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EPA Extends Comment Period on Proposed Cleanup Plan for the Nyanza Chemical Waste Dump Superfund Site in Ashland, Mass.

Public Comment Period ends March 30, 2020

Contact Information: 
David Deegan (

ASHLAND, MASS. - The U.S. Environmental Protection Agency (EPA) has extended the comment period on the proposed cleanup plan for groundwater at the Nyanza Waste Dump Superfund Site in Ashland, Mass. through March 30, 2020.

Substantial cleanup at the site has already taken place, and the new cleanup proposal outlines additional measures to be taken as part of the ongoing efforts to clean up groundwater at the site. The cleanup proposal is detailed in a document called a Proposed Plan, which gives specifics on the cleanup actions being proposed. On Jan. 23, EPA hosted a Public Information Session at the Ashland High School Auditorium in Ashland, followed by a Public Hearing at the same location.

EPA's Proposed Plan for Operable Unit 2 (OU2) Groundwater at the Nyanza Chemical Waste Dump Superfund Site includes the following components:

  • Additional studies to identify any additional sources of "dense non-aqueous phase liquid" (DNAPL). Residual DNAPL is believed to be the source of elevated levels of volatile organic compounds (VOCs) detected within the contaminated groundwater plume.
  • Additional DNAPL recovery to enhance existing extraction efforts if further DNAPL sources are encountered.
  • Treatment of groundwater within the source area to address VOC contamination in deep overburden and shallow bedrock zones using in-situ chemical oxidation.
  • Long-term monitoring to evaluate remedy performance in both the source area and the downgradient plume areas of concern.
  • Land use restrictions (called "Institutional Controls").

In addition to these cleanup components and institutional controls to ensure contaminated groundwater is not used for drinking water, and the continued operation, monitoring, and maintenance of the existing vapor mitigation systems in place to address short-term vapor intrusion risk, the overall remedy will continue to include periodic reviews, at a minimum, every five years to assess protectiveness of the remedy.

The remedy which EPA has proposed for OU2, including construction, operations and maintenance, and long-term monitoring, is estimated to cost approximately $20.5 million and is estimated to take approximately 5 to 10 years to design and implement. A more detailed description of this proposal is outlined in the Proposed Plan and in the OU2 Feasibility Study Report (FS) dated January 2020.

More information:

EPA is accepting written comments from the public and other interested parties on the proposed cleanup plan which may be submitted by March. 30, 2020. The Proposed Plan is available, along with instructions about submitting comments, and information about EPA's previous and ongoing efforts to address contamination at the Nyanza Chemical Waste Dump Superfund Site, is available at:

After EPA has received comments and questions during the public comment period, EPA will summarize the comments and provide responses in the Responsiveness Summary which will be part of the Record of Decision (ROD). The ROD will select the final remedial action and will provide the rationale of EPA's selection.

Comments can be sent by mail, email, or fax to: Lisa Thuot, EPA Remedial Project Manager, 5 Post Office Square, Suite 100, Boston, MA 02109, fax- (617) 918-0129, If you have questions on how to comment, please contact the EPA Community Involvement Coordinator, ZaNetta Purnell at (617) 918-1306 or