RFI - Black & More - Stormwater Management Plan

 Proposed Stormwater Design
Roof Water Drainage
The architectural drawings show the lowset block structure being demolished and an extension to the highset structure in its place.
This would mean the existing downpipe arrangement would need to be demolished, including existing below ground pipes and
kerb adaptors. This will allow for new guttering and downpipes to be installed.
Please refer to the attached mark-up for the proposed drainage scheme.
 -    The catchment in blue to be directed to a kerb adaptor on Weyba Road
 -    The catchment in red to be direction to a kerb adaptor on Swan Street (including connection of the pit from the car parking
      area.
This proposed scenario will result in:
 -    Q100 = 15L/s out of kerb adaptor 1
 -    Q100 = 23L/s out of kerb adaptor 2
Note these values are for the 1 in 100-year event, therefore are well within limits.
Also, it was assumed that a new guttering and downpipe arrangement was possible due to the extension. Locations of downpipes
have not been considered and are to be confirmed with the architect. The aim of the stormwater arrangements is to split roof
water flows between the 2 kerb adaptors, relatively evenly.


Overland Flow
The existing ground levels provide for adequate surface drainage and will not change. Proposed landscaping works will maintain
the exiting surface drainage outcome, i.e. the development will maintain minimum 1% surface grades to the street(s) to promote
sheet flow.
When the car park is resurfaced, a 450x450mm drainage pit shall be installed and connected to the kerb adaptor on Swan Street.
The sealed carpark surface will grade toward the drainage pit.
Furthermore, when the car park is resurfaced it should be raised above the surrounding area (nominal 100mm), which will prevent
surface run off entering the carpark.




Please do not hesitate to contact our office should you wish to discuss this further.




195 Weyba Road SMP
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