Closing the Buckhorn Mine
The closure of the mine is a planned event; it is well established in the pre-mining planning documents that the mine was only anticipated to engage in active mining operations for 7.5 years. Even so, Crown/Kinross and the Department of Ecology (Ecology) are struggling to ensure that the closure and reclamation of the mine site are conducted in a way that returns the site to its pre-mining condition.
With the gold ore at the Buckhorn Mine exhausted, the Crown/Kinross mining company has expedited reclamation. This is a financial decision that will save the company money as the employees and contractors work themselves out of a job. Surface reclamation has involved plugging the mine adits and re-contouring the ground surface to resemble pre-mining conditions. In fall 2017, the treatment facility was decommissioned and the administration buildings were removed. The shop has been retrofitted to accommodate those functions, but for a period of time, the site lacked a facility to treat the water.
Unfortunately, the commitments Crown/Kinross made to Washington citizens via Ecology remain sourly in arrears. The company continues to interpret Ecology’s inaction at enforcing permit requirements as consent, and proceeds in a mode that that best suits them, putting corporate interests before local and environmental concerns. As a prime example, the mine dismantled the mine water treatment facility before it brought a replacement online. For a period of time last fall, there was no treatment of mine contaminated groundwater as required by the mine’s permit, which requires the company to maintain a capture zone by pumping and treating contaminated water. Ecology provided the company with a temporary approval of the new treatment facility, but it was supposed to operate in conjunction with the existing (now non-existing) treatment facility.
Contaminants from mining continue to spread down-gradient in the ground water to surface water. Crown/Kinross has failed to take adequate actions to control these discharges. In addition, the mining company has failed to submit an approvable hydrologic closure plan as required 30 days before actual mine closure to eventually bring the mine site into permit compliance. The mining company has rapidly implemented closure activities that might not be approved if they faced regulatory scrutiny. While the company has laid pipes to be buried under the re-contoured site, almost to the top of Buckhorn Mountain to recirculate treated water during closure, their location has not been approved nor is there a monitoring plan that includes cleanup benchmarks. In fact, the mining company has requested that the two water quality monitoring locations within the mine be eliminated. To ensure compliance there should be more monitoring – not less.
In addition to the failure to complete an acceptable closure plan, Crown’s failure to develop and execute an appropriate adaptive management framework has led to continuous and unabated water quality problems at the mine. Ecology has never approved an updated Adaptive Management Plan, though an approvable update was required by July 2014. Crown must develop a plan that incorporates the significant changes to the mine site that have and will be made now that the mine is closed. One result of the dysfunctional and outdated adaptive management regime is that negative water quality impacts from the operation of the mine have not been adequately addressed. The mine continues to propose actions that would compromise the compliance monitoring at the mine and draw more contaminants away from the mine, instead of implementing actions that were agreed to in the 2013 penalty settlement with Ecology. Actions listed in the settlement include geophysical surveys, tracer tests, and constructing additional dewatering wells, among others.
OHA has registered these and other concerns regarding the regulatory oversight of the Buckhorn Mine closure with Ecology. Given the known risks gold mining presents to the environment, this mine’s specific track record of continuous contamination, and the existence of a carefully developed, judicially upheld NPDES permit, there is no reason to allow Crown’s blatant disregard of the law to continue.
Mine reclamation phase involves re-grading of the mine site, removal of the mine facilities, and re-vegetation, followed by two-years of post-reclamation monitoring. Hydrologic reclamation will continue until water quality is maintained at pre-mining levels for ten years.
An important factor not anticipated in the planning process is that the mine has been unable to contain and control mine contamination to within the permitted boundary. Reclamation of the hydrologic system will likely be arduous and time consuming.
During the mine planning period, closure was expressed as the period of time from the end of reclamation until the water treatment system is no longer required. The time estimated for the closure period was thought to be comparable with the time it would take for the Gold Bowl section of the mine workings to flood. At this point, it is not clear how long the treatment system will have to operate, to bring the water quality back to what it was before mining, but it could be for a very long time.
Water quality and groundwater levels will be used to define the post-closure period; as a result, the actual timeframe for this period is fluid. At some point, the water level in the mine will reach equilibrium. Long-term water quality may be affected by seepage of poor-quality water from the Damaged Rock Zone located above the water table once the hydrologic system has reached equilibrium. The planning documents indicate that Ecology wants a 10-year monitoring period to see any water quality impacts in down-gradient groundwater monitoring wells.
The National Pollution Discharge Elimination System (NPDES) permit requires various mine-related plans be updated to reflect current conditions and also sets forth a framework and timeline for the reclamation plan.