Fact Sheet #99-08 Chemical Spill 10 (CS-10) Source and Plume Update Fact sheet providing information on the Chemical Spill 10 source area, groundwater plume, and cleanup. The purpose of this fact sheet is to provide updated information to the public regarding the cleanup of the Chemical Spill 10 (CS-10) soils and groundwater plume. In addition to this fact sheet, we encourage you to read other fact sheets such as Chemical Spill 10 (CS-10), Groundwater Treatment Technologies, and Chemical Spill 10 (CS-10) Plume Response Decision, which provide background information. Words in italics are defined in the glossary at the end of this fact sheet. They are only italicized the first time they are used. Background/History The CS-10 source area is located in the south-central area of the Massachusetts Military Reservation (MMR). The primary source is the 38-acre area of the former BOMARC Missile Site and Unit Training Equipment Site (UTES). The Boeing Michigan Aerospace Research Center (BOMARC) Missile Site was operated from 1960 to 1973. Spills and releases of chemicals occurred historically in this area. The UTES has operated since 1978 to maintain and store armored and other wheeled vehicles. Eleven other potential source areas which likely contribute to the plume, have been identified in the vicinity of the CS-10 plume within the MMR boundaries. The CS-10 plume extends from the former BOMARC missile site to the edge of Ashumet Pond (see Figure 1). The plume is approximately 17,000 feet long; a maximum of 4,000 feet wide, and varies in thickness up to 140 feet. In general, the CS-10 groundwater plume is over 120 feet below ground surface and 60 feet below the water table along most of its length.
The primary contaminants of the CS-10 plume are trichloroethylene (TCE), perchloroethylene (PCE), and 1,2-dichloroethylene (1,2-DEC). However, ethylene dibromide (EDB) has been detected sporadically below safe drinking water standards within the CS-10 plume. Source Area Cleanup In 1996, more than 180 former waste storage/disposal structures and associated contaminated soils were removed from areas throughout the MMR. At the CS-10 source areas, fifteen drainage structures also were removed, and approximately 700 cubic yards of excavated soils were recycled on-base using a process called asphalt batching. Additional soil sampling in the source area identified PCE, total petroleum hydrocarbons (TPH), pesticides, metals, polychlorinated biphenyls (PCBs), and poly-nuclear aromatic hydrocarbons (PAHs). PCE was detected in soils up to 920 parts per billion and TPH was detected at levels requiring treatment. When evaluated for human health or ecological risk, the safe limit was exceeded for some or all of these compounds. Additionally, radiological surveys and testing of the source area soils and buildings for explosives were conducted to ensure no radioactive or explosive compounds were present. After receiving input from the public and the EPA and DEP, a decision was reached on cleanup of the remaining soil contaminants. AFCEE and EPA signed the Record of Decision (ROD) for the CS-10 source area on August 16, 1999 with MassDEP concurrence. The ROD explains the cleanup alternatives evaluated and selected for a site. The source areas will be excavated to remove the contaminated soil to prevent further migration of these contaminants to the subsurface environment. Excavating more contaminated soil will further clean up source areas. Approximately 1,700 cubic yards of contaminated soil will be excavated during this work. Soils will be tested prior to disposal off-site at an approved disposal facility or recycling at an on-base asphalt batching plant. Asphalt generated on base is planned to be used as a subgrade material in the paving of roads located on-base. If necessary, any deeper soil contamination will be treated on-site with soil vapor extraction technology to reduce contaminant concentrations and minimize the potential for contaminants to move into the groundwater. Soil vapor extraction involves extracting the vapor located within soil pores, which holds the contaminants, through wells installed into dry soil above the water table. The vapor is then passed through carbon vessels and the treated vapor is discharged to the atmosphere. There are various ways that AFCEE is addressing public concerns with regard to on-base asphalt batching. The public has asked to be notified before any work starts. To ensure the safety of workers and the public, AFCEE will conduct an air-monitoring program for dust and chemical vapor emissions. If at any time air monitoring reveals that safe levels are exceeded, work will be stopped immediately. Additionally, emergency equipment shutdown procedures, properly trained workers, and a fire prevention plan will help minimize the potential risk of exposure for workers and the public beyond the on-base plant. Currently, a portion of the BOMARC area is used by the Army National Guard as a Unit Training Equipment Site. Equipment is maintained there using several pollution prevention techniques to ensure that it does not contribute additional contamination to the soil or groundwater. In addition, the Joint Program Office has overseen additional cleanup work at the CS-10 source area. At the former power plant (Building 4606) located in the BOMARC area, interior walls have been removed due to the presence of asbestos-containing materials. The results of air monitoring indicated that no asbestos was released during the asbestos removal work. Additionally, over 200,000 gallons of water were pumped out of the basement of this building, treated to remove any contamination, and then transported to the on-base wastewater treatment plant during the past summer. After the water was removed, oil was observed entering the basement from a sump in a sub-basement. Analysis of the oil determined that it was likely waste compressor oil with traces of refrigerant, metals and PCBs. The oil has been pumped and transported off base and disposed of at a licensed facility. Removal of the asbestos-containing material in the basement is now underway. After that, the source of the oil will be investigated. Finally, a pilot test for an innovative technology at the source area began in August 1998. Two reactive walls were installed in the ground immediately downgradient of the source area. Reactive wall technology involves placing a barrier or "wall" of granular iron filings vertically into the ground across a groundwater plume. As the contaminated groundwater flows through the wall, chlorinated compounds, such as TCE and PCE react chemically with the iron ultimately to produce non-toxic chloride ions and non-toxic hydrocarbons. Plume Cleanup During 1997, extensive public dialogue was held on options to clean up the CS-10 groundwater plume. Public meetings, posterboard sessions, meetings in residences, and other outreach activities were conducted to gather input from the public. After consideration of comments the remedial project managers from AFCEE, EPA, and MassDEP agreed, by consensus, that extraction, treatment and reinjection (ETR) technology would be used to treat the CS-10 groundwater plume. The selected alternative was designed with consideration of property access issues and adverse impacts to sensitive ecological areas along the shoreline of Ashumet Pond. Treatment systems are being brought into operation in a phased approach. The first was the Sandwich Road ETR system which began operation May 18, 1999, approximately two weeks ahead of the Federal Facility Agreement (FFA) enforceable milestone of May 31, 1999. The second, is an in-plume treatment system that began operation June 24, 1999, four days ahead of the FFA enforceable milestone of June 28, 1999. The third system is treatment at the south and southwest lobes of the plume. That treatment system currently is being designed. It is scheduled to be in operation by April 30, 2000. Another part of the cleanup decision included some additional studies of the leading edge of the plume to examine further the relationship between the plume and Ashumet Pond. A summary of each is described below. Sandwich Road System The Sandwich Road system extracts contaminated groundwater from the aquifer using eight extraction wells. The extracted groundwater is then piped underground to the Sandwich Road treatment plant located on-base. It is then treated through various filters and tested to ensure reduction of contaminants. The clean water is then returned to the aquifer through six reinjection wells. The treatment plant also has been cleaning contaminants from the Storm Drain–5 North groundwater plume. The plant was expanded, adding additional tanks and filters to accommodate the groundwater from the Sandwich Road system. With these modifications the plant can treat up to 1,060 gallons per minute (GPM) of groundwater from both plumes. A pilot test of recirculating well technology was conducted in the CS-10 plume near Sandwich Road during 1998. Four recirculating wells were installed, in the higher contaminant concentration area north of Sandwich Road, and operated until the Sandwich Road system was started. Over the 26 months of operation, approximately 315 pounds of TCE were successfully removed. These wells were removed from operation once the Sandwich Road extraction fence system began operating. In-Plume System The central portion of the plume, called the CS-10 In-Plume, is being cleaned up using extraction, treatment, and infiltration technology. This ETR system began operating June 24, 1999. The placement of a treatment system within the plume reduces higher concentrations of contaminants before they reach the extraction wells of ETR systems used in the southern and Sandwich Road parts of the plume. The CS-10 In Plume treatment plant treats water from five extraction wells and returns the treated groundwater through perforated Poly Vinyl Chloride (PVC) pipe in two infiltration trenches. The infiltration trenches are located south of the southern and southwestern lobes of the CS-10 plume on MMR property, as shown on the attached figure. The system is designed to treat 1200 gallons of groundwater per minute to non-detectable contaminant concentrations using four 20,000-pound carbon treatment vessels. South/Southwestern System A treatment system is being designed for the southern and southwestern lobes of the CS-10 plume (see Figure 1). The cleanup objective for this system is to enhance the CS-10 In Plume and Sandwich Road systems in order to clean up the entire CS-10 groundwater plume and thereby restore the aquifer. The south/southwestern system will increase the speed at which contaminants are removed from the aquifer and minimize cleanup timeframes. This system also is designed to help slow further spreading of the plume. During the fall of 1999, public meetings will be held to provide information on and to solicit public comment on the proposed designs. An enforceable milestone of April 30, 2000 has been set for this system to start operation. Leading Edge/Ashumet Pond Studies When the cleanup decision for the CS-10 plume was made among AFCEE, EPA, and DEP, three additional concerns were addressed. First, the residents that live between the base boundary and Ashumet Pond were not in favor of a treatment system in their neighborhood. Also, it would be difficult to put a treatment system very close to the pond shoreline without some potential ecological injury to the pond. And third, the leading edge of the plume needed further definition. In response to those points, the RPMs decided to place the ETR system along Sandwich Road on the west side, which is located on base property. This minimizes disruption to the neighborhood and the pond. Also, they decided to conduct additional studies of Ashumet Pond to characterize the interaction between the plume and the pond. Late in 1998, a groundwater plume containing TCE was found between Ashumet and Johns ponds. In order to determine the source of the TCE plume, a number of studies are currently underway. Study activities in 1999 on Ashumet Pond include sampling of groundwater beneath the pond, followed by monitoring well installation through the bottom of the pondusing sonic drilling methods. Drilling will begin along the eastern shore of Ashumet Pond and will proceed toward the northern shore along the anticipated path of the TCE plume. Based on the results from this initial drilling, additional on-pond locations will be sampled to determine whether other plume areas, such as CS-10, are present beneath the pond. Further, the United States Geological Survey (USGS) completed passive vapor diffusion sampling in the northern portion of Ashumet Pond shoreline in July 1999 and results are expected to be presented during the Fall of 1999. Next Steps Many activities approved by EPA and MassDEP are occurring at the same time to remove both the source area and groundwater contamination. These activities include:
Glossary Boeing Michigan Aerospace Research Center (BOMARC): an Air Force operated facility included missile launch and maintenance facilities, electrical power generation and fuel storage tanks. ethylene dibromide (EDB): an additive in aviation gas to control the build-up of lead in the engines. extraction, treatment and reinjection (ETR): a system that extracts groundwater, treats it to remove contaminants and reinjects or infiltrates the treated water into the aquifer. groundwater plume: a body of groundwater containing contaminants that exceed federal and state drinking water levels or other risk-based levels at multiple test well locations. Contaminated water can result when fuels, solvents, or other contaminants are spilled or released on the ground. When these materials filter through the sandy Cape Cod soil, they encounter groundwater. As the groundwater moves, the contaminants are carried with it, creating a groundwater plume. lobe: usually used to describe a separate portion of a main body of a groundwater plume. metals: any of various opaque, fusible, ductile, and typically lustrous substances, which are good conductors of electricity and heat. monitoring well: a well from which water level and water quality data is collected. passive vapor diffusion samplers: a small bottle placed in a plastic bag and buried several inches into the pond bottom. Vapors migrate through the plastic and into the bottle where they can be analyzed for contaminants by a laboratory. perchloroethylene (PCE): also referred to as tetrachloroethene; a man-made solvent commonly used for metal degreasing and in dry-cleaning clothes. pesticide: an agent used to destroy pests. plume response alternative: a specific configuration of treatment system(s) to be compared and evaluated. polychlorinated biphenyls (PCBs): any of several man-made compounds once widely used in insulating oil in transformers and other electrical devices. PCBs have been used commonly since the turn of the century and may be found almost anywhere through the use of solvents, pesticides, chemical sealers, explosives, or rocket fuels. poly(cyclic/nuclear) aromatic hydrocarbons (PAHs): polyaromatic hydrocarbons are present in heavier petroleum hydrocarbon blends and particularly in coal tars, wood treating chemicals, and refinery waste sludges. reactive wall technology: an innovative cleanup technology that involves placing a barrier or "wall" of granular iron filings vertically into the ground across a groundwater plume. As the contaminated groundwater flows through the wall, chlorinated compounds, such as TCE and PCE react chemically with the iron to ultimately produce non-toxic chloride ions and non-toxic hydrocarbons. remedial project managers: the program managers appointed by the Air Force Center for Environmental Excellence (AFCEE), the U.S. Environmental Protection Agency (EPA), and the Massachusetts Department of Environmental Protection (DEP). soil vapor extraction: extracting the vapor located within soil pores, which holds the contaminants, through wells installed into dry soil above the water table. The vapor is then passed through carbon vessels and the treated vapor is discharged to the atmosphere. total petroleum hydrocarbons (TPH): an overall concentration of petroleum hydrocarbons. Petroleum is a mixture of a variety of hydrocarbon compounds. TPH can be measured from a variety of petroleum products such as kerosene, diesel fuel, heating oil, gasoline etc. trichloroethylene (TCE): a solvent used to dissolve or disperse another substance such as oil, and is often used in metal degreasing. For More Information Doug Karson, Community Involvement Specialist Jim Murphy, Community Relations Coordinator Ellie Grillo, Community Involvement Coordinator
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