(This post is the eighth in a series describing the Site Investigation activities that are taking place or will be in the areas around the Saint-Gobain facility.)
A preliminary Groundwater Management Zone (GMZ) was outlined in the March 2017 Consent Decree between Saint-Gobain and the State of New Hampshire. This preliminary boundary is based on available data from drinking water supply wells.
Additional Site Investigation activities will be needed in the larger area around the facility, and the preliminary GMZ may change based on these findings. Most of these activities are likely to start in 2019. However, several phases of work are currently under way, or have already been completed:
- Soil Testing at Home Gardens: NHDES approved a work plan for additional testing of soils in home gardens in close proximity to the Saint-Gobain facility
http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4707039
http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4728566)
Saint-Gobain’s consultant, Golder Associates Inc. (Golder), has made initial notifications to the property owners about the sampling, and is in the process of scheduling the sampling. - Additional Private Well Testing: NHDES approved a work plan for additional residential supply well testing outside of those areas currently receiving alternate water. Sampling was completed at properties previously sampled by NHDES that had levels of PFOA and PFOS greater than 35 ppt. The work plan and NHDES’ comments are here:
http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4708556
http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4689986
NHDES also requested that Saint-Gobain submit a work plan for additional residential supply well testing to be completed as properties in the impacted areas are connected to public water: http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4727532. This testing is necessary to assess whether the change in pumping conditions from shutting off individual supply wells would change how the contamination is moving in the groundwater. NHDES is reviewing Saint-Gobain’s work plan for this testing, and will be issuing a comment letter once our review is complete: http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4738035 - Modeling Report: Saint-Gobain’s consultants prepared a report summarizing the results of modeling of PFOA through the facility’s air emissions, how PFOA was deposited onto the ground surface, and how PFOA moved through soil and groundwater in the areas around the facility. NHDES is currently reviewing this report, and will issue a comment letter with our findings once our review is complete: http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4739062
- MVD 4/5 Investigation: Saint-Gobain completed an investigation into groundwater quality in the areas around the MVD supply wells 4 and 5. NHDES is currently reviewing this report, and will issue a comment letter with our findings once our review is complete: http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4649008
- Soil Testing: Saint-Gobain completed soil sampling at sensitive receptor and agricultural properties in Merrimack and Litchfield. All of the samples had levels of PFOA and PFOS less than NHDES’ soil guidance level for direct contact of 500 parts per billion (ppb). NHDES is currently reviewing this report, and will issue a comment letter with our findings once our review is complete: http://www4.des.state.nh.us/IISProxy/IISProxy.dll?ContentId=4647908