The recommendations presented in this report are relevant only upon the provisions that information supplied by our client regarding site preparation and the position of the proposed residence and the proposed effluent disposal area/s are accurate. It is the client’s responsibility therefore to ensure that accurate details have been conveyed to the Consulting Engineers prior to production of this report. It should also be understood that whilst our test has been conducted within the appropriate guidelines and with suitable diligence to accurately determine the ground conditions, on occasions excavations may indicate significant variations to the ground conditions specified in the test report. Should any of these situations occur, the consulting Engineers must be contacted for appropriate advise and/or alternative recommendations.


The primary objective of the onsite and soil evaluation is to assess the permeability of the soils where on-site domestic sewerage treatment and disposal systems are required, and that the installation of thus on-site domestic sewerage treatment and disposal system is appropriate for the site and potential loading in terms of type, size and location. It is also to ensure that all on-site sewerage treatment and disposal installations do not harm the environment or present a risk to public health.


Site testing is conducted in accordance with A.S.1547-2012, “On-site Domestic wastewater management” and the “On-Site Sewerage Code”. STA Consulting Engineers is also N.A.T.A. registered for appropriate test Procedures.


Householders will be required to maintain all components of their systems in working order. Systems not satisfying basic performance requirements will be required to undertake the necessary maintenance, repair or replacement by the owners. Minimal use of strong detergents and chemicals is strongly advised. Laundry and kitchen detergents should contain no more than 3% Phosphorus by weight. Use biodegradable products as per manufacturers recommendations. Do not dispose of excess grease and fats down any sink holes. Power must not be turned off when going on holidays. Notify the Manufacturer’s maintenance engineer when going away for long periods of time. Upon sale or renting of the property, the owner shall inform the manufacturer of the system and ensure that the new occupants assume responsibility of the maintenance agreement with the manufacturer and council. Maintenance inspections should be carried out at the required intervals form the operation date by a technician accredited by the manufacturer and/or local council. (Refer manufacturer’s requirements).


The use of water reduction features is beneficial to the performance of an effluent disposal system as it reduces the amount of effluent produced within the dwelling. Following are the guidelines as per AS1547-2012 appendix 4.2D for water reduction features.

Standard Water Reduction Features:-.

Dual flush 11/5.5 litre water closets, shower-flow restrictors, aerator faucets (Taps) and water conserving automatic washing machines.

Full Water Reduction Features:-

Reduced flush 6/3 litre water closets, shower-flow restrictors, aerator faucets, front loading washing machines and flow/pressure control valves on all water-use outlets.


Waste disposal units are not recommended where on site treatment and disposal is used, as an increase in both settle able and floatable solids will result. The increase in scum and sludge is not desirable and it is not
considered that the raw materials can be utilised and/or disposed as solid materials in the first instance. Consulting engineers must be notified if a waste disposal unit is installed so the design of the on-site disposal
system can be checked as being adequate. All aeratered systems can not have grinders installed.


Unless otherwise advised, service trenches are to be positioned that they are not within the zone of influence of the proposed dwelling. If required, service penetrations are permitted through the middle third of the footing beam. Penetrations outside this zone are to be undertaken only under the advice of The Consulting Engineers. All pipe work and fittings are to comply with the relevant Australian Standards and Local Authority Regulations.



Toilet paper that disintegrates easily should only be used. Try to distribute the household load as evenly as possible, spread washing across the week instead of concentrating it all on one day. The build-up of sludge in the bottom of the tank must be removed on an average of every 8 years for small domestic tanks. (Refer
Manufacturers specifications) All vents shall be mosquito proofed and properly maintained. Mosquitos can breed in the environment of the tank.


Do not allow foreign objects (e.g. nappy liners, disposable nappies, sanitary napkins, condoms etc.) to enter the system. Foreign objects will block the system. Do not wash paint brushes in the laundry tubs. The result to the system is disastrous. Do not wash your dog in the laundry tub. Do not prevent easy access to any inspection opening. Do not cover tanks with earth, cement, pavers or any other material. Do not allow roof or surface water to enter any part of the system.

Suitable Vegetation for Effluent Disposal Areas

Check with the Local Authority as to suitability and any restrictions on vegetation types.

Buffallo Kikuyu
Ground Cover
Acanthus mollis Liriope muscari
Coprosma x kirki Ophiopogon
Grevillea poorinda, Royal Mantle
Bougainvillea Kennedia
Hardenbergia Lonicera japonica
Hibbertia scandens Pandea jasminoides
Agapanthus preaecox Gazania x hybrida
Astor novi – belgii Salvia x superba
Canna x generalis Stokesia laevis
Chrysanthemum maximum Viola hederacea
Abelia x grandiflora Euphorbia pulcherrima
Acacia longifolia Hebe speciosa
Callistemon citrinus Jasminum mesnyi
Cassia bicapsularis Jasminum officinale ‘Grandiflorum’
Ceratostigma Jasminum polyanthum
Chaenomeles lagenaria
Correa alba
Cotoneaster glaucophyllus
Leptospermum flavescens
Cotoneaster lacteus
Nerium oleander
Cotoneaster pannosus
Plumbago auriculata
Cuphea ignea
Pyracantha fortuneana
Euonymus japonicus
Thunbergia alata
Euphorbia milii
Westringia fruticosa
Angophora costata Leptospermum laevigatum
Banksia integrifolia Leptospermum petersonii
Callistemon salignus Melaleuca armillaris – Sandy soil
Casuarina glauca Melaleuca linariifolia – Clay soil
Casuarina stricta Melaleuca quinquenervia – Sandy soil
Eucalyptus botryoides Melaleuca styphelioides – Clay soil
Eucalyptus robusta Photinea x fraseri ‘Robusta’
Hakea salicifolia Tristaniopsis laurina
Hakea saligna

More information:

Water Tank Pumps
Rainwater Tanks
Septic Tank Systems