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Reconnaissance soil geochemistry at the Riverton Uranium Mill Tailings Remedial Action Site, Fremont County, Wyoming

Open-File Report 2012-1257
By:  and 
https://doi.org/10.3133/ofr20121257

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Abstract

Soil samples were collected and chemically analyzed from the Riverton Uranium Mill Tailings Remedial Action Site, which lies within the Wind River Indian Reservation in Fremont County, Wyoming. Nineteen soil samples from a depth of 0 to 5 centimeters were collected in August 2011 from the site. The samples were sieved to less than 2 millimeters and analyzed for 44 major and trace elements following a near-total multi-acid extraction. Soil pH was also determined. The geochemical data were compared to a background dataset consisting of 160 soil samples previously collected from the same depth throughout the State of Wyoming as part of another ongoing study by the U.S. Geological Survey. Risk from potentially toxic elements in soil from the site to biologic receptors and humans was estimated by comparing the concentration of these elements with soil screening values established by the U.S. Environmental Protection Agency. All 19 samples exceeded the carcinogenic human health screening level for arsenic in residential soils of 0.39 milligrams per kilogram (mg/kg), which represents a one-in-one-million cancer risk (median arsenic concentration in the study area is 2.7 mg/kg). All 19 samples also exceeded the lead and vanadium screening levels for birds. Eighteen of the 19 samples exceeded the manganese screening level for plants, 13 of the 19 samples exceeded the antimony screening level for mammals, and 10 of 19 samples exceeded the zinc screening level for birds. However, these exceedances are also found in soils at most locations in the Wyoming Statewide soil database, and elevated concentrations alone are not necessarily cause for alarm. Uranium and thorium, two other elements of environmental concern, are elevated in soils at the site as compared to the Wyoming dataset, but no human or ecological soil screening levels have been established for these elements.

Suggested Citation

Smith, D., Sweat, M.J., 2012, Reconnaissance soil geochemistry at the Riverton Uranium Mill Tailings Remedial Action Site, Fremont County, Wyoming: U.S. Geological Survey Open-File Report 2012-1257, Report: iv, 23 p.; 1 Appendix, https://doi.org/10.3133/ofr20121257.

ISSN: 2331-1258 (online)

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Reconnaissance soil geochemistry at the Riverton Uranium Mill Tailings Remedial Action Site, Fremont County, Wyoming
Series title Open-File Report
Series number 2012-1257
DOI 10.3133/ofr20121257
Year Published 2012
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Central Mineral and Environmental Resources Science Center
Description Report: iv, 23 p.; 1 Appendix
Time Range Start 2011-08-01
Time Range End 2011-08-31
Country United States
State Wyoming
County Fremont
Other Geospatial Riverton Uranium Mill
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Additional publication details