Appendix F - Geo-Environmental Investigation Report · RAL24/0003

                                      PROPOSED SUBDIVISION
                                      41 TALLOWWOOD PLACE, BLACK MOUNTAIN

The nominal land application area as shown in Figure 1 would therefore be appropriate, and it is assessed that
that there is enough room to site the wastewater irrigation area with the necessary setbacks on the new lot.
The need for a reserve area is generally applied to septic tank systems, producing low quality (Primary
Standard) effluent, due to increased potential for fowling and failure of the trenched land application area to
occur. As the use of aerated wastewater treatment systems is proposed, which are capable of delivering high
quality (Secondary Standard or better) effluent, the risk of fouling and system failure is negligible. Proposed
wastewater irrigation can be easily repaired in-place as required, so the addition of a separate reserve area is
not warranted.
7.4.2            System Positioning
Positioning (‘setbacks’) of the land application systems must be in accordance with the horizontal and
vertical setback distances recommended in Tables T2, T3 and T5 of the Queensland Plumbing and
Wastewater Code 2019, as summarised in Tables 4 and 5 below.
Table 4: Setbacks for subsurface land application area for on-site sewage treatment plant
                                                                                                              Horizontal separation distance
  Site Feature
                                                                                                        Upslope           Downslope            Level


 Property boundaries, pedestrian paths, walkways, recreation areas, retaining wall, and
                                                                                                             2m                4m                2m
 footings for buildings and other structures.


 Inground swimming pools.                                                                                                    6m


 Inground potable water tank.
                                                                                                                             6m
 (Secondary standard effluent or better)

Note:    Distances measured from the edge of trench/bed excavation or subsurface irrigation distribution pipework to the nearest point of the feature.



Table 5: Setback distances for on-site sewerage facilities (Protection of surface and groundwater)
                                                                                                              Separation Distance

 Site Feature
                                                                                           Advanced Secondary                  Secondary Effluent
                                                                                                Effluent

Surface Waters:
  Top of bank of permanent or intermittent water course, lake, bay or
      estuary;
  Top water level of a surface water source used for agriculture,                                    10 m                              30 m
      aquaculture or stock purposes;
  Open stormwater drainage channel or drain;
  Bore or a dam.

 Unsaturated soil depth to a permanent water table (vertically)                                       0.3 m                            0.6 m

Note:    Distances measured from the edge of the irrigated wetted area to any point of the feature.


Unsaturated soil depths of 0.6 m (i.e. depth to rock or wet soil) and 0.3 m are recommended for Secondary
and Advanced Secondary effluent, respectively. Test pits indicate that such adequate unsaturated soil
depths are available across the proposed effluent disposal area.
The layout for effluent treatment and disposal on the new lot shall be decided at building stage, in
conjunction with a design provided by a NC registered evaluator.




22 May 2023
Report No. 23099-001-Rev0                                                 21