MCU14/0056 Response to SARA - Consulting Report

          3.0      Site Based Assessment
          3.1      High Risk & Medium Risk Area
          The hydrocarbon, oil-based liquids and the runoff associated with them are generally the main substances
          that make the high risk and medium risk areas distinct from each other. Traditionally, the forecourt of a
          service station that includes the dispensing area and the fill points is classified as the high risk area. The
          primary concern in the design of service stations in Australia has always been to cover this area and direct
          the stormwater runoff away from this zone to medium risk area. Figure 3.1 shows the proposed under
          canopy area (forecourt area), which is approximately 538m2. The grades on site are designed in a way so
          that the runoff from medium risk area will not enter the forecourt zone and the high risk area will not be
          impacted by flooding of medium risk area. Moreover all the possible spills in the high risk area are directed
          to SPEL Puraceptor for further treatment.




          Figure 3.1 – Under canopy area at proposed service station at Cooroy, QLD


          As illustrated in this figure all high risk areas (Canopy) are contained within the bunds and will be directed
          into a SPEL Puraceptor. The remaining pavement is considered medium risk areas and will be directed
          away from high risk areas. The Intensity – Frequency – Duration (IFD) of the site is shown in Figure 3.3,
          which has been extracted from the Bureau of Meteorology. According to this information the worst runoff
          from the forecourt area for duration of 6 minutes and an ARI of 20 will be 31.8L/s.




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