Challenge: To address multiple site characterization deficiencies identified by regulators and move the Site forward towards closure. 

Solution: INTERA assisted in developing closure strategies and implementing additional site characterization activities at the Lisbon Tailings Facility, located south of La Sal, Utah. The supplemental site characterization includes assessing the geochemistry and hydrogeology of a fault, additional characterization of the contaminant plumes emanating from two former tailings impoundments, geochemical modeling of the contaminant plumes and groundwater in the vicinity of the fault, and revisions to the site conceptual model and flow and transport model. We conducted a field program that included site-wide groundwater monitoring, well installation, fault characterization, and aquifer testing to address numerous site characterization deficiencies identified by the Utah Division of Waste Management and Radiation Control (DWMRC), the State administrator for NRC. The information and data collected during the field program are being incorporated into an improved site conceptual model that includes the characterization of groundwater impacts, geochemical and hydrologic modeling, evaluation of plume migration, and evaluation of tailings impacts. 

Results:  The additional data that INTERA collected and analyzed successfully addressed the site characterization deficiencies identified by DWMRC and is leading to the development of Alternative Concentration Limits for the ultimate closure of the Site.