ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY

CALIFORNIA GULCH LAKE COUNTY, COLORADO SUPERFUND CASE STUDY

A Once Toxic “Moonscape” from Mining and Smelting Is Returned to Fertile This case study is part of a series focused on ecological Pasture and Native Prairie revitalization conducted Historical mining in Lake County, Colorado, resulted in during contaminated releases of tailings and water with high metals concentrations site remediation and via California Gulch to the Upper Arkansas River and reuse; these case studies associated irrigation ditches. These releases created are being compiled by unvegetated mine waste deposits in the floodplain and the U.S. Environmental agricultural land with areas of reduced or no productivity. Protection Agency (EPA) Over the years, the tailings continued to erode and re-deposit Technology Innovation along the Upper Arkansas River, creating a 9-mile stretch of and Field Services Division river containing barren mine deposits. Many of these deposits (TIFSD). The purpose of accumulated along eroding stream banks and were coated these case studies is to with metals salts that washed into the river during storms. provide site managers with Vegetation and the soil information on ecological community were limited by reuse, including principles high metals concentrations, Topics Highlighted in for implementation, low pH, insufficient macro- this Case Study: recommendations based and micro-nutrients, poor ✓✓Attractive Nuisance on personal experiences, physical properties, and ✓✓Bioavailability a specific point of contact, reduced water holding ✓✓Erosion and a network of sites capacity. with an ecological reuse • Invasive Species During a series of component. • Predator Control demonstration projects and ✓✓Recreation ultimately a remedial action, ✓✓Soil Amendments the fluvial deposits and irrigated meadows were amended ✓✓Use of Native Plants with organic residuals, lime, and fertilizer and seeded with native and crop species to produce a stable vegetative cover • Use of Volunteers that reduces dust, erosion, washing of metals into the river, • Water Management and the availability and toxicity of metals contaminants. • Wildlife Habitat: Testing conducted by EPA and the U.S. Department of • Freshwater Wetland Agriculture (USDA) showed that total concentrations of metals ✓✓Prairie of concern in soil did not change, but that bioavailable lead, • Saltwater Wetland • Savannah Ecological Revitalization = the process of returning ✓ land from a contaminated state to one that supports ✓Stream functioning and sustainable habitat. • Woodland

May 2011, EPA542-F-11-007 www.cluin.org/ecotools 1 ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY cadmium, and zinc concentrations are now greatly reduced. Stable stream banks with minimally intrusive engineering materials that support native plants were created to replace the eroding tailings. Approximately 210 acres of the contaminated soils were converted to pasture and recreational lands. As a result of this ecological revitalization, cattle grazing has resumed on land that was barren for more than 80 years and a public recreation area with trails, river access, and fishing areas now operates on remediated fluvial tailings deposits. Fly fishing enthusiasts now enjoy a scenic panorama of native grasslands in the Eroding streambank prior to treatment floodplain. Background What are Pyritic Soils? • The California Gulch Superfund site was Pyritic soils contain pyrite, which is a listed on the National Priorities List (NPL) mineral also known as “fool’s gold.” Pyrite in 1983 and consists of about 16 square is used to produce iron ore and sulfuric miles in Lake County, Colorado. Operable acid, and when it is present in the soil, it Unit 11 (OU11) includes the Arkansas River can cause the soil to be acidic. from the confluence of California Gulch downstream to the confluence with Box The fluctuating water table and the acidic Creek, approximately 9 miles downstream. conditions, in turn, caused zinc and lead The site encompasses both private and in the tailings to form soluble salts that public lands. wick to the soil surface during dry portions • Mining, mineral processing, and smelting of the year. A metal salt crust with zinc in and near Leadville produced gold, silver, concentrations of greater than 90,000 lead, copper, manganese, and zinc for more milligrams per kilogram (mg/kg) formed than 130 years. Wastes generated during on the soil surface. The soil was toxic to the mining and ore processing contained riparian vegetation and became highly metals, such as cadmium, copper, lead, and susceptible to continued erosion by the zinc. river. • Wastes were washed downstream and deposited as discrete parcels along an 11- Why Not Just Remove mile stretch of the Upper Arkansas River. the Waste Deposits? The fluvial deposits are pyritic soils with no natural soil structure and are characterized Removal of the tailings was not feasible by lack of vegetation, low pH, and high because of (1) the potential to destabilize metals. streambanks and cause massive changes in the river system, (2) the potential for • Over the years, the wastes eroded, re- tailings to enter the river during field deposited along the river, and accumulated activities, (3) the high cost of replacement in deposits up to 4 feet deep. The rise and topsoil, and (4) the difficulty of locating fall of the water table resulted in alternating an acceptable repository for contaminated reducing and oxidizing conditions, creating soil. an extremely acidic soil pH (1.5 to 4.5).

2 California Gulch, Lake County, Colorado Superfund Case Study ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY

Biosolids, or organic residuals, have been used at a wide range of sites both alone and in combination with other materials to restore disturbed sites. Research has consistently demonstrated that biosolids are highly effective, in many cases more so than topsoil replacement, for restoration of disturbed ecosystems. In addition, biosolids, applied at restoration rates of more than 50 tons per acre, provide sufficient organic matter to improve the physical properties Streambank after treatment and nutrient status of the soil, while • Irrigation with contaminated water reducing the availability of metals. Some from the Arkansas River impaired the additional examples of Superfund sites productivity of adjacent ranchlands, where biosolids have successfully been causing reduced forage and increased used include the following: exposure of livestock to toxic concentrations of metals contaminants. • West Page Swamp (Bunker Hill), Shoshone County, Idaho: Ecological Revitalization http://faculty.washington.edu/clh/wet. Initial Research and Field Studies html The Region 8 Removal Program, EPA’s • Palmerton Zinc Pile, Carbon County, Environmental Response Team (ERT), Pennsylvania: and USDA researchers initiated ecological http://www.epa.gov/aml/tech/ revitalization at the site in 1998 by developing palmerton.pdf a recipe of biosolids and lime to be applied • Sharon Steel, Mercer County, to the fluvial deposits. The intent of these Pennsylvania: amendments was to reduce the mobility, http://www.epa.gov/reg3hwmd/npl/ bioavailability, and toxicity of metals in PAD001933175.htm the soil and provide a more hospitable • Oronogo-Duenweg Mining Site, growth environment for vegetation and soil Jasper County, Missouri: organisms. The amendments were applied http://www.itrcweb.org/miningwaste- to four “demonstration areas” using a front- guidance/cs34_oronogo_duenweg.pdf end loader and mixed into the top 12 inches of tailings using an industrial disc, a plow, or an excavator. The plots were seeded and in some installed in these subsequent demonstration cases irrigated because of the low precipitation. areas to evaluate the relative merits of various The resulting vegetation in the demonstration lime amendments and of adding wood chips to areas reduced the following: erosion, exposure the treated soil. to contaminants, formation of metals salts on Extensive evaluation of the physical and the surface and subsequent leaching into the chemical properties, toxicity, and function river, and transport of metals to groundwater. of soil, and of ecosystem function suggested Subsequent demonstration areas were treated that the soil amendments have restored with various combinations of biosolids pellets, function to the fluvial deposits. After 1 year, biosolids compost, cow manure compost, the addition of lime and biosolids generally limestone, and sugar beet lime. Test plots were improved soil quality, increased pH, decreased

California Gulch, Lake County, Colorado Superfund Case Study 3 ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY initiated to treat an additional 20 acres of fluvial deposits plus 160 acres of irrigated Consider the Potential for meadows located on private and public lands. Attractive Nuisance Issues The remedy was based on lessons learned Assessments such as chemical extraction during the initial field studies and on work at tests, ecological evaluation, and modeling a similar site, the Clark Fork River NPL site in can be used to ensure that a remedy is Montana. protective of both humans and wildlife. Lime, organic material, and fertilizer At the California Gulch OU11 site, for application rates were identified based on example, a wide range of earthworm, fish, a statistical evaluation of characteristics at and small mammal testing was conducted the site for the irrigated meadows. Typical to determine whether the revitalized agronomic methods, including calibrated habitat was creating an attractive nuisance spreaders and agricultural deep till or to the wildlife at the site. Results showed industrial discs, were used to apply and mix that the bioavailability of heavy metals soil amendments. A drill seeder was used present on site was dramatically reduced to apply a seed mix tailored to landowner after treatment with soil amendments and preferences such as grazing and forage that wildlife exposure to metals is within production, and straw mulch was spread to acceptable limits. For additional details on protect the seed until spring germination. attractive nuisance issues, please visit the A hybrid approach was taken to establish the following website: http://www.epa.gov/ lime application rate for each fluvial deposit. tio/download/remed/542f06003.pdf In general, one of the following two “master” application rates was assigned to each deposit, the mobility of metals, and reduced soil depending on lime requirement data that toxicity; plant and soil microbial activity identified current acidity and potential acidity also increased and a plant community was created by the pyritic soils: (1) 3 percent lime established. Stakeholders were concerned that by weight, and (2) 6 percent lime by weight. leaving the waste in place would create an However, a custom lime rate was selected attractive nuisance and be harmful to wildlife for deposits with an extremely high lime attracted to the newly vegetated area, but the requirement. The lime and phosphate fertilizer treatment reduced the potential for ingestion was applied to the full depth of tailings and of contaminants by wildlife by decreasing the mixed, and then organic matter was added extractable metals in the soil. Assessments and tilled to a depth of 12 inches. Initially, an during 2005, 2009, and 2010 indicate that the excavator was used to blend the amendments vegetation established on the demonstration into the fluvial deposits. However, the process areas is robust, reproducing, and permanent was slow, so the excavator was replaced by an many years after it was first planted. Allu mixer that is capable of precision work Revitalization Activities along uneven boundaries and can manage large (up to 12-inch) rock. The fluvial deposits As a result of the initial research and field were hand-seeded with a riparian seed mix studies, stakeholders who previously approved by the land manager (either the expressed concern about the viability and private landowner or Colorado State Parks), protectiveness of in situ treatment and raked, and mulched before winter arrived. revegetation of the fluvial deposits became proponents and recommended approval of The streambanks adjacent to the fluvial EPA’s plans for similar work on the remaining deposits were often compromised because of fluvial deposits and in contaminated irrigated the absence of vegetation caused by metals meadows. In 2008, a remedial action was toxicity or low pH. Tilling amendments 4 California Gulch, Lake County, Colorado Superfund Case Study ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY into the tailings would further destabilize the streambanks and leave Stakeholders Involvement entire treatment areas open • EPA – EPA Region 8 provided the site characterization, to erosion, so stream bank mapping, alternatives analysis, demonstration project stabilization measures funding and implementation, feasibility study, risk were needed. Stakeholders assessment, remedial action planning and implementation, expressed concern over and coordinated with a large group of agency and local armoring banks with stakeholders over the entire life of the project. EPA riprap or gabion baskets participated in a multi-agency effort that successfully during the demonstration coordinated Comprehensive Environmental Response, projects; therefore, in a Compensation, and Liability Act (CERCLA) and Natural few locations, bendway Resource Damages activities. EPA’s Environmental weirs and root wads were Response Team (ERT) provided research and development used protect the bank and assistance for the initial field studies, including contracting enhance fish habitat. The with the USDA for research assistance. remedial action used soft • Landowners – Community members, especially engineering techniques to landowners in and around the California Gulch OU11 create well-vegetated banks site, were actively engaged in selection, design, and that protect the remediated implementation of the remedy to ensure private and public areas in the near term, but lands returned to beneficial use. will also accommodate natural stream migration in • Local Government Authorities – Lake County had a the long term. Streambank vested interest in the end use of the site and wanted ensure stabilization tools included it met the goals of its master plan. The demonstration the following: projects were coordinated with a Lake County Open Space Initiative project that created a fishing lake, river access, • Excavation of and informative trails. contaminated soil within 10 feet of • State and Federal Natural Resource Trustees – EPA and the streambank and state and federal natural resource trustees, including the replacement with clean U.S. Fish and Wildlife Service, the U.S. Bureau of Land fill Management, the U.S. Department of Justice, the Colorado Department of Public Health and Environment, the • Rock roll along the toe Colorado Division of Natural Resources, and the Colorado of the stream bank Attorney General’s Office, coordinated site assessment, • Coir roll (biolog) along remedy selection, and remedy design to ensure EPA the toe of the stream CERCLA efforts were consistent with long-term restoration bank or behind the rock actions. Trustees also provided input to EPA during roll remedial design and construction to ensure the remedy • Sedge (Carex spp.) protected, and in some cases enhanced, species habitat. plantings • Colorado State Parks — Colorado State Parks worked with • Mature willow (Salix EPA to identify access road and borrow area locations that spp.) transplants fit with long-term land use priorities. • Tipped willows that • Potentially Responsible Parties (PRPs) – A Consent extend into the river Decree settlement with the PRPs provided funding for the remedial action. The Carex plantings and mature willow transplants

California Gulch, Lake County, Colorado Superfund Case Study 5 ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY were harvested from the adjacent floodplain. These tools were used in various combinations to address the diversity of streambank conditions encountered. Performance criteria were developed to measure the success of the remediation: • Soil criteria include post-treatment soil characteristics such as pH, lime requirement, organic carbon, and electrical conductivity. • Vegetation criteria include seedling density (first-year measure only), cover, species richness, biomass, and evidence of Fishing along the revitalized streambank reproduction. 5 to 7 years after treatment and of riparian • Irrigated meadows criteria were reference areas. developed from the results of pre- • Streambank criteria were based on an remediation sampling in contaminated and adaptation of the Riparian Evaluation uncontaminated meadows System (RipES) developed by Reclamation • Fluvial deposits criteria were based on the Research Group for the Clark Fork River characteristics of the demonstration areas site. The remediation areas are also monitored for erosion, bare areas, and weeds. Incorporating Recreation Lessons Learned into the Remedy 1. Consider all aspects of the remedy in Land use changed during the lifetime of estimating costs: During the initial the project. Historical ranch land was demonstration project, biosolids were purchased by a Colorado community for provided at no cost by the Denver Metro the water rights and was designated for Wastewater Treatment Facility, but the cost recreational use, and another historically of transportation over steep mountain roads ranched property was purchased by was not covered. During the remedial natural resource trustees to provide critical action, the compost supplier was selected habitat. In addition, Lake County’s the for a low cost and high organic content High Lonesome Recreation area — which product, but the quality of the compost included a fishing lake, river access, and degraded over time and newer material was a trail through demonstration plots with not fully composted, leading to elevated paths, bridges, and signage describing the ammonia and salt content and reduced remediation and site ecological features — vegetation production. A quick response was developed in the project area. A to changes in materials quality, identified portion of the site is also located in the during a construction quality assurance Arkansas River Headwaters State Park. and quality control (QA/QC) monitoring Construction roads required during program, saved long-term maintenance remediation were located to minimize costs and headaches. impacts to vital bird habitat, and some of the roads will be used for long-term fishing 2. Equipment tailored to site requirements: access and recreational use. Incorporation of soil amendments into deep and sometimes rocky fluvial deposits using

6 California Gulch, Lake County, Colorado Superfund Case Study ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY traditional construction equipment was inhibiting the growth of new vegetation. labor-intensive and yielded inconsistent Rainfall is approximately 17 inches, further results. The construction contractor limiting growth and allowing capillary therefore identified and procured an Allu rise of metals salts during dry periods. mixer that was productive, reliable, and Vegetation stress was observed in the cost-efficient; provided consistent mixing; demonstration areas during the early years and dealt with rock and mud. The Allu after treatment because of drought, so worked with precision near stream banks performance standards for the subsequent and around existing vegetation and could remedial action were developed to handle large (up to 12 inch) rock without accommodate unusual weather patterns or breaking down, leaving very few areas other uncontrollable events. unamended. Rock segregated during 6. Incorporate stakeholder priorities the Allu mixing process was used for when possible: Concerns about specific streambank stabilization. streambank stabilization techniques were 3. Integrated design: The project drew overcome when stakeholders suggested from site-specific research performed by slight design modifications that would ERT, USDA, Colorado State University improve fish habitat while providing and others, plus technology transfer from protection of remediation areas without experience at the Clark Fork River site in increasing costs. Access roads in the Montana, thus providing high confidence recreation area were more acceptable when in the outcome of the remedial action. The EPA agreed to leave certain roads in place early laboratory tests, test plots, and larger- for long-term recreational paths and river scale field demonstration projects paved access. the way for acceptance of the larger-scale 7. Work with the entire system: A fluvial remedial action, and experience on the geomorphologic assessment of the Clark Fork River site provided insight into Arkansas River provided valuable effective implementation of the design- information on the vulnerability of the build project. specific river reaches, assisting with the 4. Availability of resources differs remedial design. The geomorphologic depending on the region: The source of assessment was valuable to natural biosolids in the area “dried up” when a resource trustees and other stakeholders nearby mine reclamation project acquired and will be used in future natural resource all of the biosolids from nearby mountain improvement efforts by the State of communities, so the remedial action Colorado and federal agencies. relied on cow manure compost, a plentiful resource in the Colorado Front Range. The sugar beet lime used during remediation is a waste product from the sugar beet industry in eastern Colorado and contained approximately 20 percent moisture, making it much easier to spread and less likely to produce dust than dry lime. 5. Climate can affect the success of revitalization: Leadville is the one of the highest elevation incorporated towns in North America, at 10,200 feet. The growing season is approximately 60 to 70 days, Smith Ranch vegetation assessment, 2010

California Gulch, Lake County, Colorado Superfund Case Study 7 ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY

Additional Information Websites to obtain additional information on the California Gulch site and ecological revitalization include the following: EPA Region 8 Superfund Program, California Gulch http://www.epa.gov/region08/superfund/co/calgulch/

Wildlife Habitat Council Case Study 11, Upper Arkansas River Tailings Restoration http://www.wildlifehc.org/ewebeditpro/items/O57F3067.pdf

University of Washington Upper Arkansas River Alluvium Remediation, Biosolids Demonstration, Leadville, Colorado http://faculty.washington.edu/clh/leadville.html

Cost and Performance Summary Report, In Situ Biosolids and Lime Addition at the California Gulch Superfund Site, OU 11 http://www.brownfieldstsc.org/pdfs/CaliforniaGulchCaseStudy_2-05.pdf

Leadville, Colorado: Moving Beyond the Scars of Mining, Integrating Remedial Design and Site Reuse http://www.epa.gov/superfund/programs/recycle/pdf/cal_gulch.pdf

EPA’s Eco Tools Website http://www.clu-in.org/ecotools/

Ecological Revitalization: Turning Contaminated Properties into Community Assets http://www.clu-in.org/download/issues/ecotools/Ecological_Revitalization_Turning_Contaminated_Properties_ into_Community_Assets.pdf

Frequently Asked Questions about Ecological Revitalization of Superfund Sites http://www.clu-in.org/download/remed/542f06002.pdf

Revegetating Landfills and Waste Containment Areas Fact Sheet http://www.clu-in.org/download/remed/revegetating_fact_sheet.pdf

Ecological Revitalization and Attractive Nuisance Issues http://www.epa.gov/tio/download/remed/542f06003.pdf

For additional information on the California Gulch site, you can also contact these project managers: Michael Holmes, RPM Harry Compton, Environmental Response Team (303) 312-6607 (732) 321-6751 [email protected] [email protected]

Michael Zimmerman, On-Scene Coordinator Jan Christner, PE (303) 312-6828 URS Operating Services, Inc. [email protected] (505) 797-1154 [email protected]

If you have any questions or comments on this fact sheet, please contact: Michele Mahoney, EPA [email protected]

8 California Gulch, Lake County, Colorado Superfund Case Study