Landslide

In May 2011, a large slope failure below the Buckhorn Mine sent a wall of mud and large trees flowing down Gold Bowl Creek. Just below the mine facilities and one of the treated mine water discharge areas, the side hill of Gold Bowl Creek gave way, sending mud cascading thousands of feet, uprooting large trees and scouring the creek drainage of all vegetation 12-15 feet high. Surface water monitoring site SW-9 was obliterated by the May 14, 2011 landslide. A replacement monitoring point was established at SW-9A.

According to Geology (Chernicoff & Whitney, 2002), blasting that accompanies mining, quarrying, and road construction can trigger mass movement. Vibration from these activities can force apart grains of loose sediment, eliminating the friction between them. Sometimes human activity, such as mining, may combine with natural factors to increase the chance of mass movement.

Crown/Kinross consultant Golder Associates performed a dye test to see if treated mine water discharged to the stormwater ponds DA 10/11 was connected to the massive mudslide that blew out the side hill of Gold Bowl Creek in May 2011, uprooting trees and scouring over half a mile of creek. In summary, the results showed that DA 10 contributed to flows in the slide area. OHA does not consider the DA 11 test conclusive because it occurred after the slide area had dried out. There was no flow by the time of the test. Ecology has curtailed treated mine water discharge to these locations.

The National Pollution Discharge Elimination System (NPDES) states, “Discharges must not cause erosion or slope instability.” Crown/Kinross went to great lengths to represent this spring’s mudslide as unrelated to the mining activity. However, as noted above, a connection was established.

As a result of landslides, two of the four treated water discharge points were restricted, and the company sought additional places to discharge treated mine water. Additional environmental review will be necessary to examine the impacts of discharging large quantities of treated water into yet unidentified locations, before the new discharge points can be permitted. It is in everyone’s best interest for new discharge points to be developed; otherwise, water builds up in the mine.

Water Quality Requirements Violated

• Concentrations of mine-related contaminants have been increasing in surface water and in groundwater since the mine operations began
• Water infiltrating through the PAG development rock has leached contaminants into Gold Bowl Creek
• Erosion from treated mine discharge has contributed to slope instability
• Other unpermitted mine discharge has entered surface water

The increases in nitrate and chloride concentrations in SW-14 made it apparent that a preferential pathway exists between the mine area and upper South Fork Bolster Creek.

The mine has leaked contaminants since it began operations. The mine’s monitoring shows that the mine has failed to maintain a capture zone, which is supposed to keep mine contaminants out of surrounding ground and surface water. Recent water quality violations began with the spring thaw in May 2011, when a major mudslide erupted below one of the treated mine water discharge locations. The landslide released a 20 foot wall of mud, scouring the vegetation and ripping out trees for half a mile down Gold Bowl Creek.

During May and June, water quality in Gold Bowl Creek exceeded standards for nitrates from blasting and sulfates from acid generating rocks. Sulfide rock removed from the mine is stored on the surface, exposed to the elements and can form sulfuric acid. Nitrates from blasting have also been elevated in Bolster Creek, west of Buckhorn, and in groundwater wells east of the mine.

Unfortunately, discharges of pollutants have been occurring from the mine that are not permitted by the NPDES. In fact, the permit specifically states that no other discharges are permitted. However, contaminants from the mine and waste rock pile discharges have increased in ground and surface water, sometimes in excess of Water Quality Standards (WQS), and yet since April 2008, Ecology has not issued violations for failure to maintain the capture zone, nor for discharges from the waste rock pile. Throughout 2011, OHA continued to encourage Ecology to hold the company accountable for these non-permitted discharges.

Reporting Issues

As part of the response to the Department of Ecology’s Administrative Order #8820, Crown/Kinross updated the Groundwater flow model for the Buckhorn Mine. OHA reviewed the Nov. 2011 Golder report entitled, “Updated Groundwater Flow Model and Mine Inflow Estimates,” and provided comments to Ecology. OHA found the report to be lacking coverage of some critical issues, including omission of grouting to minimize groundwater inflow to the mine and a lack of numeric estimates of groundwater inflow to the mine.

Development Rock Reporting Needs Improvement

Water leaching through development (waste) rock piles, especially in the spring, has increased pollutants in ground and surface water. Kinross is required to submit a report to the Department of Ecology each quarter to provide an analysis of the past quarter’s development rock information.

Ecology rejected the 1st quarter report submitted in August and is requiring the company to generate a report based on criteria at that time.

Crown/Kinross made commitments at the March 15, 2011 Annual Meeting regarding reporting of development rock, including mapping faults and applying shotcrete. No information about faults was in the quarterly report, and shotcrete application was limited.

Contaminants travel through faults or other preferential pathways in the underground mine. Faults and voids in the cemented rock fill (CRF) are identified during mining. OHA had asked that these features be identified in the quarterly reporting to help track contaminant transport. OHA also suggested that increased shotcreting would increase groundwater protection. This suggestion comes as a result of failure of the capture zone, uncertainty related to seasonal fluctuations, and the unreliability of the groundwater flow model. OHA is concerned that the large backlog of PAG DRZ in the underground mine and the failures of the capture zone are degrading water quality around the mine.

OHA also recommended that ore headings should be analyzed for acid generating potential and if it is determined to be PAG, the area should be shotcreted before CRF is applied for ground control. Until this point, it appears that ore has not been tested to determine whether it is potentially acid generating (PAG)!

NPDES Permit Up for Renewal

In the midst of these serious issues, the National Pollution Discharge Elimination System (NPDES) permit came up for renewal. An administrative extension was granted. OHA maintained that at the very least, the NPDES renewal should increase reporting during the spring freshet so that discharges from the waste rock can be more thoroughly monitored. In 2011, one downstream well was monitored once a month, which is insufficient both in frequency and scope to ensure that water quality changes during freshet would be noticed. OHA also strongly suggested that any increase in contaminants beyond the background baseline levels should be highlighted and watched for increasing trends, and all water quality violations should be noted.

2012 brought official recognition of the Water Quality permit violations, which were swiftly appealed by the company.

Buckhorn Mine Violates Water Quality Permit

On July 16, 2012, the Buckhorn Mine was fined $395,000 for water quality violations.

The largest part of Ecology’s July 2012 penalty was issued for failing to capture and treat mine contaminants for 94 days, thereby violating the NPDES permit. According to OHA’s analysis, the capture zone has been violated since July 2008, for a total of more than 1,640 days.

If a capture zone is not maintained, mine water can enter the groundwater system without treatment. Changes in water quality in stations downgradient of the mine indicate that the hydraulic containment system provided by the mine (capture zone) is not fully effective in containing mine water. Water quality monitoring data for South Fork Bolster Creek station SW-14 shows elevated concentrations of nitrite plus nitrate above background values in every sample collected since July 2008, which demonstrates that Crown has failed to maintain a capture zone on the west side of Buckhorn Mountain. The NPDES strictly forbids any discharges other than those that are permitted and there is no permit to discharge pollutants into Bolster Creek.

Crown Denies Responsibility for Water Problems

The mining company appealed Ecology’s July 2012 penalty for permit violations at the Buckhorn Mine, denying responsibility for causing the Gold Bowl landslide and for failure of the mine’s capture zone. Crown challenged the amount of the penalties as too high.

Despite the thorough documentation of slope stability problems below treated water discharge locations, and water quality problems below the waste rock piles, the company denied responsibility.

The Buckhorn Mine Adaptive Management Plan (AMP) for Water Quality Changes Due to Mining clearly states, “Mitigation elements incorporated into the Buckhorn Mt. Project to protect surface water and groundwater quality include: Containment of mine water within the mine as a result of the capture zone that develops surrounding the underground mine and dewatering wells.”

There is not an exception written into the language of the mine plans allowing for some of the contaminants to escape the capture zone. All contaminated water emanating from the mine should be captured. The monitoring program laid out in the AMP clearly aims “to determine… whether the mine and dewatering wells are creating a capture zone to contain seepage from the mine, development rock and ore stockpiles.” The plan does not call for partial containment of seepage. Based on the AMP, OHA has an expectation that Crown Resources will maintain a separation between contaminants generated from the Buckhorn Mine and the environment; however, contaminants are emanating beyond the footprint of the mine.

The appeals have since been settled.

2012 In Review – OHA Issues with the Buckhorn Mine

In 2012, OHA’s issues and concerns prompted numerous memos and letters to Crown/Kinross and regulatory agencies. OHA started the year in early January with a memo to Ecology, commenting on Crown’s consultant’s Updated Groundwater Model (Nov. 2011) and Crown’s response to Administrative Order 8820. After a thorough review of the details, OHA concluded that the report does not demonstrate that the revised groundwater flow model is calibrated to site conditions, nor is it capable of simulating mine conditions (such as leakage of mine-related contaminants to area streams). The revised model failed to simulate the effects of high precipitation and recharge in 2011, and the report has not adequately demonstrated that there is an effective capture zone around the mine. A revised report should be prepared that more directly addresses the success of model calibration and how shortcomings of the model can be improved.

OHA wrote letters to and met with Crown, explained our problems with their proposal to discharge treated mine water into Gold Creek, and provided suggestions of analysis that should be done for last year’s annual review. Crown’s response was that if OHA wants this work to be done, we should do it ourselves.

In February 2012, OHA prepared a memo showing that Crown has failed to maintain the capture zone, in violation of the waste discharge permit.

A year ago in March, OHA presented a memo to all the participants of the mine’s annual review meeting, with recommendations of modifications to the Adaptive Management Plan (AMP), based on concerns that the reporting ignores relevant information and fails to provide thoughtful analysis of conditions at the mine. Some of the main points of the memo are:

1. The Shotcrete Evaluation is incomplete, lacks objectivity, and for consecutive years has failed to include basic DRMP (Development Rock Management Plan) and AMP requirements. OHA recommends that the 2011 shotcrete evaluation be rejected and that an independent third party submit a new evaluation.
2. Discharge from the PAG stockpile should be monitored and reported for volume/flow and water quality monthly, with the exception of during spring runoff, when it should be monitored daily.
3. Additional piezometers and monitoring wells should be installed to reliably establish the extent of the capture zone.
4. An analysis of ground water elevations, precipitation and dewatering rates should be conducted to better predict the need for water treatment and underground storage.
5. A new evaluation of geochemical predictions, influent quality and outflow quality should be conducted.

In April 2012, OHA provided Ecology with a synopsis of the shotcrete requirements, including recommendations for enforcement. Shotcrete is a fine-grained cement that helps provide a barrier between reactive rock and preferential pathways to groundwater. Many of the requirements have either been ignored or only partially implemented by Crown.

In June 2012, OHA presented numerous memos to Ecology, beginning with input on Crown’s application for NPDES permit renewal, to supplement the discussions and to increase protection of the environment. OHA raised concerns about the Adaptive Management Plan (AMP) being outdated; a new AMP should be created to reflect what has been and is being learned from the actual data, as well as the operational changes that have been or should be made. Ecology requested we present a memo on the subject, the main points of which are outlined below:

1. Annual reporting of operational changes should be required, including an explanation of each issue that has been addressed and the changes that have been proposed or implemented. Without a record of these changes, implementation of adaptive management cannot be effectively evaluated.
2. Seeps and Springs: The 2007 AMP addresses impacts of dewatering on the Nine Acre Wetland. Operational changes designed to avoid further landslides have reduced or eliminated two effluent discharge points, leaving most effluent from the mine to be discharged into the Nine Acre Wetland. This AMP should be revised to reflect the current situation.
3. Mine Dewatering and water supply impacts to streamflow: To provide mitigation of dewatering impacts, this AMP requires monitoring to determine whether the infiltration gallery is functioning properly, where water is returned to the soil. It appears that the “gradual increase of discharge” to the gallery was not adhered to, and in the absence of performance evaluation, its functions were compromised. This objective should be updated.
4. Water Quality Changes Due to Mining Operations: Various adaptive management strategies have been adopted to mitigate water quality changes at the mine. The AMP should be updated to reflect the current situation, including increased analysis of data, action levels and mitigation strategies. Adaptive management for failure of the capture zone should be considered, including additional monitoring, analysis and remedial actions.
5. Development Rock Management: The AMP should be updated to reflect the current situation, including increased analysis of data, action levels and mitigation strategies. These updates should consider actual water quality conditions, implementation of shotcrete requirements, and realistic assessment of discharges from PAG stockpiles.
6. Slope Stability: Current monitoring and adaptive management of slope stability is ineffectual. If there is any doubt regarding this statement, the current monitoring plan should be evaluated in light of the 2011 landslide. The new AMP should provide for evaluation and management of slope stability.

Also in June 2012, OHA provided Ecology with a memo regarding Crown’s mischaracterization of the 002 treated mine water discharge location.

In October 2012, OHA commended Ecology’s regional director for issuing the penalty to Crown for violating their permit and provided additional examples of provisions that have been violated, including failure to notify Ecology when monitoring values exceeded background values.

The public can access permit documents such as permits, fact sheets, and public notices through PARIS (the Permit and Reporting Information System). 

Buckhorn Mine Related Documents

Documents, including water right decisions, can be requested from Ecology