(Adapted from Timeline Poster by GeoTrans, Inc. and information from Draft Phase II Remedial Investigation Report, August 2002)
1951-First battery separator plant built by Dewey & Almy.
1954--WR Grace acquires Dewey & Almy.
1954-1982 WR Grace produces materials to make concrete additives, organic chemicals, container sealing compounds, latex products, and paper and plastic battery separators. WR Grace disposes of industrial wastes in unlined impoundments [lagoons, etc.] through 1980.
July 1978-New Daramic plant goes on line.
October 1978- Vinylidene chloride (VDC---also known as 1,1-dichloroethene or DCE) found in Assabet Water Supply Wells 1 & 2.
December 1978-Assabet Wells 1 & 2 closed.
1979-Acton Water District develops new wells; hydrogeologic study commissioned to determine extent/sources of contamination; ACES formed. Construction Products opens at Acton site.
1980-MADEP issues Administrative Order to WR Grace mandating investigation and cleanup of the site; EPA and Grace enter into Consent Decree; WR Grace stops on-site waste disposal.
1982-All WR Grace manufacturing, discontinued at Acton site except Daramic battery separator facility & Construction Products.
1983- Site added to EPA National Priorities List, (Superfund Sites).
1985- WR Grace installs aquifer restoration system to treat contaminated groundwater.
September 1989 - EPA issues Record of Decision for Acton site with 3 separate work tasks (operable units):
January 1991-WR Grace closes Daramic battery separator plant.
September 1993-EPA/MADEP conditionally approve final design specificationsfor Grace's remedial action plan.
September 1994-WR Grace begins soil remediation work.
July 1996-Soil remediation work essentially complete.
September 1996-Construction Products Division shuts down concrete additive distribution facility
December 1996-Demolition of buildings and capping of landfill completed.
Spring 1997-Landfill seeded. Operable unit one complete and operable unit two deemed unnecessary.
March 1998-Statement of work for operable unit 3 approved by EPA and DEP.
August 1998-WR Grace submits Initial Site Characterization Report for Groundwater RI/FS.
April 2000-EPA/DEP approve workplan for Phase I remedial Investigation for Groundwater RI/FS.
2000-Present - Annual monitoring of groundwater.
2000-2002 - WR Grace performs field work for Remedial Investigation, to delineate full extent and nature of contamination.
2001 - WR Grace identifies contaminant plume to northeast, near Town wells, also under Assabet River to the south. Further sampling proposed to determine areal extent of plumes.
Spring 2002 - Deep bedrock wells test positive for contaminants.
2002-Present - Acton Board of Health imposes administrative hold on private irrigation well permits within 500 feet of contamination plume; public hearing on moratorium continues.
August 2002 - WR Grace submits Phase II Remedial Investigation Report, showing contamination discharging to Assabet River to the south, and extending under residential areas in northeast, beyond Fort Pond Brook, and reaching three Public water supply wells.
June 2003 - WR Grace/EPA Public Information Meeting identifies primary site contaminants: vinylidene chloride (1,1-dichloroethene), vinyl chloride and benzene; and secondary site contaminants: manganese, iron, and arsenic.
Oct. 2003 - Public Information Session, sponsored by ATSDR, asking community for their site-related health concerns, for upcoming study.
2003-2004 -- Two separate public health evaluations underway. Both due to be completed in Spring 2004.
Spring 2004 - The following documents are due to be submitted by WR Grace: