Pipeline company Plains All American said operations to remove the damaged section of a pipeline that spilled oil off the California coast could begin Tuesday.

California Gov. Jerry Brown declared a state of emergency for Santa Barbara County last week after a section of so-called Line 901 ruptured and spilled about 500 barrels of oil off the coast of Refugio State Beach.

Plains said it conducted a line inspection in early May to determine the status of the pipeline.

"Although the final report is still being developed, we requested and received an expedited preliminary inspection report to determine if there are any areas that need investigating prior to emptying the remaining oil in the line," Patrick Hodgins, senior director of safety for Plains, said in a statement Monday. "Based on this rough cut of the data and in accordance with our company's integrity management plan, we identified four locations on Line 901 that we plan to investigate as part of our customary procedures."

Plains officials apologized for the incident. A valve fault at a pumping station operated by Plains in 2014 resulted in the release of about 10,000 gallons, or 238 barrels of oil. Los Angeles officials said the oil was "knee-high" in some areas following the release.

The company said it couldn't determine the cause of the Refugio release. Operations to remove the damaged section of the pipeline are expected to begin within the next 24 hours.

Hodgins said workers already deployed elsewhere along the pipeline's route are working on preventive maintenance issues and are not there as part of the emergency response effort.

At the site of the release area, the company said more than 70,000 cubic feet of oiled soil has been removed. On the beach, crews are working to manually clean residual oil from the shoreline and, offshore, more than a dozen vessels are deployed with absorbent boom to capture remaining sheen.