RFI - Attachment 4 - Engineering Response Package · MCU22/0171

DME Projects Pty Ltd
P.O. Box 7481
Sippy Downs, QLD, 4556
Tel 0438 157 612
ABN 79 224 274 637

                                       Response to Information Request – 128 Gympie Tce Noosaville
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due to the sandy soils and scouring/nuisance from stormwater flows in the park area resulting from
this development is not expected.

A small catchment (25m2) from the ramp section of the driveway cannot be free draining to the
street as it is below kerb invert level. The lower strip drain is proposed specifically for this
catchment. 1%AEP 5min peak flows will be 2.4l/s and well within the capacity of a 100mm pipe at
1% grade. This same event would deliver 693l of water to the basement sump. A 600 sq pit is
proposed as the basement sump. This has a holding capacity of around 200 litres. Typical
stormwater packaged pump stations are supplied with pumps capable of transferring >150l/m
(2.5l/s) at 2m head. See link https://www.strongmanpumps.com.au/product/storm-water-drainage-
system.

In the unlikely event that the sump pump completely fails, 1%AEP runoff could result in 10mm depth
of inundation over approximately 40m2 of the basement floor.

A 1%AEP 2hr duration storm will deliver 157mm rainfall to the catchment with peak flows of around
0.6l/s. This will deliver, 3.8m3 of water to the sump for discharge by the pump. If the pump fails this
would result in 13mm depth of inundation across the basement floor (290m2). This is not
considered to be a significant threat to life or property and can be further contained with additional
grading of the basement slab in detail design phase. The development incorporates a battery room
in the basement. This battery will run the pump during a power failure.

The final location of the sump will be determined during the structural and details design phase
however the engineering drawings have been amended to show an outlet pipe provision to the
surface level stormwater pit adjacent to the southern boundary.

We trust that this additional information is acceptable to Council and look forward to approval of
the proposed work. If you have any questions regarding this response please contact me directly.


Yours Faithfully



Dale Martin - Director
B Eng (Civil), RPEng, RPEQ
DME Projects Pty Ltd