MCU14/0056 Response to SARA - Consulting Report

                                                                                                                              ENG
                                                            Engineering Report & Stormwater Management Plan
                                                    Date:          27/01/2015        Document No.:        14012-ENG-04.Docx

                                                     By:              AvT            Revision No.:                F


  Based on the calculated peak flows, the detention volume required for proposed multi-use
  development is shown in the table below.


                                                   INITIAL VOLUME
Reduction
                   r=             (Qi-Qo)/Qi
   ratio                                                           0.146 0.146 0.146            0.146      0.146 0.146
  Inflow
                   Vi=             4tc*Qi/3                l/s
 Volume                                                             702     962        1123     1341       1697       1956
                                                               3
                  Culp         Vs=(r(1+2r)/3)*Vi           m         44         61      71           85     107       123
                                                               3
Volume to         Boyd             Vs=r*V=                 m        103     141         164      196        248       286
 Retain          Carroll Vs=(r(3+5r)/8)*Vi                 m   3
                                                                     48         66      77           92     116       133
                                                               3
                 Basha         Vs=(r(2+r)/3)*Vi            m         73     101         118      140        178       205
                                                               3
             Average Volume to Retain =                    m        67       92        107       128       162        187
        Table 5.13:            Detention Summary

  Based on these calculations it was determined that a detention storage volume of 187m3 is
  required to ensure that the developed flow is equal to or less than the undeveloped flow.

  The size of the detention basin will be confirmed during detailed design in conjunction with
  the Site Based Stormwater Quantity Management Plan (SBSQMP) prepared by Storm Water
  Consulting Pty Ltd. It is noted that the SBSQMP has determined that a detention basin is only
  required for Q1, Q5 and Q10 stormwater events therefore the proposed detention basin size
  is considered to be suitable for this development.

  It is proposed that all runoff from the impervious areas are to be drained to the detention
  basin. The detention basin will be owned and maintained by the property owner.

                         g. Maintenance

      Construction Phase Management Plan
  Potential construction phase impacts include the following:
  • Sedimentation and erosion
  • Management of contaminated soils and materials on the site Construction Material (such
      as cement)

       General
  The objective of the Construction Phase Management Plan is to comply with the requirements
  of the Queensland Environmental Protection Act 1994 and Environmental Protection (Water)
  Policy 2009 so that the environmental values of effected receiving waters are maintained or
  enhanced. In essence the purpose of the Plan is to prevent polluted stormwater being
  discharged to the local waterways.



  A PO Box 26, Carina Q 4152                                                                                 21 | P a g e
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  W www.vtce.com.au