Attachment D - Stormwater Management Plan · 132008.175.04

Runoff from main landscaped areas will be intercepted and conveyed via a
landscaped swale located along the site’s western boundary to a series of RIPs
and shallow landscaped basin at the south-western corner of the site.

 RIPs will be aggregated within the basin and flows greater than the 1% AEP
major design event will be directed toward the POSCWPas dispersed sheet
flow via a broad weir.

Refer to engineering drawings at Appendix A for details.


5.0    RAPID INFILTRATION PITS (RIP’s)

RIPs consist of a bottomless stormwater pit which promotes infiltration
through its base.

Crushed rock and multiple layers of geofabric and “sacrificial sand” are
installed at the base of the RIP to protect against clogging of dune sands
below.

RIPs are subject to routine inspection and maintenance by the building’s body
corporate and such maintenance is critical to their ongoing function. (refer
Maintenance Schedule at Appendix B).

RIPs have been installed on all previous stages of Settlers Cove and proven to
work very well.

Refer engineering drawings at Appendix A for RIP details.




6.0    CALCULATIONS

       6.1    RIP Infiltration (100year ARI events)

              Alta Projects engineers (formally Tate) were involved in
              formulation of the over-arching development approval
              document and EMP1.

              Such involvement included construction of a prototype RIP on
              the Settlers Cove site and field testing to determine infiltration
              rates. Results were consistent indicating a liner relationship
              between driving head and infiltration rate such that:


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A6107/L9/SMP/RevA/Aug 2021                                                   Page 4 of 7
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                     Brah101 Pty Ltd t/as ALTA PROJECTS