Appendix A - Copy of Existing Approval · 132008.1128

                                                                                     132008.1128
Stormwater Quality Management
63.   A stormwater quality treatment system must be provided for the development which
      achieves compliance with the Management Objectives specified in Section 4 of the
      Girraween Stormwater Management Plan prepared by Ecological Engineering and
      dated 22/12/2006. The Stormwater Management Plan (SWMP) submitted with the
      application is specifically not approved and a revised site SWMP consistent with the
      above is required to be provided with the application for Operational Works. The
      revised site SWMP is to specifically address the following:
         63.1.     Stormwater detention storage for downstream flood mitigation is not required
                   for this site and is to be deleted from the design. The stormwater devices are
                   to be raised in order to eliminate or reduce retaining structures and instead
                   provide batters to the biofiltration surface
         63.2.     Revised MUSIC modelling is to be provided demonstrating how the
                   Girraween Stormwater Management Plan pollutant load reduction targets
                   and frequency of discharge targets for surface flows to the national park will
                   be achieved
         63.3.     Groundwater and in-situ infiltration testing is to be undertaken at the RL of
                   the proposed infiltration surface/interface for each proposed device and is to
                   be used to inform the design
         63.4.     Level spreaders must be provided at the interface between all discharge
                   locations and the adjoining National Park. The plans must be supported by .
                   calculations demonstrating all proposed level spreaders are appropriately
                   sized to dissipate flows at non-erosive velocities for peak runoff events up to
                   and including the 1 in 100 year ARI event of critical duration. Level spreaders
                   are to be provided parallel to the downstream natural surface contours.
64.    The works must be undertaken in accordance with an Operational Works approval
       and the latest version of the Water Sensitive Urban Design Technical Design
       Guidelines for South East Queensland, and must include in particular:
         64.1.     Stormwater quality treatment devices of a size and location generally in
                   accordance with those documented in the revised site SWMP required by
                   the above condition; and
         64.2.     Bioretention devices which:
                   64.2.1. Are designed generally in accordance with IPWEQA Standard
                           Drawing No. WSUD-001
                   64.2.2. Incorporate a coarse sediment forebay (in addition to the required
                           filter media surface area), which is sized in accordance with the
                           latest version of the Water Sensitive Urban Design Technical Design
                           Guidelines for South East Queensland and designed generally in
                           accordance with IPWEQA Standard Drawing No. WSUD-005
                   64.2.3. Have safe, unobstructed and all weather access from the road
                           frontage for maintenance purposes, particularly for the coarse
                           sediment fore bay
                   64.2.4. Are provided with a high flow bypass to ensure that flows which
                           exceed the treatment capacity of the device are bypassed in order
                           to avoid damaging of the filter media or subjecting the filter media to
                           excessive sediment loads.




PD·DA·FM5815·0210412009                                                        Page 11 of 24