WW Sewerage design standard 2014 - V5.docx

SEWERAGE DESIGN STANDARD

Supplementary Information to the WSAA Sewerage Code of Australia WSA 02-2002-2.3 Melbourne Retail Water Agencies Version 1.0

Western Water December 2014

CAPITAL DEVELOPMENT | SEWERAGE DESIGN STANDARD

Version: 0.1 Controlled Document Document Owner: STANDARDS TEAM Ref: CAPDEV - STANDARD - SEWERAGE DESIGN Page 2 of 33 Uncontrolled when Printed Authorised: GENERAL MANAGER SUSTAINABLE WATER SOLUTIONS Date Authorised: 20 December 2014

Executive Summary

This Design Standard has been produced as a guide for use by technical personnel involved with the design and construction of gravity sewers within Western Water’s service area. The design and construction of sewer mains required for provision of services to subdivisions and other land development works should be carried out in accordance with this Design Standard and the WSAA Sewerage Code of Australia WSA 02-2002-2.3 Melbourne Retail Water Agencies Edition Version 1.0 (“the Sewerage Code”). The requirements set out in this Design Standard take precedence over those in the Sewerage Code.

This document is a guideline only, and not intended to be a detailed specification for the purposes of the design and construction of sewer mains. Designers and constructors are responsible for the respective aspects of the design and construction process and the justification of any variations from the requirements set out in the Sewerage Code and this Design Standard. Where there are any discrepancies or inconsistencies between the Sewerage Code, this Design Standard, or any other documents, standards or practices these should be discussed with Western Water prior to proceeding.

Enquiries or suggestions relating to the information set out in this Design Standard are welcome and can be directed via email to [email protected] Western Water will update this document as changes become necessary, and the most up to date version will be available on our website. This edition applies to all developments and sewerage design projects issued to commence design on or after the publication date unless otherwise stated in writing by Western Water.

mailto:[email protected]



Table of Contents

Part 1: Planning and Design .................................................................................................... 6

2 SYSTEM PLANNING ........................................................................................................ 6

2.1 Sewerage System Philosophy and Definition .................................................................. 6

2.1.4 Level 3 operating units ......................................................................................... 6

3 FLOW ESTIMATION ........................................................................................................ 6

3.2 Design Flow Estimation Method ................................................................................... 6

3.2.1 General .............................................................................................................. 6

4 DETAIL DESIGN ......................................................................................................... 6

4.3 Horizontal Alignment of Sewers ................................................................................... 6

4.3.1 General .............................................................................................................. 6

4.3.7 Horizontal curves in sewers................................................................................... 7

4.5 Pipe Sizing and Grading .............................................................................................. 7

4.5.1 General .............................................................................................................. 7

4.5.4 Minimum pipe sizes for maintenance purposes ........................................................ 8

4.5.9 Maximum grades for septicity................................................................................ 8

4.6 Vertical Alignment of Sewers ....................................................................................... 9

4.6.1 General .............................................................................................................. 9

4.7 Corrosion Prevention .................................................................................................. 9

4.7.2 Internal corrosion ................................................................................................ 9

5 PROPERTY CONNECTION ................................................................................................ 9

5.3 Methods of the Property Connection ............................................................................. 9

5.3.1 General .............................................................................................................. 9

5.6 Location of Connection Points ...................................................................................... 9

5.7 Y-Property Connections .............................................................................................. 9

6 MAINTENANCE STRUCTURES ........................................................................................ 10

6.2 Locations of Maintenance Structures .......................................................................... 10

6.3 Spacing of Maintenance Structures ............................................................................ 10

6.3.1 General ............................................................................................................ 10

6.3.2 Maintenance Structure Spacing – Reticulation Sewers ............................................ 10

6.4 Special Considerations for Location of Maintenance Structures ...................................... 11

6.6 Maintenance Holes (MH) ........................................................................................... 11

6.7 Maintenance Shafts (MS) .......................................................................................... 12

6.7.3 Property Connection Sewer into MSs and TMSs ..................................................... 12



MRWA 6.7.4 Inspection Shafts (IS) ................................................................................. 12

7 ANCILLIARY STRUCTURES ............................................................................................ 13

7.2 Water Seals, Boundary Traps and Water-Sealed MHs/Gas Check MHs............................. 13

7.2.1 General design parameters ................................................................................. 13

7.3 Water Seals and Gas Check MHs ................................................................................ 13

7.3.2 Design parameters for water seals and gas check MHs ........................................... 13

7.6 Near-Horizontal Boreholes ........................................................................................ 13

7.6.2 Design Requirements ......................................................................................... 13

7.8 Inverted Siphons ..................................................................................................... 13

7.8.2 Design parameters for inverted siphons ................................................................ 13

7.9 Overflows / Emergency Relief Structures (ERS) ........................................................... 14

8 STRUCTURAL DESIGN .................................................................................................. 14

8.1 General .................................................................................................................. 14

9 DESIGN REVIEW AND DRAWINGS ................................................................................. 14

9.1 Design Review ......................................................................................................... 14

9.2 Design Drawings ...................................................................................................... 14

9.2.4 Structures ........................................................................................................ 14

Part 2: Products and Materials ............................................................................................... 16

10 PRODUCTS AND MATERIALS OVERVIEW ..................................................................... 16

10.6 Selection Guide for Pipeline Systems ....................................................................... 16

Part 3: Construction ............................................................................................................. 16

17 PIPE LAYING AND JOINTING ..................................................................................... 16

17.2 Horizontal and Vertical Deflection of Sewers ............................................................... 16

17.2.3 Horizontal curves ............................................................................................... 16

17.12 Bored Pipes under Roads, Driveways and Elsewhere ................................................. 16

21 FILL ....................................................................................................................... 16

21.1 Trench Fill .............................................................................................................. 16

21.1.1 General ............................................................................................................ 16

21.1.3 Compaction of trench fill ..................................................................................... 16

21.1 Drives and Tunnel Fill .............................................................................................. 17

22 ACCEPTANCE TESTING ............................................................................................. 17

22.6 Deflection (Ovality) and Grade Testing of Flexible Sewers ............................................ 17

22.7 CCTV Inspection ..................................................................................................... 17

24 CONNECTION TO EXISTING SEWERS ......................................................................... 18

27 DEFECTS LIABILTY PERIOD ....................................................................................... 18



Appendix A – Sewerage Design Checklist ................................................................................ 19

Appendix B – CCTV Inspection Acceptance Criteria For Newly Constructed Sewerage Assets.......... 24



Part 1: Planning and Design

2 SYSTEM PLANNING

2.1 Sewerage System Philosophy and Definition

2.1.4 Level 3 operating units

2.1.4.2 Sewage pumping stations (SPSs)

New sentence: Western Water may permit the use of sewer grades flatter than standard where there is opportunity to avoid the need of a SPS. Refer to Section 4.5.1 for further details.

3 FLOW ESTIMATION

3.2 Design Flow Estimation Method

3.2.1 General Include the following specific information for design flow estimation in Western Water’s area: For estimation of design flows in Western Water’s area, use the values specified in the following table. For catchments where these values are known or expected to vary, they should be adjusted accordingly.

Parameter Value

Flow (L/lot/day) 450 for new lots (post 2012)

555 for existing lots (prior to 2012)

Population per lot 2.5 (for new lots post 2012)

PortionWet (% of sewer network below groundwater table) 35%

PortionImpervious (% of gross plan area impervious) 90%

Soil aspect, Saspect 0.8

Network defects and inflow aspect, Naspect 0.4

Containment ARI (years) 5

I1,2 (from design rainfall isopleth – AR&R, Volume 2) 19mm/hr

4 DETAIL DESIGN

4.3 Horizontal Alignment of Sewers

4.3.1 General Include the following general information: The horizontal alignment of sewers generally depends upon the following critical inputs:



• Location of existing services; • Location of existing easements; • Location of existing above ground features (power poles, trees etc.); • Areas of environmental significance; • Areas of cultural heritage significance; • Council requirements for works within land owned by Council; • VicRoads requirements for works within the road reserve of VicRoads declared roads and freeways; • VicTrack and/or V/Line requirements for works within railway reserves; • Melbourne Water and/or Southern Rural Water requirements for works in the vicinity of waterways; • Community preference (typically for larger sewers); • Minimum offset requirements from private or public property.

4.3.7 Horizontal curves in sewers New paragraph: Western Water approval is required for all horizontal curves and sweep bends.

4.5 Pipe Sizing and Grading

4.5.1 General Replace the first sentence with the following: Pipe size and grade is typically based upon the following factors:

• Ability to transport the design flow; • Ability to achieve self-cleansing velocity at least once per day; • Effect of topography, geotechnical conditions and existing services on the pipe grade; • Pipe material (various materials having different hydraulic roughness characteristics).

Western Water may consider the use of flat grades on reticulation, branch or trunk sewers where there is opportunity to avoid the need for a sewage pumping station. New paragraph: At the planning stage, consideration should be given to whether a sewage pumping station can be avoided by using grades flatter than those specified in Table 4.3. Western Water may permit the use of such grades after an assessment of the following information submitted by the developer/designer:

• Demonstration that sewer capacity and minimum air space requirements will not be compromised; • Maximum daily velocity that will be achieved in the flat sewers; • Likely maintenance schedule that will be required over the life of the sewer; • Net Present Value (NPV) analysis over the life of the pumping station and sewer, to demonstrate

the total life cycle cost benefit of avoiding the need for a pumping station; • Demonstration that the sewer can be constructed at the grades specified, and discussion of the

measures that will be taken during construction to reduce the risk of the sewer being laid flatter than the design grade.



4.5.4 Minimum pipe sizes for maintenance purposes Western Water deems the pipe grades in the Sewerage Code to be too flat for a DN150 reticulation sewer with 1 to 4 units upstream, and has minimum pipe size requirements for industrial areas.

Reticulation sewers to industrial areas are required to be 225mm diameter or greater unless otherwise approved in writing. Property connection branches in industrial areas are required to be 150mm diameter unless a larger connection is required to cater for estimated flows from particular site use proposed. Replace Table 4.3 with the following table:

TABLE 4.3 MINIMUM PIPE SIZES FOR RETICULATION AND PROPERTY CONNECTION SEWERS

Diameter (DN) No of Units Minimum Grade No of Units Minimum Grade

Residential Industrial & Commercial

100mm Not permitted for any reticulation sewers

150mm 1 to 4 units 1 in 80 1 to 4 units1 N/A

5 plus units 1 in 150 5 to 15 units1 N/A

225mm 1 to 15 units N/A 1 to 4 units1 1 in 100

16 to 50 units 1 in 200 5 to 15 units1 1 in 150

50 plus units 1 in 300 16 to 30 units1 1 in 200

50 plus units1 1 in 300

1 to 4 units2 1 in 100

5 to 20 units2 1 in 150

20 plus units2 1 in 300 NOTES: 1 Applies only to commercial lots ≤ 300 m2 and properties zoned the equivalent of “light” or “urban”

industrial. 2 Applies only to commercial and industrial properties other than specified in Note 1. 3 Minimum grades for property connection sewers are 1 in 60 for 100mm diameter and 1 in 80 for

150mm diameter.

4.5.9 Maximum grades for septicity

4.5.9.2 Reticulation sewers

The Sewerage Code limits only the pipe half-full velocity to 3m/s. Replace the first sentence with:

Sewers must not be laid at grades were the maximum velocity will exceed 3 m/s in either partial flow, full flow or under pressure flow.



4.6 Vertical Alignment of Sewers

4.6.1 General Include the following additional factors:

(h) Requirements for crossing the assets of Council, Vicroads, VicTrack and other authorities; (i) Requirements of Melbourne Water and/or Southern Rural Water for crossing drains, creeks and

waterways; (j) Geotechnical conditions; and (k) Topography.

4.7 Corrosion Prevention

4.7.2 Internal corrosion Replace the last sentence with the following:

Western Water requires the application of an approved lining or protective coating on all new maintenance hole (MH) structures on sewers ≥DN450, gas check MHs, rising main discharge MHs, sewage pumping station wet well/ valve pit chambers, and other specific structures as directed. Where a rising main discharges to a gravity sewer system, the Designer shall undertake a detailed odour and septicity assessment as outlined in Western Water’s Sewage Pump Station Design Standard and WSA 04-2005. This assessment shall include a predictive analysis of hydrogen sulphide generation to determine likely odour and corrosion impacts at the point of discharge and recommend any appropriate control and/or elimination measures.

5 PROPERTY CONNECTION

5.3 Methods of the Property Connection

5.3.1 General New paragraph: Where a property connection is required within the close proximity to a maintenance hole, it is preferred for the property connection to be connected directly to the maintenance hole, where practical.

5.6 Location of Connection Points New sentence: For both undeveloped and developed lots, property connection points are to be located beyond the property or easement boundary by a minimum of 500mm.

5.7 Y-Property Connections Delete entire clause and replace with the following:



Western Water does not permit the use of “Y” property connections.

6 MAINTENANCE STRUCTURES

6.2 Locations of Maintenance Structures Western Water does not permit Maintenance Shafts to be used. The following table replaces the equivalent rows of Table 6.1:

Application Acceptable Options

MH MS TMS/IS

Change of grade at same level YES NO NO Change in sewer horizontal direction YES NO NO Permanent end of a reticulation sewer YES NO YES

Only where there is a MH within 45m

downstream Straight sections of sewer between MHs

YES NO NO

6.3 Spacing of Maintenance Structures

6.3.1 General Western Water requires spacing of maintenance structures to be determined by access from the downstream maintenance hole. The inefficiency, occupational health and safety and environmental risks (of solids spills) associated with jetting from upstream access chambers to clear blockages and perform maintenance is unacceptable to Western Water. Replace the second paragraph with: The design shall ensure that access to every part of a sewer is achievable from the downstream maintenance hole using equipment installed on a service vehicle legally parked on the nearest boundary of the nearest road or readily accessible public land. “Legally parked” shall include street side parking in road carriageways (but not freeways) and public care parks, but shall exclude parking within the minimum specified distance of intersections. The measured distance between the service vehicle and the maintenance structure shall be the slope distance in steep terrain, together with an allowance for the vertical drop from ground level to sewer invert inside the maintenance structure itself. Where these criteria cannot be met, the design shall include appropriate provisions for maintenance access

6.3.2 Maintenance Structure Spacing – Reticulation Sewers The maximum distance permitted by Western Water between maintenance holes is 100m. Replace the first two sentences with: For reticulation sewers, the maximum distance between any two consecutive maintenance structures shall be 100 m and subject to the provisions of Clause 6.3.1. Max distance X is the lesser of: X = 100 m, or

X = 150 m – dist. to parked truck – depth of maintenance structure



Western Water requires a MH to be located within 45m downstream of the permanent end of a reticulation sewer. Replace Figure 6.1 with: Where the last maintenance structure is a TMS or IS, a MH must be located with 45m downstream.

6.4 Special Considerations for Location of Maintenance Structures

Western Water does not permit sewers to be located within the 1 in 5 year flood level. Replace point (ii) with the following:

(ii) Location of sewers and MHs within the 1 in 100 year flood level shall be avoided as far as practicable. Prior Western Water approval is required for the location of any new sewer inside the 1 in 100 year flood level. Location of a sewer MH below the 1 in 5 year flood level will not be permitted.

6.6 Maintenance Holes (MH)

6.6.2 Types of MH construction

Western Water does not permit the use of precast maintenance holes. Replace this section with the following: Standard MH construction shall be poured in situ comprising a poured base, channels and walls with a poured or precast concrete cover slab. Precast MHs must not be used unless written approval is obtained from Western Water. Such approvals will only be granted in exceptional circumstances. MH construction details are shown on Drawings SEW-1301-V, SEW-1302-V, SEW-1303-V, SEW-1304-V, SEW-1305-V, SEW-1306-V, SEW-1307-V and SEW-1308-V. Special MH construction may be permitted by Western Water. These include using other corrosion-resistant materials such as PVC either as formwork or as a corrosion barrier, in conjunction with non-standard construction techniques that may offer lower life cycle costs. MHs may also be constructed from PE and other plastic materials provided that an approved product is used. Special MH construction details are shown on Standard Drawings SEW-1310-V, SEW-1311-V and SEW-1312-V and Drawings SEW-1309-V and SEW-1313-V.

6.6.8 Ladders, step irons and landings

New sentence: Step irons and ladders shall be located directly over the downstream MH base channel within 1050mm and 1200mm diameter MHs. In MHs larger than 1200mm diameter the stepirons and ladders shall not be located over the MH base channel and shall be located with an unobstructed area immediately in front of the step irons or ladder as per Clause 6.6.6. Step irons and ladders shall be located a minimum of 200mm from any drop pipe within the MH.



6.6.9 MH Covers

New sentence: MH covers are to be circular Gatic type which are opened with the standard Gatic lifter and have a concrete infill.

6.7 Maintenance Shafts (MS) Western Water does not permit Maintenance Shafts to be used, except as a TMS. Delete all references to the use of MSs (except at TMSs) in the entire Section 6.7.

6.7.3 Property Connection Sewer into MSs and TMSs Not used. Western Water does not permit property connections into MSs, TMSs or ISs.

MRWA 6.7.4 Inspection Shafts (IS) Western Water requires ISs to be upstream of all property connection branches at the termination of reticulation sewers. Replace this section with: Inspection shafts (ISs) are generally an acceptable alternative to TMSs for sewers ≤DN225. ISs shall only be used at the design locations detailed in Table 6.1. Where ISs are installed at the termination of reticulation sewers, i.e. for branches less than 45 metres in length, the IS shall be constructed upstream of all property connection branches. IS types include: (a) Terminal (Type A) – used in conjunction with a property connection immediately downstream. (b) Vertical drop (Type B) – not used by Western Water. (c) Intermediate (Type C) – not used by Western Water.

MRWA 6.7.4.2 Vertical drop inspection shaft (Type B)

Not used by Western Water

MRWA 6.7.4.3 Intermediate inspection shaft (Type C)

Not used by Western Water



7 ANCILLIARY STRUCTURES

7.2 Water Seals, Boundary Traps and Water-Sealed MHs/Gas Check MHs

7.2.1 General design parameters New paragraphs: Gas check MHs are not usually required by Western Water and shall not be provided without prior approval. Boundary traps are not usually required by Western Water, but shall be provided where required by Western Water.

7.3 Water Seals and Gas Check MHs

7.3.2 Design parameters for water seals and gas check MHs New paragraphs: The design of any gas check MH if required, shall be undertaken in accordance with specific design requirements as provided by Western Water.

7.6 Near-Horizontal Boreholes

7.6.2 Design Requirements Additional requirements: Rubber ring or solvent cement jointed PVC may only be used for bores of 3 pipe lengths or less. Where Western Water approval has been obtained for the use of bored PE, the design drawings shall specify that the pipe shall be internally de-beaded prior to commissioning. Design grades flatter than 1:180 will not be permitted for bored PE.

7.8 Inverted Siphons

7.8.2 Design parameters for inverted siphons Additional sentence in point (ii):

(ii) The siphon shall incorporate an inlet and outlet structure, which facilitates maintenance and inspection. The purpose of the inlet and outlet structures on new siphons is that they enable one siphon to be taken offline for cleaning and inspection whilst the second stays in operation.

Western Water requires a pipe material analysis to be undertaken for inverted siphons. Replace point (xi) with:

(xi) A pipe material analysis shall be carried out to assess the preferred pipe material for inverted siphons. Typical pipe materials include fully welded PE and steel.

Western Water requires a scour point to be included in the inverted siphon design. Odour and septicity control also needs to be considered. Include new design parameters:



(xv) A scour point shall be provided at the lowest point in the siphon. The low point shall be located close to the inlet or outlet structure and shall be designed to take into account ease of access for maintenance activities (including access for Western Water vehicles and eduction trucks). Western Water’s preference is for the low point to be located as close as possible to the inlet structure so that blockages can be cleared from upstream. (xvi) For long siphons, the plugged flow conditions are conducive to septic conditions. All siphons shall be designed to ensure that septicity is managed and odour control measures are implemented.

7.9 Overflows / Emergency Relief Structures (ERS) Additional sentence: All identified critical spill points including ERSs shall be also fitted with an independent ‘Fail Safe’ alarm to provide early detection of system blockages, equipment failure or hydraulic overloading that if left unreported have the potential to result in a sewage spill. The Fail Safe alarms shall be fully independent of any other monitoring and be provided with dedicated back-up power.

8 STRUCTURAL DESIGN

8.1 General New paragraph to define trench fill specification used by Western Water: For works within Western Water’s service area, the MRWA Backfill Specification 04-03.1 (revision 1) shall apply.

9 DESIGN REVIEW AND DRAWINGS

9.1 Design Review Western Water requires the Sewer Design Checklist (attached in Appendix A of this Design Guide) to be completed and submitted along with the design drawings for auditing purposes. New paragraph: Once the design has been completed, Design Drawings shall be submitted to Western Water for auditing purposes, accompanied by Western Water’s Sewer Design Checklist which shall be completed by the designer. In general, Western Water will audit designs in the order they are received. It is Western Water’s expectation that all designs submitted for auditing will comply with Western Water’s design standards and will match the information provided in the accompanying Sewer Design Checklist. Where discrepancies are found, the designer will be expected to revise the design drawings and/or checklist and submit them for re-auditing.

9.2 Design Drawings

9.2.4 Structures New items to be included on the Design Drawings:

(j) A base detail must be shown for MHs where there are three or more incoming sewers, two or more drops, angles of deflection greater than 90 degrees, unusual configurations of incoming sewers, or sewers are offset from the centre of the MH.



(k) A base detail must be shown for any connections to existing MHs, unless connection is to an existing stub that will not need to be modified. The detail shall show the existing layout and the modifications that are required so that the minimum working spaces are maintained in the MH. It is expected that existing MHs will be inspected as part of the design to confirm that they are suitable for a new connection.



Part 2: Products and Materials

10 PRODUCTS AND MATERIALS OVERVIEW

10.6 Selection Guide for Pipeline Systems New paragraph: Pipe and other associated products used on Western Water sewerage works shall be approved Western Water products and materials. Written approval from Western Water must be obtained for any alternative pipe materials prior to their proposed use.

Part 3: Construction

17 PIPE LAYING AND JOINTING

17.2 Horizontal and Vertical Deflection of Sewers

17.2.3 Horizontal curves Replace last sentence with: Western Water approval is required for curves and sweep bends on sewers ≥225mm diameter New sentence: All curved sewers shall be accurately surveyed and recorded on the as-constructed drawings including offset from property boundary, curve radius, and tangent points.

17.12 Bored Pipes under Roads, Driveways and Elsewhere New sentence:

A CCTV report shall be submitted at the completion of the work. The report must be prepared in accordance with Western Water’s CCTV Inspection Standard: Supplementary Information to the WSAA Conduit Inspection Reporting Code of Australia WSA 05-2013-3.1 Third Edition

21 FILL

21.1 Trench Fill

21.1.1 General New sentence at end of 1st paragraph: For works within Western Water’s service area, the MRWA Backfill Specification 04-03.1 (revision 1) shall apply.

21.1.3 Compaction of trench fill New sentence: Flooding or jetting of fill materials in excavation is not permitted under any circumstances.



21.1 Drives and Tunnel Fill New sentence at end of 1st paragraph: For works within Western Water’s service area, the MRWA Backfill Specification 04-03.1 (revision 1) shall apply.

22 ACCEPTANCE TESTING

22.6 Deflection (Ovality) and Grade Testing of Flexible Sewers Western Water requires Laser Light Profiling to be undertaken on all newly constructed sewer systems to test deflection and grade. New paragraph:

Laser light profiling shall be undertaken on newly constructed sewer systems based on the criteria set out in Clause 22.7 for the purpose of:

• Recording of sewer deflection (ovality). • Recording of sewer grade against chainage to verify the sewer has been graded as per the

design. The Contractor shall submit a Laser profiling report containing the following:

• Video in AVI format. • Ovality profile in MS Excel or PDF. • Long section chart/grade profile in MS Excel or PDF. • Written summary outlining the results in relation to the acceptance criteria as stated in Table

22.7 (deflection) and 23.2.3 (grade). The Laser Profiling/CCTV Contractor must demonstrate to Western Water that they have undergone training in the use of the Laser Profiler and are competent in its use. The Laser Profiling equipment must be regularly serviced and certified to WRc standards by a reputable certification scheme. Prior to use, the equipment shall be calibrated in accordance with the manufacturer’s recommendations and documentation to this effect available on site.

With Laser Profiling being used to assess sewer deflection, ovality proving using a proving tool is not required in addition to Laser Profiling.

22.7 CCTV Inspection Western Water takes a risk based approach to determining CCTV inspection requirements of newly constructed sewer systems. New paragraph: Western Water requires CCTV inspection of all newly constructed sewer systems, over and above the requirements for MH vacuum testing, deflection testing, air/vacuum testing and compaction testing, in the following circumstances;

• All sewers ≥300mm - <750mm diameter require CCTV and Laser Profiling Ovality inspections to be undertaken.

• All sewers ≥750mm diameter require either Infrared distance meter inspection or CCTV and Laser Profiling Ovality inspection. (subject to equipment availability).

• All sewers <DN300mm diameter which are greater than 5 metres in depth or have been constructed using trenchless methods require CCTV and Laser Profiling Ovality inspections to be undertaken.



• All reticulation sewers <DN300mm diameter and less than 5 metres in depth shall be acceptance tested using a proving tool (ovality ball) unless there is evidence of unusual installation problems or risks.

A CCTV report shall be submitted at the completion of the work. The report must be prepared in accordance with Western Water’s CCTV Inspection Standard: Supplementary Information to the WSAA Conduit Inspection Reporting Code of Australia WSA 05-2013-3.1 Third Edition. Acceptance criteria for newly constructed sewerage assets shall be as per Appendix B. Testing shall be undertaken as per Table below:

Diameter (DN) CCTV

Deflection Testing

Flexible Pipes Rigid Pipes (ie.

VC) Proving Tool Laser Profiling Ovality Inspection

≥300mm YES N/A YES N/A

<300mm where depth >5m or has been constructed using trenchless methods

YES N/A YES N/A

<300mm ON WW

REQUEST1 YES ON WW REQUEST1 N/A

Note 1. On WW Request at the initiation prior to award of contract

24 CONNECTION TO EXISTING SEWERS New paragraphs: Cut-ins to live sewers shall only be carried out by contractors accredited to work on live sewers. The contractor must have obtained a Works Approval and a Certificate of Entry from Western Water for the date and time of the sewer connection. These forms are available at www.westernwater.com.au. The contractor must provide all confined space entry equipment and staff in accordance with Occupational Health and Safety regulations current at the time, and provide appropriate bypass pumping arrangements and standby equipment prior to attempting a connection to a live sewer. New section 27:

27 DEFECTS LIABILTY PERIOD Unless otherwise advised by Western Water, the Defects Liability Period for all sewer works shall be 12 months.

http://www.westernwater.com.au



Appendix A – Sewerage Design Checklist

Criteria Complete Comments

Survey Datum

Is the Australian Height Datum (A.H.D) noted on design plans?

Is the Australian Map Grid (A.M.G) / Geocentric Datum of Australia (G.D.A) noted on design plans?

Are PBMs and/or TBM's shown on design plans and are AMG/GDA co-ordinates for these PBMs/TBMs shown?

Has the whole catchment (required to be controlled through this development) been controlled?

Gravity Sewers, Rising Mains or Siphons

Are all sewers along the front of properties located within road reserve and not within the property unless otherwise approved by Western Water?

Are there any curved sewers? Note that curved sewers are only permitted for 150mm diameter sewers.

Are all curved sewers designed correctly (radius greater than the standard, jointing technique, no property connections on the curved sections etc.)?

Is minimum cover achieved on all pipes?

Has continuously jointed pipe been specified for any water crossings?

Are there any railway crossings? Has the crossing design been carried out in accordance with the Australian Standards and VicTrack requirements? Has VicTrack provided written approval? Note a detail drawing for the railway crossing to 1:500 scale in addition to a locality plan should be provided.

Are all maintenance structures located out of the railway reserve? Is a minimum of 1m clear space provided around maintenance structure near confined boundaries?

Are there any freeway crossings? Has the crossing design been carried out in accordance with the Australian Standards and VicRoads requirements? Has VicRoads provided written approval?

Does the alignment of the pipeline cross at right angles to the freeway?

Are all maintenance structures located clear of the freeway reserve?

Are minimum clearances from other services achieved?




Are there any crossings of Council Drains or Melbourne Water/Southern Rural Water drains/waterways? Has written approval to the design been obtained?

Does the location of the rising main comply with Western Water requirements?

Western Water approval for installation of Siphon received?

Do offsets of the sewer comply with WSAA standards?

Have all existing utilities been identified on drawings?

Has a Dial Before You Dig (DBYD) search been carried out?

Are any works proposed within a VicRoads declared road?

Are any works proposed in the vicinity of Melbourne Water assets and/or waterways? Has the design taken into account Melbourne Water requirements?

Has the requirement for odour control measures been assessed and incorporated into the design?

Maintenance Structures

Does the distance between maintenance structures comply with standards (i.e. generally 100m as per Western Water requirements)?

Are all maintenance structures numbered in accordance with standards?

Is the area subject to flooding?

If subject to flooding, do all maintenance holes have bolt down covers and are all cover levels above the 1 in 5 year storm event level?

Are there any gas check maintenance holes? Has the use of gas check maintenance holes been approved by Western Water?

Are Gas Check maintenance holes located in the road reserve and are there ultimately more than 50 lots connected to it?

Are there any maintenance holes greater than 6m in depth?

Are landings, handgrips, ladders etc. in accordance with standards and are correct materials specified on design plans?

Are structural computations of maintenance structures deeper than 6m provided?

Are all maintenance structure locations in accordance with Western Water standards and with a minimum of 1m clearance from confined boundaries?

Are minimum clearances to other services achieved?

Are the maintenance holes’ cover class and cover size noted on design plans?




Have any pre-cast maintenance holes been specified? Has their used been approved by Western Water?

Are correct diameters of maintenance holes nominated on design plans, as well as the minimum diameter to be used?

Is detailed MH table design required to be submitted? (e.g. two or more internal drops, three or more incoming sewers, sewers offset from the MH centre, angle of deflection >90o)

Are MH table designs in accordance with standards?

Are there any sewers or other underground structures to be built next to existing structures?

Are guidance notes provided to the contractor for excavation next to existing manholes to preserve stability of the manholes during construction?

Where connecting to existing MHs, have these been inspected as part of the design and are details provided on the drawings of the existing layout and modifications required? Are working spaces still to standard?

Design of Gravity Sewers (including Hydraulics)

Are the correct pipe diameters specified in accordance with standards?

Does the grade of each pipe comply with standards?

Are IL's of sewers correctly identified?

Are all pipe materials, pipe classes, jointing methods etc. specified on design plans and are they all approved products?

Is the trench width provided or referred to relevant design standards?

Has the embedment material been specified and is it suitable for the pipe and geotechnical conditions?

Are compaction requirements for trench bottom (if required), embedment, and backfill specified or referred to relevant Australian Standards?

Are backfill design specifications provided or referred to WSAA code drawing or relevant standards?

Are embedment types specified according to WSAA standard drawings or cross section details provided?

Are any grades steeper than 1 in 10 or flatter than 1 upon diameter?

Have trench stops been provided where required?

Is the velocity through the pipe below 3 m/s in both partial and full flow (or under pressure flow if a pressure main)?




For steeply graded sewers, is the energy dissipated in the maintenance hole?

Are there any sewers greater than 5m in depth?

Has the ground conditions report been provided for sewers deeper than 5m?

Are there wet/poor ground conditions?

Has a specialist geotechnical assessment been made?

Has adequate trench design been made and relevant details provided?

Has an Emergency Relief Structure (ERS) been incorporated in design?

Have HGL details been submitted ensuring that there is no possibility of overflow upstream at MHs, property drains, etc?

Are structural design computations for trench design sewer pipes provided?

Are water seals (i.e. boundary traps) specified where required, and has Western Water approval been obtained for their use?

Property Connections

Are all properties provided with a property branch/connection and is the type of branch/connection nominated on design plans?

Have any Y-property branches/connections been nominated? (note not permitted)

Is the depth for property connections junctions and end fittings in accordance with the standard?

Do property connections extend beyond the property/easement boundary by a minimum of 500mm?

Gravity Sewers greater than 225mm in Diameter

Are self cleansing/slime stripping velocities achieved at PDWF?

Is the class of pipe and all embedment details shown on design plans?

Are any sewers surcharging under 1 in 5 year floods (i.e. PWWF)?

Are property connections only on sewers 300mm in dia. and less?

Inverted Siphons

Are minimum velocities achieved at PDWF?

Does the difference in inlet level and outlet level comply with Western Water standards?




Has the siphon hydraulics been designed to confirm sediments are flushed through the downstream reach of the siphon during PDWF?

Hazard Identification and Risk Assessment

Has the designer, in designing the sewerage system element that is being audited, integrated hazard identification and risk assessment methods to eliminate the risk of injury throughout the life of the system?



Appendix B – CCTV Inspection Acceptance Criteria For Newly Constructed Sewerage Assets



TABLE B1 ACCEPTANCE CRITERIA FOR RIGID SEWERS – VITRIFIED CLAY, STEEL REINFORCED CONCRETE

Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Acceptance determination and explanation Cracking C L, C, S, or M Surface cracking is common in concrete and is usually

not of concern. Such cracking is usually of limited extent and does indicate structural failure. However, surface cracking that is extensive may indicate a problem with concrete quality. Report in remarks for the Water Agency to review. Surface cracking is unlikely in VC products currently on the market although it should be noted that internally glazed VC pipes are now again available. If surface cracking is observed report in remarks for the Water Agency to review.

Fracturing F L, C, S, or M Not acceptable – all of these types of cracking are indicative of poor handling, unsatisfactory installation or overloading.

Breaking B D, M, or E Not acceptable.

Deformation D Not acceptable.

Collapsed X Not acceptable.

Porous sewers (pipes) PP

Not acceptable.

Surface damage S * Not applicable to VC

S, AV*, or W Report and refer to Water Agency for acceptance determination.

Z Identify, report and refer to Water Agency for acceptance determination.

AP*, AM*, RC*, CP*, H* or WS*

Not acceptable - unlikely to be observed in new construction.

RV* or RVP* Not acceptable - cover to reinforcement is clearly less than specified in relevant pipe standard.

continued



Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Acceptance determination and explanation Lining defective PL** ** Applicable to plastics lined concrete pipes only

D, E, WD or L Defects indicated not acceptable. The lining is placed during manufacture in the top 330° of the pipe and is required to be joined after installation at each pipe joint.

Z Lining on invert of pipe (pipe installed upside down) – not acceptable. Identify other defects, report in remarks and refer to Water Agency for acceptance determination.

Deposits on wall or invert DE

E Not acceptable - should not occur in new sewer.

S or R Not acceptable.

C Not acceptable.

W or Z Identify material, report in remarks and refer to Water Agency for acceptance determination.

Exfiltration EX Not acceptable – exfiltration is most likely associated with a joint defect or broken pipe.

Infiltration S S, D, R or G Not acceptable.

Ingress of soil ING Not acceptable.

Roots R T, F, or M Not acceptable – the presence of roots indicated a possible problem with installation at joints, poor quality concrete, cracks and/or fractures.

Joint displacement JD

L Not acceptable – if joint displacement exceeds maximum specified by manufacturer for the joint.

R >5 mm for pipe sizes up to DN 250 >10 mm for pipe sizes from above DN 250 to DN 500 >20 mm for pipe sizes above DN 500

Not acceptable.



Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Acceptance determination and explanation A Normally unacceptable on ‘straight’ sewers (see

maximum limits for ‘curved’ sewers below). Report deflection and refer to Water Agency for acceptance determination. For ‘curved’ sewers using ‘pulled’ pipes report the distance between the end of spigot and end of socket (adjoining pipe) at worst point and the angular deflection at the joint. Refer to Water Agency for acceptance determination.

Jointing material (seal) intrusion) JI

R N, HH, HL or B Not acceptable.

Z Report and refer to Water Agency for acceptance determination.

Point repair RP L, I, S, H or IC Some techniques may not be acceptable in new sewers. Report and refer to Water Agency for acceptance determination.

Z Identify repair technique, report in remarks and refer to Water Agency for acceptance determination.

Defective repair RX M or P Not acceptable.

B or Z Determine extent of ‘bellies’ or other defects. Report and refer to Water Agency for acceptance determination.

Obstruction OB B, M, I, J or C Not acceptable.


P or S Report and refer to Water Agency for acceptance determination.

Flow (water) level WL

>15mm or 5% whichever is the greater (no flow from upstream and no blockage or debris downstream)

Not acceptable above the limit indicated. Flow (water) level above a nominal level may be caused by flow from upstream or a blockage, debris in the invert or some other feature downstream. It is not a defect itself. It does indicate a defect. However, where there is no flow from upstream and there is no blockage downstream, the most likely defect indicated in this



Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Acceptance determination and explanation situation is gradient misalignment (i.e. one of more pipes have dropped below the grade and ponding has occurred).

Defective junction JX

P, D, B, BC, SR, SE or Z

Not acceptable.

Connection CN G or P Not acceptable - junction required.



TABLE B2

ACCEPTANCE CRITERIA FOR FLEXIBLE SEWER PIPES – PLASTICS (PVC, PE, PP, GRP), DUCTILE IRON AND STEEL

Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Remarks Cracking C L, C, S, or M S Not acceptable. Not usually a feature of these pipe

materials but may be apparent in cement mortar linings and internal corrosion barrier (“gel-coat”) of GRP. Report as Lining defective ‘PL’.

L, C, S, or M W Not acceptable. Not usually a feature of these pipe materials but where it does occur, it would generally indicate excessive external loads from construction equipment.

Fracturing F L, C, S, or M Not acceptable.

Breaking B D, M, or E Not acceptable.

Deformation D >5% after 60 days Not acceptable.

Local or point deformation – no code

No code Record General Comment GC

Report and refer to Water Agency for acceptance determination. An unusual feature with many possible causes.

Collapsed X Not acceptable.

Porous sewers (pipes) PP

Not acceptable. Not likely to be a feature of these pipes.

Surface damage S W Report and refer to Water Agency for acceptance determination.

Z Identify, where possible, report and refer to Water Agency for acceptance determination.

CP or H Not acceptable. Unlikely to be observed in new construction.

Lining defective PL D●, E●* or B●* Not acceptable * Applicable to internal corrosion barrier in GRP pipes * Applicable to PE internal lining of ductile iron and steel pipes



Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Remarks Z Identify other defects, where possible, report and refer

to Water Agency for acceptance determination.

Deposits on wall or in invert DE

E Not acceptable - Should not occur in new sewer.

S or R Not acceptable.

C Not acceptable.

W or Z Identify, where possible, report and refer to Water Agency for acceptance determination.

Exfiltration EX Not acceptable – exfiltration is most likely associated with a joint defect or broken pipe.

Infiltration S S, D, R or G Not acceptable.

Ingress of soil ING Not acceptable.

Roots R T, F, or M Not acceptable – the presence of roots indicated a possible problem with installation at joints, poor quality concrete, cracks and/or fractures.

Joint displacement JD

L Not acceptable – if joint displacement exceeds maximum specified by manufacturer for the joint.

R >5 mm for pipe sizes up to DN 250 >10 mm for pipe sizes from above DN 250 to DN 500 >20 mm for pipe sizes above DN 500

Not acceptable.

A Normally unacceptable on ‘straight’ sewers (see maximum limits for ‘curved’ sewers below). Report deflection and refer to Water Agency for acceptance determination. For ‘curved’ sewers using ‘pulled’ pipes report the distance between the end of spigot and end of socket (adjoining pipe) at worst point and the angular deflection at the joint. Refer to Water Agency for acceptance determination.

Jointing material R N, HH, HL or B Not acceptable.



Defect/Feature Characterisation 1 Characterisation 2 Quantification 1 Remarks (seal) intrusion) JI Z Report and refer to Water Agency for acceptance

determination.

Point repair RP L, I, S, H or IC Some techniques may not be acceptable in a new sewer. Report and refer to Water Agency for acceptance determination.

Z Identify repair technique, report in remarks and refer to Water Agency for acceptance determination.

Defective repair RX

M or P Not acceptable.

B or Z Determine extent of ‘bellies’ or other defects, report and refer to Water Agency for acceptance determination.

Obstruction OB B, M, I, J or C Not acceptable.


P or S Report and refer to Water Agency for acceptance determination.

Flow (water) level WL

>15mm or 5% whichever is the greater (no flow from upstream and no blockage or debris downstream)

Not acceptable above the limit indicated. Flow (water) level above a nominal level may be caused by flow from upstream or a blockage, debris in the invert or some other feature downstream. It is not a defect itself. It does indicate a defect. However, where there is no flow from upstream and there is no blockage downstream, the most likely defect indicated in this situation is gradient misalignment (i.e. one of more pipes have dropped below the grade and ponding has occurred).

Defective junction JX

P, D, B, BC, SR, SE or Z

Not acceptable.

Connection CN G or P Not acceptable - junction required.



TABLE B3

ACCEPTANCE CRITERIA PIPE AND FITTING CONFIGURATION – ALL SEWERS The configuration of items in a new sewer is usually defined in design drawings, standard drawings and specifications Compliance with some of these requirements may be determined by inspection

The inspector shall have a copy of design drawings, standard drawings and specifications applicable to the works being inspected for reference in determining the acceptance of nominated and other features.

The following table describes nominated features that are to be reported to the Water Agency.

Feature Description Acceptance determination and explanation

Rocker pipes

These a shorter pipes than the normal unit pipe length and are required by some Water Agencies adjacent to structures such as maintenance holes, other structures and concrete encasement The purpose is to allow for differential settlement between the structure and the pipeline without cracking, fracturing or distortion of the pipe adjacent to the structure

The required length of rocker pipe and the configuration of pipes at the structure are specified in design drawings, standard drawings and or specifications for particular pipe materials. The inspector should record the distance at each joint adjacent to the structure to determine the length of the rocker pipe and report it in remarks. Length outside of tolerance of ± 150mm of required length not acceptable – refer to Water Agency for acceptance determination.

Bends Bends occur in some sewers at changes of direction and or grade. In some cases compound bends (vertical and horizontal) may be encountered In small diameters up to DN 225 bends are likely to be moulded or post-formed long radius. For ≥DN 225 it is likely that bends will be fabricated in a ‘lobster back’ with a series of mitre cuts and the pipes joined with epoxy, hot air welding or some other technique

Not acceptable if the camera unit cannot pass through the bend. Not acceptable if jointing materials at mitres intrude more than 10mm into the sewer. The transition to bend from straight line should not exceed the angular deflection for the joint system used Record joint deflection if observable. Where the installation of the bend results in ponding the acceptance criteria applied for maximum water level in the previous tables shall also be applied. The distance at the start and finish of bends shall be recorded in the inspection report.

Connections This is where another sewer to provide a service for a customer has been connected to the pipeline being inspected after the pipeline has been installed The connection is formed by making a hole in the original pipe and setting the connecting pipe in place

Not acceptable.



Feature Description Acceptance determination and explanation This feature is not part of new sewer construction

continued

Junction A junction is a prefabricated fitting installed as part of the original construction or post construction by inserting the junction fitting in the pipeline Junctions are provided to allow customers to connect house drains directly to the sewer or allow a property connection sewer to be extended to the customer’s property Acceptable configurations of junctions should be specified by the Water Agency

Not acceptable if configuration varied from Water Agency’s specification/standard drawing. All junctions for direct customer connection should be provided with a PVC plain wall solvent weld socket with screwed cap or for VC, a plugged VC to PVC plain wall adaptor Inspect each junction lateral and report compliance

Maintenance shafts and chambers

Provide access to the sewer for maintenance equipment but not person entry May have an integral bend or may have an adjoining (generally upstream) long radius bend Can have up to three inlets

Not acceptable if the CCTV camera and transportation unit cannot traverse through the maintenance shaft. The transition to maintenance shaft from bend or straight line must not exceed the angular deflection for the joint system used Record joint deflection if observable and refer to Water Agency for acceptance determination.

WW Sewerage design standard 2014 - V5.docx

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