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Waste Site Cleanup & Reuse in New England
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Map this site in Cleanups in My Community
 Ashland,  Massachusetts
 Middlesex County
 Street Address: MEGUNKO RD
 Zip Code: 01721

 EPA ID #: MAD990685422
 Site ID #: 0100948
 Site Aliases: Nyanza,

 Site Responsibility: Federal, State

 Proposed Date 10/23/1981
 Final Date 09/08/1983

Site Description
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The Nyanza Chemical Waste Dump site is a 35-acre parcel of land located adjacent to an active industrial complex. From 1917 to 1978, the site was used to produce textile dyes, intermediates, and other products. Nyanza Inc. operated on this site from 1965 until 1978, when it ceased operations. Large volumes of industrial wastewater containing high levels of acids and numerous organic and inorganic chemicals, including mercury, were generated by these companies. Some of the wastes were partially treated and discharged into the Sudbury River through a small stream, referred to as Chemical Brook. Over 45,000 tons of chemical sludges generated by Nyanza's wastewater treatment processes, along with spent solvents and other chemical wastes, were buried on site. The area that contained the largest amount of buried waste and exposed sludge is referred to as the Hill section. The current owner leases the old plant grounds to various businesses. Approximately 10,000 people live within 3 miles of the site.

Threats and Contaminants
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The groundwater, soil, sediments, and surface water are contaminated with heavy metals and chlorinated organics. The groundwater and soil are also contaminated with spent solvents and chemical wastes. Vapors originating from spent solvents in shallow groundwater have also been detected inside some area buildings. Health threats include direct contact with or accidental ingestion of contaminated groundwater or soil, and inhalation of vapors inside some area buildings. Sudbury River fish are contaminated with mercury.

Cleanup Approach
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This site is being addressed in five stages: initial actions and four long-term remedial phases (operable units or OUs) focusing on source control and cleanup of the soil, off-site groundwater, wetlands, and the Sudbury River.

Response Action Status
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Initial Action This site is being addressed in five stages: initial actions and four long-term remedial phases/operable units focusing on source control and cleanup of the soil, off-site groundwater, wetlands and drainageways, and the Sudbury River.

Initial Actions In 1987 and 1988, EPA excavated an underground storage vault containing 12,025 tons of material; 300 tons of contaminated soils were incinerated, and an additional 356 tons of soils were excavated and disposed of at an approved off-site facility.

Source Control and Soil OPERABLE UNIT 1: EPA's source control remedy included excavating all outlying sludge deposits and contaminated soils and sediments associated with these deposits, consolidating this material with the on-site Hill sludge deposits, capping the Hill section to prevent water from entering it and spreading contaminants, constructing a groundwater and surface water diversion system on the upgradient side of the Hill area, backfilling the excavated areas to original grade, establishing a vegetative cover in the wetland areas, and constructing a more extensive groundwater monitoring system to allow for future evaluation of the cap. Approximately 60 percent of the 13-acre cap in an area of existing lagoons, sludge pits, and buried building debris was covered with earth from on-site excavations in clean areas. The remaining portion of the area that was capped was excavated to bedrock to create a cell for the disposal of contaminated soils and solidified sludges from the on- and off-site cleanup areas. The site was fenced. More than 65,000 cubic yards of contaminated soil were excavated and placed in the landfill in 1990. Final construction of the site cap was completed in 1991. All cleanup actions were completed in late 1992. The Massachusetts Department of Environmental Protection is currently responsible for conducting operation and maintenance activities.

Off-site Groundwater OPERABLE UNIT 2: EPA selected an interim remedy to clean up the off-site groundwater contamination in 1991. The selected remedy was to pump and treat the contaminated groundwater from the most contaminated portions of the plume for five years. However, due to the discovery of additional contamination, this remedy was re-evaluated to determine whether it is still likely to be effective. After additional data collection and risk assessment activities, with added emphasis on potential indoor air contamination, EPA outlined modifications to the remedy in an "Explanation of Significant Differences" in 2006. The revised interim remedy includes the extraction of dense non-aqueous phase liquid (DNAPL) from the groundwater plume as well as the installation of vapor mitigation systems in a number of homes overlying the contaminated groundwater plume. Forty indoor air vapor mitigation systems were installed in 2007. These systems are inspected annually by the MassDEP. EPA also conducted a series of subsurface investigations to locate pockets of recoverable DNAPL. Based on these studies, two wellhead treatment systems were constructed and began withdrawing groundwater in September 2013. In addition, EPA began a semi-annual evaluation of groundwater conditions; these evaluations will continue through 2015. EPA, along with other stakholders (MassDEP, Town of Ashland) will evaluate the new data as it relates to selecting a final groundwater remedy for the site,

Wetlands and Drainageways OPERABLE UNIT 3: Preliminary sampling showed that sediment and surface water of adjacent Eastern wetlands and drainageways between the site and the Sudbury River were contaminated with heavy metals. In 1993, EPA selected the remedy to excavate the contaminated sediment and place these materials with in on-site landfill. The design of the remedy was completed in 1998 and cleanup activities began in March 1999. Over 45,000 cubic yards of mercury-contaminated sediments were excavated from four areas (Eastern Wetland, Trolley Brook, Outfall Creek, and Lower Raceway) and disposed of in the on-site landfill. EPA completed all remedial and restoration activities by August 2001. The Massachusetts Department of Environmental Protection is currently responsible for conducting operation and maintenance activities.

Sudbury River: OPERABLE UNIT 4: Initial investigations showed that sediments and fish are contaminated elevated concentration of mercury attributable to the Nyanza site. EPA gathered U.S. Government and university scientists to conduct additional studies focused on mercury due largely to its potential for bioaccumulating in fish and mammals. The scientists' findings were placed in local repositories in late 1997 and published in May 2000. From the fall of 2003 through the summer of 2004, EPA conducted extensive sampling along the entire 26 miles of river in support of both revised Risk Assessments. Media sampled include fish, sediment, surface water, crayfish, and mink as well as tree swallows, songbirds, kingfisher and ducks. EPA has completed its review of this data and prepared the final Supplemental Human Health Assessment (2006) and Ecological Risk Assessments (2008) both of which are available via links below. Additional sampling (2008) has taken place to develop and calibrate a Mercury Fate and Transport computer model which was used to evaluate the effectiveness of various remedial alternatives. This evaluation is described in the Draft Feasibility Study (June 2010). In September 2010, EPA memorialized its cleanup decision by signing the Nyanza OU4 (Sudbury River) Record of Decision (see link and description below). The selected remedy relies on monitoring, institutional control such as continued posting of warning signs, and the addition of a thin-layer sand cap over the most-highly contaminated sediments. In 2011, EPA and the U.S. Army Corps of Engineers completed supplemental investigations to aid in the preparation of the Remedial Design. The Remedial Design was completed in May 2013. During the interim period during which EPA was awaiting project funding, EPA Region 1 collected fish (in 2014) from that portion of the Sudbury River to be capped. Based on a larger decrease in fish tissue concentration than was predicted, in 2015, EPA suspended the sand capping so as to conduct more fish tissue monitoring in other portions of the Sudbury River. This effort is on going.

Environmental Progress
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The excavation of contaminated soil and capping of the Hill area of the site have reduced the potential of exposure to hazardous substances by controlling contaminant migration and isolating wastes. Wetland excavations and restoration have eliminated the on-going mercury contamination source to the Sudbury River. In 2007, the EPA re-posted the river with signs warning against the consumption of contaminated fish. Annual inspection of warning signs has occurred in both 2011, 2012, 2013 and 2014. These actions have made the Nyanza Chemical Waste Dump site safer while remaining cleanup actions are being evaluated.

Current Site Status
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In early 2006, the Massachusetts Department of Public Health announced the findings of their multi-year study regarding the link between unusually high cases of rare cancers and past site exposures. See DPH's web site for information on the Ashland Nyanza Health Study Final Report issued in April 2006.

In August 2006, EPA released a draft Explanation of Significant Differences (ESD) regarding the groundwater cleanup (Operable Unit 2) at the site to address the installation of vapor mitigation systems in 40 to 50 structures (mostly homes) located in the northeast portion of the plume and the extraction of DNAPL with off-site treatment and disposal of the extracted DNAPL with possible enhancements. These actions are outlined in greater detail in the ESD, which can be viewed via the link under "Decision Documents" below. Construction of the vapor mitigation systems was completed in 2008 while work on the DNAPL extraction system is ongoing. The long-term maintenance of the Vapor Intrusion systems is performed annually by the MassDEP. EPA continues to conduct exploration adjacent to former source areas to determine the feasibility of removing severely-contaminated groundwater.

Regarding OU4 (Sudbury River), risk assessments were completed in 2006 (Human Health) and 2008 (Ecological). The human health assessment concluded that a risk of adverse health effects exist to a "Recreational fisherman" (i.e., a person whom might consume their catch at a certain frequency). There is human health risk from either contact with or ingestion of surface water or sediment. In regard to the completed ecological risk assessment, 229 measurement endpoints (species from various river reaches) were assessed. While some model-predicted results indicated the possibility of risk, the results of site-specific sampling (birds, mammals, fish) concluded that there are no "population level" ecological risks. The public comment draft of the Feasibility Study was released in June 2010 along with EPA's "Proposed Plan" for cleanup of the Sudbury River (Operable Unit 4). In September 2010, after consideration of public comments, EPA selected a comprehensive remedy for the Sudbury River. The major components of the remedy are as follows:

• Enhanced Natural Recovery (ENR) consisting of the addition of a 6-inch layer of sand in a portion of Reach 3 with the highest levels of mercury contamination in sediment. This area includes approximately 84 acres in Framingham Reservoir 2, north of the Fountain Street Bridge and extending to the Reservoir No. 2 dam. The addition of a sand layer effectively accelerates natural recovery processes by which contaminated sediment are normally buried and diluted.

• Monitored Natural Recovery (MNR) in other reaches of the river. Throughout much of the river, fish are expected to become safe for regular consumption within a reasonable timeframe through natural recovery and without any active remediation. EPA would continue to take samples to monitor this progress.

• Limited Action for Reach 8 (Great Meadows National Wildlife Refuge). This includes monitoring of contamination levels in fish, to determine the impact of the selected remedy and of ongoing atmospheric deposition on fish tissue. However, fish tissue contamination levels in Reach 8 are not expected to decline to levels that would permit consumption in quantities assumed for a recreational angler.

• Institutional Controls throughout the river consisting of community outreach as well as posting and maintenance of signs advising against the consumption of fish where they are unsafe for regular consumption.

• No Action for Reaches 5 and 7 since there are no unacceptable risks to either a child or an adult recreational angler in these reaches.

• Periodic Five-year Reviews of remedy protectiveness and performance.

EPA and the USACE conducted numerous pre-design studies in the Summer 2011. This information was used in the completion of the Draft Remedial Design (Draft Remedial Action Work Plan). The Final Design was completed in May 2013. In the ensuing months, during which time EPA was awaiting remedy funding, EPA Region 1 collected additional fish form Framingham Reservoir No. 2 (a.k.a., Sudbury River Reach 3) for mercury analysis. The result of these fish indicated an approximate 22% reduction of mercury in fish tissue. The reduction was not predicted by a previously used computer model and, as a result, EPA has suspended the placement of the sand cap pending additional fish tissue monitoring which is underway (i.e., Summer 2015).

Site Photos
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SDMS 452933
Facing east, this photo shows the remediated and restored 5.5 acre Eastern Wetland.

SDMS 452934
Nyanza OU4 - Sudbury River Target areas.

Links to Other Site Information
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Disclaimer Instructions about PDF

Newsletters & Press Releases:
Recent Press Releases about this project (if any)  
EPA Plans Modification to Groundwater Cleanup, August 2006 (504KB)  
Fact Sheet for the Sudbury River Study, OU4, October 1, 2007 (10.95 MB)  
Fact Sheet for the Sudbury River Study (Spanish Version), OU4, October 1, 2007 (7.69 MB)  
Remedial Proposed Plan OU4, June 1, 2010 (1.81 MB)  
Proposed Plan Public Informational Meeting Presentation, June 1, 2010 (3.69 MB)  
Public Meeting Presentation on WASP Computer Model, June 24, 2010 (2.08 MB)  
Fact Sheet: Fieldwork Planned around Framingham Reservoir No. 2, April 1, 2011 (485 KB)  
Fact Sheet: Fieldwork Planned around Framingham Reservoir No. 2 (Spanish Version), April 1, 2011 (497 KB)  
Fact Sheet: Fieldwork Planned around Framingham Reservoir No. 2 (Portuguese Version), April 1, 2011 (500 KB)  
Frequently Asked Questions (FAQ), OU 4, February 2013 (62 KB)  
Presentation for the Draft Remedial Action Work Plan, September 2012 (2.29 MB)  
Presentation for Stakeholders Meeting with Framingham Board of Selectmen, May 2013 (2.50 MB)   
Presentation of Ecological Considerations Associated with Thin-Layer Capping, September 2, 2013 (4.59 MB)  

Federal Register Notices:
Final NPL Listing  

Administrative Records:
Administrative Record Index, OU 01 Record of Decision (ROD), September 4, 1985 (1,063 KB)  
Administrative Record Index, OU 02 Record of Decision (ROD), September 23, 1991 (803 KB)  
Administrative Record Index, OU 03 Record of Decision (ROD), March 30, 1993 (889 KB)  
Administrative Record Index, OU 02 Explanation of Significant Differences (ESD), December 7, 2006 (585 KB)  
Administrative Record Index, OU 04 Record of Decision (ROD), October 1, 2010 (1.64 MB)  

Reports and Studies:
Final Report for Human Health Indoor Air Risk Assessment, October 25, 2005 (1.99 MB)  
Final Human Health Risk Assessment, Operable Unit 4, May 1, 2006 (5.69 MB)  
Final Dense Non-Aqueous Phase Liquid (DNAPL) Alternative Memorandum, June 16, 2006 (165 MB)  
Nyanza Groundwater Contamination and Indoor Air: How Vapor Mitigation Systems Will Help Affected Homes, August 2006 (119KB)  
Final Supplemental Baseline Ecological Risk Assessment, Sudbury River, Ashland, Massachusetts, December 1, 2008 (Opening file is 21.0 MB with links to external pdf file)  
Metrowest Growth Management Committee Comments on the Human Health Risk Assessment, December 5, 2008 (3.62 MB)  
EPA Response to Comments from Metrowest Growth Management Committee on the Human Health Risk Assessment, January 21, 2009 (1.16 MB)  
Metrowest Growth Management Committee Comments on the Supplemental Baseline Ecological Risk Assessment, September 30, 2009 (1.20 MB)  
EPA Responses to Comments from Metrowest Growth Management Committee on the Supplemental Baseline Ecological Risk Assessment, October 27, 2009, (2.91 MB)  
Public Comment Draft Feasibility Study (FS) Operable Unit 4, June 1, 2010 (20.7 MB)  
Remedial Action Work Plan (RAWP) - Reach 3 Operable Unit 4, April 3, 2013 (64.6 MB)  
2013 Groundwater Monitoring Data Summary - Operable Unit 2, May 2013 (15.7 MB)  

Decision Documents:
View Records of Decision (RODS) on-line (EPA HQ)  
Record of Decision (ROD), OU 02, September 23, 1991 (7.32 MB)  
Draft Explanation of Significant Differences (ESD) for public comment, August 2006 (2.18MB)  
Explanation of Significant Differences (ESD), OU 02, September 29, 2006 (2.43 MB)  
Record of Decision (ROD), OU 04, September 30, 2010 (8.32 MB)  

Other Links:
NPL Site Narrative at Listing:  
Site Progress Profile  
Massachusetts Department of Public Health's Ashland Nyanza Health Study Final Report, April 2006.  
Five Year Review Report, November 10, 1993 (2.04 MB)  
Second Five Year Review Report, August 17, 1999 (1.86 MB)  
Third Five Year Review Report, April 12, 2004 (2.11 MB)  
Addendum to Third Five Year Review Report, September 01, 2006 (106 KB)  
Fourth Five Year Review, May 13, 2009 (7.06 MB)  
Addendum to the Fourth Five Year Review Report, September 29, 2011 (4.42 MB)   
Fifth Five Year Review Report, May 13, 2014 (7.17 MB)  

Site Repositories
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Ashland Public Library, 66 Front Street, Ashland, MA 01721

OSRR Records and Information Center, 1st Floor, 5 Post Office Square, Suite 100 (HSC), Boston, MA 02109-3912 (617) 918-1440

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EPA Remedial Project Manager: Daniel Keefe
Site Responsibilities: Sudbury River (Operable Unit 4)
Address: US Environmental Protection Agency
5 Post Office Square, Suite 100
Mail Code OSRR07-1
Boston, MA 02109-1367
Phone #: 617-918-1327
E-Mail Address: keefe.daniel@epa.gov

EPA Community Involvement Coordinator: Pamela Harting-Barrat
Address: US Environmental Protection Agency
5 Post Office Square, Suite 100
Mail Code: ORA20-1
Boston, MA 02109-3912
Phone #: 617-918-1318
E-Mail Address: harting-barrat.pamela@epa.gov

State Agency Contact: Jennifer McWeeney
Address: 1 Winter Street
Boston, MA 02108
Phone #: 617-654-6560
E-Mail Address: jennifer.mcweeney@state.ma.us


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Last updated on Wednesday, November 4th, 2015
URL: http://www.epa.gov/region1/superfund/sites/nyanza