The Ottati & Goss/Great Lakes Container Corporation Site is located on the west side of Route 125 in Kingston, New Hampshire. The Ottati & Goss Inc. (O&G) portion is approximately one acre in size and the Great Lakes Container Corporation (GLCC) portion comprises approximately six acres.
From the late 1950s through 1981, portions of the Site were used for storage and/or reclamation of drums containing solvents and other organic chemicals. Used chemical drums were cleaned with corrosive rinse solutions that were disposed on-site.
In October 1981, EPA removed approximately 4,300 drums of unknown chemical waste from the O&G portion of the Site. The Site was added to the National Priorities List in September 1983.
The potentially responsible parties conducted a voluntary drum and contaminated soil excavation and disposal operation at the GLCC portion of the Site during 1984 and 1985. The total volume of contaminated soil, drums, and metal debris removed was approximately 12,800 tons.
The Record of Decision (ROD) for the site was signed by EPA in January 1987 and generally consisted of : excavating approximately 19,000 cubic yards of soil and sediment to be treated on Site using incineration and thermal aeration; installation of a groundwater extraction, treatment, and discharge system for the treated groundwater; site grading, demolition/disposal of above-ground and below-ground structures including a building, utilities, and underground storage tanks; a soil cover; and long-term monitoring of the Site and Country Pond.
As called for in the ROD, a low temperature thermal aeration (LTTA) process was mobilized in 1988 for the treatment of the soils on the O&G portion of the Site, and the cleanup was completed in 1989.
In 1993, EPA demolished and removed the GLCC building and several underground storage tanks.
The remedial design for cleaning up the soil was completed in December 1997. In the spring of 2000, the U.S. Army Corps of Engineers (ACoE) completed the design specifications for the soil and sediment remediation of the GLCC Site and wetlands, respectively. In the fall of 2000, the State took the GLCC property through eminent domain.
In the fall of 2000, the ACoE assigned a remedial action contractor to perform the remedial action of soils at the GLCC site and the wetland sediment. In August 2001, the ACoE remedial action contractor began the soil/sediment cleanup on site. The PCB-contaminated sediments in the wetlands were excavated, then backfilled with "clean" manufactured fill. Hummocks and hollows were constructed to provide topographic variability, as in a natural wetland. Trees and shrubs were planted in the remediated wetlands with the long-term plan to return the area to a functioning forested wetland. Excavated contaminated sediments were disposed off-site at a permitted landfill facility. The soil/sediments in the uplands were treated by low temperature thermal desorption. The remedial action was completed in the summer of 2002.
Annual sampling of down-gradient residential water supply wells has occurred since 1993. To date, there have been no site-related contaminants detected in any of the residential wells above site-established interim clean-up levels or State drinking water quality standards.
The EPA is continuing to utilize the Corps of Engineers to monitor and maintain the restoration of the forested wetland area located east of Route 125. Findings to date indicate that the survival rate of previously planted trees and shrubs varies and has required numerous replantings. Also, phragmites, an invasive species that poses a risk to the success of restoration efforts, has had to be managed. Subsequently, additional trees and shrubs were planted, and herbicide was applied to eradicate the Phragmites in 2005, 2006 and 2007. Continued wetland monitoring and maintenance activities are scheduled for 2008 to ensure the successful restoration of the forested wetland.
During the summer of 2007, EPA amended the groundwater remedy as defined in the 1987 ROD from active extraction with above ground treatment to in-situ chemical oxidation (ISCO). ISCO involves the injection of an oxidant directly into the groundwater to break down contaminants into non-hazardous by-products such as water, salt and carbon dioxide. The goal for ISCO is to achieve significant mass removal of contaminants, with the intent of eventually achieving drinking water standards in groundwater. Activated persulfate, which is capable of oxidizing all Site-related contaminants, was selected as the preferred oxidant for use at the Site. Oxidant delivery will be accomplished by injecting directly into semi-permanent wells, direct-push rods, and screened injection wells. On-site ISCO pilot studies conducted in late 2007 and early 2008 supported the full-scale ISCO design. Typically, ISCO is applied in stages, often annually, to allow for the most effective treatment of contaminants that may be adsorbed in lower permeable soils (e.g., silts and clays). The first and second stage of full-scale ISCO implementation was successfully applied during the summers of 2008 and 2009.
Subsequent site-wide groundwater sampling events occurred between each full-scale ISCO application to monitor the effectiveness of each treatment. The results of the sampling following the initial ISCO application showed significant reductions in contaminant levels over pre-ISCO conditions. Site groundwater data from a spring 2010 site-wide groundwater and soil sampling event will be evaluated to assess the need for a third consecutive year of ISCO injections, i.e., during the summer of 2010. Should site data support a decision to allow additional time for the effectiveness of previous ISCO injections to be fully understood, there may not be an ISCO application performed during the summer of 2010. However, additional ISCO injections may be applied in future years, as data may suggest appropriate.
During the full-scale ISCO applications, EPA monitored local surface water conditions for potential impacts. Nearby North and South Brooks were monitored for key physical parameters on 15 minute intervals beginning with the first ISCO injection of each season and continuing beyond the end of each application. An additional meter was also placed upstream of the Site to monitor for background conditions. In addition, periodic water samples were collected for laboratory analysis for Site-related contaminants, presence of oxidant and breakdown products. To date all stream meters have shown no indications of water quality conditions straying from the normal background readings, evidence that the oxidant has not impacted local surface waters nor is it significantly migrating off-site by way of surface waters.
Air quality monitoring was not necessary during the full-scale ISCO applications, due to there being no emissions from this process. The oxidant (sodium persulfate) is delivered to the site in granular form in sealed containers which are in turn stored in cargo containers that are kept closed and locked. A container of oxidant removed from a cargo box is immediately loaded into a mixing hopper where its specially designed discharge opening allows for direct mixing with water and sodium hydroxide solution (a catalyst). No off-gassing occurs during the mixing process. Once injected into the subsurface, the oxidant is consumed in the organic destruction process and essentially becomes inactive within two to four weeks.