AS PUBLISHED Negotiated Report (Representations made) MCU23 0094 · MCU23/0094

                                    runoff and ensures that sediment basins are sized to accommodate the additional
                                    volume of runoff.
                              (iii) Prior to each rainfall event ensure concentrated stormwater flow paths are
                                    provided with capacity in accordance with IECA (2008) Table 4.3.1 and do not
                                    cause water contamination, rill or gully erosion, sedimentation or damage to
                                    structures or property
                      (e)     Minimise sediment released from the site
                              (i)   All site sub-catchments greater than 2,500m2 in area, are to be provided with
                                    sediment controls which are designed, implemented and maintained to a
                                    standard which would achieve at least 80% of the average annual runoff volume
                                    of the contributing catchment treated (i.e. 80% hydrological effectiveness) to
                                    50mg/L Total Suspended Solids (TSS) or less, and pH in the range 6.5–8.5.
                                    Where this is proposed to be achieved through the use of sediment basins, the
                                    following applies:
                                     (i) each basin is sized and operated in accordance with either a Type-A or
                                           Type-B sediment basin as documented in IECA (2008) Appendix B (June
                                           2018), based on the contributing catchment area including undisturbed
                                           catchments which cannot be diverted;
                                     (ii) each basin is to be provided with an automated system of flocculant dosing
                                           and a suitable supply of flocculant/coagulant, with the type of
                                           flocculant/coagulant determined based on Chemical Coagulants and
                                           Flocculants Fact Sheet (IECA, 2018);
                                     (iii) markers are provided within each basin indicating the maximum sediment
                                           storage level and any additional water storage capacity for water reuse
                                     (iv) during discharge from the primary outlet system, the concentration of total
                                           suspended solids (TSS) discharged does not exceed 50mg/L and that pH is
                                           within the range of 6.5-8.54. These discharge standards apply equally to any
                                           intentional release of any water captured or stored within the site;
                                     (v) The hydraulic structures such as inlets, outlets, spillways must be
                                           structurally sound for the design events as specified in IECA (2008); and
                                     (vi) The sediment basin is to be constructed and operational before any
                                           disturbance occurs in the catchment upslope of the basin. Accumulated
                                           sediment from basins and other controls is to be removed and disposed of
                                           appropriately without causing water contamination.
                              (ii) For site sub-catchments less than 2,500m2 in area and where it is not feasible to
                                    divert runoff from these small disturbed areas of the site to a sediment basin,
                                    compensatory erosion and sediment controls are implemented prior to rainfall to
                                    ensure that erosion of those of areas is minimised and Type 2 or Type 3 sediment
                                    controls are provided in accordance with IECA (2008).
                              (iii) Controls are to be installed to minimise the tracking of dirt from the site onto
                                    roadways. Any dirt on roadways caused by vehicles leaving the site is to be
                                    removed without causing water contamination, prior to rainfall and at least at the
                                    end of each work day.
                      (f)     Manage works within waterways
                              (i)   Waterways, including perennial and permanent waterways, are not to be altered,
                                    nor riparian (including rehabilitated) vegetation disturbed without prior written
                                    approval of the relevant administering authority.
                              (ii) Work within waterways is to be:-
                                     (i) only undertaken during the lower rainfall months;
                                     (ii) promptly rehabilitated conforming to the natural channel form, substrates
                                           and riparian vegetation as far as possible; and
                                     (iii) undertaken in accordance with Best Practice Erosion and Sediment Control,
                                           Appendix I – Instream works, Sections 14 and 16, (International Erosion
                                           Control Association, 2008).
                              (iii) Temporary vehicular crossings of waterways are to be designed and constructed
                                    to convey flows for the 63%AEP and remain stable for all rainfall events up to the
                                    10% AEP event of critical duration.

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Document Set ID: 22926712
Version: 8, Version Date: 13/05/2024