A copy of the email below was provided to the Valley News by Dartmouth College spokeswoman Diana Lawrence. It was sent to neighbors on Aug. 31, 2016. Read more here.

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Dear Neighbors, 

As part of the ongoing water quality monitoring program for the Rennie Farm site, surface water samples are collected at two offsite locations from a stream that flows into Hewes Brook (please see stream-2 and stream-3 locations on the attached map).  The stream samples are collected every two months, with the most recent two-month sample collected on July 19. The July 19and previous sampling of the stream did not detect 1,4-dioxane. 

Surface Water Sample Map by Valley News on Scribd

Our next sample collection was scheduled to occur in September, but because of the limited recent rainfall and related low surface water flow within the stream, we decided to collect samples on August 18.  Because the effects of dilution from stream flow are at or near minimum, sampling under these conditions helps to better evaluate the potential discharge of 1,4-dioxane contaminated groundwater to the brook.

1,4-dioxane was detected at a concentration of 0.52 micrograms per liter, slightly above the testing detection limit of 0.25 micrograms per liter, in one of the two stream samples (stream-3) collected on August 18.  The New Hampshire groundwater quality standard for 1,4-dixone is 3.0 micrograms per liter.  The sample was collected at a location within the current estimated path of groundwater transport, and the presence of 1,4-dioxane at this location confirms our model for the directional flow of 1,4-dioxane from the site.

After receiving this result on August 25, we collected an additional six surface water samples on August 26 from locations along the stream to confirm the results of the August 18 samples and evaluate the extent of 1,4-dioxane presence within the stream under the current flow conditions.  The results from these six samples came back negative for 1,4-dioxane.  Going forward, we are expediting the remedial pump and treat system design and installation at the site and will monitor this expanded number of stream locations on a monthly basis.

Additionally, a previously planned groundwater monitoring well that was recently installed near the surface water sampling location will be sampled later this week to further evaluate the presence of 1,4-dioxane in the stream.  The results of this sampling will be shared with you as soon as they become available to us. 

If you have concerns about your well water, we would be happy to arrange sampling and testing for 1,4-dioxane, even if your well has been tested previously.  We have tested approximately 30 homeowner wells to date, with one well testing positive for 1,4-dioxane between 4.0-6.0 microgram per liter.

GZA consultant Jim Wieck and I will be at the Rennie Farm site next Tuesday, September 6, from 4 to 6 pm to address your questions and discuss the remedial pump and treat system. Please stop by if you would like to speak with us.

As always, please feel free to contact me with any questions or concerns.

Sincerely,

Maureen

Maureen O’Leary, PhD, MBA, CBSP

Director, Environmental Health & Safety

Dartmouth College