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

                     Field testing was carried out consisting of filling the pipe with water from a
                     nearby fire hydrant and timing the rate of fall as water infiltrated sands
                     below.

                     Results were consistent indicating a linear relationship between driving head
                     and infiltration rate such that:

                     Infiltration Rate (mm/s) = 4mm/sec + 13.6 x head (m)

                     Refer to Appendix D for 2003 prototype test results.




                     6.2.2 PROTOTYPE RIP TESTING 2024

                     On 4th December 2024 further on-site prototype testing was carried out in
                     similar fashion to that completed in 2003 at a location approximating the
                     proposed RIC/Bioretention basin location on site (refer RIP/RIC site layout
                     drawing at Appendix A).

                     The 2024 prototype differed from the 2003 version in that a shorter 2.2m long
                     pipe was utilised with a rock spalls wrapped in geofabric as a base rather than
                     a simple geofabric filter over the end of the pipe.

                     Levels taken on site indicated a prototype base level of approximately RL8.8m
                     AHD.

                     Once again field testing was carried out consisting of filling the pipe with
                     water from a nearby fire hydrant and timing the rate of fall as water
                     infiltrated sands below.

                     Notably, at the commencement of testing, the 50mm diameter fire hose being
                     used to fill the pipe with water could not keep up and water levels remained
                     at or near the base.

                     After approximately 20 minutes with the fire hose on maximum flow the pipe
                     began to fill to the top allowing timing of the rate of water level fall to be
                     taken.

                     Results once again were consistent but this time indicating a significantly
                     higher liner relationship between driving head and infiltration rate such that:


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                     A6769/25/SWMP/Rev OpW(A) – Feb 2025
                                                                                                  Page 8 of 9
                     SH/PL
                                              Brah101 Pty Ltd t/as ALTA PROJECTS
Document Set ID: 23646596
Version: 1, Version Date: 21/03/2025