16-001014-01A (Swmp)

Overall Site Layout - MCU Development Application
 Concept Stormwater Management Plan Report (No. B14158.W-03A dated November 2015);
 Concept Stormwater Management Construction and Maintenance Plan (Concept SMCMP) Report (No. B14158.W-
   09A dated January 2016)
 Response to Information Request Letter No. B14158.W.10A-Response to RFI.docx dated 5 February 2016.
 Outstanding Information Request Response Letter No. B14158.W.10LA.AMcP.ms.docx dated 21 April 2016.

The above reports have been considered in the latest analysis.



1.3      RESPONSE TO APPROVAL CONDITIONS
A summary of the responses to Council’s Approval Conditions relating to stormwater management are provided in
Table 1-1 below. Some responses have been addressed in other submissions, such as the SMCMP Report
(No. 16-001014-02A dated September 2016).

Table 1-1: Summary of Responses to Approval Conditions Relating to Stormwater Management
 Item    Brief Summary of Item                      Response to Item
 59      Adequate flood immunity maintained         Design of roadworks and drainage network throughout the site ensures
         during local and regional events.          adequate management of local flows. Refer to Roadworks and
                                                    Drainage Plans. Section 3.2.6 in this report indicates basin water
                                                    surface levels provide adequate freeboard to allotment levels.
                                                    Section 1.1 in this report provides details of regional flood levels below
                                                    developed lots.
 60      Site earthworks does not adversely         Section 1.1 in this report provides details of regional flood levels
         impact flood conditions on adjacent or      and site filling well outside of regional flood extents.
         downstream properties                      Furthermore, Section 3.2.6 indicates a reduction of peak flows back to
                                                    or below existing levels discharging from the site, which demonstrates
                                                    no adverse impact to flooding downstream.
 61      Design of stormwater drainage and          Stormwater drainage and basin detailed design drawings have been
         management devices to be certified by      certified by RPEQ. Refer to Drawing No. 16-001014-400 series for
         RPEQ specialising in hydraulics.           details.
 62      Minor Drainage System Capacity – 10%       Stage 2 Operational Works drainage has been designed accordingly.
         AEP storm, Major Drainage System           Refer to Stage 2 Operational Works Design Package for details. Future
         Capacity – 1% AEP storm                    stages will also be designed accordingly. Details are also provided in
                                                    Section 3.2.8 of this report.
 63      No adverse impact to downstream peak       Section 3.2.6 in this report demonstrates that proposed detention
         flows up to and including the 1% AEP       basins are adequate in reducing peak flows to meet this requirement.
         Storm
 64      Demonstrate the Stormwater Quality         Section 4 in this report provides stormwater quality analysis, outlining
         Management Strategy meets Water            the proposed Stormwater Quality Management Strategy, which
         Quality Objectives as per the SPP, 2014.   demonstrates compliance with WQO’s for the site. Discussion of the
                                                    treatment of external catchment runoff and modelling methodology is
                                                    provided in Section 4.
 65.1    Letter from Water By Design or eWater      In the proposed modelling (refer to Section 4 in this report), there has
         where MUSIC modelling deviates from        been no deviation from specifications provided in the MUSIC Modelling
         MUSIC Modelling Guidelines (2010).         Guidelines (2010). Therefore, a letter is not required. As per previous
                                                    correspondence with Council, the pond node has not been modelled in
                                                    MUSIC. This is a conservative assumption considering that the pond
                                                    will capture suspended solids through a process of sedimentation and
                                                    provide some reduction of nutrients.
 65.2    Contingency plan with costs to be          A contingency plan has been provided in Appendix A of the SMCMP
         provided to Council. Stormwater runoff     Report. Stormwater runoff is to receive primary treatment from
         from roads and car parking areas to be     proprietary GPT’s that can remove grease and oil, and tertiary
         pre-treated for grease and oil.            treatment from Bioretention Basins before discharge into the Pond.
                                                    Note that all areas likely to generate significant amounts of grease and



16-001014-01 | STORMWATER MANAGEMENT PLAN (SWMP)                 COOROY RETIREMENT COMMUNITY, TRADING POST
| PALM LAKE RESORTS                                                                          ROAD, COOROY                        |3