Stormwater Management Report

4. 2       Con st ruc t io n Ph a se

Management of stormwater runoff during construction and the implementation of an erosion & sediment
control program is necessary to avoid impacts to receiving waters from pollutants typically generated
during the construction phase. Typical pollutants are described in Table 1 below:

Table 1 – Pollutants Typically Generated During the Construction Phase

              Pollutant                                            Sources

 Litter (Gross Pollutants)         Paper, construction packaging, food packaging, cement bags.

 Sediment                          Unprotected exposed soils and stockpiles during earthworks and building.

 Hydrocarbons                      Fuel and oil spills, leaks from construction equipment.

 Toxic materials                   Cement slurry, asphalt prime, solvents, cleaning agents, wash waters.

 pH altering substances            Acid sulphate soils, cement slurry and wash waters.

In addition to the degradation of receiving waters, impacts of inadequate erosion and sediment control
downstream from the site include:
       •    traffic safety problems;

       •    blocked drains;

       •    local flooding problems;
       •    aesthetic pollution of drainage paths; and

       •    damage to local ecosystems.
4.2.1 De si gn O bj e ct i v es

Management of stormwater runoff during construction should be undertaken in accordance with
Appendix 2 of the SPP (July 2017). The SPP outlines the design objectives for construction phase
stormwater management. These are presented in Table 2, Table 3 and Table 4.

Table 2 – SPP Appendix 2: Part 1 Construction Phase – Stormwater Management Design Objectives

               Issue             Desired Outcomes




 Drainage Control                1. Manage stormwater flows around or through areas of exposed soil to
                                    avoid contamination.

                                 2. Manage sheet flows in order to avoid or minimise the generation of rill or
                                    gully erosion.

                                 3. Provide stable concentrated flow paths to achieve the construction
                                    phase stormwater management design objectives for temporary
                                    drainage works (part 2).

                                 4. Provide emergency spillways for sediment basins to achieve the
                                    construction phase stormwater management design objectives for
                                    emergency spillways on temporary sediment basins (part 3).



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