Attachment 3 - Revised Slope Stability Assessment

Brett Hage                                                                                         22328-001-Rev1
                                                                                                 17 November 2022

Table 2: 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.
Table 3: 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. Boreholes indicate adequate unsaturated soil depths are
available.
Individual site layout shall be decided at building stage, in conjunction with a design provided by a NC
registered evaluator.
5.3.3 System Construction
Construction of wastewater land application areas must be carried out in accordance with Appendix M of
AS1547:2012 and NC requirements. In order to prevent any adverse impacts on the water quality from
effluent disposal, the elements given below shall be implemented:
       Shallow subsurface drip systems must be installed at 100 mm to 150 mm depth into 150 mm to
        250 mm of good quality sandy topsoil, in grassed of other suitably vegetated areas. Any sandy
        topsoil material won from site works may be used to supplement the soil within the respective
        disposal fields or alternatively shall be imported to the site.
       Receiving native soils will be prepared by undertaking deep ripping / shallow cultivation combined
        with the addition of organic matter (10 kg/m² raw mulch) and gypsum (1 kg/m²) to ‘break up’ any
        relatively hard clay subsoils and improve overall drainage characteristics.
       Shallow subsurface irrigation lines will run parallel to slope contours. To evenly distribute
        wastewater throughout the irrigation areas, pressure equalisation systems (i.e. pressure
        compensating drip emitters) should be installed.




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