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The former Garvey Elevators, Inc. (Garvey) grain storage facility is located at 2315 West Highway 6 in Hastings, Nebraska. Soil and groundwater beneath the facility are contaminated with carbon tetrachloride (CCl4) and other volatile organic compounds (VOCs). An approximately 4.5-mile long plume of CCl4 contaminated groundwater extends from the facility in an east-southeasterly direction. The EPA organized the Site into two OUs: OU 1 is the soil and ground water contamination at the facility and OU 2 is the contaminated groundwater plume east-southeast of OU 1. Garvey constructed the facility in 1959. The facility sits on a 22-acre parcel and consists of a concrete elevator head house and silos, flat-storage building, steel grain storage bins, and associated buildings (maintenance shop, office building and chemical storage shed). Until the mid-1980s, a fumigant containing CCI4 was used at the facility. In 1960, Garvey installed a 3,000-gallon, above-ground storage tank (AST) north of the silos to store the liquid fumigant. The fumigant was transferred via piping from the AST to a grain application gallery on top of the silos. The section of piping between the AST and the side of the silos was buried. The piping exited the subsurface at the base of the silos and extended up the north side of the silos to the application gallery on top. In the mid-1970s, a release of CCl4 at the ground surface was noted in the area where the trucks drove over the underground piping. The buried portion of the delivery pipe was excavated and found to be broken in two places: one near the AST and one near the grain elevator. The piping was completely replaced at the time. Leaks and drips were reported to have occurred during the operation period of the AST and piping. Staining in the area beneath the valve of the AST was also observed. Garvey ceased use of the liquid fumigant in 1985 and the AST was removed in 1986. The disconnected and highly corroded underground steel piping was recently found and removed during EPA’s soil excavation and cleanup activities.
What Has Been Done to Clean Up the Site?
The former Garvey facility first came to the attention of the Nebraska Department of Environmental Quality (NDEQ) in July 1994, when Garvey notified NDEQ of the presence of groundwater contamination at its facility. Garvey stated it did not know the source of the contamination. Early self-directed investigations by Garvey found carbon tetrachloride (CCl4) in the soil and groundwater samples. The CCl4 concentrations in the groundwater exceeded acceptable levels when compared to regulatory standards. Garvey also reported that the facility water supply well and several nearby private water supply wells were contaminated with CCl4 at levels greatly exceeding acceptable standards. In June 1995, Garvey enrolled in NDEQ’s voluntary cleanup program and continued investigations to identify the extent of soil and groundwater contamination beneath its facility.
In January 1999, Garvey installed and began operating a groundwater extraction and treatment (GET) system and a soil vapor extraction (SVE) system. The systems were intended only to treat contaminated soils at the source area and prevent groundwater migration from the source area. Treated groundwater was reinjected into the aquifer. The systems were not designed to address that portion of the plume that had already migrated east-southeast of the facility.
For a number of years following their enrollment in NDEQ’s voluntary cleanup program, Garvey rejected NDEQ calls to determine the extent of groundwater contamination in the area east-southeast of the facility. In May 2002, Garvey notified NDEQ that it would not sign the NDEQ Remedial Action Plan Monitoring Act (RAPMA) Memorandum of Agreement, which would have required cleanup of not only the source area, but also the contaminated groundwater plume. By this action, Garvey ceased participating in the Nebraska’s Voluntary Cleanup Program. On this basis, NDEQ requested EPA’s assistance in October 2002. At EPA’s recommendation, NDEQ performed an assessment of the site under its cooperative agreement with EPA.
In its assessment of the site, NDEQ found numerous private wells were impacted by Garvey-related contaminants in the area east-southeast of the facility and concluded that the source of the release was Garvey. In September 2005, the EPA listed the Site on the National Priorities List (NPL) and in October 2005, Garvey entered into an administrative order on consent (AOC) with the EPA to perform site characterization and cleanup activities. After performing a portion of the activities under the AOC, Garvey declared Chapter 7 bankruptcy on March 27, 2008. The EPA initiated fund-lead removal actions in May 2008 and in December 2008, began a Remedial Investigation/Feasibility Study (RI/FS) to characterize the extent of contamination and to evaluate potential remedies. The EPA determined that interim remedial actions were necessary to address threats to human health.
In June 2010, the EPA issued an interim Record of Decision (ROD) to contain and restore OU 1 groundwater and address a portion of the OU 1 soils. Remedial design activities were completed September 2011 and on-site construction activities to implement the actions in the ROD began in August 2012. In August 2012, the EPA also completed the RI/FS, issuing an FS Report that presented the development and full evaluation of remedial action alternatives to address the entire Site.
The EPA issued a second interim ROD in September 2013 to address the contaminated soil at OU 1 and the contaminated groundwater plume of OU 2. Based on recommendations by NDEQ, the EPA agreed to further studies of the feasibility of alternatives to address OU 1 groundwater before selecting a final remedy for the entire Site. The EPA’s selected remedy for OU 1 soils was excavation, treatment and disposal of contaminated soil and expansion and operation of the existing soil vapor extraction system. The EPA’s selected remedy for the OU 2 groundwater was recovery, treatment and discharge at mid-plume and leading edge of the plume. To prevent exposures to the contaminated groundwater during remedial actions, institutional controls to restrict domestic use of groundwater in the area was also selected as a component of the OU 2 remedy. The institutional control is being implemented through an ordinance of the City of Hastings.
Between September 2014 and September 2015, the EPA developed the Remedial Design to implement the cleanup activities at OU 1. In July 2016, the EPA initiated on-Site construction activities at OU 1. Approximately 68 cubic yards of soil in the area beneath the AST and the buried AST transfer pipe were excavated and placed in an above ground treatment cell. Treatment of these soils continues to date and will continue until cleanup levels are achieved. Several additional SVE wells were also constructed and incorporated into the SVE system that is addressing the in situ soils at the Site.The EPA, in September 2016, completed a remedial design for the groundwater recovery, treatment and discharge system at OU 2. To date, the system has not been constructed due to lack of available government funding.
What Is the Current Site Status?
The site is continues to be addressed through federal actions. The EPA has completed field investigations to determine the horizontal and vertical limits of the contaminants in the soil and groundwater. It has been determined that there is a contaminated groundwater plume more than four miles long and about one mile wide that extends from the former Garvey facility in an east-southeasterly direction. The primary contaminant in the soil and groundwater is carbon tetrachloride. Its degradation compound, chloroform, is present at low concentrations.
The EPA has completed design of a large-scale pump-and-treat system to will address the large contaminated groundwater plume that migrated from the former Garvey facility and will begin construction once federal funding becomes available.
The EPA continues to implement the soil and groundwater cleanup activities at the OU 1 source area. Approximately 68 cubic yards of soil has been excavated from beneath the area where the former AST was located and this soil is being actively vented to remove the low levels of CCl4 present in them. The EPA operates and maintains the groundwater extraction and treatment (GET) system to contain and address contaminated groundwater at the former Garvey Elevator facility. The EPA also continues to operate and maintain the soil vapor extraction (SVE) system to treat the contaminated subsurface soils beneath the facility. The EPA recently completed improvements to both the GET and SVE systems to increase their reliability, efficacy and efficiency.