Flooding Requirements for siting onsite Access official records where available. wastewater infrastructure (including Note proximity of LAAs to waterways LAAs) away from areas subject to and areas subject to flooding. flooding can vary between Councils. Adequate of soil to protect Note the presence of on the site or groundwater resources largely in the locality, and depth of any depends on soil type and climate. standing water in pits or bores. Land An LCA is used to determine which Areas that are unsuitable for LAAs Suitability land is suitable and unsuitable for should be excluded to determine LAAs. available LAA on the site. A number of small and separate areas are often not suitable for LAAs. Landform Landform shape and the position of Topographic maps can be used to LAAs on slopes influence drainage assess broad landform and runoff characteristics both onto (geomorphology), and specifics such any potential LAAs as well as as position on slope and shape of downslope of them (i.e. will runoff be slope should be assessed in the field, evenly shed, or concentrated or especially for any LAAs. dispersed flows?). Feature Explanation Assessment Process Rock Rock outcrops displace soil horizons Estimate the amount (% cover) and Outcrops and therefore can limit the assimilative type of any rock protruding from the capacity of LAAs for effluent. Outcrops ground on the site. can indicate shallow bedrock. Some rocks are strongly fissured and permeable and others are not. Setback Determining the most appropriate Note any constraints to required Distances position for LAAs should be prioritised setback distances being met, e.g. lot over placement of building size and shape. Site Drainage LAAs should be located in areas of Determine whether rainfall will be good surface and subsurface (soil) shed (run off) or soak in, and note drainage. any waterlogged areas, which may be indicated by hydrophilic vegetation. Stormwater LAAs should not be located in with Note evidence of run-on to potential Run-on and high run-on, without mitigation such as LAAs (such as sediment dams and Runoff upslope diversion structures.
Flooding Requirements for siting onsite wastewater infrastructure (including LAAs) away from areas subject to flooding can vary between Councils. Access official records where available. Note proximity of LAAs to waterways and areas subject to flooding. Adequate of soil to protect groundwater resources largely depends on soil type and climate. Note the presence of on the site or in the locality, and depth of any standing water in pits or bores. Land Suitability An LCA is used to determine which land is suitable and unsuitable for LAAs. Areas that are unsuitable for LAAs should be excluded to determine available LAA on the site. A number of small and separate areas are often not suitable for LAAs. Landform Landform shape and the position of LAAs on slopes influence drainage and runoff characteristics both onto any potential LAAs as well as downslope of them (i.e. will runoff be evenly shed, or concentrated or dispersed flows?). Topographic maps can be used to assess broad landform (geomorphology), and specifics such as position on slope and shape of slope should be assessed in the field, especially for any LAAs. Feature Explanation Assessment Process Rock Outcrops Rock outcrops displace soil horizons and therefore can limit the assimilative capacity of LAAs for effluent. Outcrops can indicate shallow bedrock. Some rocks are strongly fissured and permeable and others are not. Estimate the amount (% cover) and type of any rock protruding from the ground on the site. Setback Distances Determining the most appropriate position for LAAs should be prioritised over placement of building Note any constraints to required setback distances being met, e.g. lot size and shape. Site Drainage LAAs should be located in areas of good surface and subsurface (soil) drainage. Determine whether rainfall will be shed (run off) or soak in, and note any waterlogged areas, which may be indicated by hydrophilic vegetation. Stormwater Run-on and Runoff LAAs should not be located in with high run-on, without mitigation such as upslope diversion structures. Note evidence of run-on to potential LAAs (such as sediment dams and