2008/0169 Response to information request - 71 Seaview Tce Sunshine Beach · 132008.169

4.0 WATER QUANTITY- PROPOSED DEVELOPME

4.1   INTRODUCTION

The Rational Method has been used to calculate the peak stormwater runoff flow rates for the pre and post
development sites for all ARI (Annual Recurrence Interval) from the 1 year to 100 year event. Appendix B provides
detailed Rational Method calculations.

4.2   CATCHMENTS

For the pre and post development scenario a contributing catchment area of 2,620m2 was determined and has
been used in all flow calculations. The catchment corresponds to the potential impervious area proposed for the
development. The catchment plan is shown below in Figure 8.




                                        Figure 8 - Site Potential Impervious Area


4.3   CO-EFFICIENT OF RUN OFF

For the Pre Development scenario a C10 value of 0.70 (fraction impervious of 0.00) was assumed from Table 4.05.3
(b), QUDM, 2nd Edition, 2007. For the Post Development scenario a C10 value of 0.90 (fraction impervious of 1.00)
was assumed from Table 4.05.3, QUDM, 2nd Edition, 2007




 SITE BASED STORMWATER MANAGEMENT PLAN - Revision D     71 Seaview Terrace. Sunshine Beach                          9