Manly Lagoon Dredging Project - Manly Council - NSW Government

Manly Lagoon Dredging Project – Review of Environmental FactorsPrepared for Manly and Warringah Councils6 Environmental Management6.1 Summary of Mitigation MeasuresEnvironmental mitigation measures relating to each of the aspects considered in this REFare summarised in Table 6.1. The Management Plans discussed in Table 6.1 are all to beincorporated into the overall Construction Environmental Management Plan (CEMP) whichshould be prepared for the proposed works by the contractor.Table 6.1: Summary of Environmental Mitigation Measures for the Proposed WorksParameter(s)Mitigation MeasuresTopography,Geology and SoilsClimate and AirQuality› A construction Environmental Management Plan (CEMP) must be preparedby the contractor detailing how the mitigation measures specified in thisdocument, and the requirements of the technical specification (Appendix K)will be met in full;› An Erosion and Sediment Control Plan (ESCP) needs to be prepared andimplemented in accordance with Managing Urban Stormwater – Soils andConstruction (DoH, 2004);› Mud and dirt must be removed from the wheels and bodies of heavyvehicles leaving the site;› Regular inspection of the site should be undertaken for the duration ofworks to ensure that the ESCP is implemented and maintained;› An Acid Sulfate Soils Management Plan (ASSMP) has been prepared byCardno for the contractor, in accordance with the Acid Sulfate Soils Manual(ASSMAC, 1998). This ASSMP is included in Appendix E;› In order to maintain bank stability, dredging will be undertaken to give amaximum slope on the lagoon bed of 2:1 (horizontal: vertical), and nodredging will take place within 1m of the bank. In addition, the sitesuperintendent may impose additional safety margins at their discretion;› When dredging adjacent to the former landfill site at T.S. Condamine nodisturbance of the banks will be permitted. Visual gross contaminationtesting, for contamination identifiable by sight or smell will be undertakenduring dredging;› If any contaminated sediments are encountered during the proposed works,Manly and Warringah Councils and DECCW should be notified, the wasteshould be classified according to the Waste Classification Guidelines(DECC, 2009d) and DECCW should be consulted regarding appropriatedisposal methods; and› Primary silt curtains will be implemented approximately 25m upstream anddownstream of the area where dredging works are taking place, across thefull profile and depth (at high tide) of the Lagoon, to prevent the movementof any disturbed silt outside the works area. In addition, a secondarydownstream ‘back-up’ silt curtain will be deployed approximately 15mdownstream of the primary curtain.› A Dust Management Plan should be prepared for the proposed works;› Dust pollution should be minimised. Treated dredge spoil must beadequately covered during transportation from the site to minimise dustpollution and relocation of the treated dredge spoil should cease duringperiods of strong winds;2 July 2010 Cardno (NSW/ACT) Pty Ltd 115H:\Doc\2010\Reports.2010\Rep2580v4.doc