With trucks rumbling behind the secured gates of the National Grid remediation site on Long Island Avenue in Sag Harbor, the utility is moving forward with the ambitious cleanup of coal tar left in the ground for what may have been decades.
In the last month, National Grid – formerly KeySpan – has been engaged in the beginnings of a nine-month remediation of toxic soil under the now removed Hortonsphere and manufactured gas plant.
While just commencing the state-mandated plan, there has been no shortage of changes in that corner of the village, as the Schiavoni building was torn down, fences, offices and water towers erected, streets closed and a pipe line laid across the waters of Sag Harbor Cove, stretching towards North Haven where it will end at the breakwater.
And while the large scale excavation planned for the project has yet to begin, over 500 tons of soil has already been taken out of the village by an army of trucks as National Grid lays a concrete barrier wall around the perimeter of the cleanup site – a demarcation line of sorts that will define the area to be excavated in coming months.
The cleanup requires the excavation of soil containing coal tar on the site as deep as 10 to 15 feet in order to successfully remove any danger to the environment. The water table in the area, and in Sag Harbor, is so close to the surface that the excavation will require dewatering – removal of the water from the toxic soil — before that soil is trucked out to a DEC-approved disposal site. The water will then be treated and cleaned before it is pumped via the pipeline out past the breakwater near North Haven. Sag Harbor Village officials initially expressed concern the plan could have a negative effect on the salinity and therefore ecology of the area, but said this summer that salinity modeling had allayed their fears.
According to information provided by Wendy Ladd, of National Grid, most of what is being accomplished on the site so far is characterized as a “mobilization effort,” meaning the heavy lifting has yet to begin. Construction equipment, materials and temporary facilities have been set up on site, and Bridge Street is now closed and will not be open again until this coming summer. As National Grid explained this summer at a number of presentations to the village, Long Island Avenue will also be subject to temporary closures as the project moves forward.
While it may have looked as if some of the large-scale excavation at the site has already begun, according to information provided by Ladd, workers from Sevenson Environmental – the contractor performing the work for National Grid – have been digging trenches to form an underground concrete wall that will surround the site. The soil and debris removed as the trenches are dug is placed on a designated storage pad, sprayed with foam that prevents odor and dust from escaping and covered with a plastic liner until it is removed from the site. Last week, 23 trucks transported 545 tons of soil to a facility in New Jersey for disposal.
One problem that arose over the course of the last month developed when slurry, meant for the concrete barrier, accidentally broke into a village sewer line on Long Island Avenue, creating a blockage. According to a release issued by National Grid last week, the utility and the village are continuing to work on clearing the blockage, with the company providing a tanker truck to the village in the meantime to pump sewage from the pipes and transport it to the village sewage treatment plant on Bay Street.
Miller Environmental, which is installing the pipeline through Sag Harbor Cove and past the breakwater in North Haven began that process this week. According to Ladd, 2,400 feet of the total 3,740 feet of pipeline has been welded together and placed, floating, in the harbor.
According to Ladd, Sevenson Environmental will take the next several weeks to set up the water treatment plant necessary for the project. The concrete barrier wall is also still under construction, and a fabric tent, which ideally will keep odors and debris from entering adjacent properties will also be erected in the next two weeks, according to National Grid.Â