Saint-Gobain Site Investigation History
The detection of PFOA in the public water supply in 2016 prompted the investigation.
Perfluorooctanoic acid (PFOA) was first detected in a tap water sample at the Saint-Gobain Performance Plastics facility at 701 Daniel Webster Highway in Merrimack, NH, in 2016, but as far back as 1986 a company called Chemfab operated fabric coating and cast-film equipment there, using PFOA and other PFAS. Saint-Gobain purchased the facility in 2002 and continued to manufacture coated textiles and films using chemical dispersions that contained PFOA and other PFAS. The manufacturing of coated textiles at the facility involves dipping fabric into a mix of chemicals (called aqueous dispersions) and then drying or curing the fabric in tall, specially designed ovens. Prior to 2021, exhaust from the ovens passed through a network of ducts before release to the atmosphere through several stacks located on the roof. See the Air Emissions Sources webpage.
In 2016, the U.S. Environmental Protection Agency (EPA) established a long-term health advisory level for PFOA and PFOS, either individually or combined, of 70 parts-per-trillion (ppt). Parts-per-trillion is equivalent to nanograms per liter (ng/L). Under emergency rulemaking, NHDES adopted the 70 ppt health advisory as an enforceable Ambient Groundwater Quality Standard (AGQS). By 2018, numerous water supply wells were identified that exceeded the 70 ppt AGQS, and Saint-Gobain connected some of the affected households to public water. In March 2018, NHDES and Saint-Gobain entered into a Consent Decree that identified an area (called the ‘Pre-GMZ’ or Pre-Groundwater Management Zone) that encompassed the wells that exceeded the AGQS of 70 ppt and formalized a path to provide the remaining known impacted well owners with a permanent remedy, which was primarily extension of public water to hundreds of affected homes.
Site Investigation Activities
NHDES received two reports in 2019 prepared by Golder Associates, Inc. on behalf of Saint-Gobain that summarized results of investigation activities at the Saint-Gobain facility that are the subject of a NHDES Comment Letter dated June 16, 2020. The Report on 2018 Stormwater and Surface Water Activities (Volume 1 and Volume 2), dated March 15, 2019, is focused on the results of stormwater and surface water sampling conducted in 2018, as well as investigation and repair of elements of the stormwater conveyance system. The Site Investigation Report, dated April 19, 2019, presents the results and findings of the site investigation. A Supplemental Site Investigation Report that summarizes additional investigation activities and presents a screening of potential remedial alternatives was submitted to NHDES on October 14, 2020. NHDES is completing a review of this document and comments will be presented in a letter to Saint-Gobain. Additional site investigation documents are available to the public on NHDES’ OneStop webpage.
Site investigation work conducted at or adjacent to the facility includes, but is not limited to:
- Installation of 50 monitoring wells.
- Collection and analysis of approximately 500 groundwater samples.
- Collection of analysis of more than 100 soil samples.
- Collection and analysis of approximately 190 stormwater and surface water samples.
- Collection and analysis of fish tissue samples.
Permanent Alternate Water
Following the initial discovery of PFOA in area drinking water in 2016, NHDES launched a massive testing effort to determine the extent of the contamination. Saint-Gobain and NHDES worked cooperatively and quickly to address those properties at greatest risk, providing interim bottled water to impacted residents, and point of use treatment systems, point of entry treatment systems, or waterline connections to over 500 properties, primarily in Litchfield and Merrimack. The 2018 Consent Decree entered into between the NHDES and Saint-Gobain memorialized the responsibilities with respect to the work already completed and providing waterline connections to an additional 302 properties.