Superfund Information Systems: Site Profile

Superfund Site:

MOHAWK TANNERY
NASHUA, NH

Health & Environment

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What Are the Risks at the Site?

For approximately 60 years, the former Mohawk Tannery disposed of tannery process waste in the lagoons that were not designed to contain such waste. Tannery operations also disposed of residues in a series of pits and drainage basins in and around the buildings that existed at the time. The sludge and the soils in these areas are contaminated with heavy metals, dioxin, and semi-volatile organic compounds.  Additionally, EPA has determined that some of the areas discussed above and areas at the Site’s southern parcel hold asbestos containing material (ACM) on the surface and within the subsurface soil.  These contaminants are presently exposed in the open lagoon and surficial soils in various locations at the Site.  Most of the waste lies in the northern parcel in the former lagoons adjacent to the Nashua River. 

The Site is fenced but its security has been compromised; squatters/trespassers have been observed through the years.

The 2002 EE/CA included a streamlined human health and ecological risk evaluation that focused on the seven sludge waste disposal areas of the Site. In 2005 additional studies were completed to further evaluate contamination at the Site, and the risks posed by the Site contaminants.  Also, in 2013, EPA further evaluated the risks posed by soils, sediments, surface water and groundwater within the southern parcel of the Site. These risk evaluations looked at non-cancer and cancer risks to human health and concluded that the sludge waste areas within the northern parcel pose the greatest risks as they are readily accessible to trespassers. The major contributors to excess non-cancer risks to human health in these areas was the sludge waste, which contains in addition to other constituents, 4-methylphenol, arsenic, antimony, cadmium, and manganese.  The major contributors to excess cancer risks were dioxins, pentachlorophenol, arsenic, and benzo(a)pyrene.  They also concluded that the sludge waste at the Site poses a concern for ecological receptors. 

For the contaminated soils and groundwater within the northern parcel, the risk evaluations concluded that cancer risks were largely due to dioxin/furan and arsenic.  Non-cancer risks were largely due to arsenic and vanadium.  They also concluded that the contaminated soils have a potential to cause adverse effects to ecological receptors.

At the southern parcel, the risk evaluation concluded that contaminants in the groundwater exceed risk-based concentrations for residents, while contaminants in the surface and sub-surface soils exceed the risk limit for future residential receptors but not the risk limit for future recreational receptors.  It concluded that river bank surface soils and river sediments do not have risk above limits for recreational receptors.

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Contaminant Information

The 2002 EE/CA (EPA, 2002), the 2005 RI (Sanborn Head & Associates, 2005), and the 2013 SLRA (EPA, 2013) presented the findings of baseline human health and ecological risk assessment for the sludge waste disposal areas at the Site’s northern parcel, the remaining soils and groundwater at the northern parcel, and several media within the southern parcel.  Using analytical results from these investigations and the results of the human health risk and ecological evaluations, contaminants of concern (COCs) that pose threats to human health and the environment were identified.  The 2002 EE/CA (EPA, 2002), the 2005 RI (Sanborn Head & Associates, 2005), and the 2013 SLRA (EPA, 2013) presented the findings of baseline human health and ecological risk assessment for the sludge waste disposal areas at the Site’s northern parcel, the remaining soils and groundwater at the northern parcel, and several media within the southern parcel.  Using analytical results from these investigations and the results of the human health risk and ecological evaluations, contaminants of concern (COCs) that pose threats to human health and the environment were identified. 

EPA has developed preliminary removal goals (PRGs) to be achieved by a Non-Time Critical Removal Action.  The following is a list of the COCs and their respective PRGs (all units are in mg/kg).

Benzo(a)pyrene                    0.7

Pentachlorophenol                3.0

4-Methylphenol (p-cresol)     0.7

Dioxin - TCDD (expressed as toxicity equivalency [TEQ])      5.11E-05

Antimony                               9.0

Arsenic                                  11.0

Barium                                   1,000.0

Cadmium                               33.0

Chromium (total)                    1,000.0

Lead                                       200.0

Manganese                            1,000.0

Vanadium                               393.0

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Performance Measures

EPA uses performance measures to track environmental results at Superfund sites. If you have any questions or concerns about the measures at this site, please contact the site team members listed under Site Contacts.

Read more about Superfund Remedial Performance Measures.

Performance
Measure
Status at this
Superfund Site
What does this mean?
Human Exposure Under Control Insufficient Data Yes means assessments indicate that across the entire site:
  1. There are currently no unacceptable human exposure pathways; and
  2. EPA has determined the site is under control for human exposure.

No means an unsafe level of contamination has been detected at the site and a reasonable expectation exists that people could be exposed.

Insufficient data means that, due to uncertainty regarding exposures, one cannot draw conclusions as to whether human exposures are controlled, typically because:
  1. Response to the contamination has not begun; or
  2. The response has begun, but it has not yet generated information sufficiently reliable to evaluate whether there are currently any unacceptable human exposure pathways at the site.
Groundwater Migration Under Control Insufficient Data

Yes means EPA reviewed all information on known and reasonably expected groundwater contamination. EPA concluded the migration of contaminated groundwater is stabilized and there is no unacceptable discharge to surface water. EPA will conduct monitoring to confirm that affected groundwater remains in the original area of contamination.

No means EPA has reviewed all information on known and reasonably expected groundwater contamination, and the migration of contaminated groundwater is not stabilized.

Insufficient data means that due to uncertainty regarding contaminated groundwater migration, EPA cannot draw conclusions as to whether the migration of contaminated groundwater is stabilized.

Construction Complete No

Yes means the physical construction of the cleanup is complete for the entire site.

No means either physical construction is not complete or actions are still needed to address contamination.

Sitewide Ready for Anticipated Use No Yes means:
  1. All cleanup goals affecting current and reasonably anticipated future land uses of the entire site have been achieved, so there are no unacceptable risks;
  2. All required land-use restrictions or other controls have been put in place; and
  3. The site has achieved Construction Complete status.

No means that one or more of these three criteria have not been met. However, a site listed as no may still have redevelopment occurring on portions of the site and may be eligible for additional redevelopment.

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