Three workers have been confirmed dead and two are missing and presumed dead after a pipeline ruptured and exploded Nov. 9 during construction in Walnut Creek, Calif.

The dead were working on a water pipeline that the East Bay Municipal Utility District is building to transport water from Walnut Creek to San Ramon. The line is parallel to a gas pipeline. A full investigation is pending, but early speculation suggests that the water pipe had inadvertantly come in contact with the gas pipeline, triggering the explosion. Two died in the explosion and a third worker died a day later from third-degree burns. Four others are still in the hospital with moderate to severe burns. Due to safety concerns about residual gas vapors, rescue teams have been thwarted in their attempt to locate the missing workers who could be trapped inside a 15-ft-dia pipeline.

The owner/operator of the gas pipeline that runs parallel to the water line is Houston-based Kinder Morgan Energy Partners (KMP). KMP employees shut down gasoline transmission in the 10-in.line. But residual vapors caused the area to reignite twice after the initial fireball was extinguished after 90 minutes.

The 60-mile pipeline transports gasoline, jet and diesel fuel from Concord to San Jose. According to a KMP press release, "Once the fire department and Cal-OSHA provide permission to enter the site, KMP will use vacuum trucks to remove gasoline from the pipeline, assess the damage and develop a strategy to repair the line and place it back into service as soon as possible."

Because of the proximity to Bay Area refineries and alternative fuel supplies, products can be trucked into the market so no supply problems are expected.

Sources at KMP say that, with the exception of the San Jose pipeline, KMP's 3,850-mile Pacific pipeline system is operating and continues to transport fuel to California and neighboring western states. KMP officials do not expect the incident to have a significant adverse financial impact on the company.

Chris Weden, a U.S. Environmental Protection Agency official on the scene, says, "It was abundantly apparent that local authorities would be able to take care of the incident." He does not anticipate an environmental clean up to be required.

As many as 270 homes in the area near Las Lomas High School were evacuated for the day using an automated phone system. All of the victims were thought to be employees of East BayMUD's contractor or subcontractors of Livermore, Calif.-based Mountain Cascade.

An EBMUD statement says, "It's too early to be able to determine exactly what happened. We are cooperating with regulatory agencies, who are responsible for stabilizing the site and conducting a thorough investigation."

Authorities are looking into whether Mountain Cascade notified KMP immediately before digging as required by law. East Bay MUD awarded Mountain Cascade a $16-million contract in August after terminating another contractor, Cambridge, Mass.-based Modern Continental Co., for missing deadlines on the project, which is part of a comprehensive capital program to upgrade the Walnut Creek water system.

According to reports from the California Dept. of Industrial Relations, Mountain Cascade has had two deaths in the last five years–one in April 1999 and one in March 2004 when a 31-year-old worker was crushed while unloading a sewer pipe. Mountain Cascade was fined $36,000 after investigators determined the load was not properly secured.

Tuesday's incident was California's first fatal accident involving a liquid petroleum pipeline since 1989, when two people were killed at a train derailment site. The U.S. Dept. of Transportation, Office of Pipeline Safety, reported that the average number of accidents per year for liquid pipelines has been decreasing over the last ten years.