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EPA Proposes Groundwater Cleanup Plan for the Nyanza Waste Dump Superfund Site in Ashland, Massachusetts

Public Comment Period begins Jan. 14; Public Meeting Scheduled Jan. 23 in Ashland

Contact Information: 
David Deegan (

BOSTON - The U.S. Environmental Protection Agency has proposed a cleanup plan for groundwater at the Nyanza Waste Dump Superfund Site in Ashland, Massachusetts. EPA will host a Public Information Session on Jan. 23 at 6:30 p.m. at the Ashland High School Auditorium in Ashland, followed by a Public Hearing at the same location. The public will be able to provide oral comments on the proposed cleanup plan at this event.

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.

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 2019.

EPA is accepting comments from the public and other interested parties on the proposed cleanup plan. In addition to the Jan. 23 public hearing where verbal or written comments may be submitted, written comments may also be submitted by Feb. 14, 2020. The Proposed Plan is available, along with instructions about submitting comments, at:

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 specific needs for the upcoming public meeting or hearing, questions about the meeting facility and its accessibility, or questions on how to comment, please contact the EPA Community Involvement Coordinator, ZaNetta Purnell at (617) 918-1306 or

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.


EPA added the site to the Superfund Program's National Priorities List (NPL) in 1982.

From 1917 to 1978, several companies occupied the Site and manufactured textile dyes and dye intermediates, inorganic colloidal solids, and acrylic polymers. Nyanza, Inc. was the most recent dye manufacturing company to occupy the Site. Chemical wastes were disposed of in various locations on the Site property, and manufacturing wastewater effluent and overflow from an underground concrete vault were discharged into adjacent wetlands and drainageways connected to the Sudbury River. An underground vault, which was removed in 1988, was taken out of service in the 1960s or 1970s but continued to be a source of contamination. VOCs in groundwater at the Site are resulting in vapor intrusion (VI) issues in the downgradient plume AOC.

Several removal and response cleanup actions were performed at the Site between 1987 and 1992. The Site is divided into the following four Operable Units (OUs):

OU1: Consists of the capped landfill, the former Nyanza, Inc. property, and adjacent areas where chemical wastes contaminated with heavy metals, VOCs and SVOCs were disposed. A Record of Decision (ROD) was issued in 1985 and an Explanation of Significant Differences (ESD) was issued in 1992. In December 2019, construction was completed on a 5.8 megawatts direct current solar photovoltaic system on the landfill cap surface. EPA and MassDEP conditionally approved the request by Ashland Solar LLC to construct and operate the Solar Facility on portions of the Site after extensive review of the proposed project.

OU2: Consists of a groundwater plume that extends from the Site in a north/northeasterly direction toward the Sudbury River. An interim ROD was issued in 1991, and an ESD was issued in 2006. Systems to mitigate the infiltration of vapors from contaminated groundwater into homes and other structures in certain areas near the site were installed in 2007; those systems will continue to be operated, maintained, and monitored under the proposed additional cleanup. This Proposed Plan presents a final proposed cleanup action for OU2.

OU3: Consists of the Eastern Wetland and various drainageways to the Sudbury River, including Trolley Brook, Chemical Brook, Outfall Creek and the Lower Raceway. These drainageways are located between the former Nyanza, Inc. property and the Sudbury River. In 1993, EPA issued a ROD for OU3.

OU4: Consists of a 26-mile stretch of the Sudbury River which flows through five towns (Ashland, Wayland, Lincoln, Sudbury and Concord, MA) and one city (Framingham, MA) where sediment and fish tissue exhibit mercury contamination. The river was apportioned into ten sections, or "reaches" for purposes of EPA investigations and remedial activities. EPA issued a ROD for OU4 in 2010 and an ESD in 2016.

More information on EPA's previous and ongoing efforts to address contamination at the Nyanza Waste Dump Superfund Site is available at: