Stormwater Management Plan MCU17/0014

BORNHORST + WARD | DOONELLA STREET UNITS


                              1) a material change of use for urban purposes that involves a land area greater than 2500 square
                                 metres that:
                                     a) will result in an impervious area greater than 25 per cent of the net developable area, or
                                     b) will result in six or more dwellings, or
                              2) reconfiguring a lot for urban purposes that involves a land area greater than 2500 square metres
                                 and will result in six or more lots, or
                              3) operational works for urban purposes that involve disturbing more than 2500 square metres of
                                 land.

                    As the proposed development is for a material change of use that involves greater than 2500m2 of land, the
                    State Planning Policy requirements for water quality are applicable to the proposed development. As such,
                    stormwater quality treatment is proposed for development to ensure state requirements are achieved. The
                    effectiveness of the system at achieving water quality objectives was modelling using MUSIC.

         5.1        POLLUTANTS OF CONCERN

                    The key pollutants to be targeted and the minimum reductions in mean annual loads described in the State
                    Planning Policy for the South East Queensland Region area outlined in Table 4.

                                                    Table 2: South East Queensland Water Quality Objectives
                                             Pollutant                         Reduction in Mean Annual Load

                                             Total Suspended Solids (TSS)                   80%
                                             Total Phosphorus (TP)                          60%
                                             Total Nitrogen (TN)                            45%
                                             Gross Pollutants (GP)                          90%



         5.2        MODELLING/ASSESSMENT APPROACH

                    A quantitative assessment of stormwater runoff quality was considered for the catchments ultimate developed
                    scenario.

                   The predicted reductions in mean annual loads of key pollutants have been identified using the “Model for
                   Urban Stormwater Improvement Conceptualisation” (MUSIC), Version 6 (6.1.0). MUSIC is a stormwater quality
                   modelling program that provides estimates of stormwater pollution generation and the performance of
                   stormwater management measures used in series or parallel to form a ‘treatment train’.

         5.2.1      Meteorological Data

                    The first step in creating the MUSIC model was to select the appropriate meteorological data set (period and
                    time step) to be used as the basis for the runoff algorithms. Section 3.1 – Meteorological Data and Section 3.2
                    – Modelling Period and time-step, of the MUSC Modelling Guidelines details the Rainfall Data and Time Step
                    process requirements of the model, respectively.

                    The time step used for the MUSIC modelling process was: Tewantin RSL Park - 6 Minutes.




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