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Liberty Hill clean-up shifts gears after groundwater modeling

June 17, 2009
Gilford is still pushing for 100 percent removal of the coal tar on the Liberty Hill site, especially after new amendments were made to the previous plans for the Meadows Project.

"We think the town has misunderstood some of the plans that we submitted at the last technical meeting," said David Graves, spokesman for National Grid. "We always intended for this plan to adapt during the technical phase process."

The Liberty Hill saga started in the '50s when a gas tank exploded and the resulting waste was brought to Liberty Hill and buried deep by the side of the road. In 2004 the site was discovered and since then the town, the Department of Environmental Services and National Grid, the company now responsible for clean up, have been working toward removing some or all of the coal tar. While the town is adamant about removing all of the coal tar, National Grid submitted a plan that would remove 80 percent of the affected soil. The plan was to build a slurry wall around the rest to contain it.

This plan was approved by the DES and during the technical meeting between the parties to finalize and review details, National Grid was performing groundwater modeling, which can show how water is flowing now and years from now. The results of the groundwater testing showed that in the future there might be some leakage of the slurry wall. National Grid selected a well to go into and siphon off the water.

"This is just an enhancement to the plan," said Graves. "It was always intended that the plan would change once we got into the technical meetings and modeling."

Graves said that the leakage in the study was indicated to be 50 years or more in the future, if it happened, and it would be minimal. The well would be put in to take away any contaminated water in the future. The water would not start out as contaminated, Graves said, it is a prevention measure for the future. It would pump about two gallons per minute.

The town and National Grid sent a letter to DES outlining their positions. National Grid said that the timeline for natural attenuation of residual contamination does not change regardless of which remedial alternative is implemented. Graves described it as a low-level plume of low-level toxins that might appear in 50 years. Gilford officials are still requesting full removal of the contaminated soil. Graves said that it would cost some extra money, but a figure has not been determined yet and it would be a small amount comparatively.

"The distance between 80 percent and 100 percent is getting smaller and smaller," said Gus Benavides, chairman of the Board of Selectmen.

DES will look over the letters sent by both parties and technical meetings continue as the plans for the removal of the soil is detailed, finalized, debated and streamlined.

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