App B - Swmp

LINDSAY CONSULTING PTY LTD- STRUCTURAL AND CIVIL ENGINEERS
ACN 079 744 808 ABN 61 478 386 385 GST REGISTERED, AS TRUSTEE FOR THE LINDSAY FAMILY TRUST


       1.      INTRODUCTION


                The proposed development is a 3 unit double storey townhouse unit development, which
                is to be constructed at 11 Robert Street, Noosaville The purpose of this report is to
                determine the runoff from the site and to mitigate this runoff to a pre-development 0.10
                AER flow through the use of an above ground detention tank.


                The stormwater system is to be a gravity system connected into the existing stormwater
                system at the road frontage.


                In carrying out this report the following Standards and Policies have been utilised:-


                    •   Noosa Council Town Planning Scheme
                    •   Australian Rainfall and Runoff 2016
                    •   Queensland Urban Design Manual 2018


       2.      CATCHMENT CHARACTORISTICS AND HYDROLOGY


                The site is a 1296 sqm residential site with the site to be predominantly non-impervious.
                All roofs for the proposed development shall be directed to the detention tank.


                Due to the small size of the catchment the rational method was adopted in calculating the
                runoff from the site.


                The kinematic wave equation was used to determine the critical time of concentration for
                the catchment based on the rainfall from the site as calculated using ARR 2016 for
                various event intervals.


                Coefficients of runoffs from QUDM were utlised in the calculations of the runoffs from
                the site for the various return intervals.


                As per the spreadsheet contained in appendix A the runoff from the entire site was
                determined to be 59 lt/sec for the 0.10 AER and 103l/s for the 0.01 AEP for a 10 Minute
                storm with the non-worsening volume for the site for the 0.01 AEP storm determined to
                be 9000 lt. Refer calculations and table below:-




REF: 240771                                            2                        20 August 2025