Installation
Restoration Program Volume 2, Issue 1 An Air Force Center for Environmental Excellence quarterly newsletter to provide information on the Superfund cleanup at the Massachusetts Military Reservation Inside this Issue Coming Soon….The 2000 IRP Annual
Report Coming
Soon… This month, The Air Force Center Environmental Excellence (AFCEE) will publish the 2000 IRP Annual Report. This Annual Report will provide an overview of the Installation Restoration Program (IRP) activities conducted at the Massachusetts Military Reservation (MMR) during the calendar year 2000. AFCEE conducted these activities as part of its commitment to protect public health and the environment. The Annual Report will be available in at the local libraries and on our web site at www.mmr.org. For a complete library list, please refer to the back page of this newsletter. Background: In November 1998, an ethylene dibromide (EDB) detection of 0.029 parts per billion (ppb) was reported for the ECMWSNP02 microwell located in the northeast portion of Snake Pond (see map on page 3). That microwell has two screens – a shallow (S) one and a deep (D) one. The shallow screen, 02S, is 45-50 feet below the bottom of Snake Pond. The deep screen, 02D, is 80-85 feet below the bottom of the pond. The detection was in the "02D" screen. The state mandated safe drinking water standard for EDB is 0.02 ppb. In May 1999, the microwell was sampled again, and the results were non-detect for EDB. In September 1999, Ogden Environmental (an Army National Guard contractor, now called Amec) sampled this microwell as part of their investigation related to the Impact Area. Ogden reported an EDB detection of 0.110 ppb in the "02D" well. AFCEE was notified of the result in February 2000. Upon notification of these results, AFCEE attempted to sample the microwell; however, Snake Pond was frozen, preventing sampling. AFCEE was able to sample the microwells on March 14, 2000. Results of this sampling effort showed EDB concentrations of 0.404 ppb in 02S and 1.15 ppb in 02D. Due to the detection of EDB in microwell 02S, a surface water and sediment sample were collected near the microwell. Both were non-detect for EDB. Activities: Several activities were conducted to investigate these EDB detections including: sampling of additional existing monitoring wells; surface water/pore water sampling; diffusion sampling; installation/sampling of new monitoring wells, modeling; and modification of the existing FS-12 extraction, treatment, and reinjection (ETR) system. EDB was detected in some of the new and existing monitoring wells but was never detected in Snake Pond surface water or sediment pore water. Surface water samples were collected by the Sandwich Board of Health at two locations on a biweekly frequency throughout the recreation season (May through August). Using the results of the additional investigations and computer modeling, AFCEE developed a conceptual model of the EDB detections. The conceptual model shows three zones of EDB-contaminated groundwater west of the main FS-12 plume (see map for zones). Summary: Results from surface water, pore water, and diffusion sampling indicated that EDB is not upwelling into Snake Pond. Using computer groundwater modeling, changes to flow rates of certain extraction and reinjection wells were recommended in order to capture and treat the EDB that is outside the boundaries current FS-12 plume. Modeling recommendations, along with piping simulations and field tests, have resulted in turning off some extraction wells to allow for increased pumping along the axial (central) extraction wells. In addition, some reinjection wells have been turned off to reduce their hydraulic influence, which slows migration and keeps EDB from upwelling into Snake Pond. Next Steps: A contract has been awarded to design and construct a treatment system to capture and treat the EDB contamination outside the boundaries of the main FS-12 plume. The three newly identified zones will be addressed through a pump and treat project, which involves converting an existing reinjection well into an extraction well, treating the contaminated groundwater with granular activated carbon, then returning the clean water to the aquifer via existing reinjection wells. The design pumping rate is approximately 95 gallons per minute (gpm). The Massachusetts Department of Environmental Protection (DEP) and the Environmental Protection Agency (EPA) concurred with this approach. Construction began in March 2001 and system start up will begin by June 1, 2001. This modification is expected to operate for approximately three years and its performance will be monitored quarterly. FS-12 Monitoring Locations and Capture Zones
In 2000, AFCEE completed a Remedial Investigation (RI) for CS-19. The draft RI report concluded that, due to total site risk, a current ecological risk (via contaminated soils), and potential future human health risk (via drinking contaminated groundwater) exist at the site. The RI report also recommended additional soil and groundwater investigations at the CS-19 source area and groundwater investigations downgradient of the CS-19 site to further define areas of probable contamination, and to complete a comprehensive feasibility study. MassDEP and EPA agreed with these recommendations for further work. AFCEE, DEP, and EPA also agreed that the final RI report for CS-19 would be delayed until after the supplemental RI field work and data assessment have been completed. The final RI report would build on the bulk of the existing draft RI report and include the results of the supplemental RI investigation. The RI report is scheduled to be issued as a draft final report in January 2002. Included in the supplemental RI work is further soil and groundwater investigation and unexploded ordnance (UXO) clearance in work areas. There also will be work to determine whether cracked/leaking buried UXO potentially is contributing to the groundwater contamination at CS-19. Cleanup
for Source Areas In 2001, 27 source area sites are scheduled for cleanup. Approximately 18,000 cubic yards of soil from 21 sites are scheduled to be treated. Some of the contaminated soils will be taken off-site for disposal, while the remainder of the soils are undergoing a treatability study to determine the optimal treatment method. Some of the soils will be treated using a process called "cold-mix asphalt batching". The remaining 6 sites will either have soil vapor extraction (SVE) or biosparging as the implemented remedy. The soil excavation and cold-mix asphalt batching are expected to begin no later than April 25, 2001 and continue through 2001. Soil vapor extraction and biosparging do not require soil excavation as they are in-situ (in place) soil treatments. Cold-Mix Asphalt-Batching Cold-mix asphalt batching involves mixing low-level contaminated soils into a paving material by the addition of a heated emulsion (at less than 120°F). The contaminated soils are encapsulated by the asphalt, thus keeping them from leaching into the environment. The process is regulated by the DEP, and the final product is commonly used and approved as a base under asphalt-paved surfaces. This base will be capped with 1 to 2 inches of asphalt cover for durability and to limit infiltration of water. Therefore, the asphalt-batched material will not be exposed directly to traffic and the elements. Soil Vapor Extraction (SVE) As the name suggests, SVE extracts contaminants from the soil in vapor form. SVE systems are designed to remove contaminants that have a tendency to volatilize or evaporate easily. SVE removes volatile organic compounds (VOCs) and some semi-volatile organic compounds (SVOCs) from soil beneath the ground surface in the unsaturated (dry) zone. By applying an air vacuum through a system of underground wells, contaminants are pulled to the surface in vapor form. When air is injected into the ground (a process called air sparging), it passes through the soil on its way to the extraction wells. Contaminants evaporate out of the spaces between the soil particles and are extracted by the SVE process. Typically, they are treated using carbon adsorption, similar to carbon filtration of contaminated groundwater. Once the carbon filters are saturated with contaminants, they are taken off-site and recycled. Biosparging Biosparging is essentially air sparging, in that it uses injected air (oxygen) to speed up bioremediation, a treatment process that uses naturally occurring microorganisms (yeast, fungi, or bacteria) to break down hazardous substances into less toxic or nontoxic substances. Microorganisms eat and digest organic substances for nutrients and energy. Certain microorganisms can digest organic substances such as fuels or solvents that are hazardous to humans. The microorganisms break down the organic contaminants into harmless products -- mainly carbon dioxide and water. Once the contaminants are degraded, the microorganism population is reduced because they have depleted their food source.
Storm
Drain 5 South (SD-5 S) Recirculating Well Since June 1999, two recirculating well treatment systems, located below Hillside Avenue and Wheeler Road, have been cleaning contaminated groundwater from the Storm Drain 5 South (SD-5S) groundwater plume. Through the end of December 2000, both recirculating wells have treated a total of 84 million gallons of groundwater. In response to neighborhood concerns, modifications were made in 1999 to both systems. These modifications eliminated the discharge of air from the systems to the ambient air outside of each vault. Subsequent monthly air and water samples collected from each system indicated they were operating efficiently with the modifications. Therefore, vent pipes and associated support poles were removed in August 2000. The greatest concentration of trichloroethylene (TCE) detected in groundwater being treated at the Hillside Avenue treatment system was 22.0 parts per billion (ppb) when it first started operating in June 1999. Measured TCE concentrations have decreased over time, but currently are detectable in water samples collected from the system above the TCE Maximum Contaminant Level (MCL) of 5 ppb. The MCL is the maximum concentration of a given contaminant allowed in drinking water under the federal Safe Drinking Water Act. The Hillside Avenue system currently treats 60 gallons of contaminated groundwater per minute. The greatest concentration of TCE detected in groundwater being treated at the Wheeler Road recirculating well treatment system was 14.1 ppb when it first started operating in June 1999. TCE concentrations detected in samples collected from the system have decreased over time and since August 2000 have not been detectable when analyzed. Since July 1999, no detections of TCE above its MCL (5 ppb) have been measured in samples collected from groundwater monitoring wells located upgradient (the area from which groundwater flows) of the Wheeler Road system. In addition, no contaminants have been detected in samples collected from groundwater monitoring wells located immediately downgradient (the area toward which groundwater flows) of the Wheeler Road system since December 1999. Based on the information above, AFCEE recommended to the U.S. Environmental Protec-tion Agency (EPA) and the Massachusetts Department of Environmental Protection (DEP) in mid-December 2000 that the Wheeler Road recirculating well treatment system be shut down temporarily. At that time, AFCEE also recom-mended sampling additional groundwater monitoring wells near the Wheeler Road area. On December 28, 2000, the Wheeler Road treatment system stopped operating because of a mechanical failure. AFCEE decided not to repair the well due to its recommendation to shut down the well temporarily. EPA and MassDEP reviewed AFCEE’s proposal and agreed to keep the well shut down. Tours
and
Tours of AFCEE cleanup sites and facilities on the MMR also are available upon request. The tours can be combined with an on-base briefing similar to the presentation described above. For more information, please contact Douglas Karson, Community Involvement Specialist at (508) 968-4678 extension 2. Mr. Karson’s e-mail address is doug.karson@mmr.brooks.af.mil. There are several ways to obtain copies of information regarding the Installation Restoration Program. Public Information
Repositories/IRP Web Site
Where are the IRP Public Information Repositories?
Administrative Record
On-line at www.mmr.org
In our previous issue of The IRP Cleanup Report, there was an error in the Performance of Groundwater Treatment Systems Table. The TCE total listed for Chemical Spill 10 (CS-10) should have been 5110 ppb not 560 ppb. To have your name placed on the site mailing list concerning the groundwater remediation program at MMR, please complete this form and mail it to:
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