MARTINEZ, Calif. -- The company that owns the tugboat that crashed into Tesoro Corp.'s Avon wharf in Martinez has confirmed that the vessel's captain refused alcohol testing and that a crewmember tested positive for alcohol.

AmNav Maritime Services, an Oakland-based company that owns the tugboat Independence, released the statement saying they were cooperating fully with the U.S. Coast Guard's investigation into the incident. The company provides harbor assist services to the Ports of San Francisco and Los Angeles/Long Beach.

"This is extremely disconcerting. AmNav's company policy is simple. AmNav has a zero tolerance policy when it comes to the use of alcohol or drugs," AmNav Maritime spokesman Sam Sacco said in a prepared statement.

Officials said that the company would continue to assist the Coast Guard with the investigation and conduct an internal investigation of its own.

The crash occurred at about 12:20 a.m. when the tugboat, traveling from Pittsburg to its dock in Benicia, struck the pier and a network of the Tesoro Corp.'s fuel transfer pipes.

Fearing that the crash could have ruptured the refinery's main product transfer pipeline, releasing as much as 1,500 gallons of gasoline or diesel fuel, Tesoro officials sent 11 containment and collection vessels to the site.

Officials from the Coast Guard, the California Department of Fish and Game, the Contra Costa County Hazardous Materials program and the regional air and water quality control agencies responded to the wharf, but it was too dark to see the extent of the damage.

Department of Fish and Game Office of Spill Prevention and Response spokeswoman Carol Singleton said that once the sun came up, officials were met with good news -- the pipes had been bent, but not broken and the integrity of the refinery's pipeline had not been breached.

The only section that ruptured was a sampling port used to test the quality of gasoline, which released about 5 gallons of gasoline, Singleton said.