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.

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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.

In September 2000, eleven shrub species were planted in experimental plots at three different areas of the Brewery Creek Gold Mine near the Klondike River. All of these shrub species naturally grow in the mine area. The purpose of this project is to find out which of these shrub species may be useful for revetating the large open areas at the mine site, after the mine closes. It is anticipated that this information will also be useful when revegetating other mine sites in the Yukon. The three sites chosen for these experiments are a steep north-facing slope, a steep south-facing slope, and a lower, nearly level area. The shrubs were planted in six plots at each of the three sites. All three areas had been graded and seeded in 1996-97, and there was a fairly thick growth of grasses and clovers at the time the shrubs were planted. To determine if this thick growth interfered with the survivial of the newly planted shrubs, the grass and clover was first removed from one half of each plot.

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.

With assistance from the Yukon Oil and Gas Branch, EDI Environmental Dynamics Inc. developed and submitted a proposal to the Mining and Petroleum Environmental Research Group (MPERG) to conduct a study of vegetation regeneration on linear developments subject to wildfires, specifically on and in the vicinity of the winter access road leading to test well site K- 58, beginning in the first post-fire growing season. The study site was located in sub-arctic, black spruce (Picea mariana) dominated forest in a zone of continuous permafrost in the area of Eagle Plains, YT. The study examined vegetation composition and abundance, as well as soil and permafrost conditions, in four types of linear disturbances, including: 1) burned 30+ year old seismic lines; 2) a burned one-year-old winter road; 3) the same burned one-year-old winter road constructed on an existing, 30+ year old seismic line, and; 4) unburned 30+ year old seismic lines. A total of 73 (200m2) paired vegetation plots were completed within each of the above linear disturbances and adjacent forests. Overall, the vegetation was highly uniform among all types of linear disturbances and undisturbed sites in the study area. Differences in species composition and abundance were most pronounced between the burned and unburned sites, with a greater number of species present and higher vegetation cover in unburned sites. Of the three types of linear disturbances sampled, the combined disturbance of the burned one year old winter road constructed on a 30+ year old seismic line demonstrated the most notable differences in vegetation composition and abundance in comparison with the adjacent forest. In contrast, species composition and abundance in the burned winter road and burned 30+ year old seismic line were more similar to that in adjacent, burned forests. No trends in soil moisture were detected among the various disturbance types. Depth to permafrost was slightly lower in all three linear disturbances, but this difference was not significant. Depth of organic soil was significantly lower in the combined disturbance of the burned one year old winter road constructed on a 30+ year old seismic line, and was significantly higher in the burned winter road, when compared to adjacent, burned forests. Moss depth was significantly higher in unburned than burned sites. In the first post-fire year, this recent burn appears to be the dominant factor affecting vegetation composition and abundance in the study area. Re-vegetation is occurring rapidly on linear disturbances, with the dominant vascular plant species in the unburned, undisturbed forest regenerating across all disturbance types. Because the study was completed in the first post-fire growing season, it was not possible to assess regeneration of black spruce, an important structural species that is not reported to begin to regenerate until several years after a burn. Similarly, it was also not possible to assess lichen re-establishment, an important element of vegetation succession in black spruce forest that also re-establishes later than the first post-fire growing season. Continued monitoring will be required to understand the longer term response of vegetation to fire in linear disturbances.

Numerous active-layer detachments occurred in watersheds surrounding Dawson City following forest fires that burned the area during the summer of 2004. The distribution of these shallow landslides was mapped in the Mickey Creek, Steele Creek and Fifty Mile Creek watersheds. Selected slope failures were surveyed in detail to describe their geometry and geomorphological settings in order to investigate the mechanisms of failure, and to assess the effects of the forest fires on local permafrost conditions. The failures generally initiated on moderate convex slopes at shallow depths (< 65 cm ) in silty colluvium; frost tables were close to 1 m in depth. Most active-layer detachments were on the order of 5-20 m wide and 10-100 m long and occurred on slopes with a variety of aspects; however, the detachments occurred only where permafrost was present. In some cases, they developed on gentle slopes (as low as 10°) and traveled several hundred metres, depositing sediment directly into creeks, or across access trails. Their cumulative effects may significantly impact sediment transport within the watersheds. Potential concerns for fish habitat and implications for placer mining water quality regulations have consequently been raised.

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.

A large erosion cut, approximately 300 metres long and up to 50 metres deep, has occurred on a stockpile of frozen overburden on the east bank of Gold Run Creek, a placer mining area southeast of Dawson City. In September 2005 erosion control structures reinforced with live willow cuttings were installed at the site. These structures consisted of earth retaining walls built to stabilize the slope failure and a flume to convey the water past the retaining walls while the willows had time to grow and strengthen the structures. In July 2006 the site was revisited. It was found that, while the earth retaining walls were intact, the flume had malfunctioned and further erosion had occurred beyond the walls. It was concluded that the collapse of the flume was the primary cause of the failure of the erosion control project.