No signs of major fuel spill from capsized barge in SF Bay

Three days after the 112-foot barge Vengeance overturned in high winds near Yerba Buena Island, the U.S. Coast Guard worked Sunday to contain the diesel slick spilled from its depths and walked nearby beaches to check on wildlife.

The freight barge, owned by Vortex Marine Construction and contracted by BART for maintenance of its Transbay Tunnel, overturned Friday around 12:20 a.m. south of the Bay Bridge.

The barge carries 4,000 gallons of diesel fuel and 300 gallons of hydraulic fluid, said Adam Stanton, a spokesman for the Coast Guard. But it’s impossible to know exactly how much spilled without lifting the boat from the water, and that could take weeks, Stanton said.

Personnel in helicopters skimming low over the water during the weekend hadn’t noticed much of a sheen, the shimmering sign of a major spill, he said. And crews inspecting beaches around the area said they saw no signs of fuel-slicked animals.

Divers entered the 50-foot-deep channel Saturday to plug and seal the underwater vessel’s fuel vent, which was believed to have been leaking fluids into the bay.

The plug appeared to be “holding up well” Sunday afternoon, Stanton said, noting that there were no indications that the fuel had reached the shoreline, where it could slick and kill animals and plants.

This photo provided by the U.S. Coast Guard shows the 112-foot freight barge Vengeance after capsizing near Yerba Buena Island Friday. Crews Sunday were working to contain a fuel spill. This photo provided by the U.S. Coast Guard shows the 112-foot freight barge Vengeance after capsizing near Yerba Buena Island Friday. Crews Sunday were working to contain a fuel spill. Image 1 of / 7 Caption Close No signs of major fuel spill from capsized barge in SF Bay 1 / 7 Back to Gallery

Responders also over the weekend deployed thousands of feet of boom nets that are designed to contain such spills.

“If you tip something over like that, things are going to seep out when they can,” Stanton said.

Stanton said that getting the barge out of the water would be a complex and time-consuming process, noting that “every case is completely different.”

For example, it took crews almost a month to devise a plan and remove a boat that sank last year near Bethel Island, he said. The 85-foot paddleboat the Spirit of Sacramento capsized in early September on False River.

Coast Guard officials were working with the construction company and Global Diving and Salvage, hired by Vortex Marine Construction, to lift the barge out of the water.

It wasn’t immediately clear what caused the accident, though winds were whipping as high as 40 mph when it listed and capsized. No one was on board at the time.

Experts will work this week to analyze why the boat sank, including whether there was a hole in its structure, before figuring out how to remove it from the bay, Stanton said.

Michael Bodley is a San Francisco Chronicle staff writer. Email: mbodley@sfchronicle.com Twitter: @michael_bodley