Surface remediation was completed at the former uranium mill site in Riverton, Wyoming, in 1990. Residual radioactive materials (contaminated soil and debris) were removed and disposed of at Union Carbide Corporation`s (Umetco) nearby Gas Hills Title 2 facility. Ground water in the surficial and semiconfined aquifers (known collectively as the `uppermost aquifer`) below the former mill and tailings site has been contaminated. No contamination has been detected in the deeper, confined sandstone aquifer. The contaminant plume extends off site to the south and east. The plume is constrained by surface wetlands and small streams to the east and west of the site and by the Little Wind River to the south. Fifteen monitor wells installed in 1993 were sampled to better define the contaminant plume and to provide additional water quality data for the baseline risk assessment. Samples also were collected from domestic wells in response to a request by the Wyoming Department of Environmental Quality in January 1994. No contamination attributable to the former uranium milling operations have ever been detected in any of the domestic wells used for potable supplies.

Surface remedial action is complete at the Spook Uranium Mill Tailings Remedial Action Project site in Wyoming. Based on an evaluation of site characterization data, the US Nuclear Regulatory Commission, US Department of Energy, and state of Wyoming have concurred in the determination that a program to monitor ground water is not required because ground water in the uppermost aquifer is Class 3 (limited use) (40 CFR 192.21(g)(1993)).

The NIPER Reservoir Assessment and Characterization Research Program incorporates elements of the near-term, mid-term and long-term objectives of the National Energy Strategy-Advanced Oil Recovery Program. The interdisciplinary NIPER team focuses on barrier island reservoirs, a high priority class of reservoirs, that contains large amounts of remaining oil in place located in mature fields with a high number of shut-in and abandoned wells. The project objectives are to: (1) identify heterogeneities that influence the movement and trapping of reservoir fluids in two examples of shoreline barrier reservoirs (Patrick Draw Field, WY and Bell Creek Field, MT); (2) develop geological and engineering reservoir characterization methods to quantify reservoir architecture and predict mobile oil saturation distribution for application of targeted infill drilling and enhanced oil recovery (EOR) processes; and (3) summarize reservoir and production characteristics of shoreline barrier reservoirs to determine similarities and differences. The major findings of the research include: (1) hydrogeochemical analytical techniques were demonstrated to be an inexpensive reservoir characterization tool that provides information on reservoir architecture and compartmentalization; (2) the formation water salinity in Patrick Draw Field varies widely across the field and can result in a 5 to 12% error in saturation values calculated from wireline logs if …

The existing switchyards at Western Area Power Administration's (WESTERN) Seminoe and Kortes facilities, located approximately 40 miles northeast of Rawlines, Carbon County, Wyoming, were constructed in 1939 and 1951, respectively. The circuit breakers at these facilities are beyond or approaching their service life and need to be replaced. In addition, the switchyards have poor access for maintenance and replacement of equipment, and their locations create potential for oil spills into the North Platte River. WESTERN is proposing to consolidate the switchyard facilities into one new substation to provide easier access, restore proper levels of system reliability, and decrease the potential for oil contamination of the river. This environmental assessment (EA) was prepared to evaluate the impacts of the proposed Seminoe-Kortes Consolidation Project. 57 refs., 12 figs., 8 tabs.