The Disposal of Contaminated Dredged Material from Greater Vancouver, British Columbia, Into the Neighbouring Strait of Georgia
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ALL DREDGED UP AND NO PLACE TO GO: THE DISPOSAL OF CONTAMINATED DREDGED MATERIAL FROM GREATER VANCOUVER, BRITISH COLUMBIA, INTO THE NEIGHBOURING STRAIT OF GEORGIA By RICHARD ARTHUR GORHAM LL.B., The University of Western Australia, 1974 B.Sc, The University of British Columbia, 1979 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Resource Management Science) . We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1985 ©Richard Arthur Gorham, 1985 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6(3/81) i i ABSTRACT The thesis provides an integrated review and analysis of strategic scientific information from which management procedures for the environmentally acceptable disposal of dredged materials from Greater Vancouver into the Strait of Georgia are determined. An analysis of reported and suspected contamination of Vancouver's waterways identifies trace metals and hydrophobic organic chemicals that warrant concern by authorities responsible for the management of dredged material disposal. The processes, transformations and pathways of these contaminants in the marine environment subsequent to dredged material disposal are reviewed. It is argued that areally confined degradation of suitable disposal sites is of negligible concern, but that release of contaminants from the disposal area, were it to occur, could have unpredictable and perhaps substantial environmental conse• quences. The major potential pathway of contaminant release from dredged material during or subsequent to disposal is via the resuspension and transport of fine particulate material. Biological accumulation of contaminants and their trans• port through the food chain is a potentially significant release pathway for hydrophobic organic contaminants. Biological transformation to more soluble metabolites is also potentially significant for mercury and some of the less chlorinated and lower molecular weight organic compounds of concern. Desorptive release of contaminants from the disposed sediments into solution is usually negligible, with the possible exceptions of cadmium and mercury. i i i A review of the physical factors that promote contaminated sediment erosion and dispersion during or subsequent to dredged material disposal identifies oceanographic characteristics where such release will be minimal. There are only four areas within the Strait of Georgia that exhibit these characteristics. Two of these areas are adjacent to valuable and sensitive biological resources and are consequently unsuitable as ocean dumping sites. Dredged material disposal at the other two sites, one near Smelt Bay, Cortes Island, and the other off McNaughton Point, Sechelt Peninsula, should result in minimal adverse environmental impact. Available methodologies to identify dredged materials with contaminant levels that preclude their environmentally acceptable disposal at these recommended sites are discussed. i v TABLE OF CONTENTS Page No. Title Page Acknowledgements ix 1.0 INTRODUCTION I 1.1 Study Purpose 8 2.0 A SCIENTIFIC PERSPECTIVE I I 2.1 Containment or Dispersion II 2.2 Release 14 2.3 The Chemistry of Contaminant Behaviour 15 2.4 Chemicals of Environmental Concern 19 3.0 DREDGING AND DREDGED MATERIALS IN THE LOWER MAINLAND 22 3.1 Dredging in the Vancouver Region 22 3.2 Sediment Contaminants in the Vancouver Region 25 3.2.1 Trace Metals 36 3.2.2 Organic Contaminants 42 3.3 Conclusion 56 4.0 TRACE METAL PATHWAYS AND PROCESSES IN THE MARINE ENVIRONMENT 59 4.1 Introduction 59 4.1.1 Trace Metal Speciation 62 4.2 Trace Metal Release During Water Column Passage 66 4.2.1 Salinity Alteration 67 4.2.2 Alteration of Redox and pH Conditions 70 4.2.3 Field Monitoring 75 4.3 Trace Metal Release from Settled Sediments 77 4.3.1 Chemical Release Processes 77 4.3.2 Biological Release Processes 81 4.3.3 Conclusion 1 92 4.4 Environmental Effects of Released Trace Metals 96 4.4.1 Cadmium 96 4.4.2 Mercury 99 V Page No. 5.0 ORGANIC POLLUTANT PATHWAYS AND PROCESSES IN THE MARINE ENVIRONMENT 104 5.1 Introduction 104 5.2 Release of Organic Contaminants to the Water Column 106 5.3 Biological Uptake of Organic Contaminants 117 5.4 Biological Transformation 127 5.4.1 Microbial Degradation 128 5.4.2 Metabolism by Higher Organisms 129 5.5 Properties, Bioaccumulation and Metabolism of Organic Contaminants of Concern 131 5.5.1 Polychlorinated Biphenyls (PCBs) 5.5.2 Hexachlorobutadiene (HCBD) 136 5.5.3 Polychlorinated Dibenzofurans (PCDF) 138 5.5.4 Pentachlorophenol (PCP) 140 5.5.5 Chlorinated Benzenes 141 5.5.6 Polyaromatic Hydrocarbons (PAHs) 144 5.5.7 Phthalate Esters (PAEs) 150 5.6 Conclusion 152 6.0 • PROCESSES EFFECTING THE PHYSICAL DISTRIBUTION OF DISPOSED DREDGED MATERIAL 157 6.1 Introduction 157 6.2 During Water Column Passage 158 6.3 Subsequent to Settling 161 6.3.1 Physical Factors Effecting Sediment Resuspension 161 6.3.2 Biological Factors Effecting Sediment Resuspension 165 6.4 Conclusion 167 7.0 DISPOSAL SITE OPPORTUNITIES WITHIN GEORGIA STRAIT 170 7.1 Recommended Disposal Site Characteristics 170 7.2 Identification of Potential Disposal Sites 173 8.0 RESOURCES IN CONFLICT 182 8.1 Introduction 182 8.2 Groundfish 185 8.3 Bent hie Crustaceans > 189 8.4 Molluscs 191 8.5 Pelagic Fish 196 8.6 Marine Mammals 202 8.7 Marine Birds 204 8.8 Human Recreation 209 8.9 Parks and Reserves 21 I 8.10 Cone lusion 213 Page No. 9.0 CONCLUSIONS 221 9.1 Introduction 221 9.2 Dredged Sediment Criteria 225 9.3 The Need for Field Assessment 230 10.0 LITERATURE CITED 233 VI 1 LIST OF FIGURES Figure Page No. 1. Location map - Strait of Georgia 4 2. Location map - Greater Vancouver 5 3. Schematic representation of contaminant transport and fate 16 k. Freundlich adsorption isotherm 108 5. Bioaccumulation of six chlorinated benzenes in guppies 121 6. Relationship between current, speed, particle diameter, and sediment erosion, transport and deposition. 163 7. Georgia Strait - Location of proposed dumpsites 175 8. Location of proposed North Stuart Channel dumpsite (Area I) 176 9. Location of proposed McNaughton Point dumpsite (Area 2) 177 10. Location of proposed Comox and Denman Island dumpsites (Area 3) 178 11. Location of proposed Smelt Bay dumpsite (Area k) 179 vii i LIST OF TABLES Table Page No. I. Comparative towing costs for Point Grey and ocean disposal sites. 6 II. Quantity of dredged materials disposed at dumpsites adjacent to the lower mainland, 1976-79. 24 III. Contaminant concentrations in False Creek and Burrard Inlet sediments. 26 IV. Potential anthropogenic sources of trace metal contamination of Vancouver's water• ways. 29 V. Canadian Environmental Contaminants Act list of priority chemicals. 31 VI. EPA priority pollutant list showing classi• fication by extraction group. 33 VII. Priority ratings for industrial chemicals in British Columbia and the Yukon. 34 VIII. Contaminants of concern identified or sus• pected within Vancouver sediments. 37 IX. Trace metals in sediments of the Fraser River. 38 X. Levels of metals in sediments from the Fraser River and the Columbia River, B.C. 40 XI. Summary of incidents of human poisoning by toxic metals in the aguatic environment of Japan. 61 XII. Mechanisms for trace mineral bonding. 64 XIII. Potential dredged material disposal areas in Georgia Strait. 174 XIV. Species names of organisms cited in Section 8.0. 184 XV. Quantification of resource conflicts at the proposed ocean dumping sites. 214 XVI. Comparative towing costs for recommended disposal sites. 218 ix ACKNOWLEDGEMENTS The successful completion of this thesis is in no small part due to my wife, Catherine, who has given me encouragement and support (as well as a charming daughter) during its preparation. I also owe extreme gratitude to Maria Mees for her uncomplaining and extremely efficient word processing of the manu• script. 1 INTRODUCTION The environmental management of dredged materials is faced with the residue of past neglect. Urban, agricultural and industrial activities adjacent to many areas of our coast have resulted in accumulations of contaminants within the sediments. The sediments of protected bays and estuarine areas are especially prone to interrment of contami• nants. Sediments that have been contaminated by chemicals from surface runoff and groundwater inflow, or from industrial and domestic waste discharges, present a difficult problem when dredging is required. The removal and relocation of coastal and harbour sediments is often essential to establish and maintain navigational waterways and port facilities. However it can also promote the release of potentially deleterious materials into the pelagic and benthic environment. If this release tends to favour uptake of the contaminants by marine organisms, then either short- or long-term deleterious effects may occur. Dredging and dredged material disposal involves the mechanical agitation of the sediments, their exposure to the water column and their relocation into a physical, chemical and biological environment that may differ substantially from the dredged site. Contaminant release may result from each of these processes. 2 Water quality perturbations at the dredge site generally subside rapidly upon cessation of dredging activities (Lee, 1976; Fulk, Gruber and Wullschleger, 1975; Wakeman, 1976; Hoos, 1976). Mitigative measures (e.g. techniques, timing and rate of dredging) may be necessary to reduce potential impacts upon particularly sensitive biota, but our dependence upon navigable waterways will otherwise generally override our concern for the short-term environmental effects at the dredge site.