SALEM — The National Grid underground electric transmission cables that run down Derby Street have been leaking oil into the South River basin for years, according to the state Department of Environmental Protection.
Although the last reported leak was four years ago, there were multiple reports in prior years, according to DEP spokesman Edward Coletta.
“One (of our workers) remembers a report of 10 leaks over one summertime,” said Coletta. “(But) we have not had a report of any kind of leak coming from that line since December 2009.”
Others, however, say the leaks persist.
“I’ve called and reported the oil spills and it’s been implied to me from DEP that they know what it is,” said Barbara Warren, executive director of Salem Sound Coastwatch, an environmental organization that monitors coastal waters.
The DEP has told her the oil is not hazardous, Warren said, but when she asked if they wanted a sample from the South River, Warren said she was told, “Don’t touch it.”
“What kind of message are you giving to the public when you say that?” she said. “I think it needs to be clarified. Is it hazardous or is it not hazardous?”
The dielectric, or mineral, oil is used as insulation in the underground, high-voltage transmission lines, replacing a more hazardous oil used years ago that contained cancer-causing PCBs, according to Coletta.
Although the oil is listed in the Massachusetts Contingency Plan as a substance that must be addressed if spilled in large quantities, Coletta said the mineral oil is “probably among the more benign oils we deal with.”
“It’s something you don’t want to have in the environment in large amounts, but it’s more benign than other oils,” he said.
He said vegetable oil is also on the state’s Contingency Plan list.
The high-voltage transmission lines that run about 1 mile from Fort Avenue to Canal Street have been making news recently as National Grid prepares to replace them. Although the utility plans to install new lines though a neighborhood near Salem Common, it says it intends to remove the old cables buried under Derby and Canal streets because they are leaking fluid.
Recently, however, two Salem city councilors asked for a waiver of the DEP regulation so a buried transmission line can remain in the ground to avoid digging up Derby, New Derby and Canal streets.
In a letter, Councilors Josh Turiel and Bob McCarthy argued that the cable “is not presenting any hazard to the city at this time, nor is it likely to as the insulation material is essentially simple mineral oil.”
They said Massachusetts is the only state with a regulation requiring removal of cables with mineral oil.
National Grid said these old cables have leaked in the past and need to be removed. They have repaired the cables numerous times and, on occasion, removed contaminated soil, a spokesman said.
“We have consistently said that these cables are nearing the end of their serviceable life and need to be replaced to make sure National Grid can continue to provide safe and reliable electric service to the city of Salem and the North Shore distribution system,” said David Graves of National Grid.
Nick Helides, who keeps his boat at Pickering Wharf, said he has seen an oily sheen on the water for years and is convinced it is caused by oil from the leaking transmission cables. It’s worse on a rainy day like yesterday, he said.
“You can go down there and actually see the stuff,” he said.
Tom Dalton can be reached at firstname.lastname@example.org.