The Environmental Impact of Submarine Tailings Disposal at the Island Copper Mine on Vancouver Island:
A Case History in Environmental Policy
Patrick Moore, Ph.D., Clem Pelletier, and Ian Horne, RPBio
In 1971 the government of British Columbia issued a permit for the Island Copper Mine to commence disposal of 33,000 tons per day of mine tailings into Rupert Inlet, a marine fjord on the northwest coast of Vancouver Island. There was considerable controversy surrounding the development, public hearings were held, and as a requirement of the permit the company was obliged to carry out a comprehensive environmental monitoring program. The results of this program provide a thorough assessment of the environmental impact of submarine tailings disposal over the 24-year life of the mine. Following closure in December, 1995, the monitoring program is continuing in order to determine the extent of marine ecosystem recovery and re-colonization. It is apparent from the findings of the monitoring program that the mine tailings were dispersed more widely than was originally predicted. It is also clear that widespread heavy metal contamination has not materialized. In retrospect it appears that submarine tailings disposal has resulted in far less severe environmental impacts than if the alternative of land disposal had been adopted. This review highlights significant aspects of public policy decision-making, design of environmental monitoring programs, and questions of interpretation of monitoring program data.
Key Words: Mine Tailings, Heavy Metals, Marine Disposal, Environmental Monitoring, Mining, Pollution.
1. The Pre-Operational Phase
When the Island Copper Mine closed in 1995, after 24 years of continuous operation, it had produced 1.3 million t of copper, 31,000 t of molybdenum, 329 t of silver, 31.7 t of gold and 27 t of rhenium. The mine had been at the center of a controversy over the environmental impact of its submarine tailings disposal system for most of its 24 year ife. Two years after closure, it is now possible to review these impacts and to observe the prospects for ecosystem recovery following the cessation of waste disposal.
In 1963, prospector Gordon Milbourne found signs of copper ore under two fallen trees near Rupert Inlet on the northern end of Vancouver Island (Aspinall, 1995). By 1969 an exploration program conducted by Utah Construction and Mining Ltd. confirmed a viable ore-body with 280 million t of low-grade ore containing copper and molybdenum and trace amounts of gold, silver and rhenium. In deciding to proceed with the development of an open-pit mine, the company did not realize that the Island Copper Mine would become a landmark in the evolution of environmental policy and law in British Columbia and Canada.
The ore body lay beneath thick second-growth rainforest on a deep layer of glacial deposit and was situated immediately adjacent to the sea on the shore of Rupert Inlet. The inlet is an extension of the Pacific Ocean and this provided the benefit of direct dockside loading of mineral concentrate onto ships bound for markets in Asia. The mine’s proximity to the sea presented some problems, however, with the disposal of waste.
1.2 The Choices: Mine or No Mine, Land or Sea Tailings Disposal?
1.2.1 Waste Rock and Mine Tailings
When developing an open-pit mine there are two main classes of waste that must be managed. First, there is the overburden and waste rock that is removed in order to reach the ore. Second, there are the mine tailings which are left over after the mineral concentrate has been extracted in the milling process. With a low-grade ore such as Island Copper’s, less than 2% of the ground rock is recoverable mineral while the other 98% must be disposed of as tailings.
Waste rock is generally trucked away from the mine and dumped in a designated area where it is eventually contoured into mounds and re-vegetated. Mine tailings are more difficult to manage as they consist of a slurry of finely ground rock plus some residual portion of chemicals used during the milling operation. In most mining operations the tailings are disposed of behind an earthworks dam that is constructed across a valley or other natural depression in the land. It is necessary to physically contain tailings because they are very susceptible to erosion, especially in high rainfall areas such as northern Vancouver Island.
At Island Copper there were about 800 million t of waste rock and 400 million t of tailings generated over the life of the mine. When moving such large tonnages of material it matters whether it is being transported uphill or downhill. A great deal of energy, and therefore expense, is required to move a tonne of rock against gravity while very little is required to go with it.
While every mine-site is different, it is usually possible to find disposal areas for waste rock and tailings that are downhill from the mine. In the case of Island Copper all the surrounding land was uphill as the mine was literally on the ocean’s edge. In addition, there was no suitable location to construct a tailings dam to where the tailings could be pumped at reasonable cost. A preliminary engineering study determined that about 750 hectares of land would be required for the tailings disposal alone, with an additional large area required for waste rock (Ker, Priestman & Associates Ltd., 1975).
These considerations led to the proposal that most of the waste rock and all the tailings be disposed of in the marine environment rather than on land. The waste rock would be used to create new land along the shore of Rupert Inlet and the tailings would be injected by pipeline into deep water offshore. Known as submarine tailings disposal (STD), this was one of the first proposals that involved detailed engineering for deep-water discharge of mine tailings to the sea.
1.2.2. The Problem of Acid Rock Drainage
The Island Copper ore body was of the sulfide variety. This means that the minerals are conducive to acid rock drainage when exposed to oxygen and water. Acid rock drainage (ARD) is produced when metal sulfide minerals are weathered and with the help of specialized bacteria, converted to acidic, water-soluble compounds that can be leached out by rain water. ARD may then contaminate groundwater and surface waters such as lakes and rivers. When life-bearing surface waters are rendered acidic there can be a dramatic decline in biodiversity and productivity. This is the most persistent of environmental impacts from the mining industry. ARD can continue to pollute waterways for many hundreds of years. If acid rock drainage can be prevented, the task of reclamation (ecological restoration) is made much more feasible. Disposing sulfide tailings under fresh or salt water immediately after milling prevents oxidation and the production of ARD.
1.2.3. The Walden Report
Faced with the novel proposal to discharge over 40,000 t per day of mine tailings into the sea the British Columbia government commissioned a report. The “Walden Report” (B.C. Research, 1970) recommended, “Where possible, tailings should be disposed of at depth in deep bodies of water.” It qualified this, however, by stating that “Underwater disposal should not be permitted where settling characteristics of the tailings, or underwater currents, preclude rapid and complete settlement.” These recommendations set the stage for 10 years of controversy and conflict.
1.3 The Institutional Framework
1.3.1. Government Agencies and their Respective Roles in Approvals
Approval of the proposal to dispose of the mine tailings in the sea required the involvement of both the Canadian federal government and the British Columbia provincial government. At the federal level the Department of Fisheries and Oceans (DFO) has jurisdiction over all waters frequented by fish, in particular the marine environment. At the provincial level both the Ministry of Mines and the Ministry of Lands were responsible for approvals. In 1967, British Columbia had adopted the Pollution Control Act, requiring a permit to be issued for any discharge of waste into the environment. The Director of Pollution Control was required to publish a notice of any application for a Pollution Control Permit and members of the public could file “objections” with the Director. When Utah Construction and Mining Ltd. applied for a permit to allow submarine disposal of their mine tailings there were 150 objections filed. While the majority of the objections were from individual members of the public, there were others from environmental groups, fisheries interests, and academics.
At that time, the Pollution Control Act gave the Director discretion over whether or not a public hearing would be held to consider the objections. After considerable delay, the Director decided a public hearing would be held, but by way of a technicality he restricted the hearing to only four of the 150 objectors. These four included three lay citizens with no expert knowledge in the field and one citizens group, the Pacific Salmon Society. The exclusion of the most active and knowledgeable groups and individuals from the public process caused even further controversy and resulted in a keen debate in the local and provincial media. The Island Copper Mine was becoming a test case for the administration of pollution control in Canada.
1.3.2. The Rationale for Submarine Tailings Disposal
Meanwhile, scientists with the federal DFO were deliberating over the choice between land and sea disposal. They were well aware of the potential for acid rock drainage if the tailings and waste rock were deposited on the land (Waldichuk, 1970). The nearby Marble River is the main spawning river for Chinook salmon in the region and there are commercial fisheries for prawn and crabs in the immediate vicinity of the mine-site. The fisheries scientists came to the conclusion that land disposal was a greater risk to the marine environment than direct disposal to the sea. They recommended to the provincial agencies in British Columbia that they favored the option of submarine tailings disposal. As stated at the time, “The Fisheries Service felt that the lesser of the two risks had to be taken. If the tailings were dumped on land, oxidation and leaching would put heavy concentrations of copper and possibly other base metals into the surface waters, which would surely damage the salmon. With the tailings put on the bottom of the inlet, at least salmon should not be harmed.” (Waldichuk, 1970).
1.4 Conflict and Controversy
1.4.1. The Rise of the Modern Environmental Movement
The controversy was made more intense by the timing of the project which coincided with the rise of the modern environmental movement in the late 1960’s. In British Columbia the Society for Pollution and Environmental Control (SPEC) had been formed and had been actively campaigning against industrial pollution. The Island Copper Mine provided an ideal focus for the campaign due to its magnitude. The very image of 40,000 t of industrial waste being discharged to the sea, no matter what its composition, provided good material for a campaign against the project.
The Director of Pollution Control’s decision to limit the number of objectors who could speak at the public hearing had the effect of galvanizing public opposition to the project. The hearing, originally scheduled for September, 1970, was postponed until December. By the time the hearing was held the construction of the mine was well underway. The Director admitted that he was only responsible for approval of the technical aspects of mine waste disposal, not of the project itself. This created a credibility problem for the government, a point that was repeated in the national media.
1.4.2. The Public Hearing
The public hearing took place in the town of Port Hardy near the mine site. The three individual objectors made very general presentations in opposition to the issuance of a Pollution Control Permit. The Pacific Salmon Society was represented by the lead author of this paper who was one of the 146 objectors the Director had earlier disallowed on a technicality. The author had approached the directors of the Pacific Salmon Society, informed them that he was doing his Ph.D. thesis research on the Island Copper Mine project, and they appointed him Vice-President of the society – and their representative at the hearings.
Utah had based their proposal for submarine tailings disposal on the contention that “the water of Rupert Inlet is stratified into layers of differing density with tidal action affecting only the surface layers” (Wheaton, 1970). Thus it was implied that the deep waters were still and the tailings would settle directly to the bottom. This claim remained surprisingly resistant to empirical evidence. When B.C. Research, under contract to Utah, found relatively high currents in the deep waters (Howard, 1970) the company continued to maintain that there was no tidal mixing between the deep and surface waters (Utah Construction and Mining Co., 1970).
The brief presented by the Pacific Salmon Society (Moore, 1970) relied on oceanographic data that had been collected previously in Rupert Inlet (Pickard, 1963 and Waldichuck et al, 1968). These data indicated the opposite of the conclusion reached by Utah. Pickard interpreted the high oxygen values in deep water and the lack of a sharp thermocline to indicate a high degree of vertical mixing, with the deep waters being periodically replaced by surface water.
The Walden Report had made it clear that it would be preferable if the tailings were to settle directly to the bottom of the inlet with no upwelling into the surface waters (B.C. Research, 1970). If there were strong tidal currents in the deep waters as suggested by Pickard’s research, it was highly likely that upwelling would occur. Other issues raised at the public hearings were potential negative impacts on commercial fisheries for salmon, crab and prawns and the possibility of bioaccumulation of heavy metals, particularly copper, through the marine food chain.
1.5 The Decision of the Director of Pollution Control
1.5.1. Technical Requirements for the Submarine Disposal System
On January 21, 1971 the Director issued a Pollution Control Permit to Utah for submarine tailings disposal. The tailings were to be first thickened by removing water and then injected at a depth of 45 m after being mixed with an equal amount of seawater. The seawater acted as a flocculent, helping the tailings particles to bind together and therefore to sink more rapidly than if they were suspended in fresh water. DFO had expressed a particular concern about the possibility of upwelling due to tidal currents. In a letter to Utah they stated “that if, in the Department’s opinion, the turbidity monitoring results indicate that a turbidity problem is developing, the Company will agree to add flocculents and/or relocate the outfall in an attempt to correct the turbidity situation” and “if the turbidity problem is considered critical, the Company will, upon request by the Minister of Fisheries, shut down milling operations until a satisfactory solution to the turbidity problem can be found and implemented.” (Hourston, 1970).
1.5.2. Effluent Standards
For the first time in BC mining history, detailed standards for every constituent of the mine tailings were included in the permit. In addition, it was stipulated that fish must survive for 96 hours in the tailings, at 100% concentration. It was DFO’s position that “if the effluent samples fail to pass five consecutive bioassays, the Company will agree to shut down the milling operations.” (Hourston, 1970).
1.5.3 The Technical Advisory Group
The Pollution Control Permit contained a requirement for Utah to establish a Technical Advisory Group to help establish an Environmental Monitoring Program to ensure the effluent standards were achieved and that the marine environment was monitored for physical, chemical and biological parameters. This group was comprised primarily of research scientists from the University of British Columbia, the University of Victoria and Simon Fraser University.
1.6 The Environmental Monitoring Program
The Environmental Monitoring Program at the Island Copper Mine is now a benchmark in the development of long-term monitoring of industrial projects for their environmental impacts. A wide range of values were variously tracked at weekly, monthly, quarterly and annual periods. These included ocean depth, turbidity, oxygen, heavy metals in seawater, chlorophyll-a as a measure of phytoplankton abundance, species biodiversity and abundance, and heavy metals in the tissues of marine organisms. Virtually every parameter that might be impacted by the tailings, and that could be measured, was included in the program.
One of the few shortcomings of the environmental monitoring program was the lack of lead-time to collect baseline data for some parameters before the tailings discharge began. Despite this, it was possible to obtain good baseline data for benthic organisms, turbidity, dissolved metals and chlorophyll-a during a 20 month period before the mine began operations. These data both confirmed the previous indication of high oxygen levels in the deep water and provided pre-discharge values for many of the parameters that were tracked during the 24-year operating life of the mine.
2. The Operational Phase
2.1 Early Results of Environmental Monitoring
Tailings discharge from the milling operations began in October 1971, and reached full production in January 1972. It became apparent soon after the discharge began, and particularly during the large spring tides in early 1972, that the tailings were upwelling into the surface waters on a regular basis. During extreme tidal events, the tailings were brought to the surface between Quatsino Narrows and Hankin Point. From here they were carried by the ebb tide out through Quatsino Narrows into the main body of Quatsino Sound. Suspended tailings could be observed as far west as Brockton Island, about 35 km from the discharge point. This provided dramatic visual evidence that Utah had been incorrect in its assertion that the tailings would remain in the deep water. Over the next five years a number of research projects investigated the nature and extent of tailings dispersal in Rupert Inlet and Quatsino Sound.
2.2 Scientific Investigation into Upwelling and Impacts
The results of the Environmental Monitoring Program conducted by Utah indicated turbidity levels averaging about four times higher at 30 m depth in Rupert Inlet during the years 1972-1975, compared with 1971 before discharge began (Island Copper Mine, 1996). Quarterly profiles of turbidity at 12 stations in Rupert inlet measured for one year before discharge and one year after discharge indicated “that the turbidity of water in Rupert Inlet has been increased throughout the entire waterbody.” (Moore, 1973). It was confirmed by independent research that “The near uniformity of oxygen content throughout the water column implies frequent mixing within the basin.” (Drinkwater, 1973). Research conducted by the Environmental Protection Branch of Environment Canada indicated that the tailings had dispersed over a much wider area of ocean bottom than had been anticipated. At Hankin Point and Hecate Cove the tailings were settling out in the productive intertidal and sub-tidal zones (Goyette and Nelson, 1977). This information was presented to the British Columbia Pollution Control Board Inquiry into the Mine, Milling and Smelting Industries held in Victoria in 1978. As a result there was a joint request from the federal and provincial Ministers of Environment for a review, to be conducted by scientists with DFO and the B.C. Ministry of Environment. The resulting report (Waldichuck and Buchanan, 1980) reviewed all aspects of the submarine tailings disposal system and reached a number of conclusions:
· In the deepest parts of the inlet, bottom organisms are being smothered by a heavy deposition of tailings. This had been anticipated.
· Judging by the presence of worms and other invertebrates in the tailings deposits, there should be rapid recolonization of the tailings (within five years) following cessation of tailings discharge.
· Tailings are being distributed over a much wider area, including intertidal and shallow subtidal areas. This was not anticipated when the disposal system was planned. (Author’s note. Clearly this was anticipated by some researchers. The Pollution Control Permit was granted on the assumption that they were incorrect and that Utah and its consultants were correct.)
· The tailings appear to be relatively non-toxic, judging by the colonization of the intertidal tailings deposits by marine plants and animals.
· There is no documented evidence, despite a thorough review, of a decline in any commercially important species during the mine operation.
· Metals are not being bioaccumulated in appreciable amounts by organisms anywhere in Rupert Inlet or Quatsino Sound, except very locally at the wharf where mineral concentrate is loaded onto ships.
· Some reorientation of the monitoring program is needed to provide better data on commercially valuable species such as prawns, crabs and salmon.
· The present evidence on ecological impact does not warrant changing the tailings disposal system to an alternative system such as land disposal.
Thus, despite the fact that the tailings were not settling in the manner specified in the Walden Report and in the Pollution Control Permit, it was determined that submarine disposal was still “the lesser of the two risks” when compared with the option of on-land disposal (Waldichuk, 1970). The review brought to an end ten years of debate within the provincial and federal agencies and from 1980 until the mine closure in 1995 the operation and the Environmental Monitoring Program were conducted on a routine basis.
2.3 Results of Environmental Monitoring Program
The results of the 25 years of the pre-operational, operational and post-operational Environmental Monitoring Program are contained in Annual Environmental Assessment Reports (Island Copper Mine 1970-1996) that are filed with the various government agencies and are available to the public. The large number of variables sampled were grouped under four headings; marine physical, marine chemical, marine biological, and tissue metal.
2.3.1. Marine Physical Monitoring
The greatest physical impact of the tailings disposal was the deposition of 400 million t of material which reduced the depth of Rupert Inlet about 40 meters, and in the deepest trench from 180 m to 130 m. In the deep waters of Rupert and Holberg inlets (below 50 m) the tailings regularly smothered the bottom, greatly reducing the number and diversity of benthic organisms such as clams and worms. Due to the upwelling of deep water caused by tidal action the waters of Rupert Inlet were consistently more turbid than other waterbodies nearby. Some of the tailings brought into the surface waters settled in limited areas of the intertidal zone, creating a sandy beach where it was previously rocky. Less than one per cent of the tailings were carried out of Rupert Inlet through Quatsino Narrows. Visible deposits of tailings occurred in Hecate Cove and in the deep waters near Quatsino Village. Chemical traces of the tailings (determined by copper content) were found as far as Brockton Island.
2.3.2. Marine Chemical Monitoring
Beginning in 1971, quarterly, and for some parameters, monthly monitoring was carried out for seawater alkalinity, pH, oxygen, and dissolved heavy metals including copper, manganese and zinc. There were no trends in any of these parameters other than a gradual reduction in dissolved zinc at most sampling stations in Rupert Inlet (Zeng and Parsons, July, 1994). The data showed that the tailings disposal did not result in a significant alteration of seawater chemistry.
2.3.3. Marine Biological Monitoring
Marine biological samples were collected to determine impacts on abundance and diversity of plankton, benthic (bottom dwelling) organisms and fish.
Chlorophyll a was monitored to provide a measure of the standing stock of phytoplankton. During the life of the mine there was a steady increase in average chlorophyll a in the surface waters, with the largest increases occurring at the heads of Rupert and Holberg Inlets in the vicinity of fresh water runoff from rivers. It is inferred that the increased phytoplankton levels were the result of increased nutrient input from the watersheds rather than from the tailings disposal ( there being virtually no nutrient content in the tailings). Therefore, despite the fact that the tailings disposal did cause increased turbidity in the inlets, this does not appear to have had any impact on primary productivity (Zeng and Parsons, July, 1994).
Monitoring for zooplankton indicated that although there are wide fluctuations from year to year, there were no observable trends in either abundance or diversity of species that could be associated with the tailings disposal (Zeng and Parsons, December, 1994).
As anticipated, the largest impact of the tailings disposal was the smothering of organisms that live in the bottom sediments in the vicinity of the outfall. In 1995, at the sampling station closest to the outfall, 15 species representing 3,746 organisms per m3 were observed. At a station in Holberg Inlet that was not impacted by tailings there were 41 species representing 3,430 organisms per m3. In contrast, at one station near the confluence of Rupert and Holberg inlets that was heavily impacted by tailings there were 40 species representing 43,600 organisms per m3 (Island Copper Mine, 1996). Therefore, despite the physical smothering, the tailings did not cause a “dead zone” and many species of benthic organisms showed a surprising degree of resilience to continuous disturbance (Burd and Ellis, 1995).
It had been expected that the tailings disposal would have a negative impact on the major commercial species in Rupert and Holberg Inlets, the Dungeness crab. A sampling program with traps at six stations showed no significant trend in either population or size frequency of crabs caught in the inlets despite increased fishing pressure by local crab fishers (Island Copper Mine, 1971-1996).
2.3.4 Tissue Metal Monitoring
Every five years resident species of fish were caught by hook and line to determine tissue metal levels. Two species of bottom dwelling shark were caught on baited longlines with 100 hooks set for four hours at five sampling stations. Catches of dogfish sharks indicate that populations have fluctuated but that there was no downward trend.
Tissue metal levels were monitored in a number of species to determine whether aquatic organisms were bioaccumulating metals either directly from the environment or by magnification through the food chain.
With a few exceptions, tissue metal levels have not increased as a result of the tailings discharge. In particular, crabs, zooplankton and fish, which are higher up in the food chain, showed no trend in tissue metal levels. Blue mussels from the copper concentrate loading dock pilings showed elevated levels of cadmium, copper and zinc. This is thought to be as a result of copper concentrate dust escaping into the water near the dock as there were no other sampling stations in Rupert Inlet that showed increased metal levels in mussels. Rockweed (Fucus sp.) showed elevated levels of copper and zinc where it was growing in tailings that had settled in the intertidal and sub-tidal zones. The data for 1996 indicate that copper and zinc levels in rockweed had returned to pre-discharge levels within months of the cessation of tailings discharge (Island Copper Mine, 1996). Rockweed showed no increase in tissue metals at other sites.
2.4 Primary Sources about Impact on Commercial Fisheries
Interviews were conducted with Robert (Babe) Howich, the major local crab fisher; Joe Chambers, the Habitat Conservation Officer with the Department of Fisheries and Oceans; Harry Hole, a fish buyer, and marine operator who has lived all his life in Coal Harbour; the main port in Holberg/Rupert inlets; and Brad Hicks, the manager of the salmon farm located in Holberg Inlet about 8 km from the tailings discharge point. (personal communications, 1997)
Mr. Howich reported that both the crab and prawn fisheries were still active in Rupert and Holberg Inlets. He stated that there are about 200 crab traps set in the inlets at any given time. During the life of the mine crabs had appeared where there were none before. He also reported that there were some areas where there were crabs before the mine opened where there are none now. He believes that fishing pressure is greater at present than it was before the mine began operations.
Mr. Chambers stated that there had never been a substantiated complaint against Island Copper, regarding the environmental impact of the tailings on marine life, in its 24 years of operation. He reported that there was no evidence that salmon had been negatively impacted and that there were more salmon returning to the Marble River now due to the operation of a salmon hatchery funded jointly by the Department of Fisheries and Oceans, Western Forest Products and BHP Minerals, the owner of the mine.
Mr. Hole reported that the tailings deposits had improved the bottom habitat for crabs and that they were now caught in locations where there had been none previously. He reported that the fishery for sea urchins in Quatsino Narrows had achieved the quota of 300,000 lbs/yr for the past three years and that there is also a high quality sea cucumber fishery in the Narrows.
Mr. Hicks stated that since 1986 when the salmon farm was established there had been no evidence of any negative impact of the tailings disposal to the Atlantic salmon that are reared in sea cages near the confluence of Holberg and Rupert inlet. He stated that the tailings had made the surface waters cloudy at times but that the only impact may have been a reduction in plankton growth, a positive impact where salmon are concerned.
The interviews strongly support the position that there has been no significant negative impact to date on commercial fisheries as a result of the tailings disposal.
2.5 Interpretation of Impacts by Outside Agencies
Shortly before the Island Copper Mine was scheduled to close at the end of 1995, there were two outside studies commissioned to evaluate the environmental impact of submarine tailings disposal. Environment Canada, in anticipation of an application for submarine tailings disposal at the nickel discovery at Voisey’s Bay in Labrador, commissioned Golder Associates to evaluate the impact of tailings disposal on the marine environment (Golder Associates Ltd., 1996). The U.S. Environmental Protection Agency, in response to a proposal by the AJ Mine Project in Juneau, Alaska to employ submarine tailings disposal, commissioned CH2MHILL to conduct a literature review on the environmental effects of tailings disposal at Island Copper (CH2MHILL Glatzel & Associates, 1996).
The Golder report stressed the need for a better understanding of the oceanography of the receiving body to better predict the eventual distribution of tailings. The report noted that tailings had dispersed over a larger area than had been predicted and that there had been physical alteration, from a rocky to a sandy bottom, near Hankin Point. It reported that there had been no significant impact on primary productivity, tissue metal levels, or commercial fisheries. The report concluded that “The environmental monitoring program for the Island Copper Mine could be considered a pioneering effort in the development of monitoring programs for industries that discharge to the marine environment.”
The CH2MHILL report was much more critical of the mine, stating that “The monitoring program database has not been fully adequate for determining adverse effects because it is not assessing the appropriate parameters for this purpose; the database also lacks statistical rigor, particularly for benthic infauna.” A reading of the report does not provide an indication of which parameters the authors believe to be more appropriate than the ones chosen for the monitoring program. The report does state that the parameters most inadequately measured were “physical changes in the environment, the resultant habitat loss, and ecological changes”. These descriptors do not appear to be sufficiently specific to be characterized as “parameters”.
The CH2MHILL report states that testing for bioaccumulation should have been conducted “at all trophic levels”, implying that this was not done. Tissue metal levels were, in fact, monitored for algae, eelgrass, zooplankton, several species of bivalves, crabs, and fish, thus covering all major trophic levels.
In a critique of the CH2MHILL report by a scientist who has participated in the monitoring program from the outset, it is pointed out that the review did not draw attention to the following points (Ellis, 1996):
· The crab fishery has maintained itself and the crabs have not been contaminated.
· A relatively small amount (<1%) of the tailings escaped from the predicted deposition area.
· Primary and secondary productivity have not been affected.
· Where tailings deposition was light there was no detectable impact on benthic organisms.
· Contrary to statements made in the report, there have been substantial modifications to the monitoring program as a result of periodic reviews.
Ellis contends that there are persistent exaggerations in the CH2MHILL report, such as the inappropriate use of the word “large” and the omission of the word “small” when describing environmental impact.
The manners in which both the CH2MHILL report and, to a lesser extent, the Golder report describe the tailings disposal raise questions about the meaning of such terms as “environmental impact”, “environmental effect”, and “footprint”. In both reports, the existence of a chemical trace of the tailings in the bottom sediments is described as an “impact” even though there is no measurable effect on any of the many parameters monitored in the sampling program for stations where such trace amounts of the tailings were observed. This raises the perennial question of thresholds. Is there some minimum level of tailings deposit below which it can be considered there is no impact? Or, should it be assumed that even a trace amount of tailings has an impact even though no impact was measured?
3. The Post-Operational Phase
3.1 De-Commissioning – Alternatives and Decisions
The last ore was removed from the open-pit in December, 1995 and shortly afterwards the tailings disposal ended after 24 years of continuous operation. A Mine Closure Plan was agreed to with government that included flooding the open-pit with seawater, reclamation of all disturbed land with vegetation, and a continuation of the Environmental Monitoring program for at least three years (BHP Minerals Canada, 1996).
The open pit was flooded with seawater by digging a trench from the shore of Rupert Inlet to the edge of the pit, which at closure had reached a depth of 370 metres below sea level. Then the trench was closed off, creating a new lake about 2 km long and 1.5 km wide. Runoff water from the surrounding waste rock dumps is collected in ditches and piped into the new lake at depth. This system is designed to prevent acid rock drainage from contaminating the waters of Rupert Inlet.
The disturbed land around the pit was contoured with bulldozers, seeded with a mixture of grasses and herbs, and planted with over 400,000 tree seedlings, mostly red alder, a native, nitrogen fixing species that can grow in poor soils. Past experience indicates that red alder will succeed on the site and form a dense pioneer forest.
With the cessation of tailings discharge, the marine environment has now stabilized somewhat and is beginning the process of recovery. The Environmental Monitoring Program will help to determine the rate and extent of recovery, in particular to see if the tailings are a suitable substrate for the benthic organisms that lived on the bottom of Rupert Inlet before the mine was developed.
3.2 Prospects for Marine Ecosystem Recovery and Re-Colonization
The disposal of 540 million t of waste rock along the shore of Rupert Inlet resulted in the creation of 260 ha of new land and nearly 4 km of new beach. The beach front was graded to a slope of 10 degrees and bays were sculpted into it to promote varying habitat. Monitoring has shown that within two years of restoration, the full range and abundance of marine organisms have invaded and colonized the new shoreline (Ellis, 1997).
During the 24 year period of tailings disposal in Rupert Inlet a considerable area of the bottom was subjected to continuous deposition of new sediments. This resulted, in some sampling locations, in a great reduction in the abundance of bottom-dwelling species.
The bottom samples taken in 1996, the first year after closure, indicate a dramatic and rapid recolonization of the sites that were most severely impacted by the tailings disposal. This recolonization is characterized by changes in species composition, increased biodiversity, and increased numbers of individuals. The 1996 Environmental Monitoring Report states, “In summary, the preliminary processing and analysis of benthic samples from 1996 shows either an increase in biodiversity related to habitat change from mud to sand bottom, or return to and sustainment of biodiversities comparable to pre-discharge levels.” (Island Copper Mine, 1996).
3.4 The Decision to Employ Submarine Tailings Disposal in Retrospect
The case of submarine tailings disposal at the Island Copper Mine poses an interesting dilemma for policy-makers. From the outset, there were three clear choices for the development; land disposal of waste, submarine disposal of waste, or no mine development. It is clear, in retrospect, that of the two waste disposal options available, submarine disposal was preferable from an environmental perspective. It is also likely, however, that submarine disposal would have been rejected if it had been more widely known that upwelling would occur so frequently. This would have left the decision between land disposal or no mine development, i.e. between potential long-term environmental damage or the loss of Canadian $3 billion in economic activity. To add to the irony, it is possible that the frequent flushing action caused by tides was partly responsible for preventing the bioaccumulation of, and toxic impact of, the constituents of the mine tailings.
3.6 Lessons Learned for Future Projects
What can we learn from the experience gained through the intensive environmental monitoring program at the Island Copper Mine? Most important, we have a detailed record of the entire life-span of the operation including baseline data prior to operation and post-operational monitoring. This record should prove invaluable in assessing and predicting the impacts of future proposals for submarine tailings disposal. We have also learned that what might appear to be “visible signs of pollution” such as the turbidity caused by upwelled tailings, are not always accompanied by actual environmental damage. This confirms the general principle that aesthetics alone cannot be relied upon to judge ecological health, that there is no substitute for scientifically sound monitoring programs that provide direct empirical evidence.
It can be stated with reasonable confidence that one year after closure of the Island Copper Mine there is no evidence of any significant environmental or economic damage as a result of submarine tailings disposal. It can be concluded, with certainty, that recolonization of the marine environment has and is occurring at a rapid rate. There has been some modification of habitat, in some areas, from rocky to sandy bottom, but the new habitat is healthy and colonized with marine life. While there may be a possibility of some future development that would result in a negative impact, no plausible scenario for such a development has been brought forward at this time.
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The Environmental Impact of Submarine Tailings Disposal at the Island Copper Mine on Vancouver Island: