ALEXANDRINA COUNCIL
Community Wastewater Management System (CWMS) Standards
Installation of Allotment Connections and Gravity Drain Extensions.
Household Connections and Minor Land Divisions.
Revision January 2016.
Craig Ostigh & Gary Lyons
Engineering & Environment
Community Wastewater Management System Standards
CONTENTS
SECTION 1 – COMMUNITY WASTEWATER MANAGEMENT SYSTEMS OVERVIEW ............................................. 3
1.1
What is a CWMS ? ......................................................................................................................... 3
1.2
Wastewater Schemes operated by the Alexandrina Council .......................................................... 3
1.3
Connection Standards ..................................................................................................................... 3
1.4
Private Pumping Sumps ................................................................................................................. 3
1.5
Process for Connection to a CWMS............................................................................................... 4
1.6
Vacuum Sewer …………………………………………………………………………………….4
1.7
Fees & Payments…………………………………………………………………………………..4
1.8
Information relating to Household Waste Control Systems........................................................... 4
1.9
Information relating to the connection to a CWMS ....................................................................... 4
SECTION 2 – CONSTRUCTION OF ALLOTMENT CONNECTIONS.......................................................................... 5
2.1
Allotment Connection Standards.................................................................................................... 5
2.2
Inspection Point Suppliers .............................................................................................................. 7
SECTION 3 – INSTALLATION OF NEW GRAVITY DRAINS ................................................................................... 8
3.1
Pipe Materials ................................................................................................................................. 8
3.2
Pipe Bedding .................................................................................................................................. 8
3.3
Pipe Laying..................................................................................................................................... 8
3.4
Trench Base Stabilisation ............................................................................................................... 8
3.5
Trenching along Footpath Reserves ............................................................................................... 8
3.6
Trenching Across Sealed Road Pavements .................................................................................... 9
3.7
Gravity Drain Alignment................................................................................................................ 9
3.8
Re-instatement of Roadways or Footpaths..................................................................................... 9
3.9
Testing of Gravitational Drains .................................................................................................... 10
3.10 Flushing of Gravity Drains ........................................................................................................... 10
SECTION 4 – INSTALLATION OF FLUSHING POINTS ........................................................................................ 11
4.1
Purpose of Flushing Points ........................................................................................................... 11
4.2
Flushing Point Standards .............................................................................................................. 11
4.3
Flushing Point Support Blocks ..................................................................................................... 11
4.4
Flushing Point Suppliers .............................................................................................................. 12
SECTION 5 – PRIVATE PUMPING SUMPS ......................................................................................................... 13
5.1
Installation and use of Private Pumping Sumps ........................................................................... 13
SECTION 6 – PROHIBITED OR RESTRICTED DISCHARGES................................................................................ 14
6.1
Release of a Prohibited or Restricted Substance into a CWMS ................................................... 14
6.2
Prohibited Substances................................................................................................................... 14
6.3
Restricted Substances ................................................................................................................... 14
6.4
Restricted Discharge Connection Requirements .......................................................................... 14
6.5
Prosecution ................................................................................................................................... 14
6.6
Grease Arrestors ........................................................................................................................... 14
SECTION 7 – Surveyed AS-CONSTRUCTED DRAWINGS .................................................................................. 15
7.1
Submission of Surveyed As-Constructed Drawings .................................................................... 15
SECTION 8 – LAND DIVISION CONTOUR PLAN REQUIREMENTS ............................................................................. 16
8.1
Minor Land Division Contour Plan Requirements....................................................................... 16
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Community Wastewater Management System Standards
SECTION 1 – COMMUNITY WASTEWATER MANAGEMENT SYSTEMS OVERVIEW
1.1
1.2
What is a CWMS ?
A reticulated Community Wastewater Management System (CWMS) provides for the collection and
carriage of septic tank effluent or sewerage by either gravity flow or by pumping either with positive or
negative pressures (vacuum), to a treatment facility that is owned, operated and maintained by the local
Council, or another agency.
Currently in SA the most common reticulated CWMS is a STEDS (Septic Tank Effluent Disposal
Scheme). These schemes comprise a gravity collection system and generally provide a connection to
each property at a depth to allow connection of the property wastewater system by gravity and may
receive the discharge from a septic tank and/or a greywater treatment tank or other approved treatment
process on the property.
Wastewater Schemes operated by the Alexandrina Council
Alexandrina Council currently owns and operates six CWMS schemes in Goolwa, Port Elliot,
Milang, Mount Compass and Strathalbyn.
Alexandrina Council staff members maintain the gravity drainage network within the road reserve,
easements and also maintain each property’s allotment connection up to the property boundary. Within
each property the ownership and maintenance of the internal drains and septic tank are the responsibility
of the land owner.
1.3
1.4
Where a sewerage scheme is under the care and control of the South Australian Water Corporation and
is situated in a proclaimed drainage area pursuant to the Sewerage Act, this document does not apply.
Connection Standards
Any new connections or extensions to the CWMS must comply with Council’s standards and guidelines
to ensure Council takes responsibility for an efficient and trouble free drainage network. To guarantee a
high standard is achieved, Alexandrina Council now requires a greater amount of information about a
proposed connection before any construction is to commence. All drainage infrastructure must also be
inspected prior to backfilling. Surveyed As-Constructed plans of each new connection and extension of
the drainage network are now compulsory to enable Council to keep up to date electronic mapping and
records of the network. This in turn enables Council officers to provide a more efficient and accurate
service to private contractors when trying to locate property connections & infrastructure.
A formal review of the standards document is undertaken every two years. However the standards may
be reviewed at any stage to ensure technical currency. Please check the council website and download
the latest version.
Private Pumping Sumps
Council does not allow the installation of private pumping sumps to ‘pump-up’ to an allotment
connection. In the instance of a new house to be constructed and connected to a CWMS, the plumbing
contractor must firstly ensure that sufficient fall exists to enable the outlet of the septic tank to drain by
gravity to the allotment connection. In some cases it may be necessary to fill the block to ensure gravity
drainage is possible.
It is the plumbing contractor’s responsibility to firstly determine the height difference between the
proposed septic tank and existing gravity drain or allotment connection before proceeding with the
installation of underfloor plumbing, perimeter drains or septic tank.
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1.5
Process for Connection to a CWMS
Prior to connecting a property to the CWMS a Licenced Surveyor or Licenced Plumbing Contractor
must contact Council to ascertain if a connection is possible or if there are any special requirements in
relation to the connection.
In the case of an existing residence or minor land division wishing to connect to the CWMS the process
is as follows:
1.
Licenced Surveyor or Licenced Plumbing Contractor to contact Council’s Technical Officer on
(08) 8555 7000 or via [email protected] during normal office hours.
2.
A Council Officer will undertake a site inspection to determine the suitability of property to
connect to the CWMS. If it is questionable that the property can connect to the CWMS using
gravity drainage, Council will require contour or level information from a Licenced Surveyor to
prove that minimum drainage gradients can be achieved.
3.
Pending suitability of site, Council will issue approval for connection to the CWMS. Council
Officer will require the plumbing contractor to provide details on how they intend on servicing the
proposed allotment/allotments and the most suitable location of the connection and route of any
gravity drains (if required).
4.
Upon Developer being granted approval and Conditions of Approval being set the Contractor can
now undertake construction of the allotment connection and drain extension (as required).
5.
On completion of work, plumbing contractor must book an inspection with Alexandrina
Council’s CWMS Planning and Assets Coordinator giving at least 48 hours’ notice. At the request
of Council representative all trenches must be left open for inspection.
6.
Within 14 days of the construction the plumbing contractor must submit a Surveyed
As-Constructed plan to Council’s CWMS Planning and Assets Coordinator of the installation.
Failure to do so will result in delays for the Developers Section 51 request.
7.
Pending a satisfactory inspection and receipt of Surveyed As-Constructed plans, Council will issue
approval of the installation to the plumbing contractor and/or Developer.
Failure by the plumbing contractor to book an inspection and submit a surveyed as-constructed plan will
result in council not issuing final approval for the installation. In the case of minor land divisions this
will prevent the developer from gaining approval of the land division, which in turn will prevent the
issuing of titles for any new allotments which are created.
1.6
In the case of a new connection to an existing property, failure to book inspections and lodge surveyed
As-Constructed plans will delay or possibly halt any subsequent applications received from the
particular plumbing contractor.
Vacuum Sewer
Process for connection into the Vacuum Sewerage System.
1. Developer will be required to have undertaken preliminary concept plans (by an accredited Vacuum
Sewerage Design Consultant/Engineering Company) and forward them to Alexandrina Councils CWMS
Assets Coordinator for assessment.
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2. Upon satisfactory assessment , Developer will be required to forward a full set of construction drawings
to Alexandrina Councils CWMS Assets Coordinator, these drawings will need to be Certified by an
Accredited Vacuum Sewerage Design Consultant/ Engineering Company or by Flovac Australia prior to
any works. These drawings will be requested in the Decision Notification Form.
3. All infrastructure upgrades will be at Developers cost.
4. All Infrastructure upgrades must be undertaken by Civil Contractors with Vacuum Sewerage Installation
Certificates. ( Certificate must be provided to Alexandrina Councils CWMS assets Coordinator prior to
works beginning. Contractor must also hold a current Drain layers Certificate and/or Licenced Plumber.
5. Prior to any Sec 51 Clearance there maybe be other conditions that are placed on the Decision
Notification Form that will need to be adhered to prior to Sec 51 being granted.
1.7
1.8
1.9
Fees & Charges
An annual service fee is attributed to all CWMS connections. All new property units and developments
are required to pay a connection fee. This levy is utilised for the ongoing maintenance and upgrade of
the expanding CWMS system. Fees and charges are adjusted each financial year and are available on the
Council Website.
To estimate your development property unit value for calculating the total service and connection fee
costs, please refer to the LGA Property Units Code for CWMS.
http://www.lga.sa.gov.au/page.aspx?u=1116
Information relating to Household Waste Control Systems
For any information relating to the installation of septic tanks, aerobic systems or household treatment
systems please contact Council’s Environmental Health Officers, on (08) 8555 7000.
Information relating to the connection to a CWMS
For any information relating to the installation of a new allotment connection or the extension to the
gravity drainage network please contact Council’s CWMS Planning and Assets Coordinator at
[email protected].
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SECTION 2 – CONSTRUCTION OF ALLOTMENT CONNECTIONS
2.1
Allotment Connection Standards
An allotment connection shall be provided (by the developer or plumbing contractor) at the lowest point
of each allotment and at a sufficient depth (min. 1000mm) to serve the entire allotment.
The minimum size of all allotment connections off a main drain shall be 100mm diameter. Allotment
connections shall be laid at a minimum grade of 1% and have sufficient depth (min. 1000mm) to allow
connection of a septic tank or sewerage system on the property to the allotment connection point by
gravity flow. The minimum depth of all connections shall be 1 metre.
The horizontal alignment of the allotment connection shall be 1.0 – 1.5 metres offset from the side
boundary of the allotment. In the case of the allotment connection providing a service to another
property via an easement, the allotment connection shall be 1.5 metres offset from the adjoining
boundary.
Each allotment connection shall have an inspection opening consisting of a 100mm diameter
vertical riser situated on the road reserve immediately adjacent to the front property boundary. The
inspection opening shall be raised to the surface and sealed with a screw threaded access cap.
The inspection opening cover shall consist of a cast iron lid incorporating a lifting keyhole with concrete
surround with the word “SEWER” clearly marked on the metal lid. All cast iron covers shall be
provided with a corrosion inhibiting coating to all surfaces. Septic tank / household style concrete IO
covers are not acceptable.
The inspection opening cover shall rest on two hardwood support rails of a minimum dimension of
50mm wide x 100mm deep x 600mm long. The rails should in turn rest on a bed of rubble or quarry sand
of a minimum 200mm in depth. Positioning the inspection opening cover on soil is not
satisfactory. If an Inspection Opening is positioned within a driveway, a 600mm x 600mm x 100mm
thick concrete support block MUST be installed underneath the concrete surround in lieu of the
hardwood support rails – please contact Council for further information if required.
When constructed the concrete inspection opening cover shall be installed so that no weight is
transmitted to the uPVC riser. All allotment connection drains shall be extended from the main drain
junction to 1000mm inside the property boundary of the allotment being served by the connection.
Diagram 2.1 – Inspection Opening Details
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Diagram 2.2 – Positioning of allotment connections relative to property boundaries
Diagram 2.3 – Positioning of allotment connections within easements
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Diagram 2.4: Connection to the gravity main.
Existing main
Expander Joint


New tee connection/
extension to main




Flow
Works to be completed by Licenced Plumber.
Plumber to complete and have appropriate council
approvals.
All materials must be SA Water approved for wastewater.
Prior to cutting into main, plumber must have all required
materials to ensure disturbance is minimised.
Must manage all requirements for existing effluent flows.
Install expander joint, tee and flushing points in accordance
with Council and manufacturers requirements.
Diagram 2.5: Connection design.
LOT 1
LOT 2
LOT 3
>5m
LOT 4
Gravity Main
Where connection exceeds 5m, a new
direct connection to the main is required.
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2.2
Inspection Point Suppliers
Approved Inspection Opening covers and frames are available from:
Cooke Precast Concrete Pty Ltd
3 Peachey Road
Edinburgh North, South Australia 5113
(08) 8209 3093
RI Industries
618 South Road,
Angle Park SA 5010
(08) 8444 8100
Bianco PCP
183 South Terrace
Wingfield SA 5013
(08) 8444 7555
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SECTION 3 – INSTALLATION OF NEW GRAVITY DRAINS
3.1
3.2
3.3
3.4
3.5
Pipe Materials
Pipes and fittings shall be of uPVC (Unplasticised Polyvinyl Chloride) Class DWV, plain/solid wall
complying with AS1260. Pipe ends shall be formed for solvent welded joints.
Pipe Bedding
Gravity drains shall be bedded on non-plastic sand suitable to provide a sound, compact and continuous
base to support the pipe at the required gradient. The sand shall be free from clay lumps, stones, organic
material, or other deleterious matter including noxious weeds and shall be of such quality as to be
capable of being wetted to achieve proper and adequate compaction to the specified standards.
Where naturally occurring dry conditions are found to exist in the trench, drains shall be laid on a sand
bedding not exceeding 75mm in thickness. Where ground water is encountered, a bed of 100mm course
aggregate (screenings) is to be used.
Pipe Laying
Gravity drains shall be laid at a minimum gradient of 1%. When cutting in to an existing drain,
expansion couplings of an approved standard are to be used.
The use of ‘Aussie Couplings’ is not permitted. Solvent cement shall be coloured, suitable for use with
rigid uPVC pipe and applied in accordance with the manufacturer’s directions. Solvent cement is to be
of the slow setting type unless otherwise approved. Compatible cleaning fluid of a distinctively different
colour to the solvent cement shall be used in accordance with the manufacturer’s directions.
Trench Base Stabilisation
If in the opinion of Council’s representative, the condition of the trench is such as to indicate that
stabilisation of the base is necessary to provide adequate support for the drain, the trench shall be overexcavated to 450mm below normal bed level. A layer of geotextile fabric shall then be placed on the
base of the trench extending 450mm up the sides of the trench. This shall be followed by a layer of
cement treated quarry rubble which shall be tamped with the excavator bucket and levelled to provide a
uniformly graded sub-base 450mm thick, on which the bedding of screenings shall be placed as
specified in Section 3.2.
Trenching along Footpath Reserves
Approval must be granted to undertake any trenching or excavations across Council’s or relevant
authority’s footpaths and forwarded to Council's CWMS Planning and Assets Coordinator prior to start.
Forms for this can be found on Councils Website.
If a gravity drain is constructed in a footpath area (not crossing a road) or easement through private
property, the trench is to be filled a minimum of 300mm above the top of the pipe with screened sand.
The sand shall be spread uniformly over the length and width of the trench and compacted using hand
compaction tools or by flooding to the satisfaction of Council’s representative. The remainder of the
trench shall consist of ordinary fill, uniformly compacted in horizontal layers of 300mm loose thickness
to not less than 90% of the maximum dry density to 100mm below the finished surface level. The top
100mm of the trench shall be backfilled with clean topsoil to 20mm above the natural surface level. The
footpath area is to be re-instated to the condition encountered before the commencement of excavation.
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3.6
Trenching Across Sealed Road Pavements
Approval must be granted to undertake any trenching or excavations across Councils or other
relevant authorities Road Pavements by the relevant authority and forwarded to Councils CWMS
Coordinator prior to start. Forms for this can be found on Council’s Website.
Where the contractor is required to trench across an existing sealed road the contractor shall cut the
bitumised surface with a carborundum or other approved type of mechanical saw prior to trench
excavation.
The saw cut shall be made to the full depth of the bitumen surface. The contractor shall make two
parallel cuts at a width of 400mm wider than the intended trench excavation. The trench shall be
excavated centrally within the saw cuts.
The trench across the road pavement is to be filled with screened sand up to a minimum of 300mm from
the road surface and compacted in 200mm layers to a minimum of 95% of the maximum dry density.
The top 300mm of the trench is to be filled with 20mm quarry rubble and compacted in 100mm layers
to a minimum of 98% of the maximum dry density. The trench across the road should be slightly proud
of the existing surface to allow for subsidence of the trench.
3.7
Following excavation across a Council roadway, the licensed plumbing contractor or licensed pipe layer
is to engage the services of an accredited sealing contractor and have all works reinstated with Bitumen
Hotmix to a satisfactory condition (failure to do so will result in delays for the Developer seeking
Section 51). Council may wish to engage a contractor to undertake the outstanding works and forward
all costs onto the plumbing contractor or pipe layer.
Gravity Drain Alignment
Gravity drains shall generally run at an offset of 1.5 metres from the front property boundary. When
connecting into an existing gravity drain, the contractor shall maintain the same offset for the new drain
as the existing gravity drain.
Common trenching for Power or Telstra is not permitted. Common trenching for effluent drains and
minor water services is permitted, with a minimum of 300mm physical separation between the pipes.
Depending on adjacent services increased separation may be requested at the discretion of the CMWS
Planning and Assets Coordinator. (For trenching specifications for SA Water mains please refer to the
SA Water - Water Supply Construction Manual).
The minimum cover over any gravity drain shall be:
Within private allotments or easements:
Within footpath reserve:
Within roadways or road crossings:
0.6m to top of pipe
0.6m to top of pipe
0.9m to top of pipe
Where the above minimum covers cannot be achieved consideration may be given to special designs
where specifically approved by Council.
Where an effluent drain shares an easement with a stormwater drain the minimum easement width shall
be 4.0 metres. Where an effluent drain only occupies an easement the minimum width of the easement
shall be 3.0 metres.
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3.8
Gravity drains shall generally traverse kerb and channel alignments at 90 degrees.
Re-instatement of Roadways or Footpaths.
Damage to any roadway or footpath during the construction of the gravity drain shall be made good at
the contractor’s expense, to the satisfaction of Council’s representative. Any paved surfaces, bitumen,
kerb, stormwater pits, fencing or concrete footpaths shall be reinstated to the original condition at the
contractor’s expense to the satisfaction of Council’s representative.
Reinstatement of council’s infrastructure is to occur within two weeks of job completion.
Diagram 3.1 – Typical Pipe and Trench Layout.
0.6 – 0.9m cover over gravity pipe.
Pipe located centrally with a constant grade. Uneven trenches are not acceptable.
Roadway or Footpath to be reinstated to Council standards.
Selected spoil backfill. Compact to 90% standard maximum dry
density. In layers not exceeding 300mm
Sand backfill to a min 300mm above pipe. Compact for pipe support.
uPVC Class DWV. Plan solid wall complying with AS1260. Gradient >= 1%
75 – 100mm Bedding, non-plastic sand, free from foreign matter.
Stabilisation may be required, refer to 3.4.
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3.9
Testing of Gravitational Drains
Council may require a gravity drain laid by a contractor to be air tested. Any drain or extension
exceeding 50m in length will automatically require testing and witnessing by a Council officer.
The Contractor shall supply all equipment and labour necessary for the pneumatic testing of the drains
as follows:





3.10
The maximum length of gravity drain to be tested at any one time shall not exceed
300m.
Testing equipment shall include a glass faced clock type pressure gauge at least 75mm
in diameter calibrated 0 to 100 kilopascals.
The Contractor shall apply the test to the drain after all backfilling and compaction
procedures are completed and all top stones and cover slabs are positioned. Allotment
connections shall be installed before the testing of the gravity drain.
The Contractor shall provide airtight seals to all openings in the drain to be tested. Air
shall be slowly introduced through a specially prepared bung until a pressure of 50
kilopascals is obtained.
The air supply shall be cut off, and providing the pressure in the drain being tested
does not fall below 40 kilopascals within 15 minutes of the air supply being turned off,
the section of drain being tested will be considered satisfactory.
If the pressure is not maintained within the specified limits the Contractor shall determine the source of
the leak(s) and rectify any problems to the satisfaction of the Council officer.
Flushing of Gravity Drains
The contractor is required to flush the gravity drain to remove sand or debris that may have accumulated
in the drain during construction. Flushing of the drain will be done with clean water and shall be at the
expense of the contractor.
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SECTION 4 – INSTALLATION OF FLUSHING POINTS
4.1
4.2
4.3
Purpose of Flushing Points
Alexandrina Council staff members use flushing points to routinely clean gravity drains using a high
pressure jetting trailer. Flushing points are usually located at regular intervals along a pipeline’s length
and at the downstream end of each pipe segment, to allow Council staff members to insert a jet rodding
spinner head at the downstream end and drag back any slime and debris that has accumulated in the
gravity drain.
Flushing Point Standards
The contractor shall install flushing points along gravity drains at a minimum of 50 metre spacing, at
the downstream end of each pipe segment or at other positions as specified by Council’s representative.
Each flushing point shall consist of a 150mm diameter vertical riser situated along the main drain. The
flushing point shall be raised to the surface and sealed with a screw threaded access cap.
The flushing point cover shall consist of a cast iron lid incorporating a lifting keyhole with concrete
surround with the word “SEWER” clearly marked on the metal lid. All cast iron covers shall be
provided with a corrosion inhibiting coating to all surfaces. When constructed the concrete flushing
point cover shall be installed so that no weight is transmitted to the uPVC riser.
Flushing Point Support Blocks
The flushing point lid is to rest on a type 2 concrete support block with a minimum dimension of 600mm
x 600mm x 100mm thick. Flushing point support blocks are to be installed where a flushing point is located
within a road reserve or drainage easement.
Diagram 4.1 – Flushing Point Details
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4.4
Flushing Point Suppliers
Approved Flushing Point covers, frames and support blocks are available from:
Cooke Precast Concrete Pty Ltd
3 Peachey Road
Edinburgh North, South Australia 5113
(08) 8209 3093
RI Industries
618 South Road,
Angle Park SA 5010
(08) 8444 8100
Bianco PCP
183 South Terrace
Wingfield SA 5013
(08) 8444 7555
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SECTION 5 – PRIVATE PUMPING SUMPS
5.1
Installation and use of Private Pumping Sumps
In NO instance is a contractor to install a private pump and sump to enable a residence to connect to a
Community Wastewater Management Scheme. Filling of the block should be considered to allow
sufficient height between the septic tank or sewer drains servicing the property and the gravity drain
situated in the road reserve.
To ensure there is adequate fall available the contractor should employ the services of an engineering
surveyor or competent person to determine the height difference between the proposed residence and the
existing gravity drain BEFORE the commencement of underfloor plumbing or the pouring of the house
slab.
The unauthorized installation of a pumping sump will result in Council not granting approval for the
residence to connect to the CWMS scheme. The installation of a pumping sump will halt the approval of
a development application proposing to connect to the CWMS.
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SECTION 6 – PROHIBITED OR RESTRICTED DISCHARGES
6.1
6.2
Release of a Prohibited or Restricted Substance into a CWMS
The following prohibited substances are not permitted to be discharged into the reticulated CWMS,
whereas a restricted substance may be permitted at the discretion of the Alexandrina Council and
subject to strict installation and operating conditions.
Prohibited Substances


6.3



6.5
6.6
Any disinfectant, or similar or other product or substance that will impact on the efficient operation
of the reticulated CWMS
Restricted Substances

6.4
Any stormwater, including roof catchment waters and rainwater tank overflows, ground surface and
subsurface drainage or seepage waters.
Any backwash and or drainage waters from a spa bath in excess of 860 litres, or a spa pool or a
swimming pool.
Any pressure relief or safety valve release from a hot water service (excluding domestic
dwellings)or boiler or pressure vessel.
Any process wastewater, or wash down water, or other backwash or drainage waters (excluding
domestic dwelling water softeners).
Effluent and wastewater from a commercial premise utilising commercial kitchens. (See Section 6.6
- Grease Arrestors).
Restricted Discharge Connection Requirements
Where restricted discharges indicated above are permitted, Council may impose additional connection
requirements and or charges to recover the increased operational costs associated with the increased
quantity and or quality of the discharge.
In some cases Council may impose additional requirements for restricted discharges, such as flow
balancing and treatment tanks, or time and controlled discharge flow rates to prevent surcharge into the
reticulated CWMS and subsequent overloading of downstream drain lines and pump stations. In some
cases such as commercial premises it may be necessary to control the temperature of restricted
discharges.
Prosecution
Persons illegally discharging prohibited substances to the CWMS or exceeding set restricted discharge
requirements as defined by quantity or quality parameters are liable for prosecution and recovery of
costs for any maintenance and damage to the reticulated CWMS as a result of the illegal or excessive
discharge.
Grease Arrestors
Commercial kitchens, restaurants or premises preparing food products will be required to install
a grease arrestor prior to entry into a septic tank. The size of the grease arrester will be in accordance
with SA Water standards. The installation of grease arrestors is the subject of a separate approval
process. For any enquires please contact Council’s Environmental Health Officer on 8555 7000.
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SECTION 7 – SURVEYED AS-CONSTRUCTED DRAWINGS
7.1
Submission of Licenced Surveyor As-Constructed Drawings
Prior to section 51 being granted the completion of an allotment connection or extension to the gravity
drainage network, the plumbing contractor is to lodge at the Council offices, a Surveyed As-Constructed
plan of the installation. The plan is to show the location of the existing gravity drain, the location
and offset distance of any new allotment connection(s) from the closest side boundary and also the
measured depth of the connection.
Where connection to the CWMS involves the extension of an existing gravity drain, the Surveyed AsConstructed plan is to also show the offset of the new drain from the nearest property boundary, the
location and measurements of any flushing points installed and the gradient of the installed drain.
All details such as the date of installation, plumbing contractors name and contact phone number, site
address and development application number (if known) are to be filled out. Failure to lodge an
acceptable Surveyed As-Constructed plan will result in delays of the final approval being granted.
CWMS Alexandrina Community Wastewater Management Standards v1.4 160421.docx
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Community Wastewater Management System Standards
SECTION 8 – LAND DIVISION CONTOUR PLAN REQUIREMENTS
8.1
Minor Land Division Contour Plan Requirements
To enable Council staff to assess the suitability of a proposed land division to connect to a CWMS,
the developer is required to lodge an engineering contour plan, undertaken by a qualified surveyor
or engineer, of the proposed development site prior to Council giving approval for the development
to connect to a wastewater scheme.
The contour plan shall cover the entire proposed development site and also include the location and
invert level of the closest allotment connection or gravity drain. Where a significant extension of the
gravity drain is to occur, surface levels are to be taken along the route of the proposed gravity drain
extension in conjunction with the engineering contour plan of the development site.
Engineering Contour plans shall consist of:
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A site plan, drawn at a scale of not less than 1:500.
The boundaries and dimensions of the site with any relevant easements plotted.
The outline and accurate location of any existing buildings or permanent structures.
The location of any existing septic tank(s) and internal gravity drains.
Contour lines across the site at a maximum interval of 0.1 metres. Levels and location of
features on site are to be recorded with accurate surveying equipment such as an electronic total
station.
The position and dimensions of any proposed building and its relationship to the boundaries of
the site.
The floor level(s) of any proposed building(s).
The location and invert level of any existing allotment connection(s). In the absence of an allotment
connection the engineering contour plan shall show the location and invert level of the closest
gravity drain suitable for connection.
Developers should contact Council prior to undertaking the engineering survey to ascertain the
location of closest allotment connection or gravity drain. The exposure of any allotment connection
inspection point lid or flushing point lid will be the responsibility of the Developer.