In order to determine which shrub species might be useful in revegetating Yukon mine sites at the time of closure, eleven species of shrubs were transplanted at three open disturbed sites at the Brewery Creek Mine in the Central Yukon in the fall of 2000. These sites included a steep north-facing slope, a steep south-facing slope, and a lower nearly level area. All three of these areas had been recontoured and seeded in 1996-97, and there was a thick growth of grasses and clovers at the time the shrubs were planted in 2000. To determine if this thick growth interfered with the survival of the newly planted shrubs, the grasses and clover were first removed from one-half of each of the test plots. Six years after the shrubs were planted, it appears that black spruce and Alaska birch are the most successful species transplanted on the north-facing site, trembling aspen and Alaska birch the most successful on the south-facing site, and dwarf birch, prickly rose and trembling aspen the most successful on the nearly level site. The planting of willow stem cuttings was not successful. After six years, the previously cleared half of each plot was once again covered with a thick growth of seeded and naturally occurring plant species. The clearing of vegetation before the transplanting of shrubs does not appear to have much of an effect on the ultimate survival and growth of the transplanted shrubs.

Two MERG-sponsored mine reclamation projects were surveyed during the summer of 2002. These included the Brewery Creek Mine where local shrubs were planted in large open areas at the mine site in 2000, and Noname Creek near Big Creek west of Carmacks where, in 2001, live willow cuttings were used at an abandoned placer mine to stabilize an eroding gully in permafrost. Because the effectiveness of reclamation projects such as these can only be determined after several year of observation, the two mine sites were revisited in 2002 to record the successes and failures of the experimental work and to make suggestions on where improvements can be made.

In July 2009 we re-visited the re-vegetation experiments, which had been set up on tailings in the period 2003-2006. The three experimental sites are at Mount Skukum, United Keno and Wellgreen. The experiments consisted of either seeding the tailings with various populations of the tufted hair grass and/ or with stratified (cold temperature treated) seed of the shrub soapberry, or making transplants of the same two species. The treatments included the addition of compost from the City of Whitehorse, addition of fertilizer as 7:7:7 pellets, addition of organic matter as sheep manure, peat or woody debris from on site and, in the case of Wellgreen, a lime addition to overcome the strong acidity. The results are striking and illustrated in the Plates 1-15. Data of performance and flowering success are shown in the Tables, as are chemical analytical data in the Figures and Tables. Plots set up in 2003 provide a nucleus for effective re-vegetation, having survived for 6 years. The success of the seedings and transplants at Mount Skukum and United Keno was good, while that at Wellgreen was very poor. Wellgreen has suffered flooding with washing out of plots and washing out of the neutralizing lime. Nevertheless, in compost additions plots at Wellgreen, set up in 2005 and 2006, a small amount of re-vegetation and survival has occurred, especially in the wetter areas near the tailings pond.

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This study was first conceived as an attempt to document the processes undertaken for the Brewery Creek Mine (referred to as Brewery Creek in this report) in the Yukon Territory and provide a description of the lessons learned from this process. The hope is that this report will be used in the future as a tool for regulatory authorities, assessors, resource development companies, and First Nations for analyzing and planning resource development projects. This report provides an analysis of some of the aspects of the first heap leach mine north of 600 from planning through to post-closure monitoring, start to finish by comparing expectations and predictions versus reality and the lessons learned through the entire process.

An extensive heap leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory. The test itself utilized an approximately 5-m-diameter crib loaded with composite ore from the northern (higher grade) end of the Williams Creek deposit. The ore was stacked to a total height of 7 m, including one meter of ore atop the emitter system. This matched the commercial heap height planned for Williams Creek at the time the test was started. By insulating the side walls of the crib, lateral heat flux was minimized. Thus, the crib replicated an interior segment of the commercial heap. Leaching was done at a flow rate that matched those commonly used in industry. Leachate temperature was about 21°C, a level achieved with no external heat input other than normal process heat transferred from electrowinning to the leachate via solvent extraction. An analysis of the test results showed that the winter conditions at Carmacks were quite typical of those expected at the mine site. Conditions included ambient temperatures below -40°C and an average temperature of -13°C. In terms of leachate flow to and from the crib, the test ran continuously from late September through mid-February. In spite of some flow system problems, leaching continued unabated. There was no freezing in the interior of the crib or in the solution reservoir at the bottom. Freezing was limited to the insulating ore over layer and a few isolated points high in the crib near the outer walls. The test clearly demonstrates that year-round heap leaching of Williams Creek ore is practical. The heap appears to be adequately insulated by a 1 m ore layer on top of the emitter system. Normal process heat should be sufficient to maintain a leachate return temperature of approximately 20 degrees Celcius at the heap. However, provisions for some supplemental heating in the commercial operation may be desirable. This would permit recycle of the heated solution if electrowinning goes off-line or if there is a long run of exposed leachate pipeline back to the heaps.

In the fall of 2001, live willow cuttings were used for stabilizing an erosion gully on a permafrost slope at Noname Creek in the Big Creek drainage. These structures (gully breaks and pole drains) were upgraded in the fall of 2003 and the early spring of 2004. In the early summer of 2004, the Noname Creek valley was burned in a wildfire. In order to assess the effects of this fire on the erosion control structures, the site was revisited in the summer of 2005. The black spruce forest on the slope above Noname Creek had been completely burned. Although the above ground sections of the pole drains and gully breaks had been scorched, the structures remained intact and most of the lower cuttings were sprouting new growth. Falling trees had damaged a few of the structures. The willow cuttings staked in the gully between the structures had also been scorched. Although many of these staked willows were apparently dead, the older ones (staked in 2001) were sprouting new growth at ground level. It is expected that the erosion control structures, although partially damaged, will survive and continue to function. It is also anticipated that the flow of water in the gully will increase as a result of the escalated melting of permafrost on the slope above Noname Creek.

The Stewart River map area (115 O&N) is the most important historic and current placer gold producing region in the Yukon. Unfortunately, the historic placer-gold deposits are becoming depleted, and more efficient mining of existing deposits and exploration for new deposits must be encouraged. Although placer deposits in the Klondike district are well described and their origin is quite well understood, placer deposits in the remaining part of the Stewart River map area have not been so well documented. The purpose of the Stewart River placer project is to describe and document the geology of known placer deposits, to interpret the formation of the placer deposits, and to relate the geology of the placer deposits to the regional surficial and bedrock geology. The objectives of the project are to aid in the exploration and mining of placer deposits by providing a comprehensive and up-to-date placer geoscience database. The utility of the placer database is that it can be used to construct placer deposit models (general summaries of given placer settings). These models then serve as predictors for future placer exploration and mining. Fieldwork for the project began in 1998 and will be completed in 2001; results of the project will be published in a final report and a resource appraisal map for placer gold.

Wetlands have been used for decades in the treatment of municipal wastewater (sewage) in many parts of the world. Since the 1980s, wetlands have been used in the treatment of acid mine drainage, usually resulting from coal mining. Recently, natural and constructed wetlands have been researched and utilized for the removal of metals from mine drainage. Most of these wetland treatment systems have been designed and used in temperate climatic areas where permafrost, extreme minimum temperatures, and limited plant productivity is not a great concern. There is interest in northern regions on the possibility of the application of wetlands as a passive treatment system for metal contaminated mine drainage. A research program investigating this possibility was initiated in the summer of 1995 in the vicinity of the United Keno Hill Mine property in central Yukon. A pilot wetland treatment system was constructed in May 1995 near the Galkeno 900 adit to determine whether it could improve the quality of its discharge. Sedges (Carex aquatilis) were obtained from a local natural wetland unaffected by any mine drainage and planted in the plot. After the plants were allowed to establish, untreated mine drainage was introduced to the wetland. Monitoring of the wetland continued for one season. Initial results showed that treatment within the wetland reduced concentrations of zinc, cadmium, manganese and nickel. Sulphate reduction in the sediments and formation of insoluble metal sulphides appeared to be the primary process responsible for their removal. In 1999, further investigations were completed on this pilot project and on some of the natural wetlands which receive untreated mine drainage. Due to insufficient volumes of water flowing through the examined wetlands, they could not be fully evaluated as to their performance in the treatment of waste water. However, sediment analyses showed that metals had been attenuated. The colonization of the transplanted sedges (Carex aquatilis) in the constructed wetland was evaluated. Successful growth and propagation was apparent. These local sedges appear to be a hardy species capable of withstanding transplanting, and appear to thrive with a minimum of effort. Metal uptake in plant tissues was also examined. Low levels were documented throughout the study area with the exception of high zinc concentration in sedges that were collected from the No Cash wetland. As Carex aquatilis, the dominant sedge found in the local wetlands, is generally unpalatable to herbivores, the low and incidental levels of metals found within the tissue of the sedges, poses little environmental concern. Overall, the preliminary results indicate that there is good potential for the use of wetlands to treat metal contaminated mine drainage.