RFI - Attachment B - Stormwater Quality Engineering Response · 132008.1128.04

Memorandum
18-001942 - Sunrise Beach Interim RAC Water Quality




                                                Figure 1 - MUSIC Model Set Up




2.2            Treatment Strategy
The onsite treatment strategy proposed for the RAC site and currently included as part of the OPW design package
(extract attached) is as summarised generally follows:

      1.   All built ground areas are collected within an internal pipe drainage system and conveyed towards the treatment
           devices at the northern boundary of the site;

      2.   A minimum one quarter of the roof area from the building will be diverted to a 30,000L tank with captured
           rainwater being plumbed in for internal and external reuse;

      3.   Flows from the pipe system and rainwater tank overflow are directed to a 50m 2 bioretention basin. The inlet of
           the bioretention basin includes an appropriately sized coarse sediment forebay;

      4.   Overflow and treated flows from the bioretention basin is directed to an infiltration basin with a floor area of
           45m2.

It is noted that only within this interim MUSIC model was the infiltration basin also modelled alongside the bioretention
basin. Typically infiltration basins aren’t modelled in MUSIC within SEQ for a number of reasons including:




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