DES stops short of complete removal at Liberty Hill

The New Hampshire Department of Environmental Services (DES) yesterday gave its preliminary approval to KeySpan Energy Delivery's proposal to remove 80-percent of the contaminated materials from land off lower Liberty Hill Road, where toxic coal tar was dumped in the early 1950s, while containing the remainder within a slurry wall topped by an impermeable cap.

Town officials and neighborhood residents have steadfastly insisted that nothing short of removing all the contaminated material is required to protect human health and the natural environment. "I am very, very disappointed in DES," said Selectman Gus Benavides in reaction to the decision. "It is upsetting, discouraging to think that 80-percent will be removed and 20-percent left in the ground. If you had cancer, would you want to be treated by a doctor who said he would remove only 80-percent of it?" he asked.

Alice Boucher, chairman of the Selectboard, said that she too was "disappointed" that DES had not called for complete removal, especially since local officials and residents had "sent the message that was what they wanted loud and clear." However, she acknowledged that "if they're not going remove all of it, this option is better than the others they proposed."

Sharing the disappointment of her colleagues, Selectman Connie Grant declined further comment until she had an opportunity to read the decision. However, she remarked that since "the town wants it all removed, I don't know if 80-percent will be enough."

Jim Martin, the DES spokesman, said that the department has scheduled a public meeting to be held in the Gilford Town Hall on March 24. The department will accept public comment on its preliminary decision for 30 days after the meeting and expects to issue a final decision within another 60 days, which would put that place that mark in late June. Martin said that the department would review the public comments and incorporate them in its final decision.

The final decision can be appealed to the Waste Management Council, a panel of 13 public members, appointed by the governor and Executive Council, representing diverse interests that advises the Waste Management Division.

In 1952, the coal tar, a by-product of an abandoned manufactured gas plant in Laconia, was dumped in a sand and gravel pit on the south side of lower Liberty Hill Road, which was subsequently filled-over and divided into house lots. However, it was only discovered by KeySpan, the corporate successor to the original gas company, in the course of litigation in 2004.

Of the five house lots — 63, 69, 77, 83 and 87 — directly affected, Keyspan has acquired three and demolished two homes in anticipation of excavating the site and dealing with the contaminated soils.

Nearly a year has passed since GEI Consultants, Inc. of Woburn, Massachusetts presented four "remedial action alternatives" (RAAs), including total removal of all contaminated material, for addressing the contamination at the site. KeySpan preferred RAA4, the least expensive of the four, which called for removing 11,000 tons of soil and leaving some 99.5-percent of the contaminated material in place contained within a slurry wall and beneath an impermeable cap. Last September DES rejected KeySpan's recommendation, stipulating that most of the contaminated material must be removed from the site.

In November, GEI proposed the alternative — RAA5 — which DES approved by letter to KeySpan yesterday. The plan specifies the excavation of "tar-impacted" soil to a depth of three feet and the excavation of "tar-saturated" soil below three feet, which would remove approximately 80-percent of the contaminated material. The letter distinguishes between "tar-impacted" and "tar-saturated" soil, explaining that the latter, which would all be removed, contains "the greatest concentrations of contaminants." The remaining 20-percent of the contaminated soil would be contained within a slurry wall and impermeable cap, the performance of which would be monitoring by groundwater sampling and regular inspections.

Altogether 33,000 cubic yards of soil would be excavated and 27,500 tons removed in 1,370 truckloads over 14 weeks at an estimated cost of $8.7-million. In contrast, removing 100-percent of the contaminated material — RAA 1 —would require excavating 114,000 cubic yards of soil and removing 121,000 tons in 6,000 truckloads over 60 weeks at an estimated cost of $15.9-million.

In support of DES's choice of RAA 5 over RAAA 1, project supervisor Michael McCluskey noted that the department is bound by regulatory criteria, among them that "the risk to human health will be reduced to the greatest extent practicable, balancing costs and benefits by evaluating the risk to human health and the environment." He said that heath and the environment are protected by eliminating exposure pathways to the contaminants, explaining RAA 5 would remove 80-percent of the contaminants and cover the remainder with three feet of clean soil and an impermeable cap while restricting use of the site to forestall exposure.

Meanwhile, McCluskey stressed that contaminants have not be detected in local residential wells, which draw from the bedrock, or in monitoring wells sunk to the bedrock. The slurry wall, he said, would prevent the migration of contaminated groundwater. McCluskey described a "small groundwater seep adjacent to Jewett Brook" the only exposure pathway for contaminated groundwater and stipulated that it must be eliminated.

Comparing the two options, McCluskey concluded that both would "eliminate direct contact exposure pathways" and in each case the restoration of groundwater quality would require approximately 35 years while RAA 5 would require more long-term management to ensure the integrity of the slurry wall and impermeable cap.

"The primary difference," he wrote, "is that with RAA 5 some contaminated soil and groundwater would remain contained within the slurry wall , where it would not pose a risk to human health or the environment."

DES found that the additional $7.2-million required to remove all the contaminated material from the site "would result in no appreciable reduction in risk to human health and would provide little or no benefit to the environment." RAA 5, McCluskey called "the most appropriate remedial action alternative with the most favorable balance of benefits and costs."

Referring to McCluskey's remarks about cost-benefit, Benavides suggested that costs trumped benefits, repeating that nothing short of complete removal was require to eliminate the risks to human health and natural resources. "They are not looking long-term," he said. "They can't guarantee that the contaminants will not escape. The slurry wall could fail. What if there were an earthquake?"

Saying that the process had reached "an impasse," Benavides said "we will consider all our alternatives." He said that "Liberty Hill will be on the agenda of our next meeting and we'll move on this right away."

Boucher, who will retire from the board this month, pointed out that "it is a preliminary decision" and said "the process has to play itself out. You don't want to put two feet into the fire before the embers have started," she remarked.