Stormwater Management Plan -OPW (A) · 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.


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A6769/25/SWMP/Rev OpW(A) – Feb 2025
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SH/PL
                         Brah101 Pty Ltd t/as ALTA PROJECTS