Gas ball cleanup is a dance of sorts

Each day, heavy machinery dances an intricate ballet around the 5-acre former gas manufacturing plant on Long Island Avenue in Sag Harbor.

As excavators gouge mountains of contaminated soil from the ground beneath an acre-sized tent, a continuous parade of giant dump trucks rumbles into the fenced-off property, 40 a day, taking on carefully sealed 10-ton loads of the tainted spoils, and receiving a thorough cleaning before being released for a return trip to deposit sites off Long Island.

The trucks stage outside the village and, when cued by radio, rush down the now closed Bridge Street into the site, five at a time, to pick up their loads. Once within the close confines of the work site, they are slowly and carefully moved through overlapping paths: one truck backs into the tent to be filled by backhoes, the next rolls past the tent entrance to turn its stern toward the opening, the full truck exits the tent and into a cleaning station, and the next backs in behind it.

Each load of dirt gets a “burrito wrap” of heavy tarpaulin, cinched tightly to prevent any of the soil from spilling out during the long journey. While the wrap is being closed by workers on a moveable scaffolding, crews below, clad in rubber suits and armed with power washers, blast the residue of the work off the trucks’ undercarriages and tires, as much to keep Sag Harbor’s streets clean as to contain every bit of contaminated soil.

In all, between 1,200 and 1,300 truck loads of dirt are being removed from the site, and an equal number re-deposited in the hole, up to 15 feet deep in places, they leave behind.

The property, owned by natural gas giant National Grid, along with a neighboring parcel owned by Diane and Gabe Schiavoni, was contaminated with coal tar, a byproduct of the gas production that took place on the property from the 1860s through the 1930s. The coal was burned, and the gases released were harvested to fuel the power plant that provided electricity to the village until the 1980s.

As the ground is excavated and re-filled, the monstrous tent is shifted around the property, to contain odors and dust from the excavation work. The tent is currently in the third of six placements. The final bits of excavation work, on a narrow peninsula of contaminated land at the southern edge of the property, will be done last and without the cover of the tent. Special foam spray will be used to control odor and dust during that phase of the work, according to Ted Leissing, the project manager for National Grid.

The loud and dirty but carefully choreographed operation, when completed later this spring—possibly by late May if all goes well—will return the property that once housed several locally owned businesses to usability. With the contaminated soil excavated and replaced with clean soil and about 1 million gallons of polluted groundwater treated and pumped through a long pipe into Shelter Island Sound, the land will be clean and completely safe for human occupation, Mr. Leissing said.

The first phase of the cleanup began in 2006 when National Grid removed the once famous Horton Sphere, a giant steel ball that was used to store natural gas pumped in after on-site gas production was halted. The famous “big blue ball” had loomed large as the most obvious structure in the village’s skyline for decades.