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Waste Site Cleanup & Reuse in New England
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 Site Type: Long Term/National Priorities List (NPL) Click to see more about Site Type and how it is used?


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 Somersworth,  New Hampshire
 Strafford County
 Street Address: BLACKWATER RD
 Zip Code: 03878

 EPA ID #: NHD980520225
 Site ID #: 0101128
 Site Aliases:

 Site Responsibility: Federal, State, Potentially Responsible Parties

 Proposed Date 12/30/1982
 Final Date 09/08/1983

Site Description
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The 26-acre Somersworth Sanitary Landfill is located approximately 1 mile southwest of downtown Somersworth. The City of Somersworth operated a disposal site on the property from the mid-1930s until 1981. Originally, the City burned residential, commercial, and industrial wastes at the site. In 1958, the dump was converted to a landfill. Unknown quantities of sludges, solvents, acids, dyes, metals, laboratory or pharmaceutical wastes, and potash were disposed of at the site. In 1981, four groundwater monitoring wells installed as part of site closure activities indicated that volatile organic compounds (VOCs) and inorganic contaminants were present. The landfill is located in a predominantly residential area of Somersworth. The former Forest Glade Park (currently known as St. Laurent Park), which was reclaimed as a recreational park in 1978, sits atop the easternmost 10 acres of the site. As of June 6, 2011 this park was removed from the City's Park Ordinance by vote of the City's Council.

An apartment building for senior citizens, a fire station, and a National Guard Armory abut the property to the east, and an elementary school is located approximately 2,300 feet northeast. Approximately 11,000 people live in Somersworth. Most of the residences in the area obtain drinking water from the Somersworth municipal supply system; however, there are at least seven private wells in the area. Peter's Marsh Brook, located adjacent to the western edge of the landfill, is a tributary of Tate's Brook, which, in turn, is a tributary of the Salmon Falls River. Both the City of Somersworth and the City of Berwick, Maine withdraw water from the river for their drinking water supplies. Water intakes are located approximately 1 mile from the landfill.

Threats and Contaminants
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The groundwater is contaminated with VOCs and inorganic chemicals. Sediments were found to contain low levels of arsenic, chromium, and lead. Peter's Marsh Brook and Tate's Brook have been shown to contain VOCs and metals, including arsenic and mercury unrelated to the landfill. Peter's Marsh Brook is considered to be the primary receptor of groundwater contamination. If private water supply wells were installed or reopened in this area or near Peter's Marsh Brook, long-term exposure to contaminated drinking water would pose potential health risks. However, the City has passed a zoning ordinance which prohibits use of the contaminated ground water.

Cleanup Approach
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Rather than implement a traditional landfill closure remedy, an innovative remedy was selected in the 1994 ROD, involving a chemical treatment wall (CTW), also known as a permeable reactive barrier (PRB), that is being used to clean ground water.

Response Action Status
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Entire Site The potentially responsible parties (PRPs) for the site contamination conducted an investigation into the nature and extent of site contamination. In the summer of 1994, remedies were selected in a Record of Decision (ROD) to clean up the groundwater, which included using an innovative PRB that destroys the VOCs as the groundwater flows through the wall, with a final cap to be determined after cleanup. The ROD also specifies a contingent remedy if the PRB is ineffective, which calls for a standard cap and a pump and treat system.
Design of the remedy began in early 1996. Construction of the permeable reactive barrier was completed in the Fall of 2000. A permeable cover, which allows precipitation to flush contaminants from the landfill through the PRB plus an infiltration gallery and a bedrock extraction well, which help in the flushing of the contaminated groundwater, were completed in the summer of 2001.

Enforcement HighlightsThe EPA entered into a Consent Agreement in 1989, requiring the potentially responsible parties to investigate the nature and extent of site contamination. The settling parties also agreed to pay past State and Federal costs for the site, and future oversight costs. EPA and 20 parties entered into a Consent Decree in late 1995 in which the settling parties agreed to design, construct, and operate the selected remedy.

Environmental Progress
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Following listing of the Somersworth Sanitary Landfill site on the NPL, the EPA determined that the site contamination did not pose an immediate threat to public health or the environment while cleanup activities are on-going. The passage of the local zoning ordinance prohibiting ground water use in the area further protects the public health. The potential for explosive levels of landfill gas to accumulate in nearby structures has been eliminated by the installation of a gas collection trench, whose construction was completed on December 2003. The ongoing monitoring of landfill gas is showing decreasing trends of methane concentrations that have reached negligible levels. These decreasing trends show that the trench is an effective measure to prevent landfill gas migration towards nearby residences.

Current Site Status
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In January 2000, the City of Somersworth adopted institutional controls (ICs) at the site to prevent the use of contaminated ground water. Ground water monitoring is continuing during ground water treatment using the permeable reactive wall. Soil gas investigations, the results of ongoing landfill gas monitoring, and a Screening Level Risk Assessment showed that there was no unacceptable risk to recreational users from inhalation exposures to the air at the surface nor dermal contact with surface soils at the landfill. Nonetheless, EPA and NHDES have identified additional precautions that must be taken by the City should the site be re-developed for recreational use (e.g. soccer fields).

On September 23, 2010, EPA completed the Second Five Year Review for the site. It concluded that the remedy is considered protective in the short-term. However, in order to be protective in the long-term, several follow-up actions listed in the Five-Year Review needed to be taken including final closure of the landfill. As of June 2012, all of the recommendations laid out on the Second Five Year Review have been implemented, except final closure.

Continuing collection of groundwater data and historical information gathered has confirmed that residents near the bedrock extraction well are not exposed to vapor intrusion concerns from the contaminated groundwater.

Further evaluation (test pitting and surface soil samples) was performed on the eastern area of the site that was previously reclaimed by the City for recreational use. The objective was to confirm that the existing fill on top of the recreational areas reclaimed by the City meets the same protectiveness standard as the existing permeable landfill cover over the remainder of the landfill at the site. Results revealed a small area that needed additional cover material since arsenic was found to be slightly exceeding NH DES soil remediation standards. On August 2013, the Settling Defendants consultant (Geosyntec) placed additional cover material over this area, graded and grass seeded the area. The locations where the arsenic State standard was exceeded, were completely covered with an additional 1 foot of clean soils. Also by the end of October 2013, all the park related structures that remained at the Site (i.e. fences and fence posts) were cut-off at ground level and removed from the Site.

In May 2013, EPA issued an Explanation of Significant Differences (ESD) requiring the establishment of additional Land Use Restrictions and a Soil Management Plan (SMP) to ensure that human health and the environment remain protective in the event that the site is re-developed in the future. On December 22, 2014, EPA reviewed and approved a Draft Notice of Activity and Use Restrictions (AUR) and a Draft SMP, and submitted them to the Settling Defendants so that they can complete the documents and submit them to NHDES for approval.

On November 2013, an EPA contractor prepared and presented to the Somersworth City Council a preliminary assessment of renewable energy opportunities for the site. As a result, the City embraced the idea of building a solar co-generation facility on top of the landfill. The City has reviewed four proposals for redevelopment of the Site with such solar project, selected a team of companies and is currently considering the approval of a viability study to be conducted and funded by the selected team of companies. If approved, the City might enter into a lease agreement with the team, based on the viability study findings.

EPA is currently conducting the Third Five Year Review for the Site which shall be completed by September 2015.

Site Photos
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SDMS 452953
Summer of 2000: Placement of iron filings into trench around landfill to
create permeable reactive barrier to treat groundwater.

SDMS 452954
August 2001: Hydroseeding permeable landfill cover.

SDMS 486905
June 2010 : Baseball and Basketball fields at southeastern corner of Site (aka St. Laurent Park).

SDMS 486904
June 2010: Landfill gas vent VP3 . View from Blackwater Road facing north.

SDMS 564590
Soil replenishment during August 2013.

SDMS 564591
Soil replenishment during August 2013.

SDMS 564592
Removal of Fence and Posts During August 2013.

Links to Other Site Information
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Disclaimer Instructions about PDF

Newsletters & Press Releases:
Press Releases about this project  
Somersworth Landfill Renewable Energy Reuse Assessment Presentation Slides, April 7, 2014 (1.91 MB)  

Federal Register Notices:
Final NPL Listing  

Administrative Records:
Administrative Record Index, OU 01 Record of Decision (ROD), June 21, 1994 (1.00 MB)  
Administrative Record Index, OU 01 Explanation of Significant Differences (ESD), May 30, 2013 (412 KB)  

Reports and Studies:
Preliminary Close Out Report (PCOR), September 9, 2005 (3.5MB)  
Final Interim Remedial Action Report for Preferred Remedial Action, September 2005 (23.2MB)  
Five Year Review Report, September 30, 2005 (3.7MB)  
Second Five Year Review Report, September 23, 2010 (3.65 MB)  
Preliminary Assessment of Renewable Energy Opportunities, November 2013 (1.26 MB)   
Third Five Year Review Report, September 23, 2015  

Decision Documents:
View Records of Decision (RODS) on-line (EPA HQ)  
Record of Decision (ROD), June 21, 1994 (4.67 MB)  
Explanation of Significant Differences (ESD), May 30, 2013 (2.90 MB)  
Institutional Controls at this site  

Other Links:
NPL Site Narrative at Listing:  
Site Progress Profile  
City of Somersworth - Chapter 19: Zoning Ordinance, January 10, 2000 (4.58 MB)  

Site Repositories
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Somersworth Public Library, 27 Main Street, Somersworth, NH 03878

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: Gerardo Millán-Ramos
Site Responsibilities: Remedial Project Manager
Address: US Environmental Protection Agency
5 Post Office Sq., Suite 100
Mail Code OSRR07-1
Boston, MA 02109 - 3912
Phone #: 617-918-1377
E-Mail Address: millan-ramos.gerardo@epa.gov

EPA Community Involvement Coordinator: Rudy Brown
Address: US Environmental Protection Agency
5 Post Office Sq., Suite 100
Mail Code ORA01-1
Boston, MA 02109 - 3912
Phone #: 671-918-1031
E-Mail Address: brown.rudy@epa.gov

State Agency Contact: Andrew J. Hoffman
Address: New Hampshire Department of Environmental Services
PO Box 95
Concord, NH 03302-0095
Phone #: 603-271-6811
E-Mail Address: andrew.hoffman@des.nh.gov


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