Revised Stormwater Management Plan

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




                           Treated Area

                                                                     Untreated Area




                                          Figure 3 Catchment Areas

4.0 WATER QUALITY MODELLING ASSESSMENT/APPROACH
4.1 Scenario Methodology

The site was modelled using split catchment source nodes, comprised of roof area, road area and
groundcover nodes. The hardstand area of pavement and outdoor dining area has been modelled
as groundcover at 100% impervious. The stormwater treatment proposed for the site consists of
one (1) rainwater tank, nine (9) Stormsacks and one (1) bioretention basin.

The runoff within the area beneath the service station bowser canopy will be captured by a grated
channel surrounding the area and directed to a holding tank. This will reduce the risk of any
potential runoff containing hydrocarbons entering the stormwater network in the event of a spill.
The holding tank will be monitored and emptied when required, particularly prior to a large rain
event. Roof runoff from the canopy will be directed to the bioretention basin for treatment.

Refer to Stormwater Quality Management Plan in Appendix B.

4.2 Stormwater Reuse

The proposed main use of the site is a service station with associated facilities and parking. The
proposed development consists of the service station bowser area, service and shop area, fast
food restaurant, drive through, outdoor dining area and associated parking and landscaping. The
water reuse at the site has been based upon the recommended rainwater tank demands for a toilet
in a commercial setting stated in Water by Design (2010) guidelines. The water use estimate per
person per day for a toilet with some water saving devices is 40L. The reuse estimated for the
service station and fast food area were based upon the water demand table produced by Gold
Coast City Council (Appendix E). The GCCC guidelines base the water use for the different land
uses upon the gross floor area (GFA) of the land use. Each land use has a different equivalent
person (EP) rate applied. The pedestal usage of 40 L/day has been applied per EP required.
Reuse for landscaping has also been included within the model based upon the guidelines in
Water by Design (2012). A conservative estimate of 600mm per m2 per year was assumed.

The following equation was used to calculate the reuse volume required to size the proposed
rainwater tank.
Covey Associates Pty Ltd                         4                                Project No: 161968
Consulting Engineers                                                                 100415 Rpt Iss B