SUPERDEDED NEGOTIATED - OPW25 0042 - Approved Plans (As Published) · OPW25/0042

                          •    Size RIPs/RICs and surrounding bio basins such that all flows up to
                               100-year ARI are infiltrated on site

                          •    Test RIP/RIC sizes derived above via a Quantitative MUSIC model to
                               predict performance of RIPs/RIC and quantify percentage of incident
                               rainfall infiltrated on site.



                     This approach satisfies both performance criteria of Council Condition 46 (f).

                     Infiltration of 100-year ARI catchment flows is a higher standard than the 10
                     year ARI required by EMP 1 or Council Condition 46 (f) and is consistent with
                     the approach taken on previous Settlers Cove projects.

                     Quantitative MUSIC modelling employs infiltration rates of 3,600mm/hour
                     (1mm/second) as recommended in the MUSICX1.0 modelling guidelines for
                     coarse sands.



                     7.1 RIP/RIC CAPACITY MODELLING- EXCEL SPREADSHEET

                     In order to model the operation of the RIP’s, a spreadsheet has been
                     developed and utilised for all previous stages of Settlers Cove.

                     Temporal patterns for Zone 3 from the Australian Rainfall and Runoff,
                     Volume 2 were applied. These temporal patterns were used in conjunction
                     with the average rainfall intensities for the Noosa region to create a series of
                     design storms of varying durations and for a range of different average return
                     intervals (ARI). Notably existing observed and documented rainfall intensities
                     from AR&R were increased by 20% as per Council ‘Climate Change’
                     requirements.

                     Temporal patterns were converted to flow rates by breaking each storm event
                     into a series of short duration storms. A triangular flow verses time
                     approximation was used for each sub storm with sub storm flows then added
                     to produce flow Vs time for RIP inflow.

                     Outflow and water depth were then calculated through iterations for the
                     duration of the storm based on the infiltration rate / head relationship
                     discussed above. A factor of safety of 2.0 was applied to the observed
                     prototype infiltration rate. Each RIP/RIC was then sized to prevent
                     overtopping in a 10-year ARI storm event of any duration, with 100-year ARI
                     storms contained within the RIP/RIC and adjacent bioretention basin.
                     __________________________________________________________________________

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