Published: 1998
Total Pages: 117
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The U.S. Department of Energy (DOE) is conducting cleanup activities at the Weldon Spring site, located in St. Charles County, Missouri, about 48 km (30 mi) west of St. Louis. Cleanup of the site consists of several integrated components. The quarry residuals operable unit (QROU), consisting of the Weldon Spring quarry and its surrounding area, is one of four operable units being evaluated. In accordance with requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended, DOE is conducting a remedial investigation/feasibility study (RI/FS) to determine the proper response to address various contaminated media that constitute the QROU. Specifically, the operable unit consists of the following areas and media: the residual material remaining at the Weldon Spring quarry after removal of the pond water and the bulk waste; groundwater underlying the quarry and surrounding area; and other media located in the surrounding vicinity of the quarry, including surface water and sediment at Femme Osage Slough, Little Femme Osage Creek, and Femme Osage Creek. An initial evaluation of conditions at the quarry area identified remaining data requirements needed to support the conceptual site exposure and hydrogeological models. These data requirements are discussed in the RI/FS work plan issued in January 1994. Soil contamination located at a property adjacent to the quarry, referred to as Vicinity Property 9 (VP9), was originally part of the scope of the QROU, as discussed in the work plan. However, a decision was subsequently made to remediate this vicinity property as part of cleanup activities for the chemical plant operable unit, as provided for in the Record of Decision (ROD). Remediation of VP9 was completed in early 1996. Hence, this baseline risk assessment (BRA) does not address VP9.
