Manly Lagoon Dredging Project - Manly Council - NSW Government

Manly Lagoon Dredging Project – Review of Environmental FactorsPrepared for Manly and Warringah Councils3 Specialist Studies, Stakeholder Consultation and Trials3.1 Specialist StudiesA number of specialist studies have either been referred to or commissioned to support thedevelopment of this REF. The purpose of the specialist reports has been to evaluate in detailspecific aspects or impacts of the project, and to identify mitigation measures required toprevent or reduce negative impact to acceptable levels. In general, reports which have beencommissioned relate specifically to those environmental risks which are perceived to begreatest, and focus primarily on water quality, and the associated risks to flora and fauna.It can be concluded from the specialist reports that provided the mitigation measuresidentified in Sections 5 and 6, are fully implemented, the proposed dredging and dewateringcan be carried out in a manner which is not expected to give rise to any significant or longterm negative environmental impacts.The following specialist studies have been considered in the preparation of this REF.Acid Sulfate Soils (ASS) AssessmentInformation on ASS within Manly Lagoon is contained in the following specialist studies: Manly Lagoon Rehabilitation Works, Site 1, Site 2 and Site 3 Vibrocoring and PushCore Sediment Sampling Exercise, involving sediment sampling undertaken by PBP(2002); Draft Manly Lagoon Rehabilitation Works, Sediment Removal from Sites 1 and 2,Statement of Environmental Effects, involving further reporting of sediment samplingundertaken by PBP (2003a); and Results of Trial Dredging 2 – Manly Lagoon Dredging Project, involving sediment andwater quality sampling undertaken by Cardno Ecology Lab (2009c) for this REF(contained in Appendix C).These studies indicate the presence of PASS and ASS within Manly Lagoon. The resultsand implications of these studies are discussed in Section 5.1.Benthic FaunaInformation on benthic fauna within Manly Lagoon is contained in the following specialiststudies: Manly Lagoon Water Quality – Benthos Report Before Dredging undertaken byCardno Ecology Lab (2009b) (contained in Appendix F).This recent study (undertaken in July 2009) indicates that limited benthic fauna exists in thearea where proposed dredging works are to take place. The results of this study arediscussed further in Section 5.4.2.2 July 2010 Cardno (NSW/ACT) Pty Ltd 16H:\Doc\2010\Reports.2010\Rep2580v4.doc