Appendix C - Engineering Report

Refer to Table 6.3a-b for a summary of the pre and post developed flows for the northern
and southern catchments. Refer to Appendix D for detailed Rational Method calculations.


               Table 6.3a Pre Vs Post Developed – Southern Flow Path – CMT 1
                          AEP     Q Pre      Q Post    Variance
                                  (m3/s)     (m3/s)
                         63%       6.14       6.15      0.04%
                         39%       8.18       8.18      0.04%
                         18%      11.37      11.38      0.04%
                         10%      13.79      13.79      0.04%
                          5%      16.57      16.58      0.04%
                          2%      21.17      21.18      0.04%
                          1%      24.425     24.434     0.04%


               Table 6.3b Pre Vs Post Developed – Northern Flow Path – CMT 2
                          AEP     Q Pre      Q Post    Variance
                                  (m3/s)     (m3/s)
                         63%       0.54       0.55       2.3%
                         39%       0.72       0.73       2.3%
                         18%       0.99       1.01       2.3%
                         10%       1.19       1.22       2.3%
                          5%       1.42       1.46       2.3%
                          2%       1.79       1.83       2.3%
                          1%       2.05       2.10       2.3%


The increases to peak discharge within the existing overland flow paths are minor and, as
noted in Section 6.1, will not result in discernible adverse impacts downstream of the site.
The existing waterways are heavily vegetated and have limited potential for future
development given the changes to the local area planning provisions and subsequent
downzoning of adjacent allotments.


No onsite detention measures are proposed as part of this development application.




                                                                                         11