SUPERSEDED Approved Plans & Document OPW25-0042 · OPW25/0042

                     5.0 RAINWATER HARVESTING AND RE-USE

                     Runoff from approximately 7,532m2 (80%) of roofed areas will be directed to
                     a rainwater harvesting tank to be located beneath back-of-house areas at the
                     south-western corner of the site.

                     Captured rainwater will be utilised for landscape irrigation and swimming
                     pool top up.

                     Alta Projects have developed a water balance model in eXcel format which
                     models tank inflow and outflow over a ten (10) year period of historical
                     rainfall data from 2013 to 2024 at Tewantin RSL Weather Station.

                     Tank performance was modelled utilising the following reuse parameters: -

                          •    Landscape irrigation = 1.5mm/m2/day
                                  o No irrigation for one day after 1.5mm of rain or more
                          •    Daily Pool top-up = Evapotranspiration – Rainfall

                     Results appear below in table 5.1




                     Table 5.1 Water Balance Model Results


                     By inspection approximately 80% reliability on rainwater reuse for pool top
                     up and landscape irrigation may be expected with a tank of 300m3 total
                     volume installed.

                     Refer Appendix G for full model.


                     __________________________________________________________________________

                     A6769/25/SWMP/Rev OpW(A) – Feb 2025
                                                                                                  Page 4 of 9
                     SH/PL
                                               Brah101 Pty Ltd t/as ALTA PROJECTS
Document Set ID: 23646596
Version: 1, Version Date: 21/03/2025