Water: Nonpoint Source Success Stories
Virginia Section 319 Success Stories, Vol. III
Cabin Branch Mine Orphaned Land Project:
Flora and Fauna Benefit from Mine Reclamation
Chief, Division of Resource Management
18100 Park Headquarters Rd.
Triangle, VA, 22172
|Primary Sources of Pollution:|
|acid mine drainage|
|Primary NPS Pollutants:|
|heavy metal concentrations|
|storm water diversion from mine site|
|dredging spoil materials|
|covering mine spoil|
|decrease in heavy metals (copper, zinc, and iron)|
|decrease in sulfate levels|
|improvements in fish community (taxa and individual numbers)|
From 1890 to the early 1920s, Cabin Branch Mine operated at a site along Quantico Creek, a tributary of the Potomac River, in Prince William County, Virginia. Large by Virginia standards, the mine had 200 to 300 people working aboveground and up to 2,400 feet belowground at any given time, excavating pyrite for use in the production of sulfuric acid.
In 1933 the Civilian Conservation Corps obtained the abandoned mine and its surrounding land, and it is now part of Prince William Forest Park. The park's 18,633 acres cover a major portion of the Quantico Creek watershed and contain one of the few remaining piedmont forest ecosystems in the National Park System. The area had been heavily farmed for tobacco since colonial times, leaving the soil degraded and subject to intense erosion. Since the area was acquired by the National Park Service, the native forest has been allowed to reclaim the overfarmed and exhausted landscape. However, the area incorporating the mine site was not able to revegetate naturally because highly acidic mine tailings were inhibiting growth.
Water quality in Quantico Creek just downstream was severely compromised because of the acid mine drainage and heavy metal contamination. During rain and storm events, surface water mobilized and carried oxidized sulphur compounds and acidic material into the creek. The resulting impacts on the water quality of the creek were low pH, high conductivity, and significant sediment loading.
Multiple funding sources
After years of coordination between the National Park Service, Geologic Resources Division and Water Resources Division; Virginia Department of Mines, Minerals and Energy; and the natural resources staff at Prince William Forest Park, the Cabin Branch Mine site was reclaimed in 1995. In addition to section 319 funding, support was provided through a grant from the National Park Service's Water Resources Division, and the balance was covered by Virginia's Orphaned Land Program administered by the Virginia Department of Mines, Minerals and Energy's Division of Mineral Mining.
The primary goal of the Cabin Branch Mine Orphaned Land Project was to improve the water quality of the downstream reach of Quantico Creek contaminated by acid drainage and heavy metals. Additional goals included making the site safer for park visitors and restoring native vegetation. Reclamation plans included diverting storm water away from the mine site to limit acidification of off-site storm waters, sealing all shafts so surface water would not enter mine workings or groundwater, covering mine spoil materials with a good soil medium, and revegetating all disturbed areas with tolerant grasses and legume species. All of these actions were designed to reduce acid mine drainage discharges, thereby reducing heavy metal concentrations in the surface waters.
Benefits to water quality and aquatic life
Water chemistry monitoring of Quantico Creek was conducted before and after reclamation of the Cabin Branch Mine site to quantify the success of the reclamation project. Initial water sampling taken after reclamation activities were completed showed a marked decrease in the presence of heavy metal contamination in Quantico Creek. A 2-year monitoring program conducted by George Mason University (see table) recently confirmed that levels of copper, zinc, and iron in the stream have been appreciably reduced since project completion; sulfate levels and conductance have also improved. In addition, remotely sensed images taken by the US Army Corps of Engineers before and after reclamation visually illustrate the elimination of acid materials from the creek itself. The George Mason study also included fish and invertebrate sampling of the stream. The fish community in the downstream reach has increased in both number of taxa and number of individuals since the project was completed. Results of invertebrate monitoring are inconclusive because of large population fluctuations during the monitoring period.
Water Quality Data Before and After Reclamation,
Cabin Branch Mine
|Element||Pre-Reclamation Concentration||Post-Reclamation Concentration|
|Copper||0.06 mg/L||0.0010–0.012 mg/L|
|Iron||0.49 mg/L||0.18–1.20 mg/L|
|Sulfate||590.0 mg/L||10.0–30.0 mg/L|
|Zinc||0.32 mg/L||0.05–0.12 mg/L|
The park's resource management staff also teamed up with U.S. Geological Survey staff to initiate a monitoring and research study to investigate the effects of storm water retention ponds, created during the reclamation project to minimize acid mine drainage from the site, on breeding amphibians. Although low pH levels and heavy metal concentrations in the surface water retention ponds have been shown to negatively affect amphibian reproduction, results of this study confirm that the ponds are doing what they were designed to do—trap contaminants from surface mine drainage and keep it from reaching Quantico Creek.
The public outreach activities integral to the project continue to be a success. Community involvement was high, and at the end of the project 150 volunteers gathered at the reclamation site to plant 5,000 native trees and shrubs. This effort will help further stabilize the streambank and assist in restoring native forest to previously bare ground.
|Story 1 | Story 2 | State Water Quality Site|
Toncrae Mine Orphaned Land Project:
Mine Site Reclamation Increases Species Diversity
Department of Mines, Minerals, and Energy
P.O. Box 3727
Charlottesville, VA 22903
|Primary Sources of Pollution:|
|acid mine drainage|
|Primary NPS Pollutants:|
|heavy metal concentrations (copper)|
|diversion of water from mine site|
|sealing of all mine shafts|
|regrading mine spoil materials|
|reduced copper levels|
|improved invertebrate community|
|reestablishment of native brook trout|
Beginning in 1993, Phase I of the reclamation included diverting unpolluted waters away from the mine site to limit effluent discharge, sealing all mine shafts, regrading mine spoil materials, constructing wetlands to treat mine seepage, and revegetating all disturbed areas with tolerant grasses and legume species. Sixteen shafts were capped and sealed, and mine markers were installed.
An innovative wetland system was also designed to naturally filter out the heavy metals before they reached the surface waters of East Prong Creek. Contaminated discharge from 16 shafts and 6 spoils dumps is routed through 6 cells of constructed wetland, 5 of which filter the drainage through bark and straw mulch, and then limestone, before discharging into the next cell. Within the cells anaerobic sulfate-reducing bacteria remove toxic heavy metals, while cattails, reeds, and other wetland plant species also contribute to metal uptake, providing a future source of nutrients for the bacteria. The treated water is finally discharged into East Prong Creek.
Phase II of the Toncrae Mine Orphaned Land Project was initiated in 1997 in response to continued chemical monitoring of the constructed wetlands. Monitoring results indicated that two of the wetland cells were not functioning as well as desired in the winter months. The goal of Phase II was to reconfigure the wetland design to increase detention time and improve performance. This phase of the project also included continued chemical monitoring to quantify success.
The reconfiguration of the constructed wetlands was required because the drainage was being oxygenated too rapidly in the winter months because of higher-than-expected flows, combined with cooler temperatures. Because of the rapid oxygenation, the system was unable to maintain the anaerobic conditions that the sulfate-reducing bacteria required to adequately break down the metals in solution. The first step of Phase II involved increasing the size of the two problem cells. The effect was to create one large wetland cell from the previous two, thereby increasing detention time and the overall time the drainage remains in an anaerobic state. Next, another much larger wetland cell was constructed below the existing cells to further increase detention time. Finally, an anoxic drain was installed to reduce oxygen levels entering the system and assist the wetlands in functioning in an anaerobic state.
Invertebrate sampling conducted before reclamation showed the invertebrate population of East Prong Creek to be severely affected below the Toncrae Mine site. Both the number of species and the total number of organisms were significantly lower than those recorded at a reference site located upstream from the mine and its toxic effluent (see figure). After project completion, copper levels were appreciably reduced: copper concentrations ranged from 9 to 32 micrograms per liter (mg/L) before the project and between 0.1 and 14 mg/L after the project. The invertebrate community showed signs of a rapid recovery. Within months of project completion, both the number of invertebrate taxa and the number of individuals were approaching reference site conditions.
Monitoring for Phase II continued through 1998. Chemical monitoring of the wetlands indicated that since reconfiguration, the wetlands are successfully removing metals, even in the cool temperatures of fall and winter.
The success of this project led the Virginia Wildlife Federation to award its 1995 Mineral Conservationist of the Year Award to the Virginia Department of Mines, Minerals, and Energy's Division of Mineral Mining. The award was granted for the successful rehabilitation of the Toncrae Mine site and East Prong Creek. The nomination for the award notes that "the creek now has a healthy animal life with growing diversity, and the revegetated land surface is now a camping and picnic ground."
The long-range goal of the Toncrae Mine Orphaned Land Project was a return of the native brook trout to the contaminated stream section below the mine site. According to residents, no fish had been seen in the contaminated section of East Prong stream in years. Biologists with the Virginia Department of Game and Inland Fisheries confirmed that although brook trout did inhabit the stream above the Toncrae Mine site, they did not occur downstream of the site. However, recent surveys conducted by the Department's fisheries biologists verify that since reclamation was completed, brook trout have successfully moved into East Prong Creek below the abandoned mine site.