Manly Lagoon Dredging Project - Manly Council - NSW Government

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Manly Lagoon Dredging Project – Review of Environmental FactorsPrepared for Manly and Warringah Councilswater samples collected on 30 July 2009, as part of the water quality monitoringprogram (Cardno Ecology Lab, 2010; Appendix H) indicated a large range in values(61 to 2433 CFU/100mL), with the higher values being upstream of the trial location;Interpretation of the PBP (2007) report, and practical experience whilst working in thelagoon suggests that the amount of fine material with which metals, nutrients andbacteria (i.e. enterococci) are associated is likely to be greatest in the uppersediment layers such as those removed during the dredging trial, while the actualdredging program will remove sandier sediments to a depth of up to 1.2m. Hence theresults of the dredging trial are likely to show higher concentrations of the parametersassociated with the fine materials than we expect to be encountered during the actualdredging program; andResidual flocculant in dredge spoil is characterised as having low potential humanhazard. It is not classified as hazardous or carcinogenic, nor are any of its ingredients(Nalco, 2009).In summary, the Trial Dredging 2 report concluded that the treated dredge spoil from the trialwas chemically suitable for application to land and that the overburden water collected fromthe geobags during dewatering would not cause any identifiable environmental harm ifreturned to Manly Lagoon in a controlled manner. The trial concluded that the dredgedsediments from the lagoon will require dosing with lime to neutralise acid sulfate potential(Cardno Ecology Lab, 2009c). There are other parameters that were not tested, includingsalinity and the presence of gross pollutants, which may affect the suitability of the treateddredge spoil for land application.2 July 2010 Cardno (NSW/ACT) Pty Ltd 28H:\Doc\2010\Reports.2010\Rep2580v4.doc
Manly Lagoon Dredging Project – Review of Environmental FactorsPrepared for Manly and Warringah Councils4 Statutory and Planning FrameworkThis REF has been prepared in accordance with NSW Environmental Planning andAssessment legislation, namely the Environmental Planning and Assessment Act 1979(EP&A Act). Under Part 5 of the EP&A Act (Section 111) there is a duty for determiningauthorities to consider the environmental impact of proposed activities. The specific aspectsof these environmental considerations are detailed in Clause 228 of the EnvironmentalPlanning and Assessment Regulation 2000 (EP&A Regulation). Section 5 of this REFidentifies each environmental factor and demonstrates that the requirements of Clause 228have been adequately addressed in this REF.The proposed dredging works do not constitute ‘designated development’ as defined inSchedule 3 (Clause 19 – Extractive Industries) of the EP&A Regulation, as the dredgingworks will be undertaken in accordance with various plans of management for the ManlyLagoon area, as outlined below.The Manly Lagoon Estuary Management Plan (Manly and Warringah Councils, 1998)followed on from the 1995 Manly Lagoon Estuary Management Study (PBP) and used therecommendations contained in this study as a basis for management strategies.The Manly Lagoon Floodplain Management Plan (DLWC, 1997) followed on from the ManlyLagoon Flood Study (MHL, 1992) and Manly Lagoon Floodplain Management Study (DLWC,1996).One of the strategies contained in these plans of management which will be supported bythe proposed works is ‘a program of dredging at selected sites to address water qualityissues’.Specific recommendations of the Manly Lagoon Estuary Management Study (PBP, 1995)have also been incorporated in the District Park Plan of Management (Warringah Council,2002), for example:Enhancement of the side bay upstream of the footbridge linking Passmore and NolanReserve; andRemoval of silt and sediment downstream of the footbridge adjacent to Nolan andPassmore Reserves.In meeting the requirements of the EP&A Act this REF has been informed by and considersthe environmental assessment procedures that are required to be undertaken in accordancewith the range of environmental planning instruments and various pieces of environmentallegislation. These are described below.4.1 State Environmental Planning PoliciesThere are two State Environment Planning Policies (SEPPs) that are applicable to theproposed dredging works.2 July 2010 Cardno (NSW/ACT) Pty Ltd 29H:\Doc\2010\Reports.2010\Rep2580v4.doc
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Manly Lagoon Dredging Project - Manly Council - NSW Government

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