In 2003, DOE implemented the first phase of an interim action system at the Moab site to address concerns regarding elevated ammonia levels in ground water discharging to the Colorado River. Uranium is the other main contaminant of concern in ground water. This first phase consisted of 10 extraction wells (called Configuration 1). Four additional configurations of wells have been added since then, for a current total of 42 wells that are designed to reduce the amount of ammonia and uranium that discharges to the river.
Ground water extraction is through Configuration 5 wells, which are located closer to the tailings pile. Extracted ground water is pumped to a storage tank for use as dust control on the pile. To date, almost 233.3 million gallons of ground water has been extracted through the interim action system, preventing 876,000 pounds of ammonia and about 4,640 pounds of uranium from reaching the river. The extraction system was shut down for the winter in November 2016, and is anticipated to be restarted by mid-March 2017.
Freshwater (diverted river water) is injected through wells in Configurations 1 and 4 as an additional way of minimizing the discharge of ammonia to the Colorado River. More than 1,575,000 gallons of freshwater have been injected in 2017. Injection was shut down temporarily on February 21, 2017, for cleanout of the freshwater pond, which facilitates removal of Colorado River sediment prior to Project use of the water. Injection is anticipated to be restarted by mid-March 2017.
DOE continues to evaluate the effectiveness of the interim action system, which will likely become part of the final ground water remedy. See the Surface Water and Ground Water web page for project documents associated with the interim action.