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Proposed Cleanup Plan for W.R. Grace Site in Acton - Public Informational Meeting Will Be Tues. July 19

Release Date: 07/08/2005
Contact Information:

Contact: David Deegan (, EPA Office of Public Affairs, (617) 918-1017

For Immediate Release: July 8, 2005; Release # dd050702

(Boston) - EPA announced today a $17 million proposed cleanup plan for the 260 acre W. R. Grace (Acton Plant) Superfund site, located in the towns of Acton and Concord, Mass.

Public comments on the proposed cleanup plan may be submitted during a 30-day public comment period, which ends on August 4th. EPA will also conduct two public meetings, one on Tuesday, July 19th to present information on the proposal to the community, and one on Thursday, August 4th to allow verbal public comments.

The proposal is the culmination of a “Remedial Investigation/Feasability Study,” initiated by Grace in 1998 and completed in 2005 under the supervision and oversight of EPA and the Massachusetts Department of Environmental Protection (MADEP). The cleanup proposal addresses subsurface groundwater plumes and contaminated wetlands and sediments. A Remedial Investigation and human health and ecological risk assessments were conducted as part of this extensive investigation.

The Remedial Investigation concluded that:

    • there are three main groundwater contaminants present at the site: vinylidene chloride (VDC); vinyl chloride and benzene (also known as VOCs);
    • metals such as iron, manganese and arsenic are at elevated levels in Sinking Pond and the North Lagoon Wetlands;
    • the levels of contamination in the groundwater plume has significantly decreased due to the Aquifer Restoration System which has been in operation since 1984.
Since being added to the Superfund list in Sept. 1983, the W.R. Grace (Acton Plant) site has undergone numerous cleanup actions, significantly addressing site contamination. The existing on-site groundwater extraction and treatment system (the “aquifer restoration system”) has pumped over 4.1 billion gallons of contaminated groundwater and removed approximately 6,195 gallons of total VOCs since 1984. Soil cleanup activities at the property were completed in 1997 and included the excavation, treatment, and consolidation of over 173,000 cubic yards of contaminated soils into an on-site capped landfill. The current groundwater investigations represent the final phase of cleanup targeted under Superfund.

The human health and ecological risk assessments examined current and future potential unacceptable risks. The assessment concluded that the were unacceptable future human health and ecological risk in portions of Sinking Pond and the North Lagoon Wetlands. These assessment also concluded that unacceptable future human health risk could result from exposure to site groundwater for drinking water or irrigation purposes if the water is not treated. Any VOC-contaminated groundwater that might impact the Acton Water District’s School Street Wellfield is currently being treated by the Water District to meet drinking water standards prior to use.

Cleanup Alternatives
Cleanup alternatives were evaluated for Sinking Pond sediments, North Lagoon Wetland sediments and groundwater. After careful study of the remaining contamination at the site and in consideration of the extensive cleanup progress made through prior and on-going cleanup actions at the site, EPA has developed a preferred alternative for this phase of the cleanup - known as Operable Unit 3. In accordance with the Superfund regulations and the National Contingency Plan, EPA used criteria such as protectiveness, compliance with state and federal regulations, short and long-term effectiveness, use of treatment, implementability, and cost in selecting the preferred alternative. Two additional criteria, community acceptance and state acceptance will be evaluated during the 30-day public comment period. The following outlines EPA’s preferred alternative and estimated cost for these three areas that EPA will present in the Proposed Plan.
      Sinking Pond Preferred Alternative:
        • Cleanup of approximately 6,800 tons of contaminated soils and sediments to address unacceptable risks
        • Redesigning of pond inlet to reduce turbidity and erosion
        • Planting of wetland vegetation along the Pond bank to prevent erosion
        • Institutional controls (e.g., access restrictions)
        • Long term monitoring and maintenance
        • Estimated costs: $6 million
      North Lagoon Wetland Preferred Alternative:
        • Cleanup of approximately 2,400 tons of contaminated soils and sediments to address unacceptable risks
        • Wetland restoration, replacement and enlargement, as necessary
        • Institutional controls (e.g., access restrictions)
        • Long term monitoring and maintenance
        • Estimated Cost: $3.4 million
      Groundwater Plume Preferred Alternative:
        • Extraction and treatment of groundwater plumes in the southeast and southwest landfill areas
        • Construction of an approximately 200 gallon per minute on-site groundwater treatment plant to replace the existing groundwater aquifer restoration system; treatment components include: air stripping, carbon adsorption, metals precipitation and discharge to sinking pond
        • Enhanced natural gradient flushing and attenuation of plume areas not captured by the extraction system
        • Long-term operation and maintenance of the extraction and treatment system
        • Long-term monitoring
        • Institutional Controls (access restrictions, groundwater use restrictions)
        • Estimated Cost: $7.6 million
Comment Period & Public Meetings Scheduled
A public information meeting will be held on Tuesday, July 19th, at the Acton Town Hall. The meeting will begin with an informal Poster Session at 6:30 p.m. Presentations will begin at 7:30 p.m.

A formal public hearing will be held on Thursday, August 4th at 7 p.m. at the Acton Town Hall.

Written comments may be submitted to EPA during the 30 day public comment period (ending on August 4th). EPA will also accept verbal comments at the formal public hearing. EPA will not respond to comments during the August 4th public hearing, but will respond in writing with EPA’s Responsiveness Summary. Comments may be submitted in writing to:

Derrick Golden, Remedial Project Manager
One Congress Street - HBO
Boston, MA 02114-2023
FAX: 617-918-2294

More information on the proposed cleanup plan is available at:

More information on the history of cleanup activity at the W.R. Grace Acton site is at:

Related Information:
W.R. Grace Site Fact Sheet
Superfund in New England