MCU21.0117 OPW21.0199-Applicant's Response to Council's IR · MCU21/0117

Applicant’s Response

4. Refer to the Revised Stormwater Engineering Report prepared by Recor Consulting (Attachment 5) and
Recor’s response to the Information Request enclosed within Attachment 4. An extract from the response is
provided below:

       The internal drainage network has been redesigned to discharge stormwater run-off from the site to
       the Pearl Street site frontage drainage system, being the legal point of discharge for the
       development. Please refer to the updated Stormwater Engineering Report and Roads and Drainage
       Layout Plan for further details.


Information Required by Council

5. Please provide revised sizing/modelling and associated engineering drawings for the detention storage
proposed for the development site, which achieves the following:

       a. Utilises a hydrologic model and is undertaken using the ensemble storms approach of ARR2019;

       b. Is undertaken generally in accordance with the procedures documented in QUDM Section 5.6.2;

       c. Demonstrates no increase in peak flows for all events up to and including the 1%AEP event, for the
       range of durations applicable to the downstream land;

       d. Accurately represents the site catchment areas and the position and catchment of each detention
       storage within the site;

       e. Accurately represents any external catchments conveyed through the site;

       f. Accurately represents any areas of the developed site which bypass the detention storage(s);

       g. Accurately represents the existing catchment and flows reporting to the proposed discharge point
       from the site, as the comparison for the developed-site discharge; and

       h. Provides existing and developed catchment plans, showing the above areas.


Applicant’s Response

5. Refer to Recor’s response to the Information Request and Revised Engineering Plans enclosed within
Attachment 4. An extract from the response is provided below:

       The drainage network and detention storage has been redesigned for the site to address the points
       raised. Pre and post development catchment plans have been prepared to represent the site
       catchments flows to each element of the drainage system, external catchments conveyed through
       the site and areas bypassing the site detention systems.

       As the pre-development site drainage flows into private property rather than the legal point of
       discharge, there is currently no predevelopment peak flow from the development into the legal
       drainage point for the site to achieve. Rather, the proposed development has been modelled to

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