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Staff Writer

HARVARD — Consistently-dropping tetrachloroethene levels measured in a plume of groundwater under the former Moore Army Airfield and a lack of measured presence since March 2006 in the north plume near the source of contamination proves the 2-year-old cleanup project successful.

That conclusion was delivered by Chuck Castellvecio, of Army contractor Arcadis Engineering, at last week’s Restoration Advisory Board meeting in Hildreth House. The total cleanup is expected to take 23 years.

Three remedies are in use to minimize arsenic and tetrachloroethene in a groundwater plume — an underground, balloon-shaped mass — that has been slowly spreading from the former Army parachute cleaning compound abutting Route 2A across the airfield toward the Nashua River and Oxbow Wildlife Area wetlands. More than 40 driven wells are used for the remedies and monitoring results.

One remedy is an Enhanced Reductive De-chlorination (ERD) system that expedites degrading carbon-based compounds by driving them through vinyl chloride to produce methane which is then neutralized.

“This area has an established five-year history, and it illustrates we are knocking things down to zero,” said Castellvecio.

A second remedy is an In-Well Stripping (IWS) system that uses two re-circulation wells to treat 20 to 30 gallons of water per minute with dissolved oxygen to eliminate impurities. What comes into the wells and what leaves them is monitored.

A third remedy, the Soil Vapor Extraction (SVE) system, removes recoverable compounds from the soil with the use of molasses.

Land-use agreements are currently in place with a property owner in the cleaned-up north plume area across Route 2A from the parachute facility, said Castellvecio. The owner has lease restrictions in the plume’s source area.

A Memorandum of Agreement (MOA) is being updated with the U.S. Fish and Wildlife Service in the southwest Plume across the airfield on the Nashua River side and a Notice of Land Use Controls is being finalized with MassDevelopment.

Board member William Ashe, in reference to MassDevelopment’s stated intent to build 200 houses on the airfield at some point, wondered what kind of land-use controls are in place.

MassDevelopment representative Ronald Ostrowski said housing would be located on the 240 acres above the spot where any runoff from the airfield groundwater might be found, and that runoff would be well-controlled.

He said MassDevelopment is also looking at rare plant species and the presence of the protected Sparrow Grasshopper in the area.

“We can’t build there anyway with current zoning,” said Ostrowski.

Massachusetts Department of Environmental Protection representative Lynn Welch said the area is currently described as a special use II in the Devens Reuse Plan. She said the department would have to approve any plan that’s forwarded.