If your house is not connected to centralised sewerage you will need to install your own wastewater treatment system. Before a wastewater treatment system can be installed you will require council approval as well as a geotechnical report. The geotechnical report, sometimes known as a site and soil report, will help determine the best wastewater treatment system for your block and your family’s needs. At Gregors Plumbing & Gas we have qualified geotechnical engineers to do this for you.

Queensland’s plumbing and wastewater code require wastewater to be treated to secondary or advanced secondary standard before it is released into trenches or irrigation fields. Gregors Plumbing & Gas understands the requirements of Sunshine Coast Regional Council and can carry out a geotechnical report and install a wastewater treatment system that will meet your needs and increase the value of your home.

  1. Conduct a site inspection, liaise with the clients and or builder.
  2. Items to be discussed:
    • Waste water system type & tank position
    • Waste water disposal area type, preferred location & set back
    • distances from boundaries etc.
    • Are you having or contemplating a swimming pool whether now or in
    • the future
    • Are you proposing a shed or other future buildings
    • Position of your rainwater tank/s in-ground or above ground
  3. Conduct Site & Soil Analysis and a Percolation Test if not already done by another party.
  4. Sketch a preliminary design for the clients for their perusal to ensure all idea’s and thoughts are addressed and seek their approval.
  5. Complete the drawings with the site plan, floor plan, 3 copies of design works, design statement, percolation report and the required forms packaged for the Council, copies for both the client and the builder.
  6. Final inspection to certify completed work


In brief, the site and soil evaluation is to assess, the individual lot for
the following:-


  • Land surface features eg. Slope, existing buildings and services, potential environmental risks and other constraints. Define the expected area for the land application system
  • Detail a subsoil investigation to examine and record the soil profile and soil features with-in the area for the expected land application area.
  • Testing the soil permeability to allocate the appropriate soil category and provide an evaluation on the Long Term Acceptance Rate (LTAR), which enables the determination of a Design Loading Rate (DLR) or a Design.
  • Irrigation Rate (DIR).


This information is then compiled ready for a Design Statement to calculate the area size required for each individual lot. To calculate the size required, the only determining factor remaining is the number of bedrooms proposed in the dwelling to be built. (The bedrooms in the dwelling denote the land application size not how many bathrooms or toilets are proposed.)


  1. Above ground spray irrigation into a garden bed
  2. Covered surface drip irrigation into a garden bed
  3. Shallow sub-surface Pressure compensated drip irrigation under turf
  4. Conventional trenches (for primary effluent systems mainly)
  5. Self-supporting arch trench (in areas where the soil is sand
  6. Conventional beds
  7. ETA/ETS Trenches
  8. ETA/ETS Beds (for areas where space is a constraint)


One of the most important parameters for the location of the LAND application areas is the separation distances both vertical and horizontal.


Pemenant water courses lake/stream/river 50M 30M 10M
Intermittent water course drain/channels/weirs 50M 30M 10M
Bore Human consumption 50M 30M 10M
Easement boundary for an unlined open water chanel 50M 30M 10M


Setback distances for sub-surface and covered surface land application area for a grey water treatment plant or an on-site sewage treatment plant


Feature Horizontal Separation Distance (metres)
Distance from the edge of trench/bed excavation or subsurface irrigation distribution pipework to the nearest point of the feature Up slope Down slope Level
Property boundaries, pedestrian paths, footings of buildings, walkways, recreation areas, retaining wall footings. 2 4 2
In ground swimming pools 6 6 6
In ground potable water tank 6* 6* 6*


9. * Note: For Primary effluent, the distance from an in-ground potable water tank must be 15 metres.


10. Setback distances for surface irrigated land application area (above ground) for a grey water treatment plant or an on-site sewage treatment plant


Feature Horizontal Separation Distance (metres)
Property boundaries, pedestrian paths and walkways 2
Water edge of a swimming pool 6
Dwellings, recreation areas 10*


11. These separation distances are based on a spray plume with a diameter not exceeding 1m or a plume height not exceeding 0.3m above the finished surface level. Distances are given in metres from the edge of the irrigated wetted area to any point of the feature.


Rural or acreage blocks cut up prior to 1994 may have a septic (primary effluent) system, providing the horizontal and vertical setbacks as per the Queensland Plumbing & Wastewater Code (QPWC) can be achieved. A reserve area needs to be identified with all septics where space for future requirements could be a constraint. The Development Approval (DA) conditions for non-sewered subdivisions after 1994 seem to be calling for secondary quality effluent systems. To be 100% sure we would need to have a look at the DA conditions for each subdivision. The Plumbing and Drainage Act 2002 calls up the QPWC in relation to non-sewered properties and providing the proposed system complies with this then there would be no reason to refuse it. However, if septic was installed on a property on which a DA required a secondary quality system the owner could be in breach of the Integrated Planning Act.


Small Trees Palms


Botanical Name Common Name Height (M)
Acacia Floribunda Gossamer Wattle 2-4
Acacia Longifolia Sallow Wattle 2-4
Banksia spp. Banksia Various
Hakea spp Hakea
Melaleuca Nesphila Western Tea Myrtle 2-4
Pittosporum Native Apricot Various
Palms Dwarf Date Palm
Golden Cane Palm




Botanical Name Common Name Height (M)
Abelia x Grandiflora Abelia 2-3
Acacia Iteaphylla Flinders Ranges Wattle
Acacia Floribunda Gossamer Wattle 2-4
Acacia Longifolia Sallow Wattle 2-4
Cassia Various Various
Charmelaucium Uncinatum Geraldton Wax 1-2
Dryandra Formosa Showy Dryandra 1-3
Eremophila Emu Bush Various
Grevillia Grevillia 1-3
Melaleuca Incana Melaleuca
Melaleuca Thymofolia Melaleuca
Melaleuca Decussata Cross-Leaves Honey Myrtle 1-2
Nerium Oleander Oleander Various
Phormium Tenax New Zealand Flax 2-2.5
Melaleuca Decussata Flinders Ranges Wattle 2-3
Hebe Veronica Various
Hibiscus spp Hibiscus
Iris Pseudacorus Yellow Flag
Cyoerus Alternifolius Umbrella Grass 0.5-1


Grasses Groundcovers Perrenials


Botanical Name Common Name Height (M)
Lomandra Longifolia Lomandra
Lomandra Histrix Lomandra
Agapanthus Preaecox Agapanthus
Astor novi-belgii Astor
Canna x generalis Canna
Vetiver Vetiver
Grevillia Poorinda Royal Mantle
Coprosma Kirkii
Acanthus Mollis