Interim measure conceptual design for remediation at the former CCC/USDA grain storage facility at Centralia, Kansas : pilot test and remedy implementation.
This document presents an Interim Measure Work Plan/Design for the short-term, field-scale pilot testing and subsequent implementation of a non-emergency Interim Measure (IM) at the site of the former grain storage facility operated by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) in Centralia, Kansas. The IM is recommended to mitigate both (1) localized carbon tetrachloride contamination in the vadose zone soils beneath the former facility and (2) present (and potentially future) carbon tetrachloride contamination identified in the shallow groundwater beneath and in the immediate vicinity of the former CCC/USDA facility. Investigations conducted on behalf of the CCC/USDA by Argonne National Laboratory have demonstrated that groundwater at the Centralia site is contaminated with carbon tetrachloride at levels that exceed the Kansas Tier 2 Risk-Based Screening Level (RBSL) and the U.S. Environmental Protection Agency's maximum contaminant level of 5.0 {micro}g/L for this compound. Groundwater sampling and analyses conducted by Argonne under a monitoring program approved by the Kansas Department of Health and Environment (KDHE) indicated that the carbon tetrachloride levels at several locations in the groundwater plume have increased since twice yearly monitoring of the site began in September 2005. The identified groundwater contamination currently poses no unacceptable health risks, in view of the absence of potential human receptors in the vicinity of the former CCC/USDA facility. Carbon tetrachloride contamination has also been identified at Centralia in subsurface soils at concentrations on the order of the Kansas Tier 2 RBSL of 200 {micro}g/kg in soil for the soil-to-groundwater protection pathway. Soils contaminated at this level might pose some risk as a potential source of carbon tetrachloride contamination to groundwater. To mitigate the existing contaminant levels and decrease the potential future concentrations of carbon tetrachloride in groundwater and soil, the CCC/USDA recommends initial short-term, field-scale pilot testing of a remedial approach that employs in situ chemical reduction (ISCR), in the form of a commercially available material marketed by Adventus Americas, Inc., Freeport, Illinois (http://www.adventusgroup.com). If the pilot test is successful, it will be followed by a request for KDHE authorization of full implementation of the ISCR approach. In the recommended ISCR approach, the Adventus EHC{reg_sign} material--a proprietary mixture of food-grade organic carbon and zero-valent iron--is introduced into the subsurface, where the components are released slowly into the formation. The compounds create highly reducing conditions in the saturated zone and the overlying vadose zone. These conditions foster chemical and biological reductive dechlorination of carbon tetrachloride. The anticipated effective lifetime of the EHC compounds following injection is 1-5 yr. Although ISCR is a relatively innovative remedial approach, the EHC technology has been demonstrated to be effective in the treatment of carbon tetrachloride contamination in groundwater and has been employed at a carbon tetrachloride contamination site elsewhere in Kansas (Cargill Flour Mill and Elevator, Wellington, Kansas; KDHE Project Code C209670158), with the approval of the KDHE. At Centralia, the CCC/USDA recommends use of the ISCR approach initially in a short-term pilot test addressing the elevated carbon tetrachloride levels identified in one of three persistently highly contaminated areas ('hot-spot areas') in the groundwater plume. In this test, a three-dimensional grid pattern of direct-push injection points will be used to distribute the EHC material (in slurry or aqueous form) throughout the volume of the contaminated aquifer and (in selected locations) the vadose zone in the selected hot-spot area. Injection of the EHC material will be conducted by a licensed contractor, under the supervision of Adventus and Argonne technical personnel. The contractor will be identified upon acceptance by the KDHE of the conceptual design presented here. In the pilot test, Argonne will install and periodically sample a network of temporary and permanent monitoring points to document (1) the contaminant distribution in the saturated and vadose zones prior to injection, (2) the distribution of the EHC material in these zones immediately following injection, and (3) subsequent changes in contaminant concentrations that occur over time in response to the imposed treatment. Argonne's investigations have shown that the lithologic properties of the unit hosting the contaminated aquifer at Centralia vary both vertically and laterally, resulting in a heterogeneous distribution of permeabilities and relatively restricted groundwater movement across much of the site.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDA
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 924691
- Report Number(s):
- ANL/EVS/AGEM/TR-07-11; TRN: US200809%%568
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Annual report of groundwater monitoring at Centralia, Kansas, in 2009.
Annual report of groundwater monitoring at Centralia, Kansas, in 2010.