British Columbia Mine Reclamation Symposium

Reclamation practices at Island Copper Mine Hillis, Ron J 1979

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Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 197 RECLAMATION PRACTICES AT ISLAND COPPER MINE Paper presented by: R. Hillis Utah Mines Ltd. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 199 RECLAMATION PRACTICES AT ISLAND COPPER MINE INTRODUCTION Island Copper Mine is located approximately 10 miles south of Port Hardy on the north end of Vancouver Island and is the largest open pit operation located on coastal British Columbia.  The mineral reserves indicate approximately 280 million tons of ore with a grade of 0.52% copper and 0.018% molybdenum. The mine is capable of moving 160,000 tons of rock per day using the con- ventional truck and shovel method. The milling operation has the ability to process up to 50,000 tons of ore per day, producing 1000 tons of copper concentrate and 15 tons of molyb- denum concentrate.  By-products found in the concentrates are gold, silver and rhenium.  The mine has its own deep sea dock and transports its copper concentrate directly to Japan. The mining operation will develop a single pit with final dimensions of 8000 feet long x 4000 feet wide x 1200 feet deep.  The estimated average stripping ratio for the twenty year operation is 2.4 tons of waste for each ton of ore. Island Copper's low grade mining operation requires the removal and dispo- sal of large volumes of waste material in an environmentally acceptable manner. At Island Copper, the mill tailings are treated and subsequently discharged, 165 feet below the surface, into the adjacent marine environ- ment (Rupert Inlet).  A portion of the waste rock is deposited as a land- fill along the shore contiguous to the pit and acts as a berm protecting the open pit from potential seawater inflow. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 200 Reclamation Plan A reclamation plan was developed at the mine with both short-term and long-term objectives.  The short-term objectives of the reclamation program are to reduce erosion through soil stabilization using vegeta- tion, and to maintain aesthetic quality around the minesite.  The long-term objectives and land use consideration for the area are wildlife habitat, recreation and forestry. The present land uses in the area other than the mine operations are wildlife habitat and i forestry. The area surrounding the mine is designated as a prime forest yield region. Before the mine operations, the topographic relief in the pit area was moderate with elevations ranging from sea level to slightly more than 400 feet above sea level.  The area was covered by second growth hemlock.  These trees were 15 to 25 inches in diameter and 100 to 150 feet tall. The ore body was overlain with glacial till which ranged in thickness from 15 feet in the centre of the pit to 300 feet on the east and west  Research Prior to Reclamation The initial reclamation research was to assess the materials overlaying the ore body.  Precipitation of 80 inches per year and the moderate temperatures year round in the area, increases the weathering of soil materials.  Research indicated that soil materials within the pit had a high calcium content coupled with a fairly alkaline pH (8.5). The organic soils associated with the relatively flat land which has a water table at or near the surface, had an acid pH.  Nutrient analysis of both types of material revealed low levels of major plant nutrients. Considerable fertility amendments would be required if these materials were to be used for reclamation purposes. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 201 RECLAMATION OPERATION As mentioned earlier, the short-term objectives of the reclamation program are to stabilize the disturbed areas and to prevent erosion.  In an area of high rainfall where 3 inches in a day is not uncommon, erosion is a serious problem.  In the spring of 1971, approximately 50 acres of the construction site area and 10 acres of road allowance were seeded by aircraft and hand-operated Cyclone Seeders.  The areas covered did not receive any special preparation prior to the seed and fertilizer application.  A mixture of grasses and legumes was applied at a rate of 60 pounds per acre.  Fertilizer (20-20-10) was applied at a rate of 300 pounds per acre at the time of seeding.  After one year of growth, grasses with a well developed root system were firmly established in the area. The areas seeded in 1971 have been monitored to evaluate the success of this form of reclamation.  An area above the plant site had no growth in April 1971.  Two months after planting, growth to a height of 4 to 6 inches was evident.  By July 1972, one year after the initial planting and after a second application of fertilizer in August 1971, the area had an excellent- cover of grasses which were producing seed.  In August 1976, five years after the initial seeding and with no tending, the same area was predomi- nantly legumes.  Alder seeds from the surrounding forest had germinated suc- cessfully and seedlings from 6 to 18 inches in height had developed.  The most recent survey of the area in August 1978 documents extensive Alder growth with trees over eight feet tall, with Conifer Hemlock growing among the Alder.  In only two years this area has demonstrated the ability of Alder to grow rapidly once it has become established.  Other areas seeded in 1971 have grown successfully.  One area with a road cut has a well developed grass cover with Hemlock and Alder covering 25% of the area.  Where the soils are nutrient deficient naturally seeded Hemlock and Spruce are present.  Some areas have developed shrubs such as Elder and Salmonberry.  These reclaimed areas have become excellent habitats for deer. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 202 In early 1971, prestripping of the pit area started. An attempt was made at stockpiling the organic soils from the lower region of the pit. Stockpiling proved to be impractical due to the water retentive character of the material. A test plot was developed to establish the potential of till as a growth medium. The till used was representative of the material that would eventually cover dump surfaces.  The test plot was divided into nine equal areas and treated with varying amounts of seeds and fertilizer.  After 5 years and no tending, plots without fertilizer did not produce a good vegetation cover.  Good plant growth was evident in plots that were fertilized. Since organic soils cannot be stockpiled, it is the practice at Island Copper to place these materials on areas which are available for immediate reclamation. In such cases, the organic soils from the stripping operations are loaded and transported by truck to an area prepared for reclamation.  The soil is then spread by bulldozer to a depth of 6 to 12 inches. In 1975, several areas on the beach waste dump were treated in this fashion.  A 6-acre plot was levelled by bulldozer and covered with a layer of overburden from a stripping operation.  In June 1976 the area was treated with 50 pounds per acre of seed and 200 pounds per acre of fertilizer (20-18-9).  This area was hand seeded and patchy.  In the spring of 1977, the bare patches were treated with additional seed and a fertilizer.  The area flourished.  During the 1978 season, plant growth was reduced as the nutrients were consumed.  White Dutch Clover became the dominant species by July 1978. Another 5-acre plot was levelled and spread with overburden in 1977.  This plot was planted with Rambler Alfalfa at 100 pounds per acre of seed and 400 pounds per acre of fertilizer (21-18-9).  The seed germinated well.  Dry weather during the summer killed off many plants and, by fall, the cover was quite sparse.  The plot was untended after seeding, but by the summer of 1978 growth had improved. Samples of the Alfalfa roots were examined and found to be nodulating successfully. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 203 In September 1976, a haul truck ramp with a side slope of up to 35° was spread with overburden.  This area was treated with 100 pounds per acre of seed and 400 pounds per acre of fertilizer (27-18-9).  The area was the first attempt at fall planting and was successful.  In January of 1977, 100 Red Alders (Alnus rubra) were transplanted onto the slope.  Survival was 78% after the first year. The north side of the pit reached its final limits in 1978 and became available for reclamation.  This area included the south side of the north waste dump and, as such, presents a challenge in terms of stabilization.  The preparation of this area started in April 1978.  Using a D8 bulldozer and trainee operators, unnecessary ditches were filled, roads recontoured and the area generally levelled.  Soil stripped from the west side of the pit was spread 6 to 12 inches thick. The reclamation operation using the operator trainee was quite successful in two ways:  we received steady use of equipment, and the new operators who normally would be doing other work were introduced to reclamation practices. After ground preparation, the area was hand seeded at a rate of 100 pounds per acre.  Seeding was followed by application of 400 pounds per acre of fertilizer (27-18-9).  The area was left untended and, by October 1978, a good cover had developed. A major consideration of Island Copper's land reclamation policy in addition to the reclamation of the surface and slope of the land waste dump, is the develop- ment and implementation of a program to reclaim the shore of the marine land- fill.  In the spring of 1978, a small portion of the beach dump foreshore was set aside for the study of reclamation methods.  A 200-foot wide section of the dump was resloped to establish a beach with a grade of approximately 10%.  After grading, the area was left to natural colonization.  The rate of colonization was monitored and both plants and animals were found on the test area seven weeks after resloping.  In 1979, a research program will be initiated to deter- mine the diversity and abundance of species on the test plot. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 204 It has been demonstrated at Island Copper that planting grasses is an effective means of controlling erosion in the short-term, but it extends the time required for natural reforestation of an area.  In time, the grasses are invaded by native species and the process of natural succession is initiated. In summary, the objective of the reclamation program at Island Copper is to reduce erosion in the disturbed areas by stabilization with grasses followed by the promotion of native species. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 205 DISCUSSION RELATED TO RON HILLIS'S PAPER Ken Crane, Luscar Stereo Ltd.  You have had no problems in handling the topsoil. Why couldn't you stock pile it for later use. ANS.  Well, you can't pile it.  It must be spread right away, because it flows. Neil Duncan, Energy Resources Conservation Board.  You showed a very brief slide of the tailings being dumped into the bay or the sea.  Oceanographer Jacques Cousteau has given a lot of bad publicity to mining operations which have done this in the tropical latitudes.  Have you been visited by Cousteau or have you had divers or anyone interested in what is happening to the tailings being discharged into the bay. ANS.  No, Mr. Cousteau hasn't shown up.  They wouldn't have much chance in diving anyway, because the turbidity would prevent them from seeing too much. Bill Burge, Sage Creek Coal Limited.  I would like to remark on how quickly the old ocean is recovering that beach area that Island Copper has. ANS.  There doesn't appear to be any reduction in growth rate.  The test plot we have there is bounded on one side by our discharge of tailings and on the other side by our waste dumping.  There is some evidence now that shows that our growth plates located there are growing better than the normal area.  I don't think we are adding any nutrients there, but it does seem to be doing quite well, and we'll know better how we are doing next year when we do our program. There's going to be a large foreshore developed as a result of that marine dump and a lot of people are concerned about what's going to happen to it when we have finished our operations. Dave Polster, Techman Ltd.   Have you given any thought to adding small amounts of Alder seed to your grass and legume mix. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 206 Ans.   Yes.  The first plot that we did on the beach in 1976 had Alder seeds in the mix, but they couldn't compete.  It may work if we plant Alder shoots or seedlings. Kerry Clarke, Arcon Associates.  Why plant Alder.  Why not Conifers. ANS.  Alders supply nitrogen to the soil.

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