B.4 Ferris-Haggerty Mine Case Study
The mining team would like to acknowledge James J. Gusek, Sovereigh Consulting who submitted this Biochemical Reactors Case Study.
B.4.1 Site Information
Abandoned Mine Land Program
Wyoming Department of Environmental Quality
122 West 25th Street
Herschler Building, 1W
Cheyenne, WY 82002
James J. Gusek
Sovereign Consulting, Inc.
12687 West Cedar Drive, Suite 305
Lakewood, Colorado 80228
Name, Location, and Site Description
The Ferris-Haggerty mine is a 100 year old abandoned underground copper mine on private land within the boundary of the Medicine Bow National Forrest near Encampment, Wyoming at an elevation of 9,500 feet. The site is situated in the remote upper reaches of Haggerty Creek, about four miles north of Wyoming Highway 70 in Section 16, T14N, R86W (Figures B.4-1 and B.4-2). At the turn of the nineteenth century it was one of the largest Copper mines in the region, producing an estimated 24 million pounds of Copper from 1898 to 1908. The mine used state of the art mining equipment, including a 16-mile aerial tramway (touted as the largest in the world at the time) for transporting metal ore to a smelter in Encampment.
The copper ore was initially extracted from the underground workings through two vertical shafts driven from the surface and later from a main haulage level, called the “Osceola Tunnel”, whereby the ore was transported to the surface using a compressed air locomotive and rail cars. The ore was then transported over the Continental Divide to the smelter in Encampment via the aerial tramway. By 1904 the mining operations were at their apex, employing 200 men and producing over $1,400,000 worth of copper. Mining operations ceased in 1908 presumably as a result of smelter fire, financial problems, mismanagement and declining copper prices. Foreclosure proceedings began in 1913 and salvage operations followed shortly. The Ferris-Haggerty Mine Site was added to the National Register of Historic Places on July 2, 1973.
The main environmental cleanup challenge presented by the mine is a substandard water discharge from the ore transporting/drainage tunnel. This water contains 4 mg/L of copper and discharges into Haggerty Creek at a rate ranging from 50 gallons per minute (gpm) to 500 gpm, depending upon the time of the year. This amount of copper has rendered the stream directly below the mine virtually lifeless.
The Ferris-Haggerty Mine site was investigated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) in the early 1990s. USEPA conducted a Preliminary Assessment in 1993 and a Site Inspection in 1994 recommending further assessment with a high priority. The State of Wyoming assumed control of the cleanup project in 1996 after the USEPA agreed with a state request not to include the mine on the USEPA’s Superfund National Priority List (NPL) site. Wyoming Game and Fish Department officials have stated that cleaning up the mine site could help reestablish the Colorado cutthroat trout (endangered species) populations in nearby Haggerty Creek.
The Wyoming Abandoned Mine Land Reclamation Program (WYAMLP) spent $2.5 million at Ferris-Haggerty preparing the mine for the mitigation of acid mine drainage. The expenditure included installation of a safety closure and stabilization of the underground workings where personnel would need access. The mine’s portal and main tunnel, the Osceola Tunnel, was rehabilitated and shored up to allow engineers to install a pilot water treatment systems and evaluate the high copper concentration source. A substantial locking closure was also installed at the portal and remains in place, preventing access to the mine.
B.4.2 MIW Chemistry
The Ferris-Haggerty Mine/Osceola Tunnel site is a high-elevation abandoned copper-mine site with acid rock drainage (ARD) characterized initially as having neutral pH, low sulfate, elevated copper concentrations, and water temperature close to freezing. The mine water has neutral pH discharge with 3 to 20 mg/L dissolved copper and low sulfate (typically less than 100 mg/L SO₄); water temperature is close to freezing (±4˚C), and the mine is accessible only by a 32-km (20-mile) snowmobile trek for nine months out of the year. Flow from the portal varies from 57 to 114 L per min (15 to 30 gpm) in the winter months to 1.7 cu m per min (450 gpm) or more during the spring runoff. Copper concentration initially observed at the portal was fairly constant all year long, somewhat independent of flow rate. However, after the completion of tunnel rehabilitation activities, a spike of elevated copper concentration and low pH (3.8) was observed coincident with the spring freshet.
B.4.3 System Design
B.4.3.1 BCR Design
The first of two pilot-scale passive treatment cells was composed of a single gravity-fed anaerobic SRBsulfate-reducing bacteria-cellAn individual unit in a treatment system. configured in a down flow mode. In the summer of 1997, a 4.6-m (15-ft) diameter and 1.2-m (4-ft) deep cell was filled with a mixture of softwood sawdust, hay, limestone, cow manure, and gypsum. The gypsum was added as a source of sulfate for the SRB. The proportions in the recipe were selected based on a six-week-long bench-scale (trashcan-size) test conducted in the summer of 1996.
The pilot cell treated a flow of 3 to 5 gpm for two years beginning in the summer of 1997. Snow depths on the site can reach 10 feet over a typical winter season, so the cell was enclosed in a shed to allow winter access for sampling, inspection, and data retrieval.
The pilot cell was designed based on an estimated sulfate reductionThe stripping of oxygen atoms from sulfate (SO₄²⁻), most often yielding sulfide (S²⁻) as an ultimate product. rate of 0.15 moles/day/cubic meter of substrateEither (a) a chemical which reacts or (b) a solid surface or (c) an electron donor., the value that was observed in the best cell in the 1996 bench-scale study. This results in a retention time in the cell of less than 12 hours.
The pilot cell was outfitted with an ISCO 6700 automatic sampler and a YSI probe to monitor pH, conductivity, redox potential, and water temperature in late October1997, just prior to a blizzard that effectively ended the short field season. No heat-trace equipment was installed; all pipes carrying water were buried and/or fitted to maintain flow to prevent freezing.
In August 1999, a second pilot-scale cell was built with a slightly different substrate mixture and buried below grade to more closely mimic the planned full-scale system (Gusek 2000). The full scale system was never constructed, however, due to land owner resistance. The surface area needed for construction just outside the portal was on privately owned patented mining claims and the land owner did not allow the system to be built. The WYAMLP installed a limestone line ditch from the portal to Haggerty Creek and closed the site out in mid-2000.
B.4.3.2 Pre- and posttreatment requirements
Due to the low mine water temperature, the initial slug of water used in incubation was heated to about 15˚C. The cell was incubated for about a week before it received full design flow of 19 L per min (5 gpm) at about 3˚C.
B.4.4 BCR Monitoring
Bi-monthly site visits via snowmobile were conducted during the winters of 1997/98 and 1998/99 to collect data and samples. Monthly sampling was conducted during the summers of 1998 and 1999. During the winters, sub-freezing air temperatures resulted in an ice covering over about 40 percent of the cell surface. Flow through the cell decreased from an initial value of 19 L per min (5 gpm) in October1997 to about 11.4 (3 gpm) in the subsequent months.
A number of physical and chemical parameters were evaluated for the pilot-scale cell from start-up in August 1997 through June 1999 in order to evaluate the efficiency of the pilot-scale cell. Parameters include copper removal, pH, sulfate reduction, redox potential, temperature, and saturated hydraulic conductivity.
B.4.5 BCR Performance
Figure 5 in Reisinger et al. shows total copper removal for the pilot-scale cell. Copper removal during the first nine months of operation (that is, from August 1997 through May 1998) ranged from 95 to 100 percent. Once more highly contaminated chute/shaft water (from deeper in the mine) was introduced in June 1998, copper removal efficiencies decreased to generally between 89 to 97 percent. The removal efficiencies noted during December 1998 (84 percent) and May 1999 (63 percent) were likely due to system upsets caused by contaminated water not being fed to the cell.
As shown in Figure B.4-5 below, the pH of the processed water remained relatively neutral even with a change in feed waters from relatively neutral pH (Osceola Tunnel portal water) to a pH ranging from about 3.5 to 4.0 (chute/shaft water). Both the SRBsulfate-reducing bacteria and limestone incorporated into the substrate recipe likely contributed to the ability of the cell to maintain a relatively neutral pH.
Sulfate reduction is an indication of the level of SRBsulfate-reducing bacteria activity. The greater the sulfate reduction, the more the SRBsulfate-reducing bacteria activity. During the first several months of cell operation, sulfate reduction was not apparent and was likely masked by the addition of gypsum into the substrate recipe. Gypsum addition was done to enhance the cell environment for the SRBsulfate-reducing bacteria during system start-up. After the first several months, the cell generally exhibited sulfate reduction, especially during the period when higher sulfate-containing chute/shaft water was being processed.
Figure 5 also shows Ev measurements for pilot cell inflow and discharge. Ev is a measure of redox potential. The more positive the Ev value, the more oxygen-enriched the water. The more negative the Ev value, the more oxygen-deprived the water. Ev values for processed water in the range of -200 millivolts (mv) or lower suggest an anaerobic environment. As can be seen in Figure 5, Ev values are generally below -200 mv with the exception of the positive value observed during June 1999. This value is likely due to the cell not processing water at the time of the site visit.
During operation, the pilot cell copper removal efficiencies were acceptable even when the cell surface was 40-percent covered in ice and the influent changed to an acidic water with a pH between 3.5 and 4. The pilot cell operated successfully (i.e., 89- to 97-percent removal of copper) for two years, after which time it was decommissioned.
B.4.6 Regulatory Challenges
The WYAMLP stated in their 2002 Annual Evaluation Summary Report that they had concerns that although the BCR cell may reduce contamination, it was unlikely to eliminate it. Because of current USEPA regulations, the WYAMLP was reluctant to assume the potential liability of becoming a principal responsible party under CERCLAComprehensive Environmental Response, Compensation and Liability Act for the mine discharge, should they make an unsuccessful attempt to correct the water quality problem.
B.4.7 Stakeholder Challenges
The primary stakeholder challenge associated with this site was negotiating the sale of sufficient land from the private property owner in order to construct a full scale treatment system. Ultimately, the WYAMLP was unsuccessful and the final system was never constructed.
B.4.8 Other Challenges and Lessons Learned
Minor temperature fluctuations may not affect SRBR overall activity all that much once the microbial suite has established itself. In the pilot scale SRBR at the Ferris-Haggerty Copper Mine/Osceola Tunnel in Wyoming, the mine effluent was typically less than 5°C. During the winter at this high altitude (9,500 feet elev.) site, the treated effluent temperature dropped to as low as 0.5°C. Yet the rate of sulfate reduction reducedIn chemistry, having gained electrons. Often gaining electrons is accompanied with gaining protons (hydrogen). As an example, when O₂ reacts with H₂, the oxygen is reduced, forming H₂O. to only about 80 percent of the 5°C benchmark rate (Gusek, 2000). This observation was incorporated into the design of a full-scale system to treat as much as 600 gpm.
A part of the temperature challenge at the Ferris-Haggerty site was mitigated by a number of design features, including:
- collecting the mine water deeper in the mine and delivering it to the SRBR cells in insulated pipes to preserve some of its ambient in-ground temperature, and
- covering the SRBR’s with an insulating layer of clean mine waste rock.
Covering/burying SRBR’s (which do not need plants or sunshine to function) can be used to solve other full scale design challenges. Other design considerations, such as seasonal changes in metal loadingMass of something per time entering a volume (volumetric loading rate) or flowing into an area (areal loading rate). rates, may further mitigate temperature effects on SRBR performance.
The advantage of low maintenance requirements for passive treatment make it attractive compared to other more active technologies, especially at remote sites such as Ferris-Haggerty.
The WYAMLP stated in their 2002 Annual Evaluation Summary Report that it would have been prudent to negotiate land acquisition as a component of access for the treatment feasibility study.
Office of Surface Mining Reclamation and Enforcement. Annual Evaluation Summary Report for the Abandoned Mine Land Reclamation Program Administered by the State of Wyoming for Evaluation Year 1997 (October 1, 1996 to September 30, 1997) and 2002 (October 1, 2001 to September 30, 2002).
URS Corporation, Portland, Maine. Passive and Semi-Active Treatment of Acid Rock Drainage of Acid Rock Drainage from Metal Mines – State of the Practice. Prepared for U.S. Army of Corps of Engineers, Concord, Massachusetts. April 2, 2003.
J.J. Gusek, P.E. Reality Check: Passive Treatment of Mine Drainage An Emerging Technology or Proven Methodology? SME Annual Meeting, February 28-March 1, 2000 Salt Lake City, Utah.
Wyoming Department of Environmental Quality – Water Quality Division. Haggerty Creek & West Fork Battle Creek TMDLs for Copper, Cadmium & Silver.
Wyoming State Historic Preservation Office. National Register of Historic Places. http://wyoshpo.state.wy.us/NationalRegister/Site.aspx?ID=81.
Publication Date: November 2013