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NPL Site Narrative for Richardson Flat Tailings
RICHARDSON FLAT TAILINGS
Summit County, Utah
Federal Register Notice: February 7, 1992The Richardson Flat Tailings site covers approximately 160 acres in a valley 1.5 miles northeast of Park City, Summit County, Utah. One source of hazardous substances on the site is a tailings dam and associated tailings materials that came from the Keetley Ontario Mine and other metal mining operations currently owned by United Park City Mines (UPCM). The most recent use of the area for tailings disposal was during 1975-81, when UPCM leased its mining properties to either Park City Ventures or Noranda Mining, Inc. The two companies constructed and operated milling facilities on UPCM properties.
A second source is a 6-acre "flood plains tailing pile"immediately west of the tailings pond on the banks of Silver Creek. Historical aerial photos show that the pile was in existence as early as 1953. During 1989-90, EPA and the State observed tailings slumping into an on-site diversion ditch and Silver Creek. The tailings contain arsenic, cadmium, copper, lead, mercury, silver, and zinc, according to EPA tests conducted in 1985 and 1989. The State classifies Silver Creek as a cold water fishery. Wetlands border the creek and diversion ditch. Water from the creek is diverted to irrigate approximately 300 acres of pastureland.
High-volume air sampling at the site in 1986 documented that arsenic, cadmium, lead, and zinc were released to the air. An estimated 4,500 people live within 4 miles of the site.
This site was proposed to the NPL on June 24, 1988 (55 FR 23988) on the on the basis of a score above the 28.50 cutoff on the original Hazard Ranking System (HRS). In response to public comment, the score fell to below the cutoff, and the site was dropped from consideration for the NPL on February 11, 1991 (56 FR 5598). It is being proposed at this time on the basis of its score on the revised HRS. New information was used to evaluate the surface water migration pathway, which is scored differently under the two systems.
For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737.