Appendix D - Geotechnical Report

Table 5: Required EAAs
                                  Min. Land             Typical Slopes        Slope Reduction           Required Land
        Proposed Lot            Application Area        Present across              Rate               Application Area
                                      (m2)                   EAA                    (%)                      (m2)
           Lot 1                      420                10 % to 20 %                20 %                     470
           Lot 2                      420                10 % to 20 %                20 %                     470
           Lot 3                      420                20 % to 30 %                50 %                     840
           Lot 4                      420                20 % to 30 %                50 %                     840
           Lot 5                      420                    <10 %                    N/R                     420

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 land application area to
occur. As the use of an aerated wastewater treatment system is proposed, which can deliver high quality
(Secondary Standard or better) effluent, the risk of fouling and system failure is negligible. Shallow
subsurface drip irrigation pipework can also be easily repaired in-place as required, therefore the
addition of a separate reserve area is not warranted.

8.4.2         System Positioning
Positioning 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 6, 7 and 8 below and overleaf.

Table 6: Setbacks for subsurface land application area for on-site sewage treatment plant
 Site Feature                                                                     Horizontal separation distance
                                                                           Upslope          Downslope             Level
 Property boundaries, pedestrian paths, walkways, recreation
 areas, retaining wall, and footings for buildings and other                 2m                 4m                  2m
 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 7: Setbacks for surface irrigated land application area for on-site sewage treatment plant

 Site Feature
                                                                                  Horizontal separation distance

 Property boundaries, pedestrian paths and walkways                                              2m
 Water edge of a swimming pool                                                                   6m
 Dwellings, recreation areas                                                                    10 m
Note:    Distances measured from the edge of the irrigated wetted area to any point of the feature.




Geotechnical Investigation
10 June 2026 | 26073-001-Rev0                                                                                              23