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Site Type: Long Term/National Priorities List (NPL)  |
NYANZA CHEMICAL WASTE DUMP |
 | Click here for interactive map
Click for interactive map |
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| Ashland, Massachusetts |
Middlesex County
| Street Address: | MEGUNKO RD |
| Zip Code: | 01721 |
Congressional
District(s): |
03 |
| EPA ID #: | MAD990685422 |
| Site ID #: | 0100948 |
| Site Aliases: | Nyanza,
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| Site Responsibility: | Federal, State |
| NPL LISTING HISTORY |
| Proposed Date | 10/23/1981 |
| Final Date | 09/08/1983 |
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Site Description
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 contains 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
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. Wetlands nearby and fish in the Sudbury River are contaminated with mercury. Sediments in the Sudbury River, just downstream of the site also have high mercury levels.
Cleanup Approach
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.
Response Action Status
| 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 empahsis on potential indoor air contamination, EPA outlined modificaitons 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. This remedy also calls for institutional controls as well as additional monitoring of groundwater and indoor air. |
| Wetlands and Drainageways | OPERABLE UNIT 3: Preliminary sampling showed that sediment and surface water of the wetlands and drainageways between the site and the Sudbury River were contaminated with heavy metals. A decision was reached in 1993 to excavate and landfill contaminated sediments from these wetlands. 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 predominantly with mercury . EPA gathered U.S. Government and university scientists to further study the mercury in particular. The scientists' findings were placed in local repositories in late 1997. From the fall of 2003 through the summer of 2004, EPA conducted extensive sampling along the 26 miles of riverin support of both the Human Health and Ecological Risk Assessments. Media sampled include fish, sediment, surface water, crayfish, and mink as well as tree swallows, songbirds, kingfisher and ducks. EPA has completd 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 is expected to be used to evaluate the effectiveness of various remedial alternatives. This evaluation will be described in the Draft Feasability Study which is expected to be completed in 2009. |
Environmental Progress
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 1998, the EPA re-posted the river with signs warning against the consumption of contaminated fish. These actions have made the Nyanza Chemical Waste Dump site safer while remaining cleanup actions are being planned and implemented.
Current Site Status
In October 2007, EPA completed the installation of 43 vapor mitigation systems in single and multi-family homes located above the contaminated shallow groundwater plume. These are sub-slab depressurization systems that collect any vapors beneath the building and direct them outdoors above the breathing zone. For more information, see the reference below regarding the September 2006 Explanation of Significant Differences (ESD).
EPA completed the cleanup of mercury contaminated sediments in on-site wetlands and drainageways by August 2001 (OU3). EPA's third Five Year Review of the Site was completed in March of 2004. The Five Year Review determined that the completed remedies (Operable Units 1 and 3) continue to be protective of human health and the environment, and that continued operation and maintenance activities will be required to maintain the protectiveness of the site.
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 Apirl 2006.
In August 2006, EPA released a draft Explanation of Significant Differences (ESD) regarding the groundwater cleanup (Operable Unit 2) at the site. The ESD requires;
1. Extraction of DNAPL with off-site treatment and disposal of the extracted DNAPL with possible enhancements.
2. Performance of routine groundwater monitoring to assess any changes in plume concentrations and migration;
3. The installation, on a voluntary basis, of vapor mitigation systems in approximately 40 to 50 structures (mostly homes) located in the northeast portion of the plume, in an area generally bracketed by Tilton Ave. and Water St. to the west, the Sudbury River to the north and to the east, and the rail road tracks to the south;
4. Performance of additional air testing, on a voluntary basis, at approximately ten (10) to fifteen (15) additional homes and businesses located above remaining areas of the plume, generally described as areas immediate west of Forest St and southeast of the Town Hall along Main St.. These homes and businesses have not yet been selected; and,
5. Installation of small diameter monitoring wells or piezometers in the areas generally described in #4 above to more accurately determine the extent of the shallow groundwater plume.
In addition, this ESD provides clarification on the use of institutional controls to prevent exposure to contaminated groundwater.
These actions are outlined in greater detail in the ESD, which can be viewed via the link under "Decision Documents" below.
Regarding OU4 (Sudbury River), risk assessments were recently 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; a recreational fisherman was assumed to consume 50 8-oz meals per year. There remains no humna health risk from either contact with or ingestion of surface water of sediment. In regard to the completed ecological risk assessment, 225 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.
Site Photos
 
Facing east, this photo shows the remediated and restored 5.5 acre Eastern Wetland. Nyanza OU4 - Sudbury River Target areas.
Links to Other Site Information
Newsletters & Press Releases:
Federal Register Notices:
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, OU02 Draft Explanation of Significant Differences (ESD), August 2006 (209 KB) | | |
| Administrative Record Index, OU 02 Explanation of Significant Differences (ESD), December 7, 2006 (585 KB) | | |
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Reports and Studies:
| Five Year Review Report, November 10, 1993 (2,093KB) | | |
| Second Five Year Review Report, August 17, 1999 (1,914KB) | | |
| Third Five Year Review Report, April 12, 2004 (2,245KB) | | |
| 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) | | |
| Addendum to Third Five Year Review Report, September 01, 2006 (106 KB) | | |
| 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) | | |
| Fourth Five Year Review, May 13, 2009 (7.06 MB) | | |
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Decision Documents:
Other Links:
Site Repositories
Ashland Public Library, 66 Front Street, Ashland, MA 01721
EPA New England Records Center, One Congress Street, Boston, MA 02114 (617) 918-1440
Contacts
| EPA Remedial Project Manager: | Daniel Keefe |
| Site Responsibilities: | Sudbury River (Operable Unit 4) |
| Address: | |
| Phone #: | (617) 918-1327 |
| E-Mail Address: | keefe.daniel@epa.gov |
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| EPA Remedial Project Manager #2: | Jim DiLorenzo |
| Site Responsibilities: | Operable Units 1, 2, and 3 |
| Address: | |
| Phone #: | (617) 918-1247 |
| E-Mail Address: | dilorenzo.jim@epa.gov |
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| EPA Community Involvement Coordinator: | Jim Murphy |
| Address: | |
| Phone #: | (617) 918-1028 |
| E-Mail Address: | murphy.jim@epa.gov |
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| State Agency Contact: | David Buckley |
| Address: | 1 Winter Street
Boston, MA 02108 |
| Phone #: | (617) 556-1184 |
| E-Mail Address: | david.buckley@state.ma.us |
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