Case Summary: United Park City Mines agrees to clean up mine waste at Richardson Flat Superfund Site in Utah

On March 7, 2014, United Park City Mines Inc. (UPCM), the U.S. Environmental Protection Agency (EPA), the Bureau of Land Management, the U.S. Fish and Wildlife Service, the Utah Department of Environmental Quality, the Utah Division of Parks and Recreation, and the state of Utah Natural Resource Trustee finalized an administrative order on consent (AOC) for engineering evaluation, cost analysis (EE/CA), removal, and restoration of more than 2,700 acres contaminated with historic mine waste at the Richardson Flat Superfund Site near Park City, Utah.

While UPCM’s assessment work will determine cleanup requirements and costs, response actions to improve environmental quality will likely include extensive excavation and removal of contaminated soils, tailings, and sediments in and along Silver Creek. This cleanup activity will be coordinated with the re-vegetation of impacted areas with native species and the restoration of wetlands and the stream channel.

On this page:

• Information about United Park City Mines
• Information about the Richardson Flat Tailings Superfund Site
• Pollutants and Environmental Effects
• Information about the Administrative Order on Consent
• Contact Information

“EPA is encouraged by United Park City Mines’ commitment to cleaning up the Silver Creek watershed. Restoring these areas and addressing the discharge of heavy metals to Silver Creek will result in dramatic improvements to aquatic habitat and water quality. These efforts will also help ensure the long-term success of work being done to address mine waste in other parts of the Richardson Flat site.”

Information about United Park City Mines

UPCM is a Delaware corporation doing business in Utah. UPCM and others conducted various mining related operations within the Park City Mining District until approximately 1969. UPCM is now owned by Talisker Land Holdings LLC, and conducts business primarily related to real estate and recreation.

Information about the Richardson Flat Tailings Superfund Site

The Richardson Flat Tailings site covers over 2,700 acres in a small valley 1.5 miles northeast of Park City, Utah. The site consists of a tailings dam and impoundment that were used to capture and hold mill tailings from the Ontario Mine near Park City, the tailings that were transported downstream to the banks of Lower Silver Creek, and an outfall known as Prospector Drain. Prospector Drain collects shallow ground water and discharges the flow partially to a constructed treatment wetland, and partially to a natural wetland area near the banks of Lower Silver Creek.

In 2007, EPA and UPCM entered into a consent decree for remedial design and remedial action at operable unit 1 (OU1). Pursuant to that decree, UPCM also conducted natural resource damage remediation. Work at OU1 is largely complete. Under the 2014 AOC, UPCM will perform an EE/CA and non-time critical removal action for (OUs) 2 and 3. OU2 encompasses the approximately 1,875 acres along Lower Silver Creek north and east of Highway 40. OU3 encompasses approximately 836 acres located east of Park City in areas along Silver Creek. UPCM is addressing OU 4, a draining adit known as Prospector Drain, via another administrative order on consent, which was finalized February 19, 2013.

Pollutants and environmental effects

The primary concerns are the site's effect on surface water quality in the area, and the potential for people or wildlife to come into direct contact with the tailings or contaminated soils. Hazardous substances at the site include heavy metals such as arsenic cadmium, copper, lead, mercury, silver, and zinc. The site is located next to Silver Creek, which is classified by the state of Utah as a cold-water fishery. Mine tailings at the site are sinking into an on-site diversion ditch and Silver Creek. Surface water coming from a diversion ditch surrounding the site is contaminated with heavy metals. This ditch empties into wetlands below the tailings dam and flows into Silver Creek. Ground water below the site is also contaminated with heavy metals.

Summary of the Administrative Order on Consent

UPCM’s engineering and cost evaluation will characterize conditions in lower Silver Creek and identify alternatives for cleanup actions to prevent, mitigate, and remedy contamination concerns. Upon completion of these analyses, and after consideration of public comment, EPA will issue an action memorandum that will document specific cleanup activity at the site.

Through a unique partnership, UPCM, EPA, and the other federal and state partners will conduct an assessment to identify impacts to natural resources and strategies to restore the resources in coordination with cleanup work. This streamlined process will save time and money during the assessment phase and will result in more resources being available to restore natural resources impacted by mining activities in the watershed.

Contact information

For more information contact

Amelia Piggott
Attorney
Region 8
U.S. Environmental Protection Agency
1595 Wynkoop St.
Denver, CO
303-312-6410
piggott.amelia@epa.gov