Appendix J - Civil Engineering Report and SBSMP

                                                                                   Noosa Residential Development
                                                                             Ref: 24553 C R002 REV03 10.08.21.docx
                                                                                                      August 2021


7        STORMWATER QUALITY ASSESSMENT
7.1      Treatment Objectives
         This assessment identifies issues relating to stormwater quality runoff and assesses possible
         methods of treatment if required. The aim of this section of the report is to determine practical
         approaches to achieving improvements in the quality of the stormwater run-off from the site that can
         be readily implemented.

         The SPP 2017 proposes assessment benchmarks criteria which apply to ‘high-risk’ development for
         stormwater. The criteria include one or more of the following:

            A Material Change of Use (MCU) for an urban purpose which involves a premises greater than
            2,500m2 of land and;
             will result in an impervious area greater than 25% of the net developable area; or
             will result in six (6) or more dwellings;
             A Reconfiguration of a Lot (ROL) for urban purposes that involves a land area greater than
              2,500m2 and will result in six (6) or more lots; or
             Operational works for urban purposes that involve disturbing more than 2,500m2 of land.

         The proposal includes an MCU for a land area of 10,113 m2 that will result in impervious area equal
         to 56% of the developable area. Hence, the development is classed as ‘high risk’ for water quality
         and the SPP 2017 assessment benchmarks requirements will apply for the development.

         The SPP 2017 suggests the development aims to:

            Avoid or otherwise minimises adverse impacts on the environmental values of receiving waters,
            arising from:
             Altered stormwater quality and hydrology;
             Wastewater (other than contaminated stormwater and sewage);
             The creation or expansion of non-tidal artificial waterways;
             The release and mobilisation of nutrients and sediments;
             Development achieves the applicable stormwater management design objectives outlined in
              Tables A and B (SPP Appendix 2); and
             Development in a water supply buffer area avoids adverse impacts on drinking water supply
              environmental values.

         Appendix 2 (Table B) of SPP 2017 and Noosa Shire Council water quality and drainage code
         suggests ‘Post Construction Phase – Stormwater Management Design Objectives’ as:

                                   Table 6 - South East Queensland (SEQ) Targets
          Total Suspended Solids        Total Phosphorus        Total Nitrogen            Gross Pollutants
                   (TSS)                       (TP)                  (TN)                     >5mm

               80% Removal                60% Removal           45% Removal                 90% Removal


         The objective is to provide the following:

            Nitrogen and Phosphorous removal;
            Gross Pollutant and Suspended Solids removal;


BRISBANE / SYDNEY / MELBOURNE / GOLD COAST / SUNSHINE COAST / DARWIN / PERTH                              Page 15