T157 Environmental Geochemistry for Modern Mining

Tuesday, 2 November 2010
8:00 AM - 12:00 PM
Room 601

CHARACTERIZATION OF THE PRE-MINING GEOCHEMISTRY OF SURFACE AND GROUND WATERS AT THE COLES HILL URANIUM DEPOSIT, VIRGINIA

Paper number: T157-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

The Coles Hill Deposit in Pittsylvania County, Virginia, is the largest undeveloped uranium deposit in the United States. This site presents a unique opportunity to conduct baseline characterization prior to the development of a proposed uranium mine in a temperate climate. The pre-mining baseline characterization will serve the dual purposes of providing a basis for monitoring environmental disturbances during mining and establishing realistic environmental targets for closure. Syn-mining characterization should emphasize areas distant from expected disturbances to monitor the effects of mining on the surrounding environment. In contrast, the undisturbed pre-mining conditions within the footprint of the proposed mine provide a reference point for establishing realistic remediation goals.

Preliminary geochemical results from a combination of historical data and more recent sampling suggest that trace element and radionuclide concentrations in ground and surface waters in the region surrounding the deposit meet regulatory standards. Groundwater within the deposit has elevated concentrations of U, Ra, and Rn relative to surrounding groundwater and locally exceeds regulatory standards. The mobility of uranium in groundwater at Coles Hill is in part controlled by the presence of low solubility uranium phosphate minerals of the meta-autunite group within the oxidized saprolite.

Geochemical data in this study are analyzed using statistical methods, including descriptive statistics and log-normal distributions, to discern variations among samples originating from different geologic sources, and from mineralized and unmineralized rock. In addition, a GIS database is being constructed to aid in spatial analysis of relevant geochemical parameters in ground and surface waters, soils, and stream sediments. Results are being used to develop a sampling strategy for a thorough baseline geochemical survey for the Coles Hill deposit and surrounding area.