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Groundwater contamination found to be 20 times the state standard at Merrimack building site

Union Leader Correspondent

May 16. 2018 10:01PM

MERRIMACK — Groundwater contamination at a level that is 20 times the state standard has been detected at a parcel next to Saint-Gobain Performance Plastics that is being eyed for 240 apartments.

This week, representatives from the New Hampshire Department of Environmental Services contacted the John J. Flatley Company to notify the developer of the test results.

“Groundwater quality data collected during this study indicates that groundwater in the construction area is impacted by polyfluoroalkyl substances,” Karlee Kenison, administrator with the Hazardous Waste Remediation Bureau within DES, wrote in an email to John J. Flatley on Monday. “Perfluorooctanoic acid was detected at concentrations of 1,400 nanograms per liter, which exceeds the New Hampshire Ambient Groundwater Quality Standards of 70 ng/L.”

Kenison goes on to state that based on the groundwater elevation data and construction profiles, DES has concerns that there is the potential for subsurface utility backfill to result in groundwater flow patterns that are sensitive to ecological receptors in the nearby Dumpling Brook.

DES is suggesting that the Flatley Company redesign its utility layout to avoid impacting the brook, and it is discouraging the developer from installing water supply wells and use of site groundwater for potable water at the future housing property, states the email.

The entire Flatley project, once complete, will convert nearly 150 acres of land into 240 apartments, 300,000 square feet of retail space and 120,000 square feet of industrial space adjacent to Saint-Gobain along the Daniel Webster Highway; the future retail space will require its own individual site plans and additional approval from the Planning Board.

Five residential buildings to accommodate 240 one- and two-bedroom garden-style apartments, a pool, tennis courts and clubhouse are included in the plans, although the first phase of construction includes four residential buildings; town permits have already been granted for the first portion of the project.

“We appreciate your help and direction and guidance from DES,” Flatley wrote Tuesday in an email to Lisa Newton of DES. “We will be working diligently to follow your suggestions as we soon get started on this project that we hope will be a tremendous asset to the Merrimack community.”

DES is discouraging Flatley from removing any soils from the property at 701 Daniel Webster Highway — directly next to Saint-Gobain’s property at 685 Daniel Webster Highway — stating that if soils are removed, it could potentially pose a risk to groundwater quality at another location and “potentially expose Flatley to liability related to resultant impacts at the receiving properties,” states Kenison’s email.

According to the correspondence, Flatley has informed DES that no soils will be removed from the property during construction. In addition, DES is recommending that Flatley consider developing a Health and Safety Plan and a separate soil and groundwater management plan to prevent exposure to site contaminants during and after construction.

Public Safety Business Environment Merrimack Local and County Government

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