at manholes shall be constructed externally in a manner as shown on Drawing S14.

Drop connections to manholes shall be constructed where the invert of the incoming sewer is more than 600mm above that of the main sewer. Internal drop connections may be approved by the Group Manager City Services only for existing manholes.

C10 Dispensation for internal drop in new works will require manholes to be 1200mm minimum diameter.

5.E.8.1 Manhole haunching & benching The fall through a manhole shall be as follows: Either (a) The invert of the outlet pipe from a manhole shall be 20mm

lower than the lowest incoming invert plus 3mm extra fall per 10 degrees of horizontal angle change between the two.

or (b) The soffit of the outlet pipe shall be level with or below the

lowest inlet soffit. or (c) On steep grades the haunching is to be extended at the same

grade of the inlet pipe which ever is greatest.

5.E.8.2 The maximum benching fall through a manhole is 600mm. 5.E.8.3 All pipe connections to manholes shall be epoxy jointed to ensure water proof joints and prevent ground water seepage.

5.E.9 Manholes in Soft Ground Where manholes are to be constructed in soft ground, acceptable construction methods shall be used to provide adequate foundation for the manhole bases.



5.F Layout 5.F.1 Pipelines within private property shall generally run parallel to lot boundaries. Where the centreline of a pipeline is further than 1.5m from a lot boundary or not parallel to a lot boundary an easement in favour of Council and/or Consent Notices shall be provided to ensure its protection. In no case shall sewer lines be laid under building sites without the specific approval of the Group Manager City Services. Standard service locations in roadings are shown on Drawing R2.

5.F.2 Manhole structures shall be clear of all boundary lines.

5.F.3 Minimum Cover Over Pipes (a) In Private Property: The minimum cover over unreinforced pipes in private property shall be 600mm. Where due to the topography, this cover cannot be provided, approved protection shall be provided for the pipeline.

Where the reticulation lines are located in the front yard of lots, the invert level shall be deep enough so as not to interfere with any future driveway construction.

(b) Under Carriageways: Pipes shall be specifically designed to support an 8.2 tonne axle design loading. Manufacturers certification shall be required for all pipes under carriageways with less than 750mm cover.



5.G Pipe Materials

5.G.1 Sanitary gravity reticulation systems constructed of the following materials will be accepted:

• PVC to be manufactured in accordance with AS/NZS 1260:1996 DN 100mm diameter and DN 150mm diameter defined as grade SN16 for up to 5m depth. DN 175mm and larger to be grade SN8 minimum or equivalent. Specific design for depths greater than 5m.

• Pipe type to be either plain wall or sandwich construction, conforming to AS/NZS 2566:1998.

• Concrete lined spiral welded steel pipe to NZS 4442 (with appropriate external protection as per manufacturer’s specification.

• Ductile Iron pipe to AS 2280 (concrete lined with loose sleeve protection)

• Concrete pipe and other materials (eg Hobas GRP to AS 3571) may be approved by Group Manager of City Services

• Only uPVC shall be used for gravity reticulation mains and service connections.

C11 Note: (i) SN 16 is the recommended equivalent of SEH C DN 100 and 150. (ii) SN 8 is the recommended equivalent of SEH in DN 175 or larger. (iii) “Stiffness”, NOT wall section, is the controlling feature in AS/NZS 1260:1999. The actual ID (and therefore flow rate) of plain wall pipe is likely to be greater than the same size/SN of sandwich construction pipe.

5.G.2 All fittings and service connections shall be factory fabricated of compatible materials to the proposed system chosen and comply with the relevant Standards. PVC fittings and service connections, DN 100mm and DN 150mm injection moulded fittings to conform to AS/NZS 1260:1999. DN175mm and larger factory fabricated PVC fittings to be made of same grade materials as specified for the pipeline.

5.G.3 Where the reticulation system is of uPVC the main line connection to each manhole structure is to be with a Standard uPVC proprietory connector (See Drawing S5) . The requirements for drop connectors are detailed in Drawings S14 and S15.

5.G.4 In potentially unstable ground or where special protection is required, the sewer pipelines should be specifically designed, using structural design as specified in either AS/NZS 2566:1998 “Buried Flexible Pipelines – Structural Design,” or the “ATV” Design Method.



5.G.5 Steel pipes shall be used where additional strength is required, however, the construction of pipelines on steep gradients, at shallow depths or under carriageways are not necessarily criteria requiring the use of steel pipes.

5.G.6 Joints

• All joints on pipes and fittings shall be factory made flexible type.

• Under no circumstances will mortar joints be permitted.

• Gibault joints shall be “denso” wrapped and sealed with approved outer wrapping.

• Gibault joints for use on pressure mains are to have a centre ring of length not less than half the pipe diameter.

• Pipe to manhole joints shall be of proprietory types and shall incorporate a “pipe short” for each joint (see Drawing S5).

5.H Bedding and Protection

5.H.1 Pipe bedding shall be designed to meet the requirements of the class of pipe used under the design loading conditions.

Non Flexible sanitary sewerage pipe shall be designed to be structurally capable of supporting the superimposed earth load and superimposed loads either static or transient. Flexible sanitary sewer pipes shall be designed and installed to utilise side support to resist vertical loads without excessive deformation.

5.H.2 The type of bedding and class of pipe shall be in accordance with the pipe laying bedding diagrams as shown in Drawing S16 (sourced from NZS 4452) or to the manufacturers specifications. PVC pipes shall be installed and tested in accordance with NZS 4452:1986, with structural design in accordance with AS/NZS 2566:1998. The manufacturers specifications take precedence.

C12 The manufacturers specifications take precedence. C13 Where the pipeline gradients are equal to or greater than 20% the Group Manager City Services may require anti-scour (cut off) blocks of a type comparable to that shown on Drawing S17. The recommended spacing for the blocks is 6m, located near the joint



Where the pipelines gradients are equal to or greater than 33% the Group Manager of City Services may require similar anti-scour (cut-off) blocks to be constructed but they shall extend to within 100 mm of the top of the ground surface and be of a type as illustrated in Drawing S17. Alternatively, such other means of providing a satisfactory foundation and support for the pipeline as may be approved by the Group Manager of City Services shall be adopted.

5.H.3 In certain circumstances, the Group Manager City Services may require that sewerage pipe be laid in concrete or encased in concrete, or protected by concrete capping.

C14 Concrete bedding or encasement is not recommended for flexible pipe. Concrete capping is recommended for

flexible pipe.

5.H.4 Pipeline Construction The construction, installation and field testing of flexible pipelines shall be carried out in accordance with NZS 4452:1986. The building Act 1991 and the Building Regulations 1992 apply for private reticulation.

5.I Testing and Acceptance

5.I.1 All sanitary sewer main and branch pipelines, including manholes and extended connections, shall be pre-tested during construction. On completion of all other engineering work within the development, there shall be a final test witnessed by representatives of Council. This test shall be the low pressure air test as set out in NZS 4452. All testing shall be carried out when backfilling is complete and prior to surface sealing and/or paving works being completed also when manholes and lines are finished and flushed. For rising mains refer to Section 5.Q

5.I.2 No infiltration will be permitted. Testing shall be in accordance with NZS 4452 using either water or air tests.

C15 Where pipes are installed below natural groundwater then a high pressure air test in accordance with NZS 4452:1986 shall be used.

5.I.3 All sewers shall be lamped between manholes to ensure the pipeline is laid straight for grade and alignment and maintained its shape (roundness).

5.I.4. Existing private infill sewers proposed as common private drains may require CCTV inspection at Applicants expense prior to consideration for approval.



5.I.5 A certificate of subdivision construction shall be provided on the form as detailed on Drawing S18, by the consent holder’s representative.

5.J Close Proximity Rules

5.J.1 Policy (a) Rising mains and trunk sewers No building shall be built over a public rising main or trunk sewer, or closer than the greater of:

• 1.5 metres from the centre of any main or sewer, or • the depth of the centre line of the sewer, plus the diameter of

the sewer from the existing/ proposed ground surface. • Reticulation sewers are for gravity pipes of DN 100 and

150mm diameter. • Trunk Sewers are gravity pipes of greater than DN 150mm

diameter.

C16 Reticulation sewers are gravity pipes of DN 100 and DN 150 diameter. Trunk sewers are gravity pipes larger than DN 150.

(b) Reticulation sewers • No building shall be built closer than 1.5 metres from the

centre of any public sewer.

5.J.2 Dispensation for Reticulation Sewers Dispensation for reticulation sewers may be approved to site the building down to 800 mm off the sewer pipe centreline subject to the following conditions:

• The depth of the sewer pipe is less than 3.0m deep from the existing/proposed ground surface;

• Additional foundation requirements of specific designed piles be installed to 200mm below the sewer invert where the building is closer than 1.5m from the sewer pipe;

• That all connections be a minimum of 1.0m outside the building;

• That all buildings be 0.5m off the outside wall of manhole structures.



5.J.3 Ancillary buildings may be exempt (for reticulation sewers)

Garages (single and double, maximum 7.2 metres), provided they are detached and do not form an integral part of the house shall be allowed to be built over reticulated sewers pipelines subject to the following conditions:

• No enclosed building or structure shall be sited over a manhole or closer than 0.5 metres off the outside wall of the manhole structure.

• Corner foundations are a minimum of 800mm off the pipeline centre line.

• Additional foundation requirements of piles are to be installed 200mm below the sewer invert, a minimum of 800mm either side of the pipeline where it enters and exits the building.

• The above recognise that dispensation is approved provided the Group Manager City Services is satisfied with the location of the building.

• No buildings will be allowed over the sewer main if there is a connection closer than 1.0m to the buildings, unless the connection is relocated to the satisfaction of the Group Manager City Services.

5.J.4 Carports / Decks / Sunrooms (for reticulation sewers) These structures may be sited over reticulation sewer pipelines provided:

• there is no connection point closer than 1.0m to the building; • No enclosed building or structure shall be sited over a

manhole or closer than 0.5 metres off the outside wall of the manhole structure.

• the structure is designed such that it can be dismantled easily in sections (bolting is the preferred method of construction);

5.K Rural and rural/residential areas

5.K.1 For Rural and Rural/Residential allotments connection will not be provided to Council’s sanitary drainage system either at present or in the future. Council has no provision for Rural and Rural/Residential areas to be incorporated into Council’s sanitary drainage system. (See Section 13 Rural Residential).

C17 Refer to EBOP Effluent Treatment Plan 1996.



5.L Sewage Pump Stations

5.L.1 Where the proposed subdivision cannot be adequately serviced by a gravity system, public sanitary sewage pumping stations will be permitted provided they are logically located and designed to service the entire catchment area of land beyond the reach of the existing gravity system. The design life shall be not less than 50 years.

5.L.2 Where isolated building sites cannot be provided with a gravity connection, consideration may be given to the use of individual privately owned sewage pump stations.

5.L.3 A sewage pump station shall be capable of serving the entire catchment for land uses likely to prevail during its economic life, and shall where necessary for sound engineering design practice, accommodate pumped flows from adjacent areas. 5.L.4 The consent holder undertaking the subdivision shall obtain a discharge permit from Environment Bay of Plenty for any emergency overflow from the pump station if required.

5.L.5 For public sanitary sewer pumping stations, as well as satisfying the requirements of the Resource Management Act 1991, the following minimum criteria shall be met:

• Two identical submersible sewage pumps, one as a duty pump and the other as a standby, shall be provided.

• Each pump shall be capable of discharging the design peak flow rate from the catchment.

• A minimum of nine hours on-site emergency storage shall be provided, based on the average dry weather flow, measured between the overflow and the first stage alarm level.

C18 Storage in upstream pipes and manholes may be used in calculating the storage volume.

• Installation of Council's standard alarm and operational data control system is required.

• An electrical on-site pump control and telemetry system, assembled and installed in accordance with the Council's standard specification is required.

Councils typical sanitary sewer pumping station site layout is shown on Drawing S19, and typical internal layout and construction details are shown on Drawings S20 to S28 (inclusive).



5.M Pump Station Layout 5.M.1 The proposed pump station shall be located on a separate lot solely for that purpose and be provided with a permanent exclusive access of not less than 2.7m paved width. The vehicle access shall be designed to accommodate a standard 8 metre rigid truck, with suitable corner widening.

5.M.2 An adequate turning area shall be incorporated adjoining the station wet well and control cabinet to accommodate light commercial maintenance vehicles.

5.M.3 The pump station lid levels shall be provided with suitable freeboard above the estimated 100 year (1%AEP) flood level. This will be of particular concern where the pumping station access is also being utilised as a designated secondary flow path.

5.M.4 Where a secondary storage well, in addition to the pump wet well, is to be provided, it shall be positioned to allow ready access in close proximity to the valve chamber.

5.N Pump Design

5.N.1 Each pump shall be capable of pumping a peak flow calculated in accordance with Sections 5.B.2 or 5.B.3. 5.N.2 Council currently operates Flygt pumps at public stations. These pumps are fitted with oil bath and temperature sensors interfaced with its alarm monitoring system. In selecting the appropriate pumps the operating conditions shall correspond as closely as possible to the point of maximum pump efficiency with the final pump choice taking account of the most cost effective operations situation.

5.N.3 To prevent unnecessary blockage all pumps shall be fitted with an impeller and have a minimum throughlet of 75mm. In isolated small stations either a cutter or grinder type may be utilised. Dispensation for small stations will be required from the Group Manager City Services. 5.N.4 All pumps shall be operated from a three phase electrical power supply system.

C19 A small station is one serving no more than 5 lots or dwellings/units.



5.N.5 In calculating the system head losses the effects of all bends and fittings beyond the pump discharge bend shall be allowed for, together with rising main friction losses based on a roughness 'ks' value of 1.5 mm. (Colebrook White formula). 5.N.6 The system static head shall be based on the difference in level between the flange of the pump discharge bend and the highest point on the rising main system. 5.N.7 The pump and rising main selection shall ensure the minimum velocity in the rising main is 1 m/s and the maximum velocity is 3 m/s under normal operating conditions

C20 If the discharge is to an existing rising main, the head shall be calculated to include the operating head in the existing rising main.

5.N.8 The gravity outlet system to which the station discharges shall be designed to accommodate the full discharge of pumps operating under emergency conditions in combination with the peak design flow from the adjoining gravity system.

5.O Wet and Storage Well Design

5.O.1 All wet and storage wells shall be designed to accommodate all anticipated loadings with particular regard to the close proximity of maintenance and operations vehicles. 5.O.2 The wet well sump volume (volume between duty pump start and stop level) shall be designed to limit pump starts to a maximum of 15 per hour, as well as to accommodate a minimum 300mm depth, which ever is the greater.

5.O.3 The design and construction of the wet and storage well foundations shall ensure minimum settlement of the completed structure and provide adequate safety against flotation. 5.O.4 In determining the appropriate wet well diameter the minimum clearance between individual pumps and side clearances shall comply with the manufacturers recommendations, together with accommodating full benching of the base.



5.O.5 Where a separate well is considered necessary to accommodate the emergency storage volume it shall be benched to direct all flow to the outlet point. The benching shall be at a minimum gradient of 1 in. 3 to allow self draining. A central channel within the storage well at a minimum of 1% gradient is acceptable. 5.O.6 The invert level of the storage well shall be a minimum of 100mm above the standby pump start level.

5.P Emergency Overflow

5.P.1 The emergency overflow pipe shall be sized to accommodate the design peak inflow rate and shall connect from the storage well or adjoining collection manhole to the approved outfall

5.P.2 The maximum level at which the overflow shall operate is to be designed to provide a minimum of 500mm freeboard to the lowest manhole lid within the pumped catchment under peak flow conditions.

5.P.3 The minimum level selected for the overflow shall be such that inundation of the station will not result from flood waters of a 100 year storm (1% AEP) or the sea.

5.Q Rising Mains

5.Q.1 Rising mains shall generally be a minimum of class PN 9 ( equiv class‘C’) pressure grade uPVC or mPVC rubber ring jointed piping or PE, as per clause 5.G.1. located clear of private property, having minimum internal diameter of 80mm for standard pumps and down to 50mm where a grinder or cutter pump has been approved.

5.Q.2 Wherever possible, to minimise the need for air release and scour valves, the gradient of the rising main shall be designed to avoid over verticals and under verticals. 5.Q.3 The rising main shall be designed to withstand all likely pressure differentials such as may result from a emergency shutdown. The class of pressure piping selected is to have a minimum safety factor against rupture of 2.0.



5.Q.4 To accommodate all out of balance forces on the main its installation and design shall be similar to that of a water main incorporating suitable anchorage at all changes of direction.

5.Q.5 Rising mains to be installed with “Sewer” marker tape laid continuously above the pipe. 5.Q.6 Testing and acceptance of rising mains shall be in accordance with Section 5.I.1 but tested to a minimum of 1000 kpa or greater as calculated in the manufacturers specifications.

5.R Station Services

5.R.1 All stations shall be provided with a water supply connection through a standard 25mm Council metered water connection (supplied by consent holder) and 20mm supply to a standard female Camlock hose connection within the valve chamber.

5.R.2 The water supply shall be protected by a Watts 009 or equivalent (Reduced Pressure Zone) 25mm backflow preventor to comply with AS/NZ 2845.1:1998. This shall be located adjacent to the station and at least 300mm above ground level.



5.R.3 As required under Section 5.L.5 each station shall be fitted with a standard on site electrical control system and alarm/operational data system. These shall be compatible with the Council’s standard system. A copy of the standard details for these works is provided in Drawings S26 to S28.

5.S Pump Station Valves, Fittings and Pipe Work Unless specifically identified to the contrary, the expression “fittings” shall be deemed to include bends, tees, valves, riser pipes and such like. The internal diameter of fittings shall be within + or – 8 mm of the diameter of adjacent joining pipe. (a) Flanges shall be raised faced and to AS/NZS 4087 PN16.

Gaskets shall be 3mm full face neoprene. (b) Bolts nuts and washers are to be 316 grade stainless steel. (c) Valves 100mm diameter and larger shall be to BS 5163, Class 1, or to AS 2638.2:1999 (Pressure rated 1600kPa), resilient faced or resilient seated, anti-clockwise closing and with cap top or gate wheel as appropriate.

50mm and smaller valves (gate valves) shall be to BS5154:1983 and clockwise closing.

(d) Pipes and bends will be cast ductile iron with gibault or flanged joints, or formed of the pipe material as detailed.

Valves, Fittings and Pipes shall be coated in accordance with AS/NZS 4158 Part 1.

5. sanitary drainage -...

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