SUPERSEDED Negotiated Decision Notice OPW25 0042 (As Published) · OPW25/0042

               32.    Slope and batters are a maximum grade of:
                      a.      1 in 6 where in proximity to waterbodies;
                      b.      1 in 4 for grassed areas;
                      c.      1 in 3 for planted areas; and
                      d.      1 in 2 for combined structural engineering and planting solutions.
                      Stormwater Drainage
               33.    Appropriate scour protection must be provided at the outlet of all stormwater pipes including
                      temporary outlets.
               34.    Works associated with this permit must not adversely impact on the existing drainage
                      conditions on other properties (e.g., by blocking or interfering with natural overland flows).
               35.    Construction of all internal stormwater drainage works must comply with the relevant
                      section/s of Australian Standard AS/NZS 3500.3.
               36.    Prior to the completion of the development, all site surfaces must be effectively stabilised
                      using methods which have achieved effective short-term stabilisation, and which will continue
                      to achieve effective stabilisation in the medium- to long-term (refer to E&SC Advisory Notes).
                      For the purpose of this condition, an effectively stabilised surface is defined as one that does
                      not or is not likely to result in visible evidence of soil loss caused by sheet, rill or gully erosion
                      or lead to sedimentation, or lead to water contamination.
                      Bioretention Basins – Construction
               37.    During construction and establishment of the bioretention devices, the supervising RPEQ
                      must ensure that the device was constructed in accordance with the document Construction
                      and Establishment Guidelines: Swales, Bioretention Systems and Wetlands (Water by
                      Design, 2009) and that the forms contained in section 3.15 including the associated
                      supporting information and data are completed. These forms and certification from the RPEQ
                      that the device has been constructed in accordance with the Construction and Establishment
                      Guidelines: Swales, Bioretention Systems and Wetlands (Water by Design, 2009), all
                      conditions of approval, and the approved engineering drawings must be submitted to Council
                      prior to commencement of use.
               38.    A construction hold point with a council delegate shall be established once the bioretention
                      device underdrainage pipe work is installed. At the time of inspection, a sample of the
                      drainage layer, transition layer, and filtration media materials must be stockpiled onsite.
                      Laboratory results must be provided for the filter media which demonstrate that the media
                      complies with the specifications contained in the latest version of the “Guidelines for Soil
                      Filter Media in Bioretention Systems” (produced by the Facility for Advancing Water
                      Biofiltration) and that the minimum hydraulic conductivity specified on the approved
                      engineering plans will be achieved. In addition, laboratory results must be provided
                      demonstrating that the transition layer and drainage layer meet the following bridging criteria:
                      a.      D15 (drainage layer) ≤ 5 × D85 (transition layer)
                      b.      D15 (transition layer) ≤ 5 × D85 (filter media).
               39.    The drainage layer, transition layer, and filtration media materials must not be installed until
                      the catchment draining to the bioretention device has 70% groundcover as determined by
                      Council’s delegate.




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Document Set ID: 24143123
Version: 4, Version Date: 26/09/2025