WR Grace Superfund Site in Acton, Public Meeting, June 12, 2003 (Meeting Summary by ACES)

*For Updates/Public Meeting Notifications join the EPA site mailing list, Contact: Sarah White, EPA Community Involvement Coordinator (617-918-1026, White.Sarah@epamail.epa.gov)*

It has been almost 25 years since contamination from the WR Grace Industrial Site was found in two Acton public drinking water wells, and 20 years since this site was included on the federal “National Priority List” for cleanup as a “Superfund Site”.

On June 12, 2003 a public meeting was held at the Acton-Boxborough Regional High School to provide an update on groundwater and other investigations at the WR Grace Superfund (hazardous waste) Site in Acton.

Site History and Current Status
Jack Guswa, from GeoTrans, Inc. (consultants for WR Grace), gave an overview of the history and current status of the WR Grace Superfund Site. The affected area in Acton is east of Parker Street and extends from the Assabet River near Route 62 in Concord to the south, northward across Lawsbrook Road and Fort Pond Brook to the School Street public drinking water wells, near School Street Extension and Route 2.

At its Acton facility, which it purchased in the 1950’s, WR Grace produced latex and rubber based products and cellulose battery separators. WR Grace disposed of industrial wastes onsite in unlined impoundments. In 1978 two Acton public drinking water wells (Assabet I and Assabet II), were found to be contaminated with a chemical used at WR Grace, 1,1-dichloroethene, also known as vinylidene chloride or VDC. In response to the contamination, the Acton Water District shut down the Assabet public wells. Both these wells, and the School Street wells are currently operating with treatment systems in place to ensure that the water meets drinking water standards, before it is distributed to the public.

Mr. Guswa showed a plume map of the extent of the VDC contamination, as known in 1984. Since that time WR Grace has been operating an “Aquifer Restoration System” (ARS), to treat contaminated groundwater and to redirect it away from the Assabet wells. Contaminated soils were removed from the site or treated and buried onsite between 1994 and 1997.

The current and final “Superfund” task is to address groundwater contamination onsite. A map of the VDC plume dated Fall 2002 shows a significant reduction in VDC concentration on the southern part of the site. It also shows an additional area of contamination to the northeast that had not been delineated in 1984. In residential areas this contamination in the northeast was found deep underground. As the contamination in this area migrates towards Fort Pond Brook and the School Street public wells it moves to shallower depths and discharges to the brook and to the drinking water wells, which are drawing it towards them.

According to Mr. Guswa, the August 2002 Draft “Remedial Investigation” Report on the WR Grace Site concluded that:

  • the extent of the contamination has been defined,
  • primary contaminants are VDC, vinyl chloride, and benzene,
  • secondary contaminants are iron, manganese, and arsenic; and
  • groundwater quality has improved due to:
  • cessation of contaminant disposal in impoundments,
  • the operation of the Aquifer Restoration System, and
  • source removal (soils).

A three-dimensional groundwater flow model has been developed and will be used to evaluate alternative cleanup options. A review of these remedial options will be submitted in a Feasibility Study due in May 2004. Two other evaluations are also due in May 2004. These are an Ecological Risk Assessment, and a Public Health Risk Assessment.

Ecological Risk Assessment
Katherine Fogarty of Menzie-Cura Associates, another WR Grace consultant, described the Ecological Risk Assessment process. Samples of surface water, sediment, vegetation, minnows, and groundwater have been collected. Plant surveys and wildlife surveys have been conducted. Reference areas that have been unaffected by the site have been selected for comparison purposes. Both toxicity testing and bioaccumulation studies will be conducted.

Public Health Risk Assessment
Lisa Bailey described the Public Health Risk Assessment process, which began with an evaluation of site conditions. Sediment, surface water and groundwater samples have been collected.

The next step is to identify ways in which individuals could come in contact with the contamination. These “exposure pathways” include potential contact with groundwater, surface water, and sediments. Exposure could be via ingestion, skin contact, or inhalation. Consumption of contaminated fish tissue will also be evaluated. The risk assessment for drinking water will assume no treatment of the water.

Two factors will be evaluated in order to characterize the risk associated with a given exposure. One factor is the “dose”, or level of exposure to the contaminant. The second factor is the toxicity of each individual contaminant, as found in the scientific literature. The exposure (dose) assessment and toxicity assessment together will be used to calculate the risk for both carcinogenic (cancer) and non carcinogenic consequences of exposure to the contaminants.

There are uncertainties associated with each step of the Risk Assessment process. To compensate for these uncertainties the risk assessment will use conservative assumptions.

Important Dates/Staying Informed
Derrick Golden, EPA’s Project Manager for the Acton WR Grace Superfund Site described the roles of the various parties and the upcoming site schedule. WR Grace performs the site related activities with oversight by the EPA and the DEP. The Acton Water District, Town of Acton, and ACES also provide input to the process.

In summary, as of now, the following reports are due in May 2004:

  • feasibility Study (evaluates cleanup alternatives),
  • Ecological Risk Assessment, and
  • Public Health Risk Assessment.

(Due dates are often extended. Reports on the WR Grace Site are available to the public in the Acton Memorial Library.)

A Public Meeting on these documents and any resulting Cleanup Proposal is likely to be scheduled for Fall 2004. A 30-60 day public comment period will follow this meeting.

Question & Answer Session
The meeting was very well attended and there were many questions from concerned residents and others.

Several people asked questions about the extent of the plume. How can we be sure that any cleanup remedy will account for future conditions? Are contaminant concentrations likely to be higher in the future in any particular areas? Will the cleanup strategies take this into account? If the site assessment done to produce the 1984 map completely missed the plume to the northeast, how can we be sure that there is not contamination in areas beyond those currently identified? The response to these questions was that through extensive monitoring the plume has been delineated and that concentrations on the site have been decreasing, in part due to the operation of the ARS and cessation of waste disposal in the impoundments. Additionally concentrations are expected to continue to decrease because of the effects of dispersion, dilution, and natural attenuation, in addition to any proposed cleanup scenario.

A related request from an audience member was for the contaminant plume maps to indicate the boundary of the areas that have been sampled. As the maps are currently drawn, areas where VDC contamination has been measured at concentrations greater than 7 parts per billion are depicted within a colored contour. Areas that are not within these colored contours may have been monitored and found not to be contaminated, OR may be contaminated, but were never sampled—so we don’t know they are contaminated. The latter scenario is reflected in the 1984 map, where the plume to the northeast is not shown, not because it was not there, but because it had not yet been sampled and delineated by WR Grace. The request was to please make it clear to the public which areas have been sampled and found to be clean, and which areas have not been sampled.

A question was asked about potential synergistic effects of chemicals. In other words, do the risk assessments consider that when there is exposure to multiple contaminants at once, the effects may be more than the sum of the effects if each chemical were contacted individually. (One plus one is greater than two.) The answer given was that each chemical will be looked at individually and then the risks will be added together, but that the risk assessment uses conservative assumptions and will be protective. The target range for cancer risk will be between 1 in 10,000 and 1 in 1 million. A risk of 1 in 1 million or lower for contracting cancer is considered acceptable, and remediation would not be required. A risk of 1 in 10,000 or higher for developing cancer is considered unacceptable, and remediation would be warranted.

One resident asked about why so much time/effort is being spent studying the issue, rather than in taking actual cleanup actions. Since we know the contamination is there (particularly under the residential area to the northeast), why isn’t it being cleaned up now? Mr. Guswa responded by discussing some of the potential remediation technologies that are being considered for the site, and some of the pilot testing that is either currently being conducted, or that was proposed and rejected.

An audience member requested that WR Grace and the Government Parties also consider an alternative cleanup technique that involves bioremediation tablets that could be delivered to contaminated areas via existing monitoring wells. He provided a packet of written information to WR Grace representatives and others, who said they would take a look at the suggested technique.

Ann Chang, LWV, stated that using the AWD School Street public drinking water wells as capture wells “gives one pause”. She asked if contaminant concentrations could have been greater in the past. For example what were the concentrations in the northeast area in 1984-1986? The response to this question was that data from other non-WR Grace investigations in the northeast area from 1984-1987, were not available until 1996.

There was a question about the public drinking water supply. Jane Ceraso, Environmental Manager for the Acton Water District (AWD) responded that the AWD tests both the raw water and the treated water for the WR Grace contaminants, and other volatile organic compounds, (VOCs), annually. The treatment towers at the Assabet and School Street wells completely remove any VOCs from the raw water.

A lawyer representing the Town of Acton asked about the cleanup standards that would be used for the site. He pointed out that Acton’s drinking water standards are more stringent than Federal standards. Mr. Golden replied that one of the requirements under the Superfund Program is that the water quality standards used be ones that are uniformly applied throughout the State.

Acton Selectman Peter Ashton made a statement on behalf of the Board of Selectmen stating the Town’s concern that the site be cleaned up as quickly as possible. He stated particular concern about the area to the northeast where the contamination is under residential areas.

Mary Michelman read a statement on behalf of Acton Citizens for Environmental Safety (ACES). It said in part: “To date there have not been any cleanup efforts on the northeastern part of the site where contamination is in bedrock, in residential areas. ….We know the contamination in the northeastern area reaches three of our public drinking water wells, and higher concentrations of contamination are being pulled toward the wells. This contamination should be cleaned out of the groundwater by WR Grace before the water reaches the public wells. .….The aquifer should be remediated to drinking water standards by Grace, so that any additional treatment by the Acton Water District is just an extra layer of protection for the public.”

At the conclusion of the question and answer period the public was invited to remain to ask any additional questions individually and to view the poster displays etc. set up around the room.

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