WOONSOCKET — Nearly a million gallons of partially treated sewage is thought to have spilled into the Blackstone River when a demolition crew at the burnt-out Seville Dyeing site accidentally ruptured an underground sewer main Friday afternoon, the state environmental agency said.
The effluent is believed to have been streaming unchecked from the broken main for more than 48 hours before a neighbor noticed and called the city's water department, said Angelo Liberti, chief of surface water protection for the state Department of Environmental Management.
City officials began taking measures to stop the flow and decontaminate the site, off First Avenue, after reporting the spill to DEM about 7 p.m. Sunday.
The long-vacant textile finishing factory was destroyed in a still-unsolved arson fire on Feb. 27. Shortly before that, a portion of the roof had collapsed under the weight of last winter's heavy snow.
At about 3:30 p.m. Friday, a worker with a wrecking crew was demolishing a portion of the foundation when he apparently broke an underground sewer main. Liberti said the worker did not report the incident and later told authorities at DEM he did not realize there was a problem.
The break apparently went undetected until shortly before the city reported it to DEM Sunday. The city learned of it from a neighbor who was near the demolition site and observed “some kind of flow,” according to Liberti.
Some of the partially treated sewage was entering a nearby storm drain, and some was collecting on land nearby.
“Either way,” said Liberti, “it was getting into the Blackstone.”
Based on the amount of time the pipe was open before the spill was contained and the volume of sewage usually passing through it, Liberti said that up to 920,000 gallons of partially treated wastewater may have found its way into the river.
By yesterday afternoon, he said, the wastewater plume was believed to have already passed through all the downriver cities and towns along the Blackstone. Nevertheless, said Liberti, out of an abundance of caution, DEM had issued an advisory against swimming in or eating fish from the river, to remain in effect through this morning.
DEM also evaluated the data against its standards for closing shellfishing beds in the upper Narragansett Bay and saw no reason to declare any of those areas off-limits.
While city officials could not be reached for comment about the incident on Monday, Liberti said he was satisfied that they had acted appropriately in responding to the incident once they learned of it.
As soon as the incident was reported to DEM, Liberti said, the city corralled resources to chlorinate the premises where sewage reached land. They also used special trucks to draw sewage from the ruptured portion of the main and carry it away for proper disposal while working on a permanent patch for the leak.
Liberti said he did not know the identity of the demolition company or the crew member responsible for the mishap. But he said DEM has not yet ruled out some type of enforcement sanctions against the parties involved.
“There's always the potential for fines,” said Liberti. “We don't know yet. We're just beginning our investigation.”