Council may permit absorption disposal systems in soils with a hydraulic conductivity of less than 0.36 mm/hr, slopes greater than 15%, or extensively paved areas.

In these cases, the design of the absorption disposal system must be prepared by a suitably qualified and experienced engineer. Details must be submitted with a development application and include an assessment of the infiltration of the soil profile, consideration of antecedent moisture conditions and performance over a variety of rainfall events.

The design must also be supported by a report from a practicing geotechnical engineer with local knowledge attesting to the suitability of the site for the system, absorption capacity of the system and demonstrate that there will be no adverse impacts on the subject land/buildings, adjoining and/or downstream properties by the re-direction or concentration of stormwater.