Pre-Request Response Application 132001.210310.1

Flood Investigation & Stormwater Quantity Management Plan                                              BROWN
                                                                                                             S1IUIrllmm-
Proposed Residential Development at Doonella Stage C
                                              -




         FLOOD INVESTIGATION & STORMWATER QUANTITY
                                         MANAGEMENT PLAN
                PROPOSED RESIDENTIAL DEVELOPMENT AT
                                         DOONELLA             -
                                                                  STAGE C

1.0       INTRODUCTION
Brown Consulting (Qld) Pty Ltd has been commissioned to undertake a Flood Investigation & Stormwater Quantity

Management Plan to support the Development Application for Stage C of the proposed "Doonella" residential
subdivision at Doonella   -
                              Stage C.
This report outlines the stormwater management strategies that will be adopted for the development to ensure there

are no adverse flood     impacts to adjacent properties as a results of the development. The scope of the investigation
undertaken and discussed in this report is as follows:

          Hydrological investigations and modelling to determine existing peak flows and post development peak flows
          at the downstream site extent;

          Modelling to determine likely changes to peak flows at the downstream site extent that results from the
          proposed residential subdivision;
      .
          Development of a management strategy to mitigate increases in peak flows resulting from the proposed
          residential subdivision at the downstream site boundary, with modelling to confirm the effectiveness of the

         strategy; and

          Hydraulic modelling to determine post development flood levels to confirm proposed lot and road levels have
         appropriate freeboard or acceptable flood immunity along the environmental corridor through the site.

1.1       Past Studies

Various stormwater management plans and related documents have previously been approved by Council prior to the

’Change to an Existing Approval Decision Notice’ issued by Council on 9 May 2008.
The stormwater management plans and related documents prepared by WBM Oceanics Australia did not investigate

flooding in the environmental corridor. The design intent and function proposed by WBM Oceanics Australia for the
management of stormwater at the Doonella subdivision has been considered when reviewing road and lot levels for
the proposed development however, this flood investigation report has been written as a stand alone document and

does not refer to the WBM Oceanics Australia reports.         The influence of flows in the environmental corridor as

determined by this report will not impact on stormwater quantity and quality outlets and infrastructure, and the WBM

Oceanics Australia approved Stormwater Management Plan does not need to be altered to account for the outcomes

of this flood investigation.

The detention basin design and stormwater management strategy for the adjacent residential development located at

the downstream end of the environmental corridor was prepared by JF&P Consulting Engineering Pty Ltd. The JF&P

Site Based Storm water Management Plan, Beckmans Green Noosaville (R~port No. M2099_SBSMP_Rev_D dated

June 2008) details the management strategy for that development and is referred to within this Flood Investigation.




B09182.W-02A                                                                                                      Page 1