August 1998

Proposed Plan to Clean Up Source Areas at the Chemical Spill No.16/Chemical Spill No. 17

Summary
After an extensive study of Chemical Spill No. 16/Chemical Spill No. 17 (CS-16/CS-17) at the Massachusetts Military Reservation (MMR), the Air Force Center for Environmental Excellence (AFCEE) has developed plans to reduce potential risk from soil contamination at these sites. AFCEE is proposing the following actions for the contamination within the CS-16/CS-17 site:

• Conduct immediate sampling and analysis to verify the bound-aries of contamination exceeding Soil Tar-get Cleanup Levels (STCLs).
• Remove the soil from the three source areas that exceed STCLs and that present the greatest risk. Treat the excavated soils by asphalt batching them on-site in a manner that will allow reuse during road paving projects.
• Perform additional sampling to ensure that previous actions removed all soil of concern and, if needed, remove and treat additional soils.

The estimated present worth cost is $2,406,072 over a 5-year time frame.

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 of this page.

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
Air Force Center for Environmental Excellence (AFCEE) will describe the Proposed Plan for CS-16/CS-17 at a public information meeting, which will be followed by an informal question and answer session.

A public meeting will be held to discuss this Proposed Plan for CS-16/CS-17 on:
Tuesday, September 8, 1998, at
Barnstable County Fairgrounds
Administration Building
Falmouth, Massachusetts
Poster session: 6-7 p.m.
Information meeting: 7-8 p.m.

For additional information on the meeting, call Doug Karson, AFCEE Community Involvement Specialist, at (508) 968-4678, extension 2.

What Do You Think?
AFCEE is accepting formal public comments on the Proposed Plan from September 9 through October 9, 1998. You don’t have to be a technical expert to comment—if you have a concern or preference, AFCEE wants to hear from you before making a final decision for these sites.

A public hearing will be held on
Wednesday, September 23, 1998, at
Unitarian Universalist Fellowship
840 Sandwich Road
Falmouth, Massachusetts
Poster session: 6-7 p.m.
Public hearing: 7-8 p.m.

You may submit a formal comment in any of the following ways:

1. Offer verbal comments during the public hearing to be held on September 23, 1998 from 6-8 p.m.
2. Submit written comments during the public comment period that will extend from September 9 through October 9, 1998, to:

HQ AFCEE/MMR
Attn: AOC CS-16/CS-17
322 East Inner Road
Otis ANG Base, MA 02542-5028

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
In accordance with Section 117(a) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), this Proposed Plan provides information on the AFCEE preferred remedial alternative for three contaminant source areas at CS-16/CS-17 at MMR. This alternative was developed with support from the U.S. Environmental Protection Agency (USEPA) and Massachusetts Department of Environmental Protection (MADEP). The purpose of this Proposed Plan is to describe the remedial alternatives AFCEE evaluated to address soil contamination at these source areas, and to identify the AFCEE preferred remeidal alternative and explain AFCEE's rationale for this preference.

The Ashumet Valley plume originates at the former Fire Fighter Training Area 1 (FTA-1), with contribution from the decommissioned MMR sewage treatment plant (STP) (CS-16/CS-17) about 1,000 ft to the south. Treatment of contaminated soils at FTA-1 began in June 1995 and was completed in September 1997. A total of 42,531 tons of soil were treated using a thermal treatment process. Soil cleanup objectives were met, the area was restored, and the source area no longer contributes to the Ashumet Valley groundwater plume. Activities to address soil contamination at CS-16/CS-17 are discussed in the following paragraphs. Groundwater contamination associated with the CS-16/CS-17 site is being addressed as part of separate studies under the Plume Response Plan.

USEPA placed MMR on the National Priorities List in 1989 for investigation under the CERCLA. A Federal Facilities Agreement, signed in 1991 and updated in 1997, required AFCEE to take the lead in investigation and cleanup activities at MMR, including CS-16/CS-17 (Figure 1).

Figure 1. General location of the CS-16 and CS-17 sites at MMR

AFCEE activities at CS-16/CS-17 carried out under the Installation Restoration Program include performing a Remedial Investigation (RI) to characterize the nature and extent of contamination. Risk assessments were conducted as part of the RI to identify potential risks to human health and the environment. The risk assessments evaluated the present and future risks to human and environmental receptors who may contact contamination under current conditions, assuming no remedial action is taken. Cancer and noncancer risks were evaluated. Additional activities included preparation of a Feasibility Study (FS) to identify and evaluate a range of remedial alternatives.

This Proposed Plan summarizes the RI and FS and presents remedial alternatives proposed for soil cleanup at three source areas at CS-16/CS-17. After careful consideration of several alternatives, AFCEE believes the proposed actions comprising the AFCEE preferred alternative will protect human health and the environment and will comply with applicable environmental laws and regulations. The three source areas and other important site features are shown in Figure 2. This Proposed Plan, which is based on the FS, describes various remedial alternatives and the AFCEE preferred alternative.

Figure 2. Detailed layout of CS-16 and CS-17

Four Categories of Cleanup Options
When evaluating the best way to address the risks presented by a site, AFCEE first looks at many technical approaches that would protect human health and the environment. Although reducing risks often involves combinations of processes, the general approaches can be grouped into the following categories.

No Action or Limited Action: leave the site as it is or restrict access and monitor site conditions. The FS assesses how well the evaluation criteria (page 8) would be met if nothing were done to reduce site risks.
Contain Contamination: leave contaminated media where it is and cover or contain it to limit exposure to, or spread of, contaminants. This approach reduces risks from exposure to contamination but does not reduce or treat contamination.
Move Contaminated Material Off-Site: remove the contaminated material (e.g., soil, sediment, waste) and treat or dispose of it at a permitted off-site 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-site facility.

Description and History of CS-16/CS-17
CS-16/CS-17 occupies approximately 80 acres along the southern MMR boundary near the Falmouth gate, as presented in Figure 1. It includes sand filter beds, sludge drying beds, and the former sewage sludge disposal area. The site is adjacent to the former MMR STP, where treated effluent was disposed of by allowing it to infiltrate through the sand filter beds or dry in the sludge drying beds. Figure 2 presents a map of these structures at the CS-16/CS-17. b

The sanitary sewer system received a variety of wastes—including waste battery acid, cleaners, solvents, and paint thinners—historically discharged from MMR operations. It is believed that organic chemicals and metals contained in these waste materials adhered to the organic matter and concentrated in the treatment system sludges.

The former STP was dismantled in 1997. All aboveground concrete structures at the STP and sand and sludge beds were removed. Remaining sludge was treated on-site to stabilize the sludge and prevent leaching of metals to groundwater in accordance with state regulatory requirements. Concrete and treated sludge were buried on-site, covered with soil, and the area seeded with grass.

The new STP is located north of the former STP. Treated effluent currently is pumped to filter beds near the Cape Cod Canal. The sand filter beds and sludge drying beds at CS-16/CS-17 are no longer being used.

The following dates summarize the history of operations at CS-16/CS-17:

Sand Filter Beds

• 1941–Twenty-four sand filter beds constructed from native sandy soils were designed to dispose of STP effluent by allowing it to infiltrate the ground.
• 1974 to 1978–Woods Hole Oceanographic Institute operated an experimental station involving a small pump building and lined "basins."
• 1983–Eight sand filter beds were rehabilitated.
• 1995–Discharge to the on-site sand filter beds was discontinued.

Sludge Drying Beds

• 1941–Twenty-two sludge drying beds were constructed.
• 1966–Discharge to the beds was discontinued.
• 1983–Two beds were rehabilitated and lined with a synthetic membrane. The first bed was used to dry STP sludge; underdrains collected the leachate and discharged it to the second bed, which held the leachate and allowed it to evaporate.

Former Sewage Sludge Disposal Area

• 1940–Disposal in sludge drying beds was initiated by stockpiling on native soils (up to 200 cubic yards of sludge per month).
• 1960–Sludge disposal was discontinued.

Previous Investigations
Evaluation of CS-16/CS-17 included the following:

• 1983–1985–U.S. Geological Survey identified the existence of a groundwater plume (Ashumet Valley).
• 1987–The STP and Off-Reservation Groundwater Study included multimedia sampling to evaluate STP activities possibly related to the Ashumet Valley groundwater plume.
• 1987–1989–The Site Investigation was conducted, including soil and groundwater sampling.
• 1994–The RI was conducted, including soil and groundwater sampling, characterization of nature and extent, fate and transport of contamination, and risk assessment.
• 1997–The FS was conducted to evaluate remedial alternatives to mitigate risk resulting from concentrations of contaminants in soil.

Why Soil Cleanup Is Needed at CS-16/CS-17
Investigations at CS-16/CS-17 identified low concentrations of volatile organic compounds (VOCs) in soil gas, semivolatile organic compounds, pesticides, polychlorinated biphenyls, and metals in sludge and in surface and sub-surface soil.

The human health risk assessment concluded that estimated cancer risks for current and future land use conditions are within or below state and federal guidelines. As measured by Hazard Indices (HIs), noncancer effects are determined to be unlikely for either utility workers or children on the site.

The ecological risk assessment summary identified the presence of HIs exceeding state and federal guidelines for terrestrial plants and wildlife. The ecological risk assessment identified unacceptable risk to the following receptors:

• Terrestrial Wildlife–Exposure to CS-16/CS-17 surface soils resulted in unacceptable risk to white-footed mouse, short-tailed shrew, and grasshopper sparrow based on the maximum detected concentrations. The majority of the elevated HIs were the result of food chain pathway exposures associated with maximum concentrations of Aroclor-1254 and dieldrin.
• Terrestrial Plants–Exposure to CS-16/CS-17 surface soils resulted in unacceptable risk to terrestrial plants. The majority of this risk was attributed to mercury and copper.

Actual or threatened releases of hazardous substances from CS-16/CS-17, 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 goals established for soil are referred to as STCLs. These levels are MMR-specific, risk- and leaching-based concentrations designed to be protective of human health and the environment. STCLs were developed during the Drainage Structure Removal Program. As described earlier, the FS summarized the site data by contaminants of concern (COCs) identified in the ecological risk assessment along with additional data collected during the SI. The data were separated into the major units of the CS-16/CS-17: filter beds, sludge beds, and the sludge disposal area. Concentration ranges for each unit were compared to the appropriate STCLs. Exceedances of the STCLs for the sludge beds include Aroclor-1254, dieldrin, chromium, copper, lead, methylene chloride, and zinc. The sludge disposal area shows elevated levels of chromium, copper, lead, and zinc. Although the maximum concentrations of some metals in the filter beds exceed STCLs, only the mean concentrations of copper and lead exceed STCLs. The risk assessment concluded that risks to ecological receptors exposed to average soil concentration for copper are below the level of concern. Lead was further evaluated for ecological bioaccumulation and was also determined to be below the level of concern. The following table summarizes the COCs and other pertinent data.

Cleanup Alternatives
AFCEE developed and evaluated six remedial alternatives for soils in the three source areas at CS-16/CS-17. With the exception of the No Action alternative, each alternative was developed to meet site-specific cleanup objectives.

Alternative 1: No Action. The No Action alternative was evaluated 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. The Limited Action alternative involves long-term monitoring and/or site inspection and the implementation of institutional controls to minimize or prevent additional deterioration of site conditions. No remedial action components are included in this alternative. Because Limited Action does not meet the cleanup objectives for this site, this alternative was eliminated from further evaluation in the detailed analysis.

Alternative 3: Permeable Cover. The Permeable Cover alternative involves the installation and long-term maintenance of a permeable cover with drainage (sand), erosion control, and vegetated loam layers.

Alternative 4: Impermeable Cover. Depending on the future use of the site, the Impermeable Cover alternative involves the installation and maintenance of an impermeable cap consisting of either asphalt or geomembrane, overlain by a soil and vegetative cover system.

Alternative 5: Asphalt Batching. The Asphalt Batching alternative involves the removal of the contaminated soils, on-site treatment using the soils as aggregate in asphalt, and use of the asphalt as a subbase for paving projects at MMR. Excavated soil would be tested before being mixed with the asphalt to confirm that the soil would meet regulatory requirements. If soil exceeded acceptable levels, it would be disposed of at a permitted, off-site facility, rather than asphalt batched.

Alternative 6: Off-Site Disposal. The Off-Site Disposal alternative consists of excavating the contaminated surface soil and transport off-site for treatment and/or disposal at a nonhazardous materials landfill.

Comparison of Alternatives
The following table summarize the comparison of alternatives evaluated in the FS. A separate detailed analysis and comparison for each alternative was performed during the FS. For simplification, the following table compares each alternative against the criteria in general terms.

Evaluation Criteria	No Action	Permeable Cover	Impermeable Cap	Asphalt Batching	Off-site Disposal
1. Overall protection of human health and the environment
2. Compliance with ARARs
3. Long-term effectiveness and permanence
4. Reduction of toxicity, mobility, or volume through treatment
5. Short-Term Effectiveness
6. Implementability
7. Cost	None	$1,296,363	$1,495,831	$2,406,072	$2,919,572
8. State Acceptance	State acceptance of AFCEE's preferred alternative will be evaluated after the public comment period.
9. Community Acceptance	Community Acceptance of AFCEE's preferred alternative will be evaluated after the public comment period.
Time to Reach Cleanup Goal	None	30 years	30 years	5 years*	5 years*
=   Meets or exceeds criteria    =   Partially meets criteria   =  Does not meet criteria		* Time is estimated to treat or dispose of soils, perform analytical sampling, backfill and provide closure reporting.

How Does AFCEE Choose a Final Cleanup Plan?
AFCEE uses nine criteria, developed by USEPA, to select a cleanup plan or remedy that meets the goals of protecting human health and the environment, maintaining protection over time, and minimizing untreated waste. The following list highlights the questions AFCEE must consider in selecting a cleanup plan. More detailed definitions are contained in the Feasibility Study Report for CS-16/CS-17.

1. Overall protection of human health and the environment: Will the alternative protect human health and plant and animal life on and near the site? AFCEE must choose a plan that meets this criterion.
2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs): Does the alternative meet all pertinent federal and state environmental statutes, regulations, and requirements? AFCEE must choose a plan that meets this criterion.
3. Long-term effectiveness and permanence: How reliable will the alternative be at long-term protection of human health and the environment? Is site contamination likely to present a risk again?
4. Reduction of toxicity, mobility, or volume through treatment: Does the alternative incorporate treatment to reduce the harmful effects of the contaminants, their ability to spread, and the amount of contaminated material present?
5. Short-term effectiveness: How soon will site risks be adequately reduced? Are there short-term hazards to workers, the community, or the environment that could occur during the cleanup process?
6. Implementability: Is the alternative technically and administratively feasible? Are the goods and services (e.g., treatment machinery, space at an approved disposal facility) to implement the alternative readily available?
7. Cost: What is the total cost of constructing and operating the alternative? AFCEE evaluates whether the plan provides the necessary protection for a reasonable cost.
8. State acceptance: Do state environmental agencies agree with AFCEE’s recommendations? What are their preferences and concerns?
9. Community acceptance: What suggestions or modifications do residents of the community offer during the comment period? What are their preferences and concerns?

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.

AFCEE’s Preferred Alternative
AFCEE’s preferred alternative for CS-16/CS-17 is asphalt batching. The areas requiring remediation are presented in Figure 2.

Under this alternative, additional sampling and analysis would be conducted prior to a record of decision to verify the boundaries of soil contamination exceeding STCLs. The soils would be stockpiled, covered to eliminate contaminant migration, and processed in a cold mix asphalt batch plant set up on-site. The asphalt emulsion coats the soil and sediment particles and immobilizes contaminants, thereby reducing exposure risk. Asphalt would be used at MMR and coordinated with similar cleanup efforts at other MMR sites. Asphalt batching has been successfully used as a treatment alternative at other MMR sites. Confirmation sampling would be conducted during the excavation process to ensure soil cleanup levels are met. The excavations would then be backfilled with clean material.

AFCEE's 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.

What is a Formal Comment?
During the public comment period, AFCEE will accept formal written comments on the Proposed Plan and will hold a public hearing to accept either verbal or written comments. It is important to note that there is a distinction between formal comments received during the public comment period and informal comments received outside the comment period. While AFCEE will respond to all comments no matter when they are received, only the formal comments, postmarked by October 9, 1998, and AFCEE's responses will be documented in the Responsiveness Summary.

You may submit a formal comment in any of the following ways:

1. Offer verbal comments during the public hearing to be held on September 8, 1998 from 6-8 p.m.
2. Submit written comments during the public comment period that will extend from September 9 through October 9, 1998, to:

HQ AFCEE/MMR
Attn: AOC CS-16/CS-17
322 East Inner Road
Otis ANG Base, MA 02542-5028

3. Submit comments by fax at (508) 968-4673.
4. Submit comments by electronic mail addressed to doug.karson@mmr.brooks.af.mil
5. Send a message by Internet to http://www.mmr.org/

Why Submit Formal Comments?
Your comment will become part of the official public record, a crucial element in the decision-making process. AFCEE will consider all formal comments received at the public hearing and all written comments received during the public comment period before making the final decision for action at the site.

The transcript of all formal comments and AFCEE's written responses will be issued in a document called the Responsiveness Summary that will accompany the Record of Decision for CS-16/CS-17. Copies of the Responsiveness Summary will be mailed to everyone who submitted a formal comment. In addition, AFCEE will announce the decision through the local news media and community mailing list.

Further Information
This Proposed Plan summarizes the information that can be found in greater detail in the RI and the FS for CS-16/CS-17. The RI, FS, and Proposed Plan are contained in the Administrative Record file for this site. The Record of Decision and Responsiveness Summary will be added upon completion. The public is invited to review the administrative record and comment on this Proposed Plan during the public comment period.

The Administrative Record is available at:

Installation Restoration Program
HQ AFCEE/MMR
322 East Inner Road
Otis ANG Base, MA 02542-5028
Phone: (508) 968-4670
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 on the MMR Web site at http://www.mmr.org.

For further information, please contact:

Doug Karson
Public Affairs Specialist
HQ AFCEE/MMR
322 East Inner Road
Otis ANG Base, MA 02542-5028
Phone: (509) 968-4678 ext. 3
fax: (508) 968-4673
e-mail: doug.karson@mmr.brooks.af.mil  

Johanna Hunter
Community Relations Manager
USEPA Region I
JFK Federal Building, RAA
Boston, MA 02203
Phone: (617) 565-3425
fax: (617) 565-3145
e-mail: hunter.johanna@epamail.epa.gov

Ellie Grillo
Community Involvement Coordinator
MassDEP
20 Riverside Drive
Lakeville, MA 02346
Phone: (508) 946-2866
fas: (508) 947-6557
e-mail: Ellie.Grillo@state.ma.us

GLOSSARY

Administrative Record (AR): a collection of documents generated during the investigation of the site placed in a central location for public review.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA): a law, commonly known as Superfund, that authorizes the federal government to respond directly to releases of hazardous substances that may endanger public health or the environment.

Drainage Structure Removal Program (DSRP): A comprehensive program to identify, characterize, and remove underground drainage structures, sumps, and associated soils at various sites across MMR.

Feasibility Study (FS): a report that identifies and screens potential cleanup alternatives for a site that requires further remedial action.

Federal Facilities Agreement (FFA): an agreement between USEPA and individual federal facilities that establishes a procedural and legal framework for investigation and performing remedial actions at Superfund sites.

Hazard Indices (HI): An indicator of the health risk associated with exposure to a noncarcinogenic chemical.

Installation Restoration Program (IRP): the Department of Defense program implemented at United States military bases to identify, investigate, and clean up contamination resulting from past operations.

National Priorities List (NPL): USEPA 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.

Present Worth: the amount of money that, if invested now and disbursed as needed, would be sufficient to cover all costs associated with the remedial action over its planned life.

Proposed Plan (PP): a document that summarizes for the public the preferred remedial action for a site and presents the rationale for the preference and seeks public comment and input of the proposed alternative.

Record of Decision (ROD): a document presenting the remedial action selected under agreement with the regulatory agencies.

Remedial Action: remediation conducted 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 extent of contamination at a site and to provide information for identifying and evaluating options for remedial action.

Responsiveness Summary: a document presenting formal comments received during the public comment period with responses.

Risk Assessment (RA): an evaluation to determine the risk posed to human health and the environment as a result of exposure to a contaminant.

Site Investigation (SI): an investigation to find contamination, if it is there, but not necessarily to determine how much contamination is there, or how far it may have gone. It is used to determine whether further investigation is required.

Soil Target Cleanup Levels (STCLs): 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.

Acronyms