Results of groundwater monitoring at Everest, Kansas, in April 2008.

LaFreniere, L. M.

Argonne National Laboratory

关键词: Surface Waters;    Precursor;    Testing;    Monitoring;    Boreholes;   

DOI  :  10.2172/946045
RP-ID  :  ANL/EVS/AGEM/TR-08-16
RP-ID  :  DE-AC02-06CH11357
RP-ID  :  946045

美国|其它

来源: UNT Digital Library

【 摘 要 】

On September 7, 2005, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) presented a Scoping Memo (Argonne 2005) for preliminary consideration by the Kansas Department of Health and Environment (KDHE), suggesting possible remedial options for the carbon tetrachloride contamination in groundwater at Everest, Kansas. The suggested approaches were discussed by representatives of the KDHE, the CCC/USDA, and Argonne at the KDHE office in Topeka on September 8-9, 2005, along with other technical and logistic issues related to the Everest site. In response to these discussions, the KDHE recommended (KDHE 2005) evaluation of several remedial processes, either alone or in combination, as part of a Corrective Action Study (CAS) for Everest. The primary remedial processes suggested by the KDHE were the following: Hydraulic control by groundwater extraction with aboveground treatment; Air sparging (AS) coupled with soil vapor extraction (SVE) in large-diameter boreholes (LDBs); and Phytoremediation. As a further outcome of the 2005 meeting and as a precursor to development of a possible CAS, the CCC/USDA completed the following supplemental investigations at Everest to address several specific technical concerns discussed with the KDHE: (1) Construction of interpretive cross sections at strategic locations selected by the KDHE along the main plume migration pathway, to depict the hydrogeologic characteristics affecting groundwater flow and contaminant movement (Argonne 2006a). (2) A field investigation in early 2006 (Argonne 2006b), as follows: (a) Installation and testing of a production well and associated observation points, at locations approved by the KDHE, to determine the response of the Everest aquifer to groundwater extraction near the Nigh property. (b) Groundwater sampling for the analysis of volatile organic compounds (VOCs) and the installation of additional permanent monitoring points at locations selected by the KDHE, to further constrain the existing contaminant plume. (c) Resampling of all existing permanent monitoring points for VOCs and biodegradation parameter analyses, at the request of the KDHE. On the basis of these studies (Argonne 2006a,b) and the CCC/USDA's past investigations at Everest (Argonne 2006c), the CCC/USDA concluded that groundwater extraction is not an effective remedial option for the main body of the groundwater plume, and the KDHE concurred (KDHE 2006); the KDHE later noted, however (KDHE 2007a), that this and other technologies might represent viable remedial options in the event of further downgradient migration of the plume toward the intermittent creek. In February 2007, the CCC/USDA presented preliminary analyses of (1) the AS-SVE remedial alternative, incorporating the use of LDBs, and (2) the risks to human health and the environment posed by the observed carbon tetrachloride plume in groundwater (Argonne 2007a). The results of these analyses demonstrated the following: (1) Neither groundwater extraction nor AS-SVE in LDBs represents a practical approach for effective remediation of the groundwater contamination at Everest (near the Nigh property). (2) Periodic sampling and analyses for VOCs conducted by the CCC/USDA documented that the areal extent and range of carbon tetrachloride concentrations detected in the groundwater plume at Everest had changed relatively little from 2000 to 2006. (3) Estimates of groundwater flow and contaminant migration times, based on the hydrogeologic properties of the groundwater flow system identified at Everest (Argonne 2003, 2006b,c), indicated that, at minimum, approximately 4 years would be required for the carbon tetrachloride plume (in the subsurface) to reach the vicinity of the intermittent creek directly west of the Nigh property, and more than 20 years would be required for the contamination to reach the identified groundwater discharge area southwest of the Nigh property. (4) The existing (January-March 2006) plume posed no immediate danger of contamination to the surface waters of the intermittent creek. In light of these observations, the CCC/USDA proposed a phased program--over approximately 2-3 years--of groundwater sampling, surface water sampling, and related monitoring activities at Everest to (1) identify locations where a phytoremediation system would be effective and determine that area's extent and (2) support the potential development of a phytoremediation treatment alternative for the site. The recommended elements of the monitoring program are summarized in Table 1.1. In conjunction with this program, both the CCC/USDA and the KDHE recommended the construction of several new monitoring wells, at locations along and near the intermittent creek west of the Nigh property (Argonne 2007b; KDHE 2007b).