Slope Stability Report 26-5-2019 OPW19-0193

TRUBUILT
SLOPE RISK ASSESSMENT REPORT



      •   Slope coverings such as jute mat, non-woven geotextiles or woven weed mats provide only
          temporary protection to slopes and should not be relied upon for long term protection of batter
          faces. For further information about the applicability of these methods seek advice from a suitably
          experience geotechnical professional;
      •   Often the most effective protection to cut slopes is afforded through the growth of weeds on the
          slope. When weeds need to be controlled or removed they should be slashed or poisoned. Weeds
          should never be torn out of slopes as this generally results in rapid degradation of the slope.

Further guidance on the maintenance of retaining walls, and cut and fill slopes is found in Australian
Geoguides LR6 Retaining Walls and LR8 Hillside Construction.


4.5        Surface Drainage Recommendations

Management of surface and groundwater flows is essential to ensuring ongoing slope stability and foundation
performance. The following recommendations are made for the configuration and maintenance of site
drainage:

      •   It is recommended that the soil be graded to fall not less than 50mm for the first metre from the
          structure with a low permeability soil;
      •   Site drainage requirements should form a planned part of the site landscaping and may need to
          modified or changed depending on the performance of the drainage in peak rainfall events. Site
          drainage should be inspected regularly and maintained as required to keep it serviceable;
      •   The site stormwater system should also account for incidental sources of water including tank
          overflows, surface flows from paved and driveway areas, and minor drains;
      •   Stormwater should be directed away from the structure to a suitable outlet structure that will slow
          and spread the flow onto the slope. The stormwater outfall should never be discharged onto bare
          natural or fill soils.

Further recommendations for surface drainage can be found in the Australian Geoguides LR5 Water &
Drainage and LR9 Effluent and Surface Water Disposal.


4.6        Recommendations for Wastewater Disposal

An investigation and assessment for the most appropriate method of wastewater and effluent treatment and
disposal has been prepared by Global Testing and is presented in their report.

The following recommendations are made with respect to the siting and construction of wastewater disposal
infrastructure:

      •   It is recommended that wastewater irrigation areas be planted with species that will promote
          undergrowth and/or have fibrous roots that aid in binding of the soil to prevent erosion;




LEONTAKIANAKOS-R-001                               Page 15                                               26 May 2019