Established in 1961, the US Army Corps of Engineers’ (USACE) Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire has conducted large scale studies in controlled refrigerated environments as one of its primary missions for the nation. Trichloroethylene or TCE was used as a refrigerant for many years in refrigeration systems used to conduct research in cold environments.
1970s and 1980s – Several major spills and leaks of TCE occurred on the CRREL property. Use of TCE was discontinued as a refrigerant in 1987, and general use of TCE at CRREL no longer occurs.
1990 – TCE was detected in three of four cooling water production wells located on the CRREL site, and in several wells across the Connecticut River in Norwich, Vermont.
Groundwater Investigations and Remediation
1993 – The US Army Environmental Command (USAEC) and the US Army Corps of Engineers New England District (NAE) began operating a continuous groundwater treatment system in accordance with New Hampshire Department of Environmental Services (NHDES) and US Environmental Protection Agency (EPA) policies and guidelines. Investigations of the sources of TCE contamination in the soil and groundwater continued through the 1990s, including pilot tests of in situ treatment of soils using injections of potassium permanganate (KMnO4).
2001 – A draft Remedial Action Plan was submitted to NHDES in 2001.
2003 – NHDES approved a Remedial Action Plan that established a Groundwater Management Zone with treatment of groundwater pumped from the on-site extraction wells, and monitoring requirements to verify that TCE contamination in groundwater was being contained on-site.
2008 – present – Sampling of treated cooling water being discharged to the Connecticut River has shown TCE concentrations to be at or below detection limits.
TCE Vapor Intrusion Detected in CRREL Buildings
2010 – Following Department of Defense (DoD) guidelines, contractors for USACE New England District (NAE) took indoor air samples in several buildings on the CRREL site to determine if TCE vapor was migrating into the buildings. TCE was detected in indoor air in several locations.
2011 – NAE launched a full scale Remedial Investigation/Feasibility Study (RI/FS) for TCE and other potential contaminants in soil, groundwater, bedrock and indoor air on the CRREL site. A contractor was selected to identify data gaps from previous investigations, and develop a new Remedial Action Plan for the site.
September/October 2011 – TCE was detected in low concentrations in the basement of the Child Development Center (CDC), but not in the upstairs daycare space. A “time-critical removal action” was implemented at the CDC that consisted of a sub-slab depressurization system (SSDS) in the CDC basement to mitigate the potential intrusion of vapor contamination into the building from the subsurface. Other interim and time-critical mitigation measures, including portable room air treatment units and sub-slab depressurization systems, have been implemented in the CRREL Main Lab and other buildings at CRREL to protect the health and safety of workers and visitors by minimizing TCE exposure.
2011- present – Additional comprehensive rounds of groundwater, soil vapor and indoor air testing have been conducted throughout the site. Soil vapor investigations are intended to identify and monitor vapor migration pathways and provide knowledge of potential off-site vapor migration.
Off-Site Sampling for TCE Soil Vapor and Indoor Air Shows No Actionable Risk on Neighboring Properties
2012-2013 – When high concentrations of TCE were measured in deep soil samples (25 to 50 feet below ground surface) near the CRREL property boundary, USACE-NAE decided it was necessary to sample buildings on abutting properties to see if TCE vapors were migrating into buildings on neighboring properties. In March 2013, property owners were notified and CRREL was given permission to sample in the Richmond Middle School, Dartmouth Housing rental units, and several neighboring business. All samples of indoor air showed concentrations below or very near laboratory detection limits and below applicable screening levels. This indicates safe conditions with respect to TCE exposure at those places.
2013-2014 – In April 2013, prior to the off-site sampling, USACE-NAE and CRREL conducted an Open House for the community to explain the ongoing investigation and reason for sampling off site. USACE also invited community members to participate on a Restoration Advisory Board (RAB) for the Hanover community in accordance with guidelines established by the DoD Environment, Safety and Occupational Health Network and Information Exchange (DENIX).
2014 – The Restoration Advisory Board continues to meet bimonthly, or more frequently as needed, to discuss the ongoing investigations and sampling results, and to communicate the restoration team’s progress to the Hanover community. A second community Open Housewas held on October 22, 2014.
2015 – The Remedial Investigation/Feasibility Study and Remedial Action Plan are expected to be completed by 2015.
For more information, please contact the Project Manager, by e-mail or by calling 978-318-8152.
Updated: January 7, 2021