The Beede Waste Oil/Cash Energy site consists of two parcels totaling about 40.6 acres on Kelly Road in Plaistow near the junction of NH Routes 125 and 121A. Waste oil recycling operations had reportedly been there since the 1920s and later facility operations included waste oil processing and resale, fuel oil sale, contaminated soil processing into cold-mix asphalt, anti-freeze recycling, and other related industries.
Contamination on the site originated from poor storage and handling of waste oil and other products as well as the unlined and uncovered storage of large contaminated soil piles. Elevated concentrations of polychlorinated biphenyls (PCBs) were first detected by DES in waste oil found in several above-ground storage tanks following complaints of odors in 1979. Numerous notices, letters of deficiency, administrative orders and court orders to cease operations and perform investigation and remedial activities were issued from 1980 to 1992.
Following the cessation of commercial operations in 1994, more than 1.5 million gallons of oily liquid waste and sludge, stored in approximately 100 above-ground storage tanks and more than 1,000 drums, remained at the facility. The tanks and drums contained hazardous waste, including PCBs, metals, and volatile organic and chlorinated organic compounds. Seventeen large soil piles, totaling more than 27,000 cubic yards and containing varying levels of contamination, were also left on-site.
Properties in the surrounding residential neighborhood are served by individual water wells. Testing of drinking water wells found contamination, generally consisting of chlorinated solvents, at some adjacent properties. DES installed treatment systems on wells with groundwater contamination levels above State standards and provided bottled water to ensure that residents can safely drink and use their water. DES and EPA continue to oversee the monitoring of water quality in residential wells in the vicinity of the site and the maintenance of the treatment systems.
Between 1992 and 1998, DES and EPA undertook interim measures and removal actions to mitigate exposure to contamination, including containment of the oil leakage to Kelley Brook and additional site fencing. In the summer of 1996, EPA initiated a time-critical removal action to remove much of the above ground hazardous waste. With the cooperation of DES and with supplemental State funding, the action was extended in 1997 to remove non-hazardous wastes, resulting in the removal and proper disposal of all tanks and drums and the materials in them.
Zones of contaminated soil and pools of oil floating on the groundwater table were found in the subsurface. The floating oil is referred to as light, non-aqueous phase liquid (LNAPL). The LNAPL at the site is contaminated with solvents, PCBs and metals. EPA conducted a non-time-critical action between 1999 and 2005 to extract as much LNAPL from the subsurface as practicable, thereby cutting-off oil seepage to the Kelley Brook wetlands and reducing the mass of this major source of groundwater contamination. Approximately 91,000 gallons of LNAPL were removed from the groundwater.
The site was added to the National Priorities List in December 1996 and with funding from EPA, the remedial investigation/feasibility study (RI/FS) was initiated in 1997 under DES management. The RI report, which characterizes site conditions and evaluates the risks to human health and the environment, was released in February 2001. The FS report, which evaluates cleanup alternatives, was released in January 2002. The proposed plan for cleanup of the site was presented for public comment in June 2002. EPA carefully considered all comments received during the proposed plan’s public comment period and, with DES’s concurrence, selected the preferred alternative as the most appropriate remedial action for the site. This cleanup decision is documented in the Record of Decision (ROD) that was signed on January 9, 2004.
The ROD calls for remedial actions that will be protective for the reasonably anticipated future use of the site, which includes elderly housing, a community center and recreational fields. The ROD requires the excavation of sediments, soil piles and contaminated soil that is less than 10 feet below ground surface (bgs) for off-site treatment and/or disposal. Contaminated soil greater than 10 feet bgs, which is acting as a source of groundwater contamination, will be treated in-place using soil vapor extraction, and may possibly include heating the soil to enhance the removal of contaminants remaining in the deep soil. Contaminated groundwater will be extracted and treated on-site to restore it to Ambient Groundwater Quality Standards prior to on-site disposal. A groundwater management zone will be established to manage the contaminated groundwater and institutional controls will be implemented to prevent the excavation of soils greater than 10 feet in depth.
In 2006, negotiations were conducted with a group representing the major potentially responsible parties (PRPs) to reach an agreement to design and implement the remedial action. The agreement was formalized in a Consent Decree (CD) and calls for the PRPs to clean up the site under the oversight of the EPA and DES. On April 16, 2007, the CD was lodged in the District Court for New Hampshire and the PRPs (now “Performing Parties” ) initiated some of the preliminary planning work associated with the $48 million comprehensive site cleanup plan selected in the 2004 ROD. The CD was entered by the Court on July 22, 2008 and, immediately thereafter, field work associated with several pre-design investigations and studies commenced.
From 2009 through 2011, the Performing Parties conducted pre-design investigations, under EPA and DES oversight, to support the design of the cleanup action. Pre-design investigations included soil and sediment investigations to further delineate the extent and volume of contaminated soil (including soil piles) and sediment that will require excavation or treatment. Several treatability studies were also conducted to determine the appropriate means to eliminate the sources of groundwater contamination and to treat the contaminated groundwater. Field test and laboratory analyses were conducted to determine the need for thermal enhancement of the soil vapor extraction system. The results of this treatability study indicate that thermal enhancement of the soil will effectively remove the subsurface contamination that poses a long-term treat to groundwater quality. Another treatability study was conducted to determine the best treatment technology to employ in treating the contaminated groundwater and achieve the groundwater cleanup goals. Additional field tests and infiltration tests were performed to support an extensive groundwater modeling effort to determine the design for the groundwater extraction, treatment and discharge system.
In 2011, the sequence for the implementation of the remedial action activities was modified to accelerate the groundwater treatment component of the remedy and thereby address one of the principal threats to public heath. The sequence of implementation includes: 1) implementation of the groundwater treatment system; 2) excavation and removal of contaminated landfill material and contaminated sediments in Kelley Brook; 3) implementation of the thermally-enhanced soil vapor extraction system to eliminate the sources groundwater contamination at depth; and 4) excavation and removal of contaminated shallow soils.
Construction of the first phase (the groundwater extraction, treatment and discharge system) is scheduled to start in 2012 and the other phases will be implemented through 2016.