ECM_22343539_v1_Stormwater Management Report

                  Temporary Drainage Works                        Anticipated Operation Design Life and Minimum
                                                                               Design Storm Event


                                                                  <12 Months        12-24 Months         >24 Months

                  Where located immediately up-slope of an                     1 in 10 year ARI/10% AEP
                  occupied property that would be adversely
                  affected by the failure or overtopping of the
                  structure

                  Culvert Crossing                                             1 in 1 year ARI/63% AEP


                 Table 4 – SPP Appendix 2: Part 3 Construction Phase – Stormwater Management Design Objectives
                 for Emergency Spillways on Temporary Sediment Basins

                               Drainage Structure                 Anticipated Operation Design Life and Minimum
                                                                               Design Storm Event


                                                                   <3 Months         3-12 Months         >12 Months

                  Emergency spillways         on     temporary     1 in 10 year      1 in 20 year        1 in 50 year
                  sediment basins                                 ARI/10% AEP        ARI/5% AEP          ARI/2% AEP

                 Best practice erosion and sediment controls must be installed to minimise the discharge of sediment
                 laden runoff during construction and to achieve the objectives outlined in Tables 2-4. This is discussed
                 in the following section.
                 4.2.2 E ro sio n and Se dim en t Co ntr ol

                 Management of stormwater runoff during construction is necessary to avoid pollution of downstream
                 waterways from sediment and gross pollutant loading. 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.

                 Best practice erosion and sediment controls must be installed to minimise the discharge of sediment
                 laden runoff during construction. Erosion and sediment control plans shall be developed during detailed
                 design phase and must be continually maintained and amended as required to minimise environmental
                 harm.
                 Erosion and sediment control plans are based on three sets of control measures:

                     •    drainage control;

                     •    erosion control; and

                     •    sediment control.


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Document Set ID: 22343539
Version: 1, Version Date: 16/03/2023