DOE-Oak Ridge Associated Universities (ORAU) Investigations Engages I2M’s Chief Hydrogeologist

In 1988, groundwater contaminated with trichloroethene (TCE) and technetium-99 (Tc-99) were identified in samples collected from residential water wells withdrawing groundwater from the Regional Gravel Aquifer (RGA) north of the Paducah Gaseous Diffusion Plant (PGDP) facility.

In 2012, DOE requested that Oak Ridge Associated Universities (ORAU), managing contractor of Oak Ridge Institute for Science and Education (ORISE), provide an independent assessment of the quality and quantity of the existing groundwater monitoring data and determine if there is sufficient information to support a modification to the boundary of the current Water Policy.

Michael D. Campbell, P.G., P.H., Chief Hydrogeologist of I2M Associates, LLC was engaged to provide technical support to ORAU. As a result of the assessment, ORAU concluded that sufficient groundwater monitoring data exists to determine that a shrinkage and/or shift of the plume(s) responsible for the initial development of this policy has occurred. Specifically, there is compelling evidence that the TCE plume is undergoing shrinkage due to natural attenuation and associated degradation. The plume shrinkage (and migration) has also been augmented in local areas where large volumes of groundwater were recovered by pump-and-treat remedial systems along the eastern and western boundaries of the Northwest Plume, and in other areas where pump-and-treat systems have been deployed by DOE to remove source contaminants. The available evidence supports adjusting the western and northwestern Water Policy boundary.

Based on the historical and modeled hydrogeological data reflecting past flow and plume attenuation, along with associated plume migration toward the northeast, the establishment of a new boundary along the westernmost margin of the earliest indication of the TCE plume is proposed and justified on hydrogeological grounds. Approximately 30% of the original area would remain within the adjusted Water Policy area west and northwest of the PGDP facility. This modification would release about 70% of the area, although individual properties would overlap the new boundary (more).