C2. Eng Report

                                                      Proposed Service Station – 175 Eumundi Noosa Road, Noosaville
                                                                                   Ref: 20769 C R001 Rev 06 09.02.17
                                                                                                      February 2018


9        STORMWATER QUALITY ASSESSMENT
9.1      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 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 greater than 2,500m 2 of land
          that:

             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 2,500m 2
          and will result in six (6) or more lots; or

          Operational works for urban purposes that involve disturbing more than 2,500m 2 of land.

         As per the SPP 2017 sites of an area less than 2,500m 2 are not required to achieve any specific
         stormwater quality reduction targets through a treatment train. Since the site has an area of 1,972m2,
         best management practice for stormwater treatment measures are to be implemented in accordance
         with Table 14-61 in Division 20 of the Noosa Shire Plan 2006 and will consist of:

            First flush device/s to divert initial flows to landscape area

         Stormwater within the proposed development shall be initially directed towards landscaped areas via
         first flush device/s. Internal hydraulic stormwater drainage shall be designed and constructed in
         accordance with AS3500.3 and all other relevant standards and guidelines.

9.2      Site Analysis and Design Strategy
         The proposed development may be categorised into two sub catchments comprising of a high-risk
         area and a low-risk area. The proposed high-risk area comprises entirely of the ground floor area
         directly beneath the proposed driveway canopy. This area is more commonly known as the fuel
         dispensing and bulk fuel unloading area. The proposed low risk area comprises of the remainder of
         the site, including the driveway, carparks, building roof, landscaped areas and paths.

9.2.1    Low-Risk Area Treatment
         Currently no stormwater quality management measures are in place for the subject site. The following
         SQID’s will be implemented to treat the low risk area:

            An in-line Gross Pollutant Trap (GPT) (SPEL Ecoceptor or approved equivalent).

         As it is highly likely that oils will be encountered on surfaces trafficked by motor vehicles, a Gross
         Pollutant Trap which meets or exceeds Councils standards for treatment will be fitted upstream of
         the proposed detention tank to capture any potential oil and petroleum prior to entering the tank.
         Internal hydraulic stormwater drainage shall be designed and constructed in accordance with
         AS3500.3 and all other relevant standards and guidelines.




BRISBANE / SYDNEY / MELBOURNE / GOLD COAST / SUNSHINE COAST / DARWIN / PERTH                                Page 18