Groundwater remediation at the Fernald preserve, Cincinnati, Ohio modeling and resulting 2014 well field operational changes - 15324
The Fernald Preserve became a US DOE Office of Legacy Management site in November 2006, for long-term surveillance and maintenance following completion (with the exception of completing groundwater cleanup) of the Comprehensive Environmental Response, Compensation, and Liability Act; environmental remediation; and site restoration. When the site was turned over to the Office of Legacy Management, approximately 76 hectares (189 acres) of the Great Miami Aquifer (GMA) remained contaminated with uranium above the final remediation level of 30 micrograms per liter. Uranium contamination is being removed from groundwater in the GMA through a pump-and-treat operation that is predicted by groundwater modeling to continue until 2033. Certifying that cleanup objectives have been met and removing the remediation infrastructure after pump-and-treat (P and T) operations are complete will require a minimum of 3 additional years. The current P and T remedy has operated well. From August 1993 through December 2013 the remedy has been used to remove 5,345 kg (11,784 lb) of uranium from the GMA. A variety of metrics are used to track how the P and T operation is progressing and are reported each year in the Site Environmental Report for the Fernald site. The metrics show that the effectiveness of uranium removal is slowly decreasing (a common observation for P and T remedies) and that operational changes needed to be considered. Several different operational changes were modeled to determine if model-predicted cleanup dates could be shortened and if the effectiveness of the groundwater remediation could be improved. With the concurrence and support of US EPA, Ohio EPA, and site stakeholders, operational changes were agreed upon and implemented in 2014 that are predicted to increase the effectiveness of the ongoing operation and shorten cleanup times for a portion of the aquifer. Although the overall predicted length of the remediation was not shortened, modeling predicts that key areas of the uranium plume will be re-mediated sooner. This paper provides a status of the groundwater remediation under way at the Fernald Preserve near Cincinnati, presents the operational changes that were implemented in 2014, and summarizes the groundwater modeling that supported the changes. This paper also illustrates the potential benefits that can be gained by pro-actively managing a pump-and-treat operation and looking for innovative ways to adjust the operation. (authors)