Coal Tar on Liberty Hill Road

Environmental officials are monitoring groundwater quality at three residences on Liberty Hill Road where it was recently learned that coal tar was buried more than half a century ago. Robert Minicucci, the project engineer with the New Hampshire Department of Environmental Services (DES), said that residential wells were first tested last June and monitoring wells were recently drilled on the properties in an effort to delineate the extent of the deposits and measure the risk of potential contamination to the groundwater.

John Ayer, Director Planning and Land Use, said that the properties lie within the bounds of the aquifer protection overlay district adopted by the town in March.

Following the initial water sampling, Minicucci wrote to the homeowners to report that tests for volatile and semi-volatile compounds known to be associated with coal tar found nothing “at concentrations above detection limits.” Nor was cyanide found in the well water. He said that the monitoring wells were intended to gather the information required to determine what measures would be necessary to remove the risks to human health and groundwater quality. Once the data from the monitoring wells was collected and analyzed, Minicucci said, DES would develop a range of options and prepare a “remedial action plan.”

Minicucci explained that the presence of the coal tar was discovered quite by chance. In 1952 a gas plant, which had operated under a number of owners on Messer Street in Laconia since 1894, exploded. By then the process of manufacturing gas from coal and oil had become obsolete and after the explosion and fire much of the facility was demolished by Gas Services, Inc., which acquired it from Public Service Company of New Hampshire (PSNH) in 1945.

In 1993, divers discovered coal tar, a byproduct of burning coal and oil to make gas, leaching through the sediment on the bed of the Winnipesaukee River. Between 1999, when the cleanup operation began, and 2001 17,000 tons of coal tar were removed from the riverbed and more than 200,000 gallons of contaminated water were treated at a cost of about $10 million.

The cost of the project was shared between PSNH and Keyspan, the corporate successor to Gas Services, Inc., which in 1982 had become Energy North Natural Gas. Minicucci said that Keyspan sought to recover a share of its expenses from its insurance carrier and when it was refused reimbursement went to court.

In the course of the proceedings, one witness recalled that following the closure of the gas plant coal tar was buried in what was then a sand and gravel pit on Liberty Hill Road in Gilford. “By all accounts jaws dropped in the courtroom,” Minicucci said.

Some years after the dumping, the pit was reclaimed and subdivided into house lots.

Coal tar is distilled, first into a series of organic products, or “coal tar crudes,” like benzene, toluene and naphthalene, then further to make a diverse range of products, including dyes, drugs, explosives, flavorings, perfumes, preservatives, resins and paints. The residue from fractional distillation is used in paving, roofing, waterproofing and insulation materials. Coal tar is listed as a Class 1 carcinogen, indicating that there is sufficient evidence that it can cause cancer in humans.

Minicucci praised Keyspan Energy for responding promptly, responsibly and effectively to the situation on Liberty Hill Road once it came to light. “They have done a real good job,” he said.