HIGHLAND VALLEY COPPER - Reclamation Monitoring
Reclamation monitoring is one of the requirements in the Reclamation Permit. The permit stipulates that revegetation efforts must be monitored to judge if vegetation is meeting the "self-sustaining" objective.
Monitoring programs are conducted annually using both conventional and remote sensing techniques
There are several components to the revegetation monitoring program at HVC.
BIOMASS PRODUCTION is measured through grid sampling of biomass at locations around HVC. Biomass sampling is compared between fertilized and non-fertilized areas, and between areas of different weather to assess any differences in productivity.
SPECIES COMPOSITION is used to determine the species diversity and self-sustaining capacity of the vegetation. The ideal composition had an abundance of legumes as well as many different types of grasses.
FOLIAR NUTRIENTS are measured in the middle of the growing season, and plants are analyzed for micro and macronutrients. This information is used to assess the stability of vegetation in locations where fertilizers are no longer being applied. In some instances, deficiencies of zinc and boron have been observed, in which case fertilizers can be supplemented for specific sites.
TOXICITY of molybdenum, copper and sulfur are monitored in vegetation to prevent adverse effects to wildlife, and in particular to ruminants. Legumes have been found to have the highest levels of molybdenum, but also the most variable concentrations.
GROWTH PERFORMANCE of native trees and shrubs have also been monitored at HVC since 1992. Certain species were determined to be preferred for this type of monitoring. On waste rock sites these include: alder, prickly rose, Saskatoon, trembling aspen, willow and wolf-willow. On overburden capped sites these include: chokecherry, Saskatoon, shrubby pentstemon, trembling aspen, willow and wolf-willow. On the Trojan tailings site these include: red-osier dogwood, willow, and wolf-willow.
STOCKING DENSITY assessments are used to document the success of revegetation efforts, and determine if wildlife goals are being met. As part of the monitoring program, areas that were planted with native shrubs but not previously seeded were compared with areas that were seeded in advance of native shrub planting.
Quantifying Monitoring Results:
Airborne remote sensing has been used to monitor vegetation and reclamation success at HVC. This method had economic and human resources advantages as compared to traditional monitoring from the field. Biomass is mapped using a normalized difference vegetation index, which showcases a difference in normal, healthy vegetation and non-vegetated surfaces (soil and rock). Following surveys in 2001, 2002, and 2003, year-to-year changes in vegetation can now be analyzed.
Molybdenosis in Ruminants
The tailings ponds contain elevated levels of molybdenum and copper with the potential to bioaccumulate in planted vegetation. Ruminants such as cattle or moose consuming forage with elevated molybdenum can incur molybdenosis. The elevated molybdenum results in a reduction in biologically available copper, or molybdenum induced copper deficiency in the consumer.
In 1994-1997 a trial was conducted on the Bethlehem tailings site grazing cattle on revegetated tailings to determine any effects from forage with approximately 32 ppm molybdenum. The following experiments were conducted:
A grazing trial was also conducted on the Highmont tailings site from 1998-2002 where molybdenum in forage was 10 times the level of the Bethlehem site. The effects of molybdenosis including lameness, loss of hair pigmentation, and diarrhea were experienced by the grazing cattle. In cases where a copper supplement was given effects were reduced.
The results of these trials show that forage grown on tailings at HVC has the capacity to induce molybdenosis in grazing cattle; however, there is also the potential to manage cattle grazing to limit or eliminate the effects.
At HVC moose consume shrubs, forbs, and grasses in the revegetated areas as part of their diet. In the winter moose can consume up to 20 kg of vegetation per day, and molybenosis is a concern. A study on molybdenosis in moose was conducted in Fall 2003; feces and vegetation were collected from several plots and analyzed in a lab. There is known a linear correlation between increased molybdenum consumption and the increase in levels in feces and urine. In the study it was found that although moose may be susceptible to molybdenosis through their forage habits, none have been found to be exhibiting molybdenosis at HVC. However, further work is needed to gather more details on the risk of moose to molybdenosis.
A 3-year study on birds in the HVC mine area was conducted in 2005, 2006, and 2007. In the 2005 avian study, 160 species were recorded. Of those, 45 species were restricted to areas that had not been disturbed by mining activity (e.g. forests), while 115 species were utilizing areas disturbed by mining activities (e.g. revegetated areas). Eighty-seven percent of the species utilizing the areas disturbed by mining activities were seen during the breeding season. However, none are thought to be year-round residents and those species are considered to be migrant at some time of the year.
Due to the mining disturbance and subsequent changes in vegetation some bird species are now in higher abundance than pre-disturbance. For example, in grassland areas the following species are now in abundance: northern harriers, rough-legged hawks, horned larks, water pipits, snow buntings, savannah sparrows, and vesper sparrows. The same is true of tailings and new wetland areas; rainbow trout in Trojan Pond are a food source for bird species at HVC which has made the tailings and new wetland areas more attractive habitat to some species.
Overall, the revegetated areas and wetlands are providing good habitat that is being utilized by avian populations. These trophic level interactions indicate that the reclamation efforts at HVC are becoming self-sustaining, and are on track with the reclamation goals.