(Information sources include: Timeline Poster by GeoTrans, Inc.; Initial Site Characterization Report, OU-3, August 1998; Draft Phase II Remedial Investigation Report, August 2002; EPA Third Five Year Review Report, September 2009; and other WR Grace Site documents.)
1951 – First battery separator plant at site, built by Dewey & Almy Chemical Company.
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), an industrial landfill and several other onsite waste areas through 1980.
1978 – New WR Grace Daramic Plant goes on line.
Fall 1978 – Organic contaminants vinylidene chloride (VDC—also known as 1,1-dichloroethene or 1,1-DCE), vinyl chloride, ethylbenzene and benzene detected in municipal drinking water supply wells, Assabet 1 and Assabet 2.
December 1978 – Assabet Wells 1 & 2 closed, (40% of Acton’s water supply).
1979 – Hydrogeologic study commissioned to determine extent/sources of contamination; Construction Products opens at Acton site; ACES begins 30+ year role advocating for thorough and protective investigation and cleanup;.
1980 – MADEP issues Administrative Order to WR Grace mandating investigation and cleanup of the site; EPA and WR Grace enter into Consent Decree that requires WR Grace to clean up waste disposal areas and to restore the groundwater aquifer to a fully usable condition; 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.
1987 – WR Grace Daramic Plant listed as a Massachusetts DEP (MADEP) hazardous waste site (21E site). There were three separate releases of oil and hexane from underground storage tanks at this site between 1982 and 1984. Even though the Daramic Plant is located on the WR Grace Superfund Site, Daramic Plant cleanup is under the Massachusetts state process, rather than under the federal EPA Superfund process.
September 1989 – EPA issues Record of Decision for Acton WR Grace Superfund Site with 3 separate work tasks, also known as operable units (OU): • OU-1 Removal and treatment of contaminated soil • OU-2 Any additional work needed to reach soil cleanup standards in waste areas • OU-3 Determine full extent of groundwater contamination and its impacts, re-evaluate Aquifer Restoration System, and address any contaminated sediments, surface water and air at the site
January 1991 – WR Grace closes Daramic battery separator plant.
March 1992 – Quarterly well monitoring begins.
September 1992 – Odor controls for air-stripping tower installed and operational; Site security measures implemented.
September 1993 – EPA/MADEP conditionally approve final design specifications for Grace’s remedial action plan for OU-1.
September/October 1994 – WR Grace begins soil remediation work. Air monitoring system installed.
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. OU-1 complete and OU-2 deemed unnecessary.
March 1998 – Statement of work for OU -3 approved by EPA and DEP.
August 1998 – WR Grace submits Initial Site Characterization Report for Groundwater Remedial Investigation/Feasibility Study (RI/FS).
September 1999 – First 5-year review issued by EPA for the Site.
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 three additional public drinking water wells/wellfields, also under Assabet River to the south. Further sampling proposed to determine areal extent of plumes.
Spring 2002 – Deep bedrock private irrigation well at a residence in the Northeast Area tests positive for contaminants.
2002 – Acton Board of Health imposes administrative hold on private irrigation well permits within 500 feet of contamination plume; holds public hearing on moratorium for future private wells in this area.
August 2002 – WR Grace submits Draft Remedial Investigation Report, showing contamination discharging to Assabet River to the south, and extending under residential areas in the northeast, beyond Fort Pond Brook, and reaching three public water supply wells/wellfields (Acton Water District School Street Wells).
June 2003 – WR Grace/EPA Public Information Meeting identifies primary site contaminants: vinylidene chloride (VDC—also known as 1,1-dichloroethene), vinyl chloride and benzene; and secondary site contaminants: manganese, iron, and arsenic.
Oct. 2003 – Public Information Session, sponsored by the Agency for Toxic Substances and Disease Registry (ATSDR) asks community for their site-related health concerns, for upcoming study.
2003-2004 – Two separate public health evaluations underway. Different methodology used for each.
- Public Health Risk Assessment by WR Grace under EPA guidance—will determine level of cleanup required; performed as part of OU-3 RI/FS process.
- Public Health Study by ATSDR (a federal agency under CDC)— will consider past and present exposures, public concerns expressed in 2003/2004, and will look at available cancer rate data.
May 2003 – Phase 2 Remedial Investigation Report issued by GeoTrans for WR Grace.
July 2004 – Draft Baseline Ecological Risk Assessment issued by Menzie-Cura for WR Grace.
July 2004 – Draft Public Health Risk Assessment Deliverable 3 issued by Menzie-Cura for WR Grace.
September 2004 – Second 5-year review report issued by EPA for the site.
July 1, 2005 – Public Review Remedial Investigation and Feasibility Study Reports, as well as Public Review Public Health Risk Assessment and Ecological Risk Assessment for OU-3 released to public.
July 8, 2005 – Proposed Cleanup Plan for OU-3 released to public.
July 19, 2005 – Public Meeting on Proposed Plan for OU-3.
August 4, 2005 – Public Hearing on Proposed Plan for OU-3.
September 2005 – OU-3 Record of Decision (ROD) signed by EPA; requires the following:
- Cleanup of contaminated sediments and soils posing an unacceptable risk to human health and/or the environment in Sinking Pond and the North Lagoon Wetlands.
- Extraction and treatment of groundwater contamination in the Southeast & Southwest Landfill Areas on the Grace Property, and at targeted areas within the Northeast Area.
- Construction of an approximately 200 gallon per minute groundwater pump and treatment system for both volatile organic and inorganic (metals) contaminants. Treatment processes for extracted groundwater will include air stripping, activated carbon (air treatment), and inorganics removal.
- Monitored natural attenuation in areas of groundwater contamination not captured by the extraction system.
- Institutional controls to prevent unacceptable exposures to contaminated groundwater until cleanup levels are met, and to protect against unacceptable future exposures to any wastes left covered/capped on-Site.
- Long-term groundwater, surface water, and sediment monitoring and periodic five-year reviews of the remedy.
August 2006 – WR Grace and EPA come to agreement on a Remedial Design/Remedial Action Statement of Work for OU-3
April 2007 – Approval for performing a topographical survey and wetland assessment/delineation is granted by EPA and MassDEP.
July-August 2007 –Pre-Design Work Plans for Sediment, the Landfill Area, and the Northeast Area conditionally approved by EPA.
January 2008 – WR Grace request to discontinue pumping from existing Recovery (extraction) Well RLF is conditionally approved by EPA, with Existing Recovery Well ELF to remain operational until new recovery wells (SELF-1 and SWLF-1) are brought on line.
August 2008 – ATSDR holds a public meeting in Acton and makes available its Public Release ATSDR Public Health Assessment, and announces a public comment period through September 2008. (As of December 2010, a final version of this report has not been issued.)
September 2008 – Reconfigured Landfill Area extraction wells now in continuous operation; includes newly installed wells SELF-1 and SWLF-2, and existing wells MLF and WLF.
November 2008 – Northeast Groundwater Pre-Design Results Report conditionally approved by EPA.
January 2009 – WR Grace petition to discontinue pumping from extraction wells NLBR-R, NLGP, SLBR, and SLGP-R in the Former Lagoon Area is conditionally approved by EPA.
April 2009 – Northeast Area Groundwater Concept Design conditionally approved by EPA.
September 2009 – Third 5-year review report issued by EPA for the site.
January 2010 – Landfill Area Concept Design and Sediment Area Concept Design conditionally approved by EPA.
April 2010 – Northeast Area treatment system begins continuous operation, providing WR Grace’s first active treatment of groundwater contaminants in this area; treatment is for volatile organic compounds (VOCs) such as benzene, vinyl chloride and VDC, as well as arsenic (an inorganic), in the most concentrated portion of the groundwater plume.
May 2010 – EPA issues “Operational & Functional Determination for the Northeast Area Groundwater Treatment & Re-injection System” following an inspection that determined that the system is operational & functional and that the construction has been completed in accordance with the approved design specifications.
May 2010 – Landfill Area extraction Well SELF-2 is installed to increase capture in the Southeast Landfill Area with the highest levels of benzene and 1,4-dioxane.
September 2010 –Final (100%) Sediment Design Report conditionally approved by EPA.
October 2010 – EPA conditionally approves “Installation of Extraction Well SELF-2, Decommissioning of Extraction Wells ELF and RLF, and Re-Evaluation of Landfill Area Groundwater Capture Zone”, confirming that WR Grace has achieved the required capture zones for the Landfill Area.