RICHMOND (CBS SF/BCN) — About 12 to 18 barrels (500 to 750 gallons) of a low-sulfur diesel fuel and flush water mix was released in a leak Tuesday at the Chevron refinery long wharf in Richmond, according to lab analysis and technical review announced Wednesday night.

Earlier, the California Department of Fish and Wildlife said that the impact from Tuesday’s petroleum product leak at the Chevron Richmond Refinery appears to be centered near the city’s Keller Beach, but no oiled wildlife or public health impacts have been found.

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Representatives from federal, state and local agencies continued working with Chevron Wednesday morning to help the company clean up the spill in Richmond.

Richmond Mayor Tom Butt joined a U.S. Coast Guard helicopter crew that flew over the area around 7 a.m. Wednesday and found sheening from Point Molate to Brooks Island, and response teams have gone to shorelines in the area to do further assessments, state fish and wildlife officials said.

“A patchy sheen from Point Molate to Brooks Island was observed during the overflight,” according to the spill Unified Command that includes Chevron, the state wildlife agency’s Office of Spill Prevention and Response, Contra Costa Health Services and the U.S. Coast Guard.

“Sheens remain visible in some areas along the southeast side of Point Richmond,” the Unified Command said. “Boom was preventatively placed in sensitive areas and there has been no reported impact in those areas.”

Public access to the water along Western Drive and at Keller Beach are closed during the response to the spill.

Among the agencies helping the clean up were Contra Costa Health Services and the U.S. Coast Guard.

“That’s good news, that we are seeing a lighter product because on a sunny day like today, it can actually dissipate that fuel from the surface,” said Department of Fish and Wildlife Spill Response spokesperson Eric Laughlin.

Crews continued to contain and collect the oil spill along the coast of Point Richmond. A total of 3,500 feet of boom was deployed in the Richmond eel grass beds north of the spill and 2,500 feet at Brooks Island south of the spill, with more in place in other sites to proactively protect sensitive areas, officials said.

“At this time, the only shoreline area known to have been affected is immediately adjacent to the Chevron wharf,” the Unified Command said in an update Wednesday night.

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Hundreds of gallons went into the Bay between 2:40 p.m. Tuesday and about two hours later when the leak from Chevron’s long wharf was stopped, according to Contra Costa County Supervisor John Gioia.

The Contra Costa County Sheriff alerted local residents of the spill around 3 p.m. Tuesday. The sheriff sent boats to assess the spill, which appeared at the refinery’s long wharf near the Richmond-San Rafael Bridge. Chevron also initiated its response plan, notifying government agencies and containing the release.

The Bay Area Air Quality Management District tweeted out at around 7:15 p.m. Tuesday that approximately 600 gallons total of the petroleum and water mixture had leaked into the Bay. The sheriff gave the ‘all clear’ around 8:40 p.m. along with a message, saying, “The emergency situation has ended. Please feel free to resume normal activities. Please open doors and windows to air out buildings and homes.”

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Chevron later identified the source of the spill as a pipeline near the wharf. It was shut down and crews secured the leak.

“The line in question is used to transport a variety of oil and products that are returned to the refinery for reprocessing,” Chevron wrote in a Facebook post on Wednesday morning.

“We did determine that there was a quarter inch hole so that hole was capped fairly quickly,” said Laughlin.

As far as the cost of the clean-up effort, Laughlin noted that Chevron would be reimbursing the agencies involved.

“The company would actually be responsible for all the time of the responders, all of the equipment, all of the helicopter time and all those kinds of things in the response,” he explained.

Chevron officials asked the public to report any oiled wildlife encounters or sightings to the Oiled Wildlife Care Network at 1-877-UCD-OWCN (1-800-823-6926).

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Don Ford contributed to this story.