Guidelines For Dredging

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BEST PRACTICE ENVIRONMENTAL MANAGEMENTGUIDELINES FOR DREDGING

BEST PRACTICE ENVIRONMENTAL MANAGEMENTGUIDELINES FOR DREDGINGEnvironment Protection Authority40 City Road, SouthbankVictoria 3006 AUSTRALIA Environment Protection Authority, October 2001Publication 691ISBN 0 7306 7578 5Printed on recycled paper

FOREWORDDredging is necessary to create and maintain shipping and boating channels so that we can continue to engagein international trade and to enjoy safe fishing and recreational boating. However, dredging has the potential forsignificant environmental impact. These guidelines identify such impacts and suggest measures that may betaken to minimise them. They have been developed in consultation with organisations that undertake dredging,dredging contractors and conservation interests.In many cases impacts are minimal, but any impacts can cause considerable public concern. For example,discharge of black anaerobic sand onto sandy beaches looks and smells unpleasant, but the environmentalimpacts are minimal, and a typical sand colour returns after a few days exposure to air. Where the impacts ofdredging are poorly known these are identified in the guidelines and addressed through monitoring or targetedresearch where this is considered more appropriate.A new mandatory process for consideration of dredging proposals is outlined. This represents a new steptowards better control of the impacts of dredging that started when EPA developed the Trial Dredge Protocol in1992. It involves a cooperative approach between Environment Protection Authority and the Department ofNatural Resources and Environment, and the issuing of a Coastal Management Act 1995 consent for dredgingworks. Further advances in dredging technology and in our understanding of the major impacts will, in time, leadto further improvements to these guidelines.Finally, I thank members of the Dredge Protocol Management Committee for their contribution to thedevelopment of these guidelines. The technical appendices were written by Greg Parry, Sue Bextream(appendix 6), Gus Fabris (MAFRI, appendix 3) and Andrew Longmore (MAFRI, appendix 4).BRIAN ROBINSONCHAIRMANi

CONTENTSFOREWORD .i1.INTRODUCTION . 11.1Objectives and Scope.21.2 Best Practice Environmental Management (BPEM) .31.3 Using these Guidelines .31.4 How to Apply for Dredging Permits.42.LEGISLATIVE FRAMEWORK . 72.1 History of Controls on Dredging . 72.2 Legislation that Affects Dredging Proposals . 73.ENVIRONMENTAL CONTROLS . 103.1 Minimise the Need for Dredging and Spoil Disposal. 103.2 Minimise Physical Effects of Spoil Disposal . 123.3 Minimise Effects of Contaminated Sediments. 153.4 Minimise Effects on Water Quality. 193.5 Optimise Dredging and Disposal Methods . 233.6 Control of Noise.283.7 Control of Odour .293.8 Establish Appropriate Monitoring Programs .304.ENVIRONMENTAL MANAGEMENT. 354.1 Environmental Improvement Plans.36APPENDIX 1: APPLICATION FORM FOR SECTION 40 (COASTAL MANAGEMENT ACT 1995)CONSENT FOR A DREDGING PROPOSAL.38APPENDIX 2: DREDGING OPERATIONS AND IMPACTS. 43APPENDIX 3: TECHNICAL GUIDELINES FOR ASSESSMENT OF CHEMICAL CONTAMINATIONOF DREDGED SEDIMENTS. 55APPENDIX 4: ESTIMATED NUTRIENT RELEASE BY DREDGING . 76APPENDIX 5: ESTIMATED MAXIMUM SUSTAINED TURBIDITY TO MAINTAIN SEAGRASS HEALTH . 79

APPENDIX 6: IMPLICATIONS OF FISH LIFE HISTORIES FOR DREDGING PRACTICES IN PORT PHILLIP BAY .83APPENDIX 7: CHECKLIST OF ISSUES REQUIRING CONSIDERATION FOR LAND DISPOSAL. 95APPENDIX 8: FORMAT FOR SUBMISSION OF ELECTRONIC MONITORING DATA TO EPA . 97GLOSSARY .99REFERENCES . 102TablesTable 1: Average sediment volumes (m3) dredged per annum to maintain channels in Victorian coastal regions.2Table 2: Typical number sediment cores to be sampled for dredging proposals removing different volumes ofmaterial (summarised from appendix 3). 14Table 3: Months in which the eggs (E), larvae (L), juveniles (J), and adults (A) of marine and estuarine fish inVictoria may be vulnerable to dredging impacts. Months in which a life-history phase of a species is sufficientlyaggregated that its vulnerability to dredging should be considered when determining the timing of dredging areshown in bold (see appendix 6 for details) . 24Table 4: Examples of typical noise limits for various types of land use, based on (1) Interim Guidelines for Controlof Noise in Country Victoria, and (2) SEPP No. N-1.30Table 5: Guidance on selection of appropriate dredges for maintenance dredging (from Bray et al. 1997). 47Table 6: Guidance on selection of appropriate dredges for capital dredging (from Bray et al. 1997) .48Table 7: Typical number of sediment cores to be sampled for dredging proposals removing different volumes ofmaterial. 59Table 8: Sample collection methods, storage conditions and holding times for the various analyses (from USEPA1991, ANZECC 1998).62Table 9: Recommended quantities of sediment or water required for various analyses(USEPA 1991; ANZECC 1998).63Table 10: Classification of grain size of sediments based on the Udden-Wentworthgrain size scale (Lewis 1984) .64Table 11: Desirable detection for contaminants in sediment and elutriate samples, basedon ANZECC (1992b) .68Table 12: Minimum and maximum screening levels for contaminants for sediments (ANZECC 1998, ANZECC ARMCANZ, 2001) and twice background levels for selected contaminants in Port Phillip Bay. Water-qualityguidelines for elutriate solutions are also shown. Consult the responsible authority for contaminants not listed 73

Table 13: Nutrient concentrations in pore water (µmol.L-1) from different regions of Port Phillip Bay,representative values from Nicholson et al. 1996 . 76Table 14: Estimated release rates of nutrients (kg/day), using data from table 1, equation 1, and theassumptions on the previous page . 77Table 15: Typical release rates (kg/day) of nutrients from major sources in Port Phillip Bay,Longmore et al. 1996. 77Table 16: Increase in concentration (µg L-1 d –1 of the element) in the water column for different regions of PortPhillip Bay, using Equation 2 and the assumptions on the previous page . 78Table 17: Range of mean concentrations (µg L-1 d –1 of the element) for nutrients in different regions of Port PhillipBay, Longmore et al. 1996. ND not determined. 78Table 18: Background measurements of attenuation coefficient for PAR in Geelong Arm.80Table 19: Frequency distribution of turbidity at 7 sites monitored continuously (15 min intervals) betweenFebruary 1996 and December 1996. 81Table 20: Habitats for marine and estuarine fish of commercial, recreational and conservation importance inVictorian coastal waters .84Table 21: Months in which the eggs (E), larvae (L), juveniles (J), and adults (A) of marine and estuarine fish inVictoria may be vulnerable to dredging impacts.84Table 22: Dredging monitoring database fields .98FiguresFigure 1: Dredging approvals process for all maintenance dredging and capital dredging in areas notsubject to a planning scheme or EES. 5Figure 2: Flowchart for assessment of contamination status of sediments to be dredged . 56

1.INTRODUCTIONThese guidelines have been developed to adviseagencies of environmental requirements fordredging in Victorian waters. They apply to bothdredging and disposal of sediments within Victorianjurisdiction. It is noted that disposal of sedimentsoff the open coast (rare in Victoria) also requires aCommonwealth permit, though sand bypassing andbeach renourishment are normally exempt.also significantly greater than in Victoria as a resultof much larger manufacturing industries havingdischarged contaminants. For example,polychlorinated biphenyls (PCBs) are majorcontaminants in several US rivers near the site ofmanufacture. PCBs are persistent toxicants inVictorian sediments, but, as they were nevermanufactured locally, quantities are seldom ofconcern and they are far below those ofcontaminated US rivers.These guidelines are based on many years ofexperience using the “Trial Dredge Protocol” and onan independent review of its effectiveness. Theyalso take into account the ANZECC guidelines fordisposal of sediments in waters underCommonwealth jurisdiction. When justified by newknowledge or understanding, the Guidelines will berevised accordingly.In Victoria most dredged sediment is clean sand(table 1). Large quantities of sand are dredgedannually to bypass harbours at Lakes Entrance,Portland and Queenscliff and in sections of shippingchannels where sand waves cause shoaling. Partsof a three nautical mile (n mile) and a 5 n milesection of South Channel in Port Phillip Bay andparts of a 1 n mile sector in Western Port shippingIn Victoria, maintenance dredging removesapproximately 1.2 million m3 of sediment annuallyfrom shipping and boating channels (table 1).Capital dredging projects occur when there is aneed for new or deeper channels. In recent years,channel are dredged periodically. There are alsomany smaller dredging projects undertaken toremove sand accumulated behind man-madecoastal structures or from the mouths of creeks andrivers to maintain navigational channels.major capital dredging works have includeddeepening the Geelong Channel (five million m31997), creation of a new berth at Webb DockThe largest volume of fine sediments is dredgedfrom shipping channels, including parts of the Yarra(450,000 m3 1997) and dredging turning basins andRiver, in the Port of Melbourne. This is deposited inberth pockets in Western Port (1.5 million m3 1967–a spoil ground 15 km south of Melbourne. Small73).quantities of fine sediments are also dredged fromshallow channels in Western Port as required.On an international scale the amount of dredging inVictoria is small. In the USA, more than 230 millionm3 are dredged annually from waterways and asimilar volume is dredged in Europe, with 40 millionTypically, fine muddy sediments cause greaterenvironmental problems as they are more likely tobe contaminated and they cause more persistentturbidity than does sand.m3 being dredged annually from waterways in theNetherlands alone (Donze 1990). The proportion ofcontaminated sediment in Europe and the USA isMaintenance dredging often involves the removal ofsediments recently deposited from estuaries. This11

dredging can be minimised by improved catchmentWestern Port 15,000management. Erosion controls in the catchmentShipping channels10,000*reduce the sediment load in rivers and reduce theSmall-boat harbours/creeks 5,000need for dredging downstream. Similarly, controlsEastern Victoriaon discharges of toxic chemicals into streamsCorner Inletreduces sediment contamination within the estuaryLakes Entrance (main entrance)and avoids the need for expensive procedures toGippsland Lakes, internal channels70,000reduce the impact of contaminated sediment whenGippsland Lakes, others70,000510,00070,000300,000dredging. In Victoria, improved environmentalregulation since the 1970s has reduced the input ofTotal1,227,000many contaminants. However, as a result ofhistorical inputs and non-point source*Based on 30,000 m3 dredged in sand wave field in1995, but not dredged since.contamination, lead from petrol and zinc fromgalvanised surfaces are still evident, and these aredifficult to control. Since the 1970s, discharges of1.1Objectives and Scopeheavy metals have declined and use of manyWater-based recreation (including boating andpersistent organics has ceased. Levels of cadmiumfishing), navigation and shipping, and maintenancein Corio Bay (Phillips et al. 1992) and mercury inof natural ecosystems are all protected beneficialflathead in Port Phillip Bay (Fabris et al. 1992) haveuses in Victorian coastal waters (EPA 1988).decreased markedly since the 1970s, and the useDredging is required to create and maintainof polychlorinated biphenyls (PCBs) and DDT,channels for shipping and boating, adequateceased during the 1970s (Phillips et al. 1992).channel depth being necessary to guaranteeTable 1: Average sediment volumes (m3) dredged perannum to maintain channels in Victorian coastalregionsLocation3Volume (m )important trade links, and to allow safe access forfishing and other commercial and recreationalboating. However, the removal and disposal ofsediments inevitably has some environmentalWestern Victoria172,000impact. Best practice involves minimising thesePortland fixed bypass110,000impacts at and near the dredging and disposalPort Fairy32,000sites. Both the cost and effectiveness of measuresApollo Bay30,000to reduce impacts need to be considered. For530,000example, costly measures to minimise smallPort Phillip BayQueenscliff90,000impacts due to limited turbidity or sedimentation,South Channel150,000adjacent to greatly modified dredge sites or spoilPort of Melbourne200,000grounds, are often not justified.Yarra (N of City Link bridge)15,000Small-boat harbours/creeks75,0002Many in the community are concerned that ourestuaries and seas are protected. While mostly

appreciating the need for safe navigation, theseBPEM publications outline key objectives relevantconcerned individuals and organisations need anto the industry or activity and suggest measures toassurance that dredging is being undertaken in aachieve these objectives. However, operatorsway that minimises environmental impacts. Theseshould feel free to consider alternatives and toguidelines describe those issues that should beapply the best site-specific solution equivalent to,addressed in order to minimise the environmentalor better than, the suggested measure. In this way,impact of dredging, and suggest measures toinnovation is not stifled and flexibility is provided,minimise impacts. Dredging technology and thewhile those seeking greater direction or certaintyeffects of dredging on the environment are alsocan apply the suggested measures.described, to better focus concerns on the moresignificant environmental issues. Most dredging inVictoria is undertaken by a small number ofagencies, most of which have had input into thedevelopment of these guidelines.1.2Best Practice EnvironmentalManagement (BPEM)The underlying philosophy of BPEM guidelines is toprovide a forward-looking approach rather thansimply reflect what is presently the norm. Whereproblems or issues occur within the industry, adirection or solution will be included.A comprehensive environmental managementsystem is an integral part of Best PracticeThe BPEM publication series provides guidelinesEnvironmental Management. For large dredgingand codes of practice for industry sectors orprojects, the principles outlined by the Internationalactivities. They outline what is needed to achieveOrganisation of Standardisation in the ISO 14000optimum environmental outcomes, consistent withseries, provide an ideal basis for such athe industry’s economic viability.management system.BPEM may encompass site selection, processFinally, a BPEM guideline is not of itself mandatorydesign, technology choice, key operatingbut the potential exists to call up such a documentparameters and procedures, contingencyin approvals, licences or permits. Regulatoryarrange

also take into account the ANZECC guidelines for disposal of sediments in waters under Commonwealth jurisdiction. When justified by new knowledge or understanding, the Guidelines will be revised accordingly. In Victoria, maintenance dredging removes approximately 1.2 million m3 of sediment annually from shipping and boating channels (table 1).

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