September 1998 Proposed Plan to Clean Up Source Operable Units At the Chemical Spill No. 10 and Fuel Spill No. 24 Site The Proposed Cleanup
This remedy will minimize risk to human health and ecological receptors (plants and animals) by limiting exposure to contaminants. Words that appear in italics are defined in the Glossary at the end of this Proposed Plan. This Proposed Plan is issued by AFCEE, the lead agency for the Installation Restoration Program (IRP) at MMR, with support from the U.S. Environmental Protection Agency (USEPA) and the Massachusetts Department of Environmental Protection (MADEP). Learn More About AFCEE’s Proposed Plan
For additional information on the meeting, call Doug Karson, AFCEE Public Affairs Specialist at (508) 968-4678 ext. 2. What Do You Think?
There are two direct ways to provide a formal comment:
Comments may also be submitted by fax at (508) 968-4673 or by electronic mail message addressed to: doug.karson@mmr.brooks.af.mil or on the MMR Web site at http://www.mmr.org. Introduction The purpose of this Proposed Plan is to describe the remedial alternatives AFCEE evaluated to address soil and sediment at nine source areas at CS-10/FS-24, and to identify the AFCEE preferred remedial alternative and explain AFCEE's rational for this preference. Groundwater contamination associated with CS-10/FS-24 will be addressed in separate studies under the Plume Response Plan. In addition, the actions proposed in this Proposed Plan will help minimize groundwater contamination and may reduce future groundwater treatment requirements. Other source remediation efforts at CS-10/FS-24, which included drainage structure removal, have been addressed separately from this Proposed Plan under the Drainage Structure Removal Program (DSRP). The DSRP involves a systematic, basewide investigation and cleanup effort to address drainage sumps that were used historically at MMR, including those at CS-10/FS-24. Removal activities conducted under the DSRP are described more completely in the Drainage Structure Removal Program Remedial Action Workplan (Jacobs Engineering Group 1995). Under the DSRP in 1996, 15 drainage structures and surrounding soils were removed; 2 drainage structures were cleaned and filled with concrete at CS-10. In addition to the drainage structures, a total of 31,550 gallons of liquids was removed from the structures and treated at an off-base industrial wastewater treatment facility, and 702 cubic yards of contaminated soils were removed and sent to an on-site asphalt batching facility. Three additional drainage structures were not removed at CS-10 because of access restrictions. AFCEE plans to perform an investigation and sampling of structures not addressed under the DSRP prior to issuance of the Record of Decision (ROD) and if necessary, address potential source area remediation. The DSRP activities are summarized in the Drainage Structure Removal Program Remedial Action Summary Report (ABB-ES 1998) currently under regulatory review. Although MADEP has already conducted a preliminary
radiological survey which showed no measurable results, AFCEE is conducting further
radiological survey and asbestos and explosives sampling and analysis at CS-10/FS-24 to
ensure that any outstanding questions are answered regarding potential human health risk
and the adequacy of the proposed remedial alternative. The results of these additional
activities will be presented before completion of the Record of Decision for the SOUs. USEPA placed MMR on the National Priorities List in 1989 for investigation under CERCLA. A Federal Facility Agreement, signed in 1991 and updated in 1997, required AFCEE to take the lead in cleanup activities at MMR, including CS-10/FS-24 (Figure 1). AFCEE’s activities to date, carried out under the Installation Restoration Program, include performing a Remedial Investigation (RI) at CS-10/FS-24 to characterize the nature and distribution of contamination. Risk assessments were performed as part of the RIs to identify potential risks from exposure to contaminants. The risk assessments evaluated the present and future risks to human health and the environment posed by existing conditions, assuming no remedial action is taken. Cancer and noncancer risks were evaluated. Additional activities include preparing a Focused Feasibility Study to develop and evaluate remedial action alternatives to reduce site risks and preparing this Proposed Plan. This Proposed Plan summarizes the RI and Focused
Feasibility Study and presents remedial actions proposed for source area soil and sediment
at nine locations within CS-10/
Four Categories of Cleanup Options No action or limited action: Leave the site as it is, or restrict access and monitor site conditions. The Focused Feasibility Study assesses how well the evaluation criteria would be met if nothing were done to reduce site risks. Contain contamination: Leave the contamination where it is and cover or contain it to prevent exposure to, or spread of, contaminants. This approach reduces risks from exposure to contamination, but it does not reduce or treat contamination. Move contaminated material off-site: Remove the contaminated material (e.g., soil, sediments, waste) and treat or dispose of it at a permitted off-base facility. Treat contamination on-site: Use a chemical or physical process at the site to immobilize, remove, or destroy contaminants. The treated material can then be left on-site. Contaminants removed by the treatment process are disposed of at a permitted off-base facility. Description and History of CS-10/FS-24
Why Is Cleanup Needed at CS-10/FS-24? At Details A, B, C, D, G, H, and I, human health risks from exposure to soil do not exceed federal and state risk management guidelines. However, based on the ecological risk assessment, surface soils at these source areas pose an unacceptable risk from metals (antimony, arsenic, cadmium, chromium, copper, lead, vanadium, and zinc), dieldrin, and/or polynuclear aromatic hydrocarbons (PAHs). At the Detail C source area, tetrachloroethylene and total petroleum hydrocarbons were identified in deeper soils at concentrations above Soil Target Cleanup Levels (STCLs). Cleanup of deeper soils at this source area will greatly reduce the potential for future migration of contaminants to groundwater. At the Detail E source area, the southern storm sewer outfall drainage ditch, the human health risk assessment concluded that benzo(a)pyrene in sediment poses an unacceptable cancer risk for future scenarios involving residential children and adults. The unacceptable cancer risk results from the combined effect of potential human exposure to contaminated sediments via ingestion and inhalation. PAHs, dieldrin, and metals (arsenic, chromium, copper, cyanide, lead, manganese, vanadium, and zinc) in soils and sediments, and metals (aluminum, cadmium, copper, lead, manganese, and zinc) in surface water at Detail E also pose an unacceptable ecological risk. At the Detail F source area, the eastern drainage impoundment, the human health risk assessment concluded that PAHs in soils pose unacceptable cancer risk for future scenarios involving residential children and adults. The unacceptable cancer risk results from the combined effect of potential human exposure via ingestion, inhalation, and dermal contact of contaminated soils. In addition, PAHs, polychlorinated biphenyls, dieldrin, and metals (aluminum, cadmium, chromium, copper, lead, manganese, vanadium, and zinc) in soils and sediments at Detail F pose an unacceptable ecological risk. Groundwater beneath and downgradient of CS-10/FS-24 is contaminated with solvent-related organic compounds. Following an extensive public decision process, a decision was announced in August 1997 on how the CS-10 groundwater plume will be treated. The Sandwich Road Fence treatment system startup is scheduled to begin June 1999. Actual or threatened releases of hazardous substances from CS-10/FS-24, if not addressed by the preferred alternative or one of the other active measures considered, may present a current or potential threat to public health, welfare, or the environment. Cleanup Goals Cleanup Alternatives The Focused Feasibility Study assessed how well the following five alternatives would meet the evaluation criteria while controlling potential adverse human health and ecological effects from exposure to soils and sediment and from potential migration of contaminants from deep soils to groundwater. Alternative 1: No Action. The No Action alternative was evaluated in the initial screening of alternatives as a baseline for comparison with other alternatives as required by the USEPA. No monitoring or remedial action components are included in this alternative. Alternative 2: Limited Action. Alternative 2 was evaluated in the detail evaluation of alternatives as a baseline for comparison with other alternatives as required by USEPA. This alternative provides no treatment of contaminated media but includes institutional controls such as access restrictions and environmental monitoring. In addition, institutional controls cannot mitigate the deeper soils contamination at Detail C, which provides a potential future source of groundwater contamination; nor can such controls be applied to the downstream off-base drainage swale at Detail F. Alternative 2 also includes 5-year site reviews of site conditions and monitoring data from remedial actions to assess whether cleanup goals have been met, to determine if the remedy remains protective of human health and the environment and to determine whether additional remedial action is justified. Alternative 3: Excavation and On-site Asphalt Batching/In Situ Thermally Enhanced Soil Vapor Extraction/Environmental Monitoring. Alternative 3 consists of three components: Excavation and on-site asphalt batching, insitu thermally enhanced soil vapor extraction, and environmental monitoring. The first component, excavation and on-site cold mix asphalt batching, is proposed to clean up the shallow soils and sediment at seven source areas (Details A, B, C, D, E, F, and I). This component involves excavating contaminated soil and sediment and mixing them with an asphalt emulsion. The asphalt emulsion coats the soil and sediment particles and immobilizes contaminants, thereby reducing exposure risk. In addition, the cold mix process minimizes the volatilization of volatile organic compounds. The stable asphalt-emulsion-coated product can be used as a subbase for paving projects. Asphalt batching has been successfully used as a treatment alternative at other MMR sites to recycle contaminated soil. Excavated soil would be tested before being mixed with the asphalt to confirm that the soil would meet regulatory requirements. If the soil exceeded acceptable levels, it would be disposed of at a permitted off-base facility. The second component of Alternative 3 includes in situ soil vapor extraction (SVE) to clean up deeper contaminated soils at one of the nine source areas (Detail C). This component involves the injection of hot air through wells installed within the contaminated soil zone to remove light and heavy hydrocarbon compounds. These compounds are recovered in adjacent vapor extraction wells and routed to an off-gas treatment system set up at the site to remove and treat the soil contaminants from the air stream. The final component of Alternative 3 involves environmental monitoring at two of the source areas (Details G and H) where soil contaminants are present at such low concentrations that remediation is unwarranted. Additional soil sampling and laboratory analysis is proposed at these two source areas to confirm that contaminant concentrations do not pose a threat to human health or the environment. Alternative 4: Excavation and Off-site Asphalt Batching/In Situ Thermally Enhanced Soil Vapor Extraction/Environmental Monitoring. Alternative 4 also consists of three components: Excavation and off-site asphalt batching, insitu thermally enhanced soil vapor extraction, and environmental monitoring. Component 1 of Alternative 4 is similar to Alternative 3 except that the asphalt batching process is conducted at an off-site location. Excavated soil and sediment would be transported by truck and treated at a batching plant using a hot or cold mixing process. Excavation and off-site asphalt batching would be used to remediate the shallow soils and sediment at seven source areas (Details A, B, C, D, E, F, and I). As described for Alternative 3, the second and third component of Alternative 4 also includes in situ SVE to clean up deeper contaminated soils at one of the nine source areas (Detail C) and environmental monitoring at two of the source areas (Details G and H), respectively. Alternative 5: Excavation and Off-site Landfill Disposal/In Situ Thermally Enhanced Soil Vapor Extraction/Environmental Monitoring. Alternative 5 consists of three components: Excavation and off-site landfill disposal, in situ thermally enhanced soil vapor extraction, and environmental monitoring. Alternative 5 is similar to Alternative 3 except for the first component. The first component proposes that contaminated soils and sediment would be excavated and disposed of at an off-site landfill permitted by USEPA to accept such waste material rather than treated on-site. The landfill lining prevents contaminants from migrating into groundwater. Excavation and off-site landfill disposal would be used to clean up the shallow soils and sediment at seven source areas (Details A, B, C, D, E, F, and I). As described for Alternative 3, the second and third components of Alternative 5 also includes in situ SVE to clean up deeper contaminated soils at one of the nine source areas (Detail C) and environmental monitoring at two of the source areas (Details G and H), respectively. Comparison of Alternatives
Summary of AFCEE’s Preferred Alternative
AFCEE's Preferred Alternative for CS-10/FS-24 AFCEE believes that this preferred remedial alternative would satisfy the requirements of CERCLA Section 121 (b), that the selected alternative is protective of human health and the environment, complies with ARARs, is cost effective, uses permanent solutions to the maximum extent practicable, and satisfies the statutory preference for treatment. Excavation and On-Site Asphalt-Batching. A total of approximately 3400 cubic yards of soil and sediment would be removed at seven of the source areas at CS-10/FS-24 (Details A, B, C, D, E, F, and I). The soils and sediment would be stockpiled, covered to eliminate contaminant migration, and processed in a cold mix asphalt batch plant set up on-site. Batched asphalt would be used at MMR and coordinated with similar cleanup efforts at other MMR sites. An underground storage tank and associated piping at Detail C would be removed during this phase of cleanup. Confirmation sampling would be conducted during the excavation process to ensure the limits of contaminated soil are met. The excavations would then be backfilled with clean material, and wetland areas at Detail F would be restored as appropriate under Massachusetts regulations. Because contaminated soil will be removed from this site and the preferred alternative does not include site access restrictions, 5-year site reviews would not be performed. Before excavation of soils and sediment at the eastern storm water impoundment (Detail F), the surface water would be removed by pumping and transported to the Base waste-water treatment plant for treatment and disposal. Confirmation sampling and laboratory analysis of sediment will be conducted prior to issuance of the ROD at the culvert outfall to the Detail F Source Area at the Base boundary and at downstream locations along the entire drainage swale. The results will be compared with the cleanup goals discussed above and additional sediment will be removed and undergo asphalt batch treatment if concentrations are above these goals. In Situ Thermally Enhanced Soil Vapor Extraction. Deeper soils contamination at the Detail C source area require in situ treatment. The preferred alternative for cleanup of these soils would involve the installation of hot air injection wells, vapor extraction wells, a vapor collection system, and a temporary impermeable cover. A mobile, thermally enhanced SVE system consisting of an air blower/burner to inject hot air and an off-gas treatment system would be set up to remove and treat organic compounds. Periodic air monitoring will occur to ensure the effectiveness of the off-gas treatment system in eliminating contaminants from the treated air stream. Confirmational sampling of deep soils would be performed to ensure cleanup goals are met. Environmental Monitoring. The preferred alternative for Details G and H involves additional subsurface soil sampling and laboratory analysis to ensure that contaminant concentrations are below cleanup goals. The relatively low concentrations of contaminants in subsurface soils at these source areas indicate that the risk to human health and the environment is within the acceptable range. What Is a Formal Comment? You can submit a formal comment in any of the following ways:
Why Submit Formal Comments? A transcript of all formal comments and AFCEE’s written responses will be issued in a document called a Responsiveness Summary that will accompany the Record of Decision for the SOUs at CS-10/FS-24. AFCEE expects to complete review of all comments, select a remedial alternative for the SOUs at CS-10/FS-24, and issue the Record of Decision documenting AFCEE’s choice late November 1998. At that time, copies of the Responsiveness Summary will be mailed to everyone who submitted a formal comment, and copies will also be placed in local libraries. In addition, AFCEE will announce the decision through the local news media and site mailing list. How Does AFCEE Choose a Final Cleanup
Plan?
Of these nine criteria, protection of human health and the environment and compliance with ARARs are considered threshold requirements that must be met for a candidate cleanup alternative to be selected. The next five criteria, called balancing criteria, are used to evaluate and compare the elements of alternatives that meet the threshold criteria. This comparison assesses which alternative provides the best balance of trade-offs with respect to long-term effectiveness and permanence; reduction of toxicity, mobility, or volume through treatment; short-term effectiveness; implementability; and cost. State and community concerns are considered modifying criteria factored into a final balancing of all criteria to select a remedy. Consideration of state and community comments may prompt AFCEE to modify aspects of the preferred alternative or decide that another alternative provides a more appropriate balance.
For Further Information
Hours: 8:00 a.m. to 4:30 p.m., Monday through Friday Information and technical documents are also available at the main libraries in the towns of Bourne, Falmouth, Mashpee, and Sandwich; at the U.S. Coast Guard library at MMR; and at the MMR Web site (http://www.mmr.org). For further information, please contact: Doug Karson Johanna Hunter Ellie Grillo Visit the Massachusetts Military Reservation on the World Wide Web: http://www.mmr.org Applicable or Relevant and Appropriate Requirements (ARARs): Federal and/or state environmental laws and regulations that must be met during the implementation and completion of remedial actions. Comprehensive Environmental Response, Compensation, and Liability Act: This law, commonly known as Superfund, authorizes the federal government to respond directly to releases of hazardous substances that may endanger public health or the environment. Cleanup: Actions taken to remove contaminants from the environment. Drainage Structure Removal Program (DSRP): A comprehensive program to identify, characterize, and remove underground drainage structures, sumps, and associated soils at various across MMR. Focused Feasibility Study: A focused study for identifying and evaluating options for remedial action to reduce risk to human health and the environment. Federal Facility Agreement: An agreement between USEPA and individual federal facilities that establishes a procedural and legal framework for investigating and performing remedial actions at Superfund sites. In situ: Refers to cleanup actions performed on soils in place without removal or excavation. Installation Restoration Program: The Department of Defense program implemented at military bases to identify, investigate, and clean up contamination resulting from past operations. Institutional Controls: Legal restrictions such as deed restrictions, zoning, fencing, or land use restrictions that prevent specified activities from occurring in specified areas to reduce or eliminate exposure. National Priorities List: USEPA’s list of uncontrolled or abandoned hazardous waste sites that are priorities for long-term remedial evaluation and response. NPL sites are eligible to receive federal funds for investigation and cleanup under the Superfund program. Proposed Plan: A document that summarizes for the public the preferred remedial action for a site and presents the rationale for the preference. Remedial Action: Action taken to reduce or eliminate the long-term risks to human health or the environment from exposure to contaminants. Remedial Investigation (RI): An investigation to gather and analyze the data necessary to determine the nature and distribution of contamination at a site and to provide information for performing a feasibility study. Risk Assessment: An evaluation of human health and ecological risk resulting from exposure to a chemical or pollutant. Site Investigation (SI): An initial investigation involving field assessments sampling and laboratory analysis as a precursor to an RI. Soil Target Cleanup Level: (STCL): MMR-specific risk-based and leaching-based concentrations of contaminants in soils developed for the protection of human health and the environment under the MMR Drainage Structure Removal Program. Source Operable Unit (SOU): A discrete action taken
at a contaminant source as part of an overall remedial response at CERCLA sites. The
action manages migration, or eliminates or
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