The Need for Valid Statistical Protocols to Establish Baseline Groundwater Quality at Uranium ISL Sites

Groundwater is vital to the future of the west; and increased demands placed on this nonrenewable resource by industry and population growth dictates the need for competent stewardship by state and federal agencies. Uranium in situ leach (ISL) mining could consume and pollute vast quantities of a limited groundwater supply if permitting authorities do not strengthen the rules for establishing baseline water quality. A summary of groundwater data in permit applications for proposed operations at Crownpoint NM, Goliad TX and Crow Butte NE will show that baseline groundwater quality is established with improper scientific methods. Baseline wells are not randomly located in the aquifer exemption zone, samples are collected from the ore-zone intervals of the aquifer, rather than through the entire thickness of the exempt zone, and groundwater quality data are assumed to follow a normal distribution without the use of statistical tests to justify the assumption. The use of improper protocols results in an elevated baseline that does not represent the groundwater quality of the exempt zone, and this allows less stringent restoration efforts and lower funding of the restoration bonds. Additionally, when the standard deviation is improperly used to set excursion limits at monitoring wells, pollution of the aquifer is allowed beyond the exempt zone. Protocols to protect groundwater are far more robust for RCRA and CERCLA sites, and similar diligence should be given to ISL operations that release hazardous metals and radionuclides to groundwater.