Stormwater Management Plan

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

The proposed development site has an area of 0.824 ha. The site receives a very small upstream
catchment which when combined with the site area gives a total area of 0.924 ha. The majority of
this upstream area is a landscaping buffer between the site and Holts Road.

6.3 XP-RAFTS Data

6.3.1 Model Scenarios

The existing and proposed conditions for the 1%, 10% and 39% AEP events were modelled in XP-
RAFTS to determine the peak stormwater flows for the site.

The three scenarios modelled for this investigation are:

      CSS_E01b - represents the existing characteristics of the subject site (pre-development);
      CSS_D01b - represents the subject site as fully developed (no detention); and
      CSS_M01b - represents the subject site as fully developed and the effects of the proposed
       detention tank.

6.3.2 Rainfall Intensities

The rainfall intensities used in XP-RAFTS are typical to Cooroy and were generated from the
Bureau of Meteorology’s online IFD data website (accessed 30 May 2016). The rainfall intensity
tables are contained in Appendix E.

6.3.3 Existing and Proposed Development Areas

The total catchment area has been modelled as one (1) catchment. The existing and proposed
catchment boundaries are the same for each modelling scenario. Refer to Figure 5 for the
stormwater quantity catchment boundary. Refer to Appendix D for a detailed Stormwater Quantity
Catchment Plan.




                           Figure 5 Stormwater Quantity Catchment Boundaries

6.3.4 Initial and Continuing Losses
Initial and Continuing Rainfall Loss parameters were adopted as per Table 6.




Covey Associates Pty Ltd                      7                                    Project No: 161968
Consulting Engineers                                                                  100415 Rpt Iss A