Underground Injection Control Program Revision; Aquifer Exemption Determination for Portions of the Lance Formation Aquifer in Wyoming

The State of Wyoming has submitted a revision to its Underground Injection Control (UIC) Program, requesting that EPA approve an exemption from classification as an underground source of drinking water (USDW) portions of the Lance Formation in the Powder River Basin in Johnson County, Wyoming. The exemption area surrounds two Class I Non-Hazardous deep injection wells that will be used to dispose of operational bleed streams (excess fluids derived from the uranium mining) from commercial in-situ leaching uranium mining operations and fluids resulting from the ground water sweep (pumping out of contaminated fluids from the aquifer) operations for restoration of the Wasatch Formation aquifer being mined for uranium under a UIC Class III permit. After careful review of the exemption request and accompanying documents, EPA has determined that they contain sufficient information to meet the criteria for exempting portions of the Lance formation aquifer from the definition of a USDW. Based on the Wyoming Department of Environmental Quality (WDEQ) concurrence with the exemption, the request of the WDEQ director, the supporting technical documentation, and the lack of any public comment on the public notice to exempt the stated portions of the Lance Formation, EPA has decided to approve Wyoming's revision of its UIC program which exempts the designated portions of the Lance Formation from classification as an Underground Source of Drinking Water (USDW).