Wastewater
The Design Process
Our Process:-
- Conduct a site inspection, liaise with the clients and or builder. 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
- Conduct Site & Soil Analysis and a Percolation Test if not already done by another party.
- Sketch a preliminary design for the clients for their perusal to ensure all idea's and thoughts are addressed and seek their approval
- 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.
- Final inspection to certify completed works.
Site & Soil Evaluation & Percolation Test
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 amount 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.)
Types of Waste Water Disposal Areas
- Above ground spray irrigation into a garden bed
- Covered surface drip irrigation into a garden bed
- Shallow sub-surface Pressure compensated drip irrigation under turf
- Conventional trenches (for primary effluent systems mainly)
- Self-supporting arch trench (in areas where the soil is sand)
- Conventional beds
- ETA/ETS Trenches
- ETA/ETS Beds (for areas where space is a constraint)
Refer to the Gallery for images.
Aqua-nova Waste Water Treatment Systems
Aqua-nova have earned the reputation of being one of the market leaders in producing quality Wastewater Systems and Environmental solutions, servicing Australian households day in, day out.
Setback Distances for Waste Water Disposal Areas
One of the most important parameters to consider in the location of Land Application Areas is the separation distances, both vertical and horizontal (Queensland Plumbing & Wastewater Code).
Surface Horizontal Separation distance requirements.
| Feature | Primary | Secondary | Advanced Secondary |
|---|---|---|---|
|
Permanent watercourses (lake/stream/river) |
50m |
30m |
10m |
|
Intermittent watercourses (dams/channels/road drains/weirs) |
50m |
30m |
10m |
|
Bore (human and or domestic consumption) |
50m |
30m |
10m |
|
Easement boundary for an unlined open stormwater channel |
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* |
* Note: For Primary effluent, the distance from an in-ground potable water tank must be 15 metres.
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 |
|
Property boundaries, pedestrian paths and walkways |
2 |
|
Water edge of a swimming pool |
6 |
|
Dwellings, recreation areas |
10* |
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.
Vertical Separation distance requirements
| Depth of unsaturated soil to | Primary | Secondary | Advanced Secondary |
|---|---|---|---|
| Permanent water table | 1.2m | 0.6m | 0.3m |
| Bedrock | 1.2m | 0.6m | 0.3m |
Suitable Vegetation for Planting
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 |
Shrubs
| 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 | |
| Ophopogon | ||
| Astor novi-belgii | Astor | |
| Canna x generalis | Canna | |
| Vetiver Vetiver | ||
| Grevillia Poorinda | Royal Mantle | |
| Coprosma Kirkii | ||
| Acanthus Mollis |
Note on Primary (Septic) Systems
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 a 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.
