Installation Restoration Program Monitoring and Sampling The goal of the Installation Restoration Program (IRP) is to clean up the groundwater with a process that is technically sound, publicly acceptable and economically feasible, and always with a commitment to protect human health and the environment. The purpose of this fact sheet is to provide general information about ongoing monitoring and sampling for the Landfill 1 (LF-1) groundwater plume emanating from the Massachusetts Military Reservation (MMR). Defining the problem is the critical first step toward cleaning up contamination at and emanating from the MMR. Defining the problem involves two primary steps: (1) determining whether contaminants are present in soil, surface water or groundwater and at what levels, and (2) defining the horizontal and vertical extent and movement of contamination. Sampling Locations A grid pattern is used to collect soil samples at various depths starting near a suspected source area. For groundwater sampling, a series of wells are installed near a source area. If contamination is found at that site, more wells are installed in the direction of groundwater flow (downgradient) to determine the extend of groundwater contamination. This process continues until no more contamination is found. Soil Sampling To determine whether contaminants are present in soil, a tool called a Geoprobe is used to collect samples. It is a hydraulic hammering device that pushes a 1-1/2 inch diameter hollow rod into the ground as deep as 125 feet below the surface. It is pulled up with soil from all levels within the Geoprobe. This soil is tested for contamination and is used to determine many future steps of a site investigation. Groundwater Sampling In order to determine whether groundwater has been contaminated, wells must be installed to collect groundwater samples. The method most commonly used to install wells is with a hollow stem auger drill rig. The drill has a spiral metal edge, similar to a cork screw, that can be screwed into the ground. The auger displaces the soil and creates a borehole into which well casing is placed. A special screen is installed in the casing at certain depths to allow water to enter the well. That water is sampled periodically and sent to a lab for testing. Ecological Monitoring The ecological studies program monitors the groundwater and the surface water ecosystems adjacent to and downgradient of each groundwater treatment system. Phase I studies establish baseline conditions in two types of areas before treatment system startup. The first type are the potentially affected ecosystems. The second type are areas not affected by MMR contaminants known; these are known as reference ecosystems. These studies include: monitoring groundwater levels; taking groundwater samples; conducting seepage meter investigations; sampling surface water; sampling sediment; sampling phytoplankton, zooplankton, macroinvertebrates, amphibians, shoreline and wetland vegetation; and conducting surveys of threatened and endangered species. Phase II ecological studies monitor the same parameters for comparison to baseline conditions and reference area conditions. These comparisons will help determine whether a treatment system is causing ecological changes. Data Analysis and Uses Once samples are collected, they are sent to a Massachusetts certified laboratory for analysis. All laboratories are required to follow strict quality assurance/quality control (QA/QC) protocols. For MMR studies, most samples are analyzed for a full suite of volatile organic compounds (VOCs) and/or ethylene dibromide (EDB) using standard methods. Some samples are also analyzed for pesticides, PCBs, metals, nutrients, and other compounds. The analytical test performed on each sample depends on which chemicals have been detected or are expected at the sample location. When the analytical data is received from the lab, trained chemists review it in accordance with EPA-established data validation guidelines. The results can be loaded into a computer database used to model various scenarios such as future groundwater movement or how to extract groundwater without affecting local pond levels, cranberry bogs, and, private and municipal well systems. It also helps to identify the extent of the contamination and determine where to place cleanup technologies for greatest effectiveness. LF-1 History and Use The landfill on the Massachusetts Military Reservation was used from 1940 through 1989 for disposal activities. The landfill has six sections or "cells," identified by the last year that waste was disposed in each particular cell. The six disposal areas include the 1947, 1951, 1957, 1970, post-1970 cells, and a natural kettle hole. The LF-1 groundwater plume was caused when rainwater soaked through the wastes in the landfill, picked up contaminants, and carried them into the underlying groundwater. Source Area Remedial Activities Groundwater data obtained during source investigations indicated that the 1970 and post-1970 cells, and the kettle hole were the major sources of groundwater contamination. Upon identifying this, the U.S. Air Force, working in partnership with the EPA and the DEP, began an interim remedial action to reduce or eliminate the cause of the contamination. The interim remedial action plan had four separate tasks:
Following the investigation, Air Force officials capped the three cells in 1995 that were contributing to the contamination in the groundwater. The cap covers about 60 acres of the 100-acre former landfill site. The cap is comprised of several layers, including a geosynthetic clay liner, a geomembrane, sand, and vegetation to prevent erosion. The cap is designed to eliminate the flow of rainwater through the landfill and, therefore, reduce the movement of contaminants from the landfill into the groundwater. Once the cap was in place, Air Force officials began monitoring groundwater near the landfill to evaluate the cap’s effectiveness and to identify any additional work that might be needed to clean the site. To gather the necessary data, the Air Force identified four monitoring wells, one upgradient and three downgradient from the site, for quarterly groundwater sampling. At the same time, the Air Force and the regulatory agencies stepped-up their investigation of the pre-1970 cells to see if those cells were contributing to the contamination of the groundwater. Data from these investigations have shown elevated levels of iron and manganese, but no volatile organic compounds (VOCs). The elevated iron and manganese levels do not present any unacceptable risk as determined by risk calculations developed by the Air Force and reviewed by the US EPA. Therefore, these cells are not contributing to the LF-1 groundwater contamination. Ongoing monitoring will help the Air Force determine the continued effectiveness of the cap, movement of the groundwater plume, and levels of contaminants. Sampling/Monitoring at the LF-1 Source Groundwater samples taken from monitoring wells near the LF-1 site indicate that the cap that was put in place over the former landfill in 1995 has been effective in controlling leachate from the site. The results have shown that wells immediately downgradient of the cap have lower levels of contaminants including: trichloroethylene (TCE); perchloroethylene (PCE); carbon tetrachloride; dichloroethylene (DCE); chlorobenzene; and 1,4-dichlorobenzene. Based upon the latest sampling data, concentrations of these compounds are below the maximum contaminant levels (MCLs) established by the U.S. Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (DEP) for safe drinking water. For example, monitoring well 20A (MW20A), which is immediately downgradient of the landfill, has provided important historical data in tracking the levels of contaminants. In 1989, MW20A had 56 parts per billion (ppb) of TCE, well above the MCL of 5 ppb. In September 1997, the TCE levels had declined to 1 ppb. PCE levels at the same well also declined with a reading of 54 ppb in 1989 and 2 ppb in September 1997. MW20B, a deeper well at the same location, has shown a similar decline of TCE, PCE, and carbon tetrachloride from 10-11 ppb in 1989 to approximately 3 ppb in September 1997. For More Information Additional information about cleanup activities is available on our web site: http://www.mmr.org. For more information, please contact the Community Involvement Office for the Installation Restoration Program by calling (508) 968-4678 or by sending an electronic mail message to: vmusgrave@mafmh.ang.af.mil Sampling/Monitoring of the LF-1 Groundwater Plume A series of monitoring events of the groundwater plume has been conducted since 1989. For example, 622 monitoring well sampling events have been conducted. Private wells in the area are in a regular monitoring program. Over the last three years, the data have shown the water quality there to be safe. Squeteague and Red Brook Harbors also have been sampled. All these data assist in characterizing the nature and rate of flow of the plume. This helps to more accurately predict what may happen to the plume over time, a critical point in making a decision for future action. Sampling and monitoring will continue in the future, including groundwater, surface water, and private wells. This is particularly critical for implementation of the monitored natural attenuation portion of the remedy.
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