Revised Stormwater Management Plan

                              STORMWATER MANAGEMENT PLAN
Client: Hass Holdings ATF The Quasar Trust                             Location: Taylor Court, Cooroy

     Table 14 - Comparison of Pre & Post-Development (mitigated) Stormwater flows in XP-RAFTS

                                                Existing                 Mitigated
          Catchment        AEP         Critical      Peak Flow      Critical   Peak Flow
                                      Duration         (m3/s)      Duration      (m3/s)
                           1%          25 min              0.630    25 min        0.624
            Site Area      10%         25 min              0.357    25 min        0.349
                           39%         60 min              0.219    25 min        0.211

7.0 CONCLUSIONS AND RECOMMENDATIONS
As described in Table 6, the stormwater treatment measures selected for the proposed
development achieve the performance criteria set by the NSC and by the State Planning Policy
(2014). Annual load reductions of TSS, TP and TN between the unmitigated and mitigated MUSIC
model scenarios have been met or exceeded. It is considered that a conservative approach has
been taken as no routing in the drainage links has been adopted.

This site based SWMP has demonstrated that the proposed development, when incorporating the
proposed detention strategies, can be undertaken with non-worsening to the quantity of runoff to
downstream environments.

Sufficient consideration of stormwater controls has been demonstrated by:

      Compliance with QUDM (2013)
      Compliance with the requirements of Noosa Shire Council’s Load Based Objectives
      Compliance with the State Planning Policy (2014)
      Compliance with the EPP (Water) 1997
      Compliance with Seqwater Development Guidelines
      Ecological sustainability in terms of the development’s impact upon receiving waters and the
       viability of the proposed site development.

The measures proposed within this report to manage stormwater quality and quantity achieve the
nominated requirements of the State Planning Policy (2014) and NSC. The proposed measures to
treat water quality at the site have exceeded the required pollutant reduction targets required by
the SPP and NSC to ensure the best possible chance of meeting the WQOs for the nearest
watercourse to the site are met to reduce any potential adverse impacts to Lake Macdonald. The
daily loads estimated in MUSIC for TSS and TN are mean values and are only marginally over the
WDOs for the nearest watercourse and due to the low concentrations of the remnant pollutants,
there is no practical or reasonable way to address the remaining concentration. This preliminary
design of the quality and quantity management measures is based on the current and best-
practice principles, and in terms of stormwater quality management, exceeds current best practice
approaches.




Covey Associates Pty Ltd                     12                                      Project No: 161968
Consulting Engineers                                                                    100415 Rpt Iss B