Hanover — Dartmouth College has sent a response letter to the attorneys for a Hanover family whose well was contaminated by the school, arguing that the residents’ threat of a federal environmental suit would not hold up in court.

The lawyers, Geoffrey Vitt and Anthony Roisman, in October notified Dartmouth that it was on deadline to respond to concerns that the college had polluted the area around Rennie Farm, a former dump site for laboratory animals near Hanover Center, and endangered the neighboring Higgins family, who learned in 2015 that their well contained a probable human carcinogen from the waste site.

The Higginses have reported health effects, including dizziness and sores on their skin, that they ascribe to the presence of the pollutant, a chemical called 1,4-dioxane, in their water. Dartmouth countered in its letter that the family had provided “no medical or scientific evidence” to bolster that assertion.

College officials on Jan. 10 offered a detailed timeline of their cleanup of Rennie Farm in addition to legal analysis indicating that Dartmouth could not be held liable for pollution under the 1976 Resource Conservation and Recovery Act, as Vitt and Roisman alleged this fall.

Dartmouth has provided the Higginses with bottled water, a filtration system for their well and access to medical advice. The college also dug a new drinking water system to which it offered to connect the Higginses, but the family declined, noting that the new well was located on the more than 200-acre Rennie Farm property.

The law allows the Higginses to sue Dartmouth in federal court and ask for injunctive relief, as well as fines that would be paid to the government. The family’s attorneys also said they can bring state-level common-law suits into the mix that could result in damages paid to the Higginses.

“The costs of this clean-up have been enormous and the estimates of litigation costs to bring such a suit to dismissal will be high, and from Dartmouth’s perspective a needless, unfortunate exercise,” said Dartmouth’s response letter, which was signed by Bruce Felmly, director of litigation at McLane Middleton of Manchester. “Similarly, the costs to the Higgins(es) to pursue such a claim would likely exceed $100,000 in expert and related costs with an extremely low probability of any court-ordered award of attorney’s fees or expert fees.”

Dartmouth officials in December estimated that the cleanup had cost the college about $8 million so far. That includes everything from a 2011 excavation of the Rennie Farm site to today, as college contractors run a series of pumps meant to remove the contaminated water from the neighborhood for treatment.

The water pumping and treatment may last as long as five years, administrators said.

The Higginses and their lawyers must wait 90 days after their initial Oct. 27 letter, according to statute, before they may bring suit in federal court in Concord.

Three scenarios could prevent action against Dartmouth now, Roisman said in an interview on Friday: if state officials sued the college first, if federal officials did so, or if the Higginses were satisfied with Dartmouth’s response.

The letter did not seem to have fulfilled that last option on Friday.

“Our clients have read the letter,” Roisman said. “Obviously they are not inclined to think there’s anything in there that exonerates Dartmouth.”

“Nothing in that letter made their water safe to drink,” he added.

Dartmouth’s lawyers also provided a step-by-step timeline of their efforts to remediate Rennie Farm, a chronology they said refuted the Higginses’ claim of negligence.

“The claims simply do not and will not hold up, either in the public scrutiny or in litigation if the Higgins(es) pursue a citizen’s suit,” Felmly wrote. “… Dartmouth has continuously worked to engage with and keep informed all state agencies and has consistently operated consistent with all state permit requirements.”

Roisman said he and Vitt had not yet reached a decision with the Higginses about their next steps, including whether or when they may bring a case to court.

“We have not consulted with our clients and have not made a decision about that,” he said. “I think it’s fair to say that nothing in that letter has led us to believe that this case has less merit than we thought it did. And a number of things in that letter have led us to believe that this case is stronger, even, than we imagined.”

Those included some “fairly obvious technical errors” that Roisman said could be corrected, but also a description of a “very gradual, step-by-step approach” to the contamination on Dartmouth’s part. Roisman questioned what he said had been the deliberative pace of Dartmouth’s work, given that the pollution was “an immediate issue for our clients.”

Roisman, who lives in Weathersfield, was called into the case by Vitt, a Norwich-based attorney who has represented the Higginses since their property was found to be contaminated.

Talks with Dartmouth led by Vitt had stalled over the conditions of the college’s possible reparations to the Higginses.

Decades ago, Roisman headed the hazardous waste litigation section of the U.S. Department of Justice and oversaw the government’s response to a contamination of the “Love Canal” neighborhood in Niagara Falls, N.Y., that helped spur the passage of the 1980 Superfund Act. He said he did not directly participate in the case, however.

Later, as a member of a pro bono legal group, Roisman helped represent residents of Woburn, Mass., in a suit over trichloroethylene dumping. The case became the subject of a best-selling book and a movie.

Rob Wolfe can be reached at rwolfe@vnews.com or 603-727-3242.