M2677 - Information request response

.




Response – Item 3
Refer to Morgan Consulting Engineers response and plans included in Attachment A. These plans have been updated to
demonstrate:
     The existing drainage catchment and flows have been captured in the updated Concept Stormwater Catchment
        Plan (20169-SK20-E) for the north-eastern corner of the site.
     All flows up to Q100 are contained within the basin as provided in the updated Stormwater Management Details
        plan - Sheet 2 (20169-SK13-D)
     A high flow weir has been designed as the top of the proposed pit structure within the basin.
     The proposed weir overflow over the retaining wall across the boundary will be for emergency cases only.
     Accordingly, all flows up to the Q100 are not expected to inundate downstream properties.

Information required
4.     Investigate and confirm the existing discharge patterns from the development site in the South-Eastern corner of
       the proposed development and demonstrate that the design will not result in any changes in flow patterns or
       discharge onto additional land which is not inundated by stormwater runoff from the site in the existing case.
       Confirm the weir design is able to be realised within normal construction tolerances.

Response – Item 4

Refer to Morgan Consulting Engineers response and plans included in Attachment A. Similarly with Item 3, the plans have
been updated to demonstrate:
     The existing drainage catchment and flows have been captured in the updated Stormwater Catchment Plan (dwg
        no. 20169-SK20-E) for the south eastern corner of the site.
     The updated Stormwater Management Details – Sheet 1 (20169-SK12-D) demonstrates that all flows up to Q100
        are contained within the basin.
     A high flow weir has been designed as the top of the proposed pit structure within the basin.
     The proposed weir overflow over the retaining wall across the boundary will be for emergency cases only.
     It is anticipated that the weir design will be able to be constructed within the normal construction tolerances.
     Flows will not inundate properties that are not already currently affected by stormwater flow.



Issue: Climate Change
PO2 of the Water Quality and Drainage Code requires that stormwater drainage infrastructure is designed to incorporate
allowance for climate change.

Information Request:
5.     Provide an updated SWMP which includes stormwater detention modelling and updated drainage designs which
       includes allowance for the 1%AEP event at end of planning period 2100.




JFP Ref: M2677P                                                                                              Page 3