Characterizing vertical contaminant distribution in a thick unconfined aquifer, Hanford Site, Washington, USA
Unique aquifer characterization techniques have been used to obtain depth-discrete water samples from a thick, hydrogeologically continuous unconfined aquifer system; groundwater results indicate that carbon tetrachloride contamination is widespread and extends deeper and at concentrations much higher than is detected in the monitoring networks at the water table. Carbon tetrachloride, a legacy waste, was used in the plutonium extraction process at the Hanford Site in south central Washington State. Vertical, depth-discrete groundwater samples were collected during well drilling throughout the region, and the samples were analyzed to determine the concentration of carbon tetrachloride present as a dissolved phase in the aquifer. Results indicate that high concentrations of carbon tetrachloride, three orders of magnitude above the allowable regulatory limit, are present at depths greater then 25 m beneath the water table. It is imperative to locate the remaining chemical inventory, determine the vertical as well as the lateral distribution of this contaminant identify its physical form, and determine the most appropriate technology for meeting the final cleanup requirements. Depth-discrete aquifer characterization throughout the uppermost unconfined aquifer system is providing this information and improving the understanding of the contaminant distribution and the hydrogeologic framework through which it moves.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 921575
- Report Number(s):
- PNNL-SA-53036; TRN: US200804%%676
- Journal Information:
- Environmental Geology, 53(4):879-890, Vol. 53, Issue 4
- Country of Publication:
- United States
- Language:
- English
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