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Evaluation of Health and Safety Plan



Consultants recently drafted the site-specific Health and Safety Plan (HASP) in regard to the proposed sampling and preliminary remediation at the Mohawk Tannery Site, located in Nashua, New Hampshire. The consultants, the U.S. Environmental Protection Agency (EPA) and the New Hampshire Department of Environmental Services (DES) have asked the New Hampshire Bureau of Environmental and Occupational Health (BEOH) to review the HASP plan to determine if the proposed protective measures are adequate in protecting those on and near the site. BEOH prepared this Health Consultation under its cooperative agreement with the U.S. Agency for Toxic Substances and Disease Registry (ATSDR).

The former Mohawk Tannery facility (a.k.a. Granite State Leathers) is located on a 30-acre parcel in Nashua, Hillsborough County, New Hampshire. The facility produced tanned hides between 1924 and 1984 and is currently inactive. The property is bordered by the Nashua River to the west and by residences to the southeast and east.

The Mohawk Tannery site was proposed for the National Priorities List on May 11, 2000. From October 2000 to January 2001, EPA performed a Time-Critical Removal Action which removed 55 drums of hazardous materials, asbestos-containing material from the former facility building, corrosive acid from a storage tank, and hazardous materials from the former clarifier facility. EPA also fixed portions of the fence around the site and boarded up the former clarifier building.

In 2000, a Public Health Assessment was developed, which examined the physical and chemical hazards present in the surface soil impoundment lagoons and adjacent areas of the Nashua River. Exposure to buried waste and contaminated soil onsite was identified as a potential exposure pathway to onsite workers. While characterizing risk outside of the known contaminated areas, workers may release or come into contact with substances that were previously buried in the ground. These releases have the potential of exposing workers, as well as the surrounding community, to chemicals related to the site.

The potential activities may result in releases of hydrogen sulfide, fugitive dust and odors. Although the HASP lists several steps that will be taken to protect on-site workers, dust/chemical releases could migrate off the site, exposing nearby residents. Since there are nearby residences abutting the eastern side of the site, measures should be taken to detect potential off-site releases of these contaminants.


Public health issues related to the proposed remedial activities include the limited potential for human exposure during these activities. Some of these concerns have been addressed in the HASP draft. These actions include onsite monitoring of respirable dust and contaminants that may become airborne, as well as a categorization of the hazards that may arise when certain tasks (e.g., soil sampling, drilling and vehicular activity) are performed. Potential exposures onsite are limited to site workers and other site related personnel since access to the site is controlled with a chain link fence. Exclusion zones, areas that restrict access to authorized on-site employees or those with proper personal protective equipment, will be designated with barriers, cones and red 'hazard' tape.

Worker protection consists of a determination matrix that includes exceedence levels for substances of concern. Substances of concern include hydrogen sulfide, fugitive dust and odors. Hydrogen sulfide is a product of decomposing organic matter. Odors are the result of various organic compounds.

The HASP draft currently has no protocol for monitoring offsite releases of contaminants of concern. The eastern perimeter of the site should be monitored due to nearby residences. There are no residences within 1,000 feet in the north, west or south perimeters of the site. Additionally, prevailing wind directions are to the east. Protective levels for the public are generally more stringent than the levels proposed for site-related personnel.

Exceedences of levels of hydrogen sulfide, dust and odors can be measured to ensure airborne concentrations are below action levels. When an action level is exceeded, work practices should be altered. This consists of wetting down soils, slowing down or temporarily halting earth moving activities, tarping disturbed areas or limiting the areal extent of test pits. Generally, any one of the actions should limit the release of all three contaminants of concern (e.g., covering a pit will limit hydrogen sulfide, dust and odor releases).

Hydrogen Sulfide

Exposure to high levels of hydrogen sulfide can result in eye irritation, a sore throat, cough, shortness of breath and fluid in the lungs. These symptoms usually go away after the exposure stops. Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness.

To protect workers at the site, hydrogen sulfide monitoring is performed once every 10 minutes during soil-disturbing activities. The worker action level occurs when hydrogen sulfide levels exceed 5,000 parts per billion (ppb) for more than 15 minutes. At this point, work practices should altered to reduce the hydrogen sulfide concentrations.

Releases of hydrogen sulfide at or above these levels could migrate off site, possibly exposing nearby residents. Therefore, hydrogen sulfide should also be monitored at the site perimeter. The monitoring protocol for hydrogen sulfide levels at the site perimeter should be set at 2,000 ppb. This concentration is in the range where reversible effects in sensitive individuals may occur. Perimeter monitoring for hydrogen sulfide should be performed three times per day, and anytime the work zone levels are exceeded. If the action level is exceeded, site workers should notify BEOH and DES by the end of the work day.


Fugitive dust, or particulate matter, can be generated through excavation. Particulate matter finds its way into living organisms through normal breathing mechanisms.  These particles may contain acids, heavy metals, biological irritants, soot, and other substances. Fine particles may be especially hazardous, as they are often too small to be screened out by the body's natural filtering systems.   Recent studies have found strong associations between airborne particulate matter and adverse human health effects, including premature death, aggravation of asthma and other respiratory diseases, and decreased lung function.

Fugitive dust is a potential exposure source during excavation activities. Respirable dust monitoring should be performed in work areas when activity is occurring. To protect on-site workers, an action level of 2.5 mg/m3 should be used. If dust levels at the work site/exclusion zone exceed this level for one hour or longer, work practices should be altered.

Again, dust releases can migrate off site, exposing residents. Site workers should monitor dust levels at the eastern boundary of the site at least three times per day and anytime work zone levels are exceeded. The action level for fugitive dust at the perimeter should be 0.15 mg/m3. If the action level is exceeded, site workers should alter work practices and notify BEOH and DES by the end of the work day.


In general, there are no practical mechanisms or action levels to address offensive odors. Odors may represent a variety of chemicals, possible resulting in physical and psychological health effects. If a strong odor is noticed, independent of hydrogen sulfide levels, work practices such as tarping should be implemented to reduce the presence of the odors. If the odor becomes objectionable or overwhelming, work should be discontinued.


BEOH has examined the site specific Health and Safety Plan for the Mohawk Tannery and has concluded that the plan does not adequately protect public health during remediation activities. Specifically, there is no air monitoring plan to ensure that nearby residents are protected during excavation/remediation activities.


BEOH recommends the following additions to the health and safety plan to ensure protection of public health during all phases of site investigation and remediation.

  • BEOH recommends monitoring of hydrogen sulfide three times per day, and anytime the worksite action level is exceeded (5,000 ppb). If the perimeter levels are exceeded (2,000 ppb), action should be taken to reduce the levels of hydrogen sulfide.

  • BEOH recommends monitoring of airborne particulate matter three times per day, and anytime the worksite action level is exceeded (2.5 mg/m3). If the perimeter levels are exceeded (0.15 mg/m3), action should be taken to reduce the levels of particulate matter.

  • Perimeter monitoring should be performed on the eastern side of the site, where the nearest residences are located.

  • If hydrogen sulfide or particulate matter levels at the site perimeter exceed the recommended action levels, site workers should notify BEOH and DES by the end of the work day.

  • Where necessary, BEOH recommends taking action if a strong or objectionable odor is noted.


Todd C. Hudson
Environmental Health Risk Analyst
Bureau of Environmental and Occupational Health
New Hampshire Department of Health and Human Services
Concord, New Hampshire
(603) 271-4664
(603) 271-3991 (fax)


The Health Consultation on the former Mohawk Tannery in Nashua, New Hampshire was prepared by the New Hampshire Department of Health and Human Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the Health Consultation was begun.

Gregory V. Ulirsch, M.S.
Technical Project Officer
Superfund Site Assessment Branch (SSAB)
Division of Health Assessment and Consultation (DHAC)

The Division of Health Assessment and Consultation, ATSDR, has reviewed this Health Consultation and concurs with its findings.

Sven E. Rodenbeck
for Roberta Erlwein

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