Guide to Domestic Wastewater Treatment Disposal Systems by xjy16440


									Guide to Domestic
Wastewater Treatment
& Disposal Systems

Environmental Health Services
Monday 8.30am to 6.30pm
Tuesday to Friday 8.30am to 5.00pm
Council Offices, Civic Drive, Greensborough
(PO Box 476, Greensborough 3088)
Telephone: 9433 3340
Facsimile: 9433 3393

Guide to Domestic Wastewater Treatment and Disposal Systems


Application                                                                                3

Drainer/Plumber                                                                            3

Preparing a Plan                                                                           4

Water Conservation                                                                         4

Options for the treatment & disposal of wastewater                                         5

       Septic Tank and Absorption trenches                                                 5
       Treatment plant and irrigation system                                               6
       Septic tank, sand filters and absorption trenches                                   8
       Transpiration / Evaporation Trenches / Beds                                         9
       All other systems                                                                   9

Setback Distances                                                                          9

Protecting and maintaining the effluent disposal area                                     10

Land Capability Assessments                                                               10

List of drainers and plumbers                                                             11

Appendices                                                                                12

       Appendix 1             Waster water Disposal Plan                                  12
       Appendix 2             Septic Tank                                                 13
       Appendix 3             Absorption Trench                                           15
       Appendix 4             Warning Sign for Surface Irrigation                         16
       Appendix 5             Typical layout of drippers and sub-surface irrigation for
                              waste water treatment plants                                17
       Appendix 6             Sand Filter                                                 18
       Appendix 7             Absorption – Transpiration Trench                  19
       Appendix 8             Setback distances for effluent disposal area                20

Maps showing areas which require soil testing                                             21

Guide to Domestic Wastewater Treatment and Disposal Systems

This guide provides information on the installation of appropriate domestic
wastewater treatment and disposal systems for owners, builders and plumbers within
Nillumbik Shire Council. For all storm water requirements you will need to contact
Councils’ Infrastructure Development Section.


Prior to installing or altering a septic system, the plumber must obtain a permit from
Council's Environmental Health Services Unit. The plumber installing/altering the
system must provide the correct information for the permit on Councils’ application
form. The ‘Permit to Install’ or ‘alter’ the system is valid for 24 months from the date
of issue.

The application fee is $206.00 for a new septic tank installation and $139.00 for an
alteration to an existing septic tank system. This fee includes a preliminary site
inspection & two inspections. Any further inspections will incur a $50.00 charge
payable before the inspection will take place.

Council's Environmental Health Services Unit must be satisfied that all wastewater
generated can be adequately disposed of within the boundaries of the allotment prior
to a building permit being issued by the Building Surveyor. On completion of works,
a ‘Permit to Use’ the septic system must be obtained from Environmental Health
Services before a certificate of occupancy is granted.

Drainer / Plumber

The installation of the septic system must be carried out by a registered plumber or
drainer. All septic tank systems must be installed in accordance with the
Environment Protection Act 1970, Septic Tanks Code of Practice 2003 and AS 1547.
A list of drainers and plumbers who install septic systems within Nillumbik Shire has
been attached at the end of this document.

The Plumbing Industry Commission requires plumbers to provide the owner with a
copy of the certificate of compliance for all works over $500. This certificate of
compliance number and the plumber’s registration/license number must be included
on the application form for septic tank system installations. This gives the Council
and the owner assurance that the work has been completed by a registered plumber
and is covered by a 6 year guarantee. A permit to use the septic system will not be
granted unless the plumber has provided the certificate of compliance number.

Further information on plumbing regulations can be found on the Plumbing Industry
Commission website,

Guide to Domestic Wastewater Treatment and Disposal Systems

Preparing a Plan

A plan showing the location and design of the septic system must be provided with
the application for a permit to install/alter a septic tank system. For information on
the details required on the plan please refer to the application form.

A photocopy of the site plan that was used in the Building or Planning process will be
useful as it already has the position of the proposed home and other features.

Owners should think carefully about the future use of the land when locating the
septic system. The location of sheds, future extensions, swimming pools, tennis
courts, driveways, possible keeping of horses, the proximity of nearby trees etc.
should be considered.

Planning and Building controls placed on the development must also be considered
when positioning the septic tank system. An effluent envelope may be designated
on the site as part of the planning permit. All wastewater must be disposed of within
this envelope unless approval from Planning has been given for disposal to occur in
another location.

A site inspection and assessment of your plans can be approved quickly, but it is in
your interest to try to get the plans right the first time! Please see appendix 1 for an
example of a septic system plan.

Note: Prior to an application being submitted to Environmental Health
      Services, the effluent disposal area must be pegged out as indicated on
      the plan.

Water Conservation

Conserving the amount of water used in the home reduces the load placed on the
septic system. Water conserving fixtures such as dual flush toilets, low flow shower
heads, water efficient tap ware, dishwashers and clothes washers can be installed.
Always check for current A, AA or AAA water conservation rating labels, and select
AAA wherever possible and affordable.

Guide to Domestic Wastewater Treatment and Disposal Systems

OPTIONS FOR                 THE       TREATMENT               AND   DISPOSAL         OF

A.     Septic tank and absorption trenches
B.     Treatment plant and irrigation system
C.     Septic tank, sand filter and absorption trenches
D.     Evaporation/Transpiration disposal trenches/beds
E.     All other systems issued with a certificate of approval by the Environment
       Protection Authority

A.     Septic tank and Absorption trenches

This includes a 3200 litre septic tank and effluent absorption trenches. In some
cases this system may require a pump to get the effluent from the septic tank to the
trenches. Further information on septic tanks and pumps can be found in appendix
2. The trenches vary in length depending on the soil type and the trench width.
Trench widths are usually 0.450m, 0.600m or 1.00m wide. For a diagram of
absorption trench construction see appendix 3.

In those areas where soil permeability is poor, a soil percolation, permeability or soil
assessment test must be conducted in accordance with the Septic Tank Code of
practice 1996 or AS 1547. The soil test will be used to determine the length of
trench required and must be submitted with the septic tank permit application. Refer
to the attached maps, which outline those areas that require soil tests. In some
instances other areas not shown on the maps may require a soil test. Councils
Environmental Health Officer’s can give further advice on this matter. A list of
companies that conduct soil tests can be found in the Yellow Pages under ‘geo-
technical engineers’ or ‘soil testing’.

The table below can be used as a guide to establish the size of trench you require.
The trench lengths listed are based on a 3 bedroom house or a daily flow of 1000
litres/day. Additional trench length may be required for larger houses. This type of
system is not appropriate for properties less than 0.8 hectares (refer to Section B &
                      Length of Trenches in metres for a daily flow of
                      1000 litres/day
Trench Width (m)      Clay Soils                            Sand/Loam soils
                      (Yarrambat, Diamond Creek,            (Warrandyte, Smiths
                      Plenty, parts of Kangaroo Ground, Gully, St Andrews,
                      Arthur’s Creek Christmas Hills,       Kangaroo Ground, Panton
                      Doreen, Nutfield, Eltham,             Hill & Strathewen)

       0.450                             210                             120
       0.600                             160                              90
       1.000                             120                              60

Guide to Domestic Wastewater Treatment and Disposal Systems

Please note the trench lengths indicated are a guide only and it is
recommended that a soil test be conducted for all properties to establish the
length of trench required.

Septic Tank Filters

Septic tank effluent filters can be placed on the outlet of the septic tank. These
reduce the solids in the effluent stream prolonging the life of the land application


Septic tanks should be pumped out every three years. If a tank is not cleaned out
when required, sludge or scum will build up in the tank and may be carried out with
the effluent clogging the disposal system. The disposal system may then need to be
reconstructed. Surface water and storm water must be diverted away from the
effluent disposal area.

Potential Advantages and Disadvantages

Sampling of the septic tank effluent is not required and servicing is only required if a
pump is fitted.

Absorption trenches are sometimes difficult to orientate on a property. A reserve
area of 100% of the design area must be provided on the property for replacement

B.     Treatment plant and irrigation system.

Aerated wastewater treatment plants produce better quality effluent than the
conventional septic tank and are available for house-hold use.

Some of the companies that sell treatment plant units are:

       - Taylex
       - Septech
       - Envirosep
       - Ozzi Kleen
       - Aquanova/Everhard Industries
       - Biocycle

Contact details for these companies can be obtained from the Yellow Pages under
‘Sewage and wastewater treatment ‘

Where effluent quality meets EPA criteria the treatment plant system can recycle
wastewater through an approved irrigation system.

Guide to Domestic Wastewater Treatment and Disposal Systems

As with option A, a soil percolation, permeability or soil assessment test will be
required to determine the area of irrigation in those regions shown on the attached
maps. The area of irrigation required in other locations is outlined below. These
areas are based on a three bedroom house or a daily flow of 1000litres/day. Larger
houses may require additional irrigation area. Again this is a guide only and it is
recommended that a soil test be conducted for all properties to establish the area of
irrigation needed.

•   Clay Soils - 400m².
    Areas that commonly have this soil type include Yarrambat, Diamond Creek,
    Plenty, Arthur’s Creek, Christmas Hills, Doreen, Eltham, Research, Nutfield and
    parts of Kangaroo Ground.

•   Sand/Loam Soils- 250m².
    Areas that commonly have this soil type include, Warrandyte, Smiths Gully, St
    Andrews, Kangaroo Ground, Panton Hill and Strathewen.

There are two types of irrigation; surface irrigation which includes drippers and
sprinklers and sub-surface irrigation. Surface irrigation requires disinfection of the
treated effluent. Each of these systems must meet the respective requirements set
out in AS1547 and the EPA Certificate of Approval.

The following conditions apply where an irrigation system is used;

    •   Recycled water is not suitable for growing fruit and vegetables.

    •   Standard house hold hose taps and garden fittings must not be used. All
        irrigation pipework and fittings must comply with AS 2698.

    •   Sprinklers which produce coarse droplets and not a fine mist must be used to
        minimise the risk of aerosol dispersion by wind drift. The spray plume must
        have a throw of less than two metres and a height of not more than 600 mm.

    •   No sprays are to be located within 15 metres of any dwelling or source of
        water supply.

    •   Before the use of the irrigation system, the irrigation area must be planted out
        and landscaped to the satisfaction of Nillumbik Shire Council. The area where
        surface irrigation is laid must be covered with mulch to a depth of 100mm.

    •   A minimum of two warning signs must be displayed in or near the irrigation
        area where drippers or spray irrigation is used. This sign must comply with
        AS 1319 and AS 1547. Please see appendix 4 for an example of a warning

Guide to Domestic Wastewater Treatment and Disposal Systems

     •   The surface irrigation system must be a permanently fixed system with
         distribution pipelines buried at a minimum depth of 100 mm. Drippers and
         sprinklers are to be spaced so that recycled water is evenly distributed over
         the irrigation area. Please see appendix 5 for a diagram of the typical layout
         for surface and sub-surface irrigation.


Treatment plants must be serviced every three months by a servicing agent in
accordance with the manufacturer’s specifications. They are also required to be
desludged every three years. Pumps and other components may need to be
replaced during the lifetime of the unit. A sample of the effluent must be taken and
analysed by an N.A.T.A registered laboratory every year to ensure that the effluent
quality meets EPA criteria.

Potential Advantages and Disadvantages

These systems allow possible water savings through recycling wastewater on garden
areas. They can distribute wastewater to irregular and isolated disposal areas.
Furthermore they can provide an even distribution across the disposal area.
If absorption trenches are installed after the plant the length can be reduced by 50%
of that required for septic tank effluent.

Dripper heads may be damaged and require ongoing replacement. Maintenance
requirements and associated operational costs should be considered when looking
at this option. Mulch may need to be replaced every 6-12 months to ensure a depth
of 100mm is maintained.

C.       Septic tank, sand filter and absorption trenches

This system includes a 3200 litre septic tank and sand filter, followed by absorption
trenches. The size of the sand filter for a three bedroom home is generally 20m²
(5mx4m). The length of trench is designed as per option A, however the sand filter
provides further treatment prior to disposal and therefore the length can be halved.
Details on sand filter construction can be found in appendix 6.

A certificate of analysis for the sand must be submitted to Council by the
plumber/drainer. Analysis of sand must be carried out in accordance with AS1141-
Methods for Sampling & Testing Aggregates.


The septic tank should be desludged every three years. .

Guide to Domestic Wastewater Treatment and Disposal Systems

Advantages and Disadvantages

The amount of area required for absorption trench can be reduced by 50% and
therefore this system can be installed on smaller lots.

If major extensions are proposed it may be necessary to extend the length of
absorption trenches. It is believed that the sand filter has a limited life (10-15 years)
however correct maintenance of the system including regular desludging of the
septic tank and /or larger sand filters can prolong this period.

D. Transpiration/ Evaporation Trenches/Beds

After the wastewater has been through the treatment process, on-site disposal can
be achieved through absorption into the soil, evaporation and transpiration. In areas
where the soil drains well disposal is largely through absorption.

The trench lengths outlined in section A are based on soil absorption. In poor
draining soils and where the rainfall is not too high evapo-transpiration trenches and
beds can be installed. Please see appendix 7 for a diagram transpiration trench

Other types of systems used for disposal of effluent when soil permeability is low
include mound trenches. Suitable fill material may be imported to the site to form a
mound usually a metre above the natural soil surface. The effluent is disposed
through a piped distribution system located in the upper part of the imported soil.

E. All other systems issued with a certificate of approval
by the Environment Protection Authority

There are many types of domestic wastewater systems which have been approved
by the EPA for use in Victoria which have not been mentioned. Some of these
include composting toilets, worm farms and reed beds. A full list of approved
wastewater systems can be found at in the ‘For Local
Government’ section.

Council’s Environmental Health Services will assess the suitability of the chosen
system for each site.


The Septic Tank Code of Practice-2003 requires minimum buffer distances between
the wastewater disposal field and other sensitive features. These are necessary to
reduce potential pollution and protect public health. Please see appendix 8 for these
set back distances. These distances may be reduced where a treatment plant or
sand filter is used.

Guide to Domestic Wastewater Treatment and Disposal Systems


   • Avoid vehicular traffic over the disposal area.
   • Ensure horses and cattle are unable to access the area.
   •   Divert storm and surface water away from the disposal area.
   •   Do not cover with paving, concrete, swimming pools, sheds or other building
   •   Do not cover the area with clay or plastic.
   •   Do not use root killing additives in the area.
   •   Check effluent area regularly for signs of seepage.
   •   Plant the disposal area with shallow rooting grasses and /or shrubs which are
       water tolerant and suitable for local conditions. Please refer to Environmental
       Health Services information brochure on plants and grasses for transpiration


Wastewater, if not properly managed can impact on BOTH public health and the
environment. Some properties are restricted in their ability to contain all wastewater
on site. Characteristics that can reduce the ability of the land to retain wastewater
on-site include small lots, steep sites, flood prone areas, poor draining soils, near by
surface water, shallow depth to bedrock and high water table.

Where there are significant site restrictions a comprehensive land assessment must
be undertaken to establish the capability of the site to sustainably manage
wastewater within the allotment boundaries. This must be done in accordance with
EPA publication 746.1 ‘Land Capability Assessment for Onsite Domestic Wastewater

Guide to Domestic Wastewater Treatment and Disposal Systems


G Browne                              Rod Laidlaw Plumbing                 Ken & Dean Shaw
20 9th Avenue                         PO Box 116                           PO Box 364
Eden Park, Whittlesea                 Wallan                               Hurstbridge
0418 357 549                          0418 330 766                         9710 1838
                                                                           0419 571 296

Jim Leonard                           Wayne Frith                          Arthur Keenan
18 Dartagook Street                   130 Christian Road                   25 Koonawarra Way
Diamond Creek                         Hurstbridge                          Diamond Creek
0407 325 602                          0418 333 054                         9438 2472
9438 1243                                                                  0412 543 675

Karingal Plumbing                     Bayswater Septics                    Glenn Bromley
(Trevor Stewart)                      Jordan McInnes                       293-301 Ironbark Road
8 Willis Street                       PO Box 121                           Yarrambat
Greensborough                         Bayswater                            0418 325 402
9435 4705                             0408 524 674
0415 536 152

Rob Meredith                          Sturrock Drainage                    Gary Smith
590 Yan Yean Road                     123 De Fredericks Lane               2A Ely Street
Yarrambat                             Yarrambat 3091                       Eltham
0418 351 075                          9436 1550                            0412 548 115
                                      0418 385 943

John Rourke                           David Mundy
11 Booyan Crescent                    820 Hurstbridge-Arthurs Creek Road
Greensborough                         Arthurs Creek
0402 015 184                          0408 103 315
9434 7225

Rob Lloyd Plumbing                    Peter Molenkamp
PO Box 246                            20 Bald Spur Road
Eltham                                Kinglake 3763
0419 107 151                          0408 176 342

Rob Kemp Plumbing                     Jamie Burrell
97 Railway Parade                     29 Ilana View Drive
Eltham 3095                           Diamond Creek
9439 8210                             0418 559 347
0418 326 868




Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 1

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 2


This is a tank through which sewage is passed to settle solids. In wastewater some
solids (sludge) settle on the bottom of the tank and others form a scum on the water
surface of a septic tank. Retained solids undergo anaerobic bacterial digestion.

The accumulated sludge and scum in the septic tank must be pumped out at least
every 3 years. (Refer to Yellow Pages - "Septic Tank Cleaning Services"). Failure to
pump out the septic tank can result in solids passing out of the tank into the
absorption trenches. This can clog the trenches and cause odour problems.

The bacteria in the septic tank can be upset or killed by excessive chemical use. The
use of strong detergents, disinfectants, acidic toilet cleaners, nappy sanitizers,
bleaches and so on should be restricted.

The plumber must bring the inspection openings of the septic tank to ground level so
any blockages entering the tank can be cleared. The manhole must also be raised
to ground-surface level. This will make maintenance a lot easier and cheaper in the

The tank must not be covered with paving, concrete or building structures etc.
Unless otherwise approved by the responsible authority, no septic tank shall be
constructed or installed closer than two metres to the foundations of any house or
other building or the boundary of any allotment.

Guide to Domestic Wastewater Treatment and Disposal Systems


A pump is required wherever there is insufficient fall to allow gravity feed. This may
be the case on flat property or where the effluent disposal field is on the high side of
the septic tank.

The pump is installed in a "pump well" and fitted with a visual or audio alarm which is
activated if the pump fails.

Pump sets should be of the submersible type. Pumps should be driven by motors
rated at 0.2 kW or more or as specified by the manufacturer.

The storage capacity of a pump well must be equal to the pump’s ability to handle
the peak hourly flow from the septic tank plus emergency storage.

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 3- Absorption Trench

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 4-Warning Sign for Surface Irrigation

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 5

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 6 –Sand Filter

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 7 – Absorption- Transpiration Trench

Guide to Domestic Wastewater Treatment and Disposal Systems

Appendix 8 – Setback distances for effluent disposal area

Guide to Domestic Wastewater Treatment and Disposal Systems

Guide to Domestic Wastewater Treatment and Disposal Systems


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