ACES, Acton Citizens for Environmental Safety, formed in 1979 in response to the contamination of two of Acton’s Town wells (40% of the Town’s water supply), with organic chemicals. Contamination was later determined to have come from a nearby industrial site, designated by EPA in 1983 as the WR Grace Superfund Site. ACES has been actively following investigation and cleanup at the Superfund Site for more than 20 years. In its 2002 Draft Remedial Investigation Report, WR Grace identified benzene, vinyl chloride and vinylidene chloride or VDC (also known as 1,1-dichloroethene or DCE), as the primary groundwater contaminants currently on site. Arsenic, iron and manganese were identified by WR Grace as secondary groundwater contaminants.

The WR Grace Superfund Site is now entering a critical phase, which will help determine the extent of groundwater cleanup at the site.

Two public health studies related to the site are currently underway. Both are due to be completed during Spring 2004. These are:

1. Public Health Risk Assessment by WR Grace, under EPA guidance: This risk assessment will help determine the future level of cleanup required at the site. It will not assess public health risks related to previous contamination levels in the drinking water or elsewhere.
2. Public Health Study by ATSDR (a federal agency under CDC): This study will consider past and/or present exposures to site contaminants and look at available public health data, including cancer rates. It will not evaluate the effect of exposure to multiple chemicals at once, but instead evaluate risk associated with each chemical in isolation.

Background information: In 1978 two Acton town wells were found to be contaminated with organic compounds. These public wells, Assabet 1 and Assabet 2, had been in operation since the early 1970’s, and in 1978 supplied 40% of the town’s drinking water. Contaminants included : Ethylbenzene, 1,1-Dichloroethylene (also known as DCE or VDC), Benzene, 1,1,1-Trichloroethane (TCA), Trichloroethylene (TCE), Methylene Chloride, Toluene, and Chlorobenzene.

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, including VDC, onsite in unlined impoundments. Onsite waste disposal was ceased in 1980.

In 1980 the US Environmental Protection Agency and WR Grace entered into a consent decree. The WR Grace Site was added to the EPA National Priority List, as a Superfund Site in 1983. Removal and treatment of contaminated soil and sludge was completed in 1997. The final step at the site is to fully characterize and delineate the groundwater contamination, (and associated sediment and surface water contamination), and to remediate the site as appropriate.

The northeast area of the site has only recently been delineated by WR Grace. The contamination in this area is in bedrock under residential areas, and is at shallower depths as the plume is drawn towards and into three public water supply wells. The well water is treated with a stripping tower before distribution as drinking water. The maximum concentrations of contaminants recently identified in the northeast area of the groundwater aquifer include: VDC (1,1-dichloroethene) = 260ppb; Benzene = 9.5ppb; Vinyl Chloride = 21ppb; Arsenic = 45.9ppb. To date there has not been any cleanup in this northeast area.

According to the current site schedule, WR Grace will submit the following critical documents during May 2004.

1. Public Health Risk Assessment
2. Ecological Risk Assessment
   The two risk assessments will determine which areas of the site will require remediation (cleanup).

3. RI/FS: Remedial Investigation/Feasibility Study: The Feasibility Study will assess different technologies and approaches to remediate the site and will propose a cleanup strategy. Public comment is welcome.