Water Supply and Sewerage Standards

Release 2 with amendments, updated Oct 2006

 

Nomenclature

Notation
EP	equivalent population	L/s	litres per second
ha	hectares	L/s/ha	litres per second per hectare
L	litres	L/EP/day	litres per equivalent population per day
kL	kilolitres	mm/hr	millimetres per hour
KPa	kilopascals	mm/wk	millimetres per week
mm	millimetres	m/s	metres per second
m	metres	m/m	metres per metre
km	kilometres	hrs/wk	hours per week
m3	cubic metres	PWWF	peak wet weather flow (L/s)
ADWF	average dry weather flow (L/s)	Qdmp	most probable PDWF (L/s)
DN	nominal diameter (mm)	Qf	flow capacity (L/s)
ID	internal pipe diameter (mm)	Qp	pump capacity (L/s)
NSA	net sewered area (ha)	S	grade (%)
PCC	daily per capita sewage contribution	TPF	total pumped flow (L/s)
PDWF	peak dry weather flow (L/s)	Vf	flow velocity (m/s)
PII	peak infiltration and inflow (L/s)
Acronyms
ABS	Acrylonitrile Butadiene Styrene	PVC	Polyvinyl Chloride
AHD	Australian Height Datum	RC	Reinforced Concrete
ARI	Average Return Interval	SAA	Standards Association of Australia
AS	Australian Standard	SDE	Sewer Dead End
BEPCON	Building Electrical and Plumbing Control	SG	Standard co-ordinate Grid
BOQ	Bill of Quantities	SMH	Sewer Maintenance Hole
BVR	Buried Vertical Riser	SMS	Sewer Maintenance Shaft
CCTV	Closed Circuit Colour TV	SPS	Sewage Pump Station
DICL	Ductile Iron	SRP	Sewer Rodding Point
DS	Downstream	SOS	Sewage Overflow Structure
ED	External Drop	SST	Sewage Storage Tank
ES	External Services	SVD	Sewer Vertical Drop
GRP	Glass Reinforced Plastic	SVE	Sewer Educt Vent
ISO	International Standards Organisation	SVI	Sewer Induct Vent
ITP	Inspection and Test Plans	VC	Vitrified Clay
MH	Maintenance Hole	WAE	Work as Executed
NCDC	National Capital Development Commission	WSAA	Water Services Association of Australia
NZS	New Zealand Standard	WSS	Water Supply and Sewerage
PE	Polyethylene	WSSS	Water Supply and Sewerage Standards

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1. Introduction

1.1 ACTEW Corporation

ACTEW Corporation Ltd ("ACTEW") is an agency responsible for the control, ownership and operation of water supply and sewerage systems within the ACT. ActewAGL Distribution (a joint venture partnership between ACTEW and AGL) operates the water supply and sewerage assets of ACTEW under an alliance contract, and is the agent of ACTEW in respect of ACTEW"s Water Supply and Sewerage Standards. The key objectives underlying ACTEW"s design policy are as follows:

1. to provide the most economic structure/asset to meet the service provision needs as evaluated over a whole life cycle;
2. to achieve the most sustainable use of resources entrusted to the care of ACTEW;
3. to optimise asset life.

Water Supply

• To provide efficient and effective water storage, treatment and distribution facilities for the urban areas in the ACT, thus creating a safe, potable and reliable supply of water to all customers;
• To at all times provide water to customers except as permitted under the Consumer Protection Code (made under the Utilities Act 2000) or during events or conditions beyond the control of ACTEW;
• To provide water of the quality specified in the Water Supply and Sewerage Service Standards Code and the Drinking Water Quality Code of Practice 2000 (each made under the Utilities Act 2000) to all relevant points of the water supply network;
• To make available the quantity of water specified in the Water Supply and Sewerage Service Standards Code (made under the Utilities Act 2000) through the water supply network;
• To be able to achieve system reliability and availability as defined in the Water Supply and Sewerage Service Standards Code; and
• To be able to meet the fire-fighting requirements agreed with the ACT Fire Brigade.

Sewerage

• To provide efficient and effective sewerage collection and disposal facilities for domestic and industrial water borne wastes, so as to achieve public health protection, a pleasant environment and water quality protection;
• To facilitate the ability of the sewage treatment plant to treat sewerage;
• To minimise the production of odours which may emanate from the sewerage network;
• To minimise the accumulation of solids and gases in the sewerage network;
• To minimise overflows in the sewerage network and to minimise these overflows into customers premises;
• To achieve sewerage network reliability and availability as defined in the Water Supply and Sewerage Standards Code (made under the Utilities Act 2000); and
• To enhance potential for the re-use of treated effluent.

1.2 Scope

This document sets out standards for the design of water supply and sewerage reticulation systems to meet the above objectives, and is applicable to the design of new development and redevelopment areas, with emphasis on works to be handled by designers or consultants (on behalf of developers). The practices should not be interpreted as relieving designers of the responsibility to properly assess all conditions, and shall not be interpreted as relieving the use of professional judgement and sound practices required in developing economic proposals.

It is expected that the durability of materials used shall be no less than 100 years for civil works and pipes, and 15 to 25 years for electrical and mechanical equipment.

This document sets out the intent to be achieved and standards that normally achieve the intent. The approval of ACTEW is required where a particular design encompasses the intent but is best resolved by not utilising a standard.

Appropriate detailed specification clauses are to be found in the ACT Public Works Basic Specification (Reference 9.1) as printed by Totalcare Industries Ltd. Specification will need to be approved by ACTEW prior to use.

The Water Supply Section (Part 2) covers the design and detailing of individual water supply reticulation systems downstream of service reservoirs. It provides a brief general background on design aspects but does not cover the planning and design of dams, treatment plants, pump stations, reservoirs or bulk supply mains. The detail design of these latter elements requires a detailed knowledge of the system, and a specialised and specific design approach based on the state of technical knowledge at the time the particular facility is required. Such design would normally be based on a Water Supply Functional Brief.

The Sewerage Section (Part 3) covers the design and detailing of sewage collection systems to be provided in urban residential, commercial and industrial areas, and provides some general requirements on the design of small sewage pump stations. It does not cover sewage treatment facilities or specialised structures (refer Part 3, Technical Requirements for Sewerage, Clause 5.3).

Practices herein should not be automatically adopted for small semi-rural developments on the periphery of the urban area. Provision of a city-standard water supply or sewerage system in such areas may be unjustifiably costly, and standards should be adopted to suit the particular situation.

WSAA (Water Services Association of Australia) as part of its National Code Initiative is developing codes for design, construction, maintenance and rehabilitation of the industry"s water and sewerage infrastructure.

1.3 National guidelines and standards

WSAA"s new Sewerage and Water Reticulation Codes of Australia, published in July 1999 and January 2000 respectively, provide technical guidelines for planners, designers and constructors servicing the land development industry or undertaking contract work on behalf of the water companies. Whilst adopting many performance requirements, the first editions essentially provide a deemed-to-comply solution to the planning, design and construction, and rely on additional information from local water agencies. These codes were prepared by a working party comprising representatives from all the Major Water Authorities, including ACTEW Corporation, based on the individual Authorities" Standards.

ACTEW"s Water Supply and Sewerage Standards (AWSSS) as contained in this release have been reviewed with the aim of national standardisation with the WSAA Codes. It is ACTEW"s intention to adopt these Codes within 2 years, with the next release of our Standards containing exceptions to the WSAA National Codes only.

The AWSSS contains a number of references to third party technical documents and Australian Standards. These documents deal in detail with materials, manufacturing, testing and installation. Design agents will need to maintain access to the latest edition of these references.

1.4 Terminology

In general the term "should" is used in reference to design practices, where it is expected that design engineers would exercise professional judgement in deciding instances where they may wish to depart from the standard practice parameters. Designers would be expected to be able to justify such departures in terms of cost savings and improved engineering performance.

The term "shall" is used in reference to standardised designs or methods that will not normally be departed from, and then only after specific approval has been obtained from ACTEW for a particular case.

The term "approval" shall be interpreted as "acceptance". All approvals given are subject to technical compliance with this document unless otherwise noted by ACTEW.

A definition of terms used throughout the various parts of this document can be referenced in Appendix A of the Asset Creation Approval Processes section.

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2. Design responsibilities

The layout and sizing of distribution and reticulation systems within a proposed development cannot be viewed in isolation, treating only the area under development. Mains within any development area shall be designed to be consistent with the optimum design for the broader Water Supply and Sewerage Systems as shown on the ACTEW provided strategy plan. The Water Supply and Sewerage Strategy Plans depict a concept for the overall servicing of the area, and show trunk mains, existing and proposed service reservoirs, pressure zones, pump stations, ventilation stations, and overflow storage tanks and/or treatment plants, as relevant.

No designer or developer can be expected to hold the knowledge required to co-ordinate this task, so for this purpose, ACTEW will nominate limiting or special conditions and supply parameters into and out of any parcel of land and/or interdependent distribution mains.

Any future extension of the system shall be accommodated in the reticulation design. Where mains in a particular development are to be extended to other developments in the future, the ends of these mains shall extend to the far boundary of the development to ensure future extension of the main does not require unnecessary excavation in areas already developed.

Design loads on all structures and members shall be made to comply with the minimum design requirements of AS 1170.

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3. Land ownership issues

3.1 Land ownership — Public land and private leases

All land within the ACT (except for Commonwealth land) is owned by the ACT Government. The ACT Government may lease land to a lessee who then has control and responsibility for maintenance and further development of this land.

Where land is being developed, works should be designed with the aim that no water and sewerage assets are constructed through land to be leased. Where this cannot be achieved, and water and sewerage assets must be located on leased land, they should be located so that access can readily be achieved, and restrictions on the use of the land (imposed by the presence of the service) can be minimised.

It is preferable that no water and sewerage asset be constructed through land already leased. Where works are intended to be constructed through such land the designer shall refer the intention to ACTEW for approval.

Where a proposed development abuts land which has the potential to be developed, the possibility of a shared water and sewerage asset exists. As it is desirable to size a single service for the full duty rather than to maintain unnecessary parallel services, the designer shall refer any intended water and sewerage assets along the boundary between leased and unleased land to ACTEW for co-ordination. Water and sewerage mains shall wherever possible be located in public land rather than in leased land.

3.2 Easements

While an easement (sewerage or water main reserve within leased property) is not the preferred location for water and sewer mains, it is sometimes necessary to create an easement to ensure that the sewer or water main is protected and can be maintained (should they be located anywhere other than in the road reserve).

Designers should be aware of the restrictions which easements place on a lease. Layouts and alignments shall be arranged to minimise the need for such reserves. Easements shall be sized to include the zone of influence of the trench for the main, shall have sufficient width to minimise the risk of consequential damage in the event of a mains failure, and shall provide sufficient width for access of construction or maintenance machinery.

Locations requiring easements for mains are private properties, public reserves, government reserves, other government owned land, private roads or accessways in both conventional and community title subdivisions, rights of way and rights of carriageway.

The designer shall advise ACTEW via appropriate design submissions of land take requirements for the hydraulic systems. The easement shall provide rights of occupation and ensure suitable conditions for operation (including drainage) and access by ACTEW.

Construction of works in the vicinity of ACTEW easements should be brought to the attention of ACTEW for consideration and, if necessary, setting of specific site requirements.

Earth cover over sewerage pipes within easements shall not be reduced without prior approval of ACTEW. Under no circumstances shall any structure be constructed nor any decrease of earth cover be undertaken within an ACTEW water supply easement.

Major permanent structures shall not be permitted within easements. These include new dwellings, extensions, and lockable structures including garages, storerooms, tool sheds or glass houses. Swimming pools and supports of decks, balconies and building overhangs will also not be permitted within easements.

Non-demountable and demountable car ports, retaining walls, masonry screen walls, and concrete slabs may be permitted near or within easements. ACTEW should be consulted for requirements associated with these structures.

All structures proposed to be constructed near or in easements are subject to easement clearance by ACTEW. Applications to infringe ACTEW easements shall be accompanied by the completed standard form Application to Infringe an ACTEW Easement.

3.3 The rights of other authorities

When the construction of a sewer or water main is to be located within close proximity of other services, the designer shall ensure that the relevant authority is advised. Agreed standard alignments are as shown on Road Verge Drawings — Drawing Nos. SEP4 — 01 to 06, Chapter 4 (Road Verges) (Reference 9.2).

Water mains and sewers shall be designed so that maintenance activities can be performed without the risk of inadvertent damage to other utilities.

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4. Landscape requirements

Landscape requirements contained within this standard are provided to ensure enhancement of an area, and specify that tree planting shall not result in tree root intrusion problems into sewers or interference with water mains.

4.1 Landscape survey

A landscape survey of the proposed area of construction disturbance shall be made. Trees requiring special consideration shall be identified and methods of preservation determined.

4.2 Clearances and trees

No tree shall be planted within 2.0 metres of a water main or within 3.0 metres of a sewer main except for some special street tree planting as shown on Road Verge Drawings — Drawing Nos. SEP4 — 01 to 06, Chapter 4 (Road Verges) (Reference 9.2). No vigorous rooting tree species shall be planted within 10.0 metres of a sewer main (e.g. poplar, willow or elm). Consideration is to be given to the use of an alternative alignment where a sewer is proposed to pass near or under existing mature trees. ACTEW provides a list of preferred tree species to be planted near mains in the brochure entitled Sewer Blockages — a detailed guide for licensed drainers and the householder (Reference 9.7). An extract taken from the brochure is included in the Asset Creation Approval Processes (Appendix N).

4.3 Design

The design is to take into account and be part of the overall Land Development Landscape Design and should allow for future changes in landscaping.

4.4 Restoration

Backfilling shall provide topsoil at the surface. Compaction of backfill shall provide for even running surface grades in the future landscape. Special care in restoration is needed on highly visible sites.

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5. Pollution controls associated with construction

A list of relevant ACT Environment Protection Legislation that needs to be taken into account when designing water supply and sewerage systems is given below:

• Aboriginal and Torres Strait Islander Heritage Protection Act 1984 (Cth)
• Building Act 1972 (ACT)
• Environment Protection and Biodiversity Conservation Act 1999 (Cth)
• Environment Protection Act 1997 (ACT)
• Environment Protection Regulations 1997 (ACT)
• Heritage Objects Act 1991 (ACT)
• Land (Planning and Environment) Act 1991 (ACT)
• Land (Planning and Environment) Regulations 1991 (ACT)
• Litter Act 1977 (ACT)
• Nature Conservation Act 1980 (ACT)
• Public Health Regulations 2000 (ACT)
• Public Health Act 1997 (ACT)
• Territory Owned Corporations Act 1990 (ACT)
• Utilities Act 2000 (ACT)
• Water and Sewerage Act 2000 (ACT)
• Water and Sewerage Regulations 2001 (ACT)
• Water Resources Act 1998 (ACT)

The ACT Environment Protection Act (1997) requires that all discharge of wastes to the waters of the ACT be licensed. The Act regards sediment from the disturbances of land as a waste.

Guidance for the preparation of erosion and sediment control strategies are available from the Environment ACT (see References 9.3, 9.4 and 9.5).

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6. Specifications

The ACT Public Works Basic Specification (Reference 9.1), together with the associated Users Guide for the Basic Specification produced by Totalcare Industries Ltd is to be used for all new works which are intended to be incorporated into ACTEW"s water supply and sewerage systems.

The designer should be aware of the content and limitations of the Basic Specification, and where design requirements deviate from, or are in excess of those of the Basic Specification, such requirements are to be included in technical exception clauses to the Basic Specification.

The requirements contained within ACTEW"s Water Supply and Sewerage Standards take precedence over the requirements of the Basic Specification where discrepancies occur between the two documents.

Any difficulties or inconsistencies arising out of the use of the Water Supply and Sewerage Standards and the Basic Specification shall be referred to ACTEW for resolution.

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7. Temporary water supply for construction purposes

A contractor engaged in development works may request the provision of a temporary water supply for construction purposes. This would normally be in the form of an overhead filling point for road tankers.

A contractor requiring such a temporary water supply is required to make an application in writing to ACTEW stating details of the contract, the estimated quantity of water required, the preferred location for the filling point, and the time during which the filling point is required. The contractor will be required to pay ACTEW for the cost of installing the overhead filling point, and for removing it at the end of the contract.

The contractor will also be charged separately by ACTEW for the water used, which will be metered.

In the case of a contract for a subdivisional development a contractor may request a temporary water supply connection to a part or whole of the water supply reticulation system in a suburb, prior to its final completion and handover. Submission of this request, and payment for the temporary connection and the estimated quantity of water to be used, shall be made in the same manner as described above for an overhead filling point.

The temporary connection will incorporate a reflux valve to prevent backflow from the division into the existing reticulation system, and a hand-wheel operated valve for the contractors control. A meter may be included in this connection. The contractor may install an overhead standpipe for the filling of tankers downstream of the wheeled valve.

In an emergency, it may be necessary for ACTEW to restrict or shut off flow through the temporary connection to maintain supply to domestic consumers.

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8. Standard drawings

Road Verge Drawings — Drawing Nos. SEP4 — 01 to 06, Chapter 4 (Road Verges) (Reference 9.2)

9. References

9.1	Totalcare document, ACT Public Works "Basic Specification — Roads, Hydraulic Services and Landscape", Edition No 1 (July 1991) as amended (including in particular Corrigendum No 1 to Volume 1, 11 December 1992) plus the associated "Users Guide for the Basic Specification".
9.2	Roads and Transport Section, ACT Department of Urban Services, "Standard Engineering Practices — Roads and Bridges", Draft No 5, 5 November 1995.
9.3	ACT Administration and NCDC, ACT (1988), "Guidelines for Urban Erosion and Sediment Controls"(Interim Manual) (available from the Environment ACT).
9.4	ACT Administration, Environment Protection Section, ACT (1989), "Guidelines on Erosion and Sediment Control on Building Sites" (available from the Environment ACT).
9.5	Enviroment ACT, ACT (1998), "Erosion and Sediment Control During Land Development".
9.6	"Water and Sewerage Regulations 2001" (ACT) and the "Water and Sewerage Act 2000" (ACT) (having replaced the "Canberra Sewerage and Water Supply Regulations 1999").
9.7	Water Division, ACTEW Corporation, ACT (1999), "Sewer Blockages — a detailed guide for licensed drainers and the householder".

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