Assistant Fire Chief Michael Dillon displays the award presented to the Providence Fire Department by the U.S. Coast Guard yesterday.

The Providence Journal / Ruben W. Perez

PROVIDENCE — The eye-popping gasoline fire that half-destroyed a wharf at a waterfront fuel terminal last summer was not sparked by a lightning strike as was widely assumed at the time, but might have been caused by an electrical short circuit, Fire Department investigators have concluded.

The Fire Department yesterday released report of the July 18 fire at the Motiva Enterprises wharf as the department received an award from the U.S. Coast Guard for the department’s response to the fire.

Investigators said that while the source of the ignition is not known conclusively, the fire began when an unusually strong gust of wind pushed an offloading tanker away from the wharf and caused unbearable tension on the tanker’s fuel delivery hose and the wharf-side apparatus to which it was attached.

The blaze began in a 60-foot tall metal gantry — the gantry supported fuel-transfer lines from tankers and barges — where a vertical and a horizontal pipe were attached. The stress of the tugging fuel delivery hose, investigators said, caused the pipes to break apart, allowing gasoline to spill onto the wharf.

That strain possibly exposed electrical wiring and possibly caused a short circuit that ignited gasoline vapors, according to the report.

The fuel erupted in a fire ball at the wharf — the spectacular images were flashed nationwide on TV — and caused a shutdown of the regional terminal, disrupting deliveries of automobile and aviation gasoline and diesel fuel. Some gasoline service stations in the region ran out of some grades of gasoline and some ran out of gasoline altogether.

Motiva, which won’t estimate the financial damage from the incident, made sufficient repairs to reopen the north berth on the wharf to barges in October and says it is serving all its customers.

The tanker Nordeuropa was finishing offloading as a thunderstorm bristling with lightning approached, and the blaze began at 10:29 p.m. But the investigation, which was a cooperative effort of the department, the Coast Guard and Motiva, found no evidence that lightning was the cause, said Michael J. Dillon, assistant fire chief for operations.

Investigators made an exhaustive frame-by-frame analysis of a video recording from a security camera on the wharf. Lightning strikes were visible on the recording, but there were no strikes seen at the time the blaze began. The recording shows, instead, the Nordeuropa moving away from the dock at 10:28 p.m., the spilling of the gasoline, which pools beneath the gantry, and then a blue spark on the gantry that apparently ignited the fire, which traveled back up the hose to the tanker.

Although the Coast Guard helped with the investigation that was recapped in the report, Coast Guard Capt. Roy Nash, captain of the Port of Providence, yesterday stopped short of embracing its conclusion. Nash, who was at the Public Safety Complex to present the award, would not directly address the lightning issue.

“It’s entirely possible that [the fire] was associated with the vessel moving off the dock,” he said.

The Coast Guard is doing what is expected to be the definitive report of the fire, which Nash said is not expected to be completed until about January 2008. The report will cover the cause, recount what lessons were learned in the incident, say whether any party should be penalized and recommend operational or other kinds of changes, if any are needed.

The Fire Department report, authored by arson investigator Joseph Dorsey, does not discuss causes other than an electrical short circuit or lightning. But acting Fire Chief Mark Pare said, “It could have been a lot of things.”

Shortly after the fire, firefighters mentioned the possibility of static electricity. Yesterday, Fire Marshal Anthony J. DiGiulio said electric current in a wharf-side cable or a spark caused by metal striking metal also could have been the ignition source.

In a brief ceremony, Nash gave Pare an award to the department “for meritorious public service” in the name of the Coast Guard commandant.

The award lauds the department for its exemplary courage, dedication and leadership in the handling of the fire while, at the same time, the department stayed ready for simultaneous emergencies that might have cropped up.

“The initial assessment, judgment and immediate actions by the first firemen on the scene were instrumental to the success of the firefighting effort…,” the award states.

“Facing dangerous fire conditions complicated by an industrial environment, severe weather, darkness, and while working from a waterfront pier, firefighters fought a four-hour battle to suppress and gain control of a major flammable liquid fire with great tenacity and professionalism.” The flames towered nearly 50 feet above the wharf, the award states.

Capt. John Healey, who was in charge of the first fire company at the scene, attended the award ceremony and recalled later how his men had to pull hoses onto the 1,000-foot-long wharf by hand, braving the fierce fire.

He said the air had been calm minutes before the fire but that the storm hit quickly and whipped up what he described as hurricane-force winds, the strongest winds he ever experienced. A gauge on the Nordeuropa recorded wind of 60 to 80 knots, or 69 to 92 mph.

Despite the difficult working conditions, which included a power and telephone failure in the terminal and surrounding area, and the danger that the fire could become a conflagration, Healey said, “We went and did what we had to do and put that fire out.” When his company arrived, Healey said, the flames and smoke were so thick that they could not tell if a fuel tank, the wharf or the ship was afire.

Healey said he was more afraid of the lightning, with his crew exposed on a pier surrounded by water, than he was of the fire.

“It was pretty intense. There were lightning strikes all around us,” he said.

He complimented the Nordeuropa’s safety systems, which quelled the onboard fire, and said that if they did not work there would have been an explosion “and I probably wouldn’t be talking to you right now.”

Pare called the fire “a significant event in the history of the Providence Fire Department” because of the size of the blaze, which rivaled the worst mill fires the fire force has coped with. “This is one that you’ll remember,” he said.

Terminal operations are “back in full,” Stan Mays, spokesman for the Houston-based Motiva, said yesterday. Motiva plans to have the south berth rebuilt and operational for the fourth quarter of the year. The availability of the deepwater south berth will enable the company to resume deliveries by tanker, which will be more cost-effective and provide a more reliable supply than what Motiva gets now, he said.

DiGiulio said the new wharf will be virtually entirely steel and concrete and much more fire-resistant than was its 100-year-old predecessor, much of which was built of wood. A seawater-pumping system will provide all the water that would be needed to extinguish a fire, he said.

gsmith@projo.com