Unified approach at Drift River Terminal

U.S. Coast Guard, the State of Alaska and CIPC work together to prevent an oil spill resulting from eruptions on Redoubt Volcano

Alan Bailey

Petroleum News

Faced with mudflows lapping at the protective dike around a tank farm holding about 6 million gallons of crude oil, the U.S. Coast Guard, the Alaska Department of Environmental Conservation and Cook Inlet Pipe Line Co. have formed a unified command to address the question of preventing an oil spill disaster at the Chevron-operated Drift River Marine Terminal at the base of Redoubt Volcano on the west side of Alaska’s Cook Inlet. Cook Inlet Pipe Line is the owner of the terminal.

Explosive eruptions at the volcano on March 22 and 23 triggered melting of ice in the Drift Glacier near the volcano’s summit, causing flooding of the Drift River that flows past the terminal’s north side. Mud flows associated with the flooding poured from the river’s southern bank, around the western perimeter of the tank farm, down the Rust Slough on the south side of the terminal and part way over the terminal airstrip. But the massive protective outer dike around the tank farm has so far done its job, with just minor amounts of mud splashing over the dike top.

However, with Redoubt eruptions continuing, a process that volcano experts say could continue for weeks or even months, on March 29 federal, state and CIPL officials announced that the time had come to form a unified command.

Team of one

“We (now) feel that it is appropriate to join as a team of one, as opposed to a team of three,” Robertson said. “We feel that uniting our forces and also bringing to bear all the various assets from the federal side, from the state side and from the responsible party … would be far better than us working independently.”

“We have been communicating with our stakeholders and they are apprised of the current situation and actions taken so far,” said Rod Ficken of CIPL.

“The Department of Environmental Conservation and the state are very concerned for the safety of the 6 million gallons of crude oil that is stored in the Drift River flood plain, and the threat that that oil poses to Cook Inlet, if nature does get the best of the situation and there is a spill,” said state on-scene coordinator Gary Folley from ADEC. “What we would like to see is quick action to eliminate that threat.”

The tank farm at the Drift River terminal stores oil from several oil fields on the west side of the Cook Inlet, in readiness for periodic transfer to tankers that carry the oil to the Tesoro refinery at Nikiski on the Kenai Peninsula. Oil reaches the terminal through a pipeline that passes down the west side of the Inlet from production facilities at Trading Bay and Granite Point.

Evacuated March 23

In 1990, following the Redoubt Volcano eruptions in 1989 and 1990, CIPL built the protective outer dikes that so far have deflected all but a smidgeon of mud out of the tank-farm enclosure during the current eruptive activity.

In fact, an inspection of the tank farm on March 30 revealed that the ground inside the protective dikes was in an identical state to its pre-eruption condition, and that the water level in Rust Slough had dropped, Commander Joseph Lo Sciuto, Coast Guard Sector Anchorage deputy commander and federal on-scene coordinator, said in a March 31 press conference.

“A lot of mud is up against the (outer) dike on the side facing Redoubt,” Lo Sciuto said. “… That mud field goes out 300 to 400 yards and then it drops off five feet, so there’s a nice wall at the end of the mud flow, and that’s what’s helping deflect the current flows we’re getting over towards Rust Slough.”

However, the unified command said that it had decided that, in addition to top priority objectives around safety, environmental protection and the protection of property, draining as much oil from the tanks as safely possible would be a key goal. There then needs to be a long-term plan for future Cook Inlet oil production, to minimize oil storage time at the terminal should more eruptions occur in the months to come.

Oil tanker

“We’ve talked to Tesoro and they are making efforts to try to get a tank ship available to go over to the terminal,” Lo Sciuto said. “The one thing that they asked us … is to do resoundings at the dock.”

However, one significant issue with removing oil from the tanks is the possibility that a near-empty tank could float off its foundations, especially since the suction from the pumps is not at the bottom of the tanks, so that even when the pumps suck dry as much as 1 million gallons of oil may remain in the two active tanks.

“When we say pump it down to a safe working level, what we’re looking at is pumping off enough oil, so that should there be flooding within the containment, the tank doesn’t become buoyant and rise up and float away,” Lo Sciuto said. “… The balance is keeping the right amount of oil in the tank, and removing the bulk of the threat.”

In a fact sheet issued April 1 the unified command listed a series of major problems with the alternative possibility of reducing tank buoyancy by filling the tanks with water. These problems include lack of an adequate water supply; the fact that water, once in a tank, would become hazardous waste without disposal facilities; the lack of a tanker certified to eventually offload the water from the tanks; and the possibility of a prolonged shutdown of oil fields in the Cook Inlet as a consequence of putting water into the tanks.

Also on April 1, the unified command announced that on the previous day it had moved cleanup equipment from Trading Bay to the terminal, but that falling ash had caused the four-man crew delivering the equipment to shelter overnight in a safe-haven building at Drift River.

“This underscores the dynamic environment we are working in,” said USCG Captain Mark Hamilton, who had taken over from Lo Sciuto as federal on-scene coordinator. “Safety of the responders is our primary concern.”

Production impact

Chevron spokeswoman Roxanne Sinz told Petroleum News April 1 that because of storage constraints Chevron had suspended production from the Anna and Bruce offshore platforms on the evening of March 30, thus cutting 1,700 barrels per day from the company’s total Cook Inlet oil production. And because of volcanic ash Chevron has had to shut in the artificial lift system at the Dolly Varden platform, thus reducing production there by 500 barrels per day.

And as of April 1 Trading Bay had sufficient remaining oil storage for seven more days of production at current rates, while the facilities at Granite Point could support about another three-and-a-half days of production, Sinz said. Sinz declined to speculate on what would happen once the storage tanks at Trading Bay and Granite Point are full.

Explosive style eruptions caused by pressure building under relatively viscous magma characterize the Redoubt and Mount Spurr volcanoes on the west side of Alaska’s Cook Inlet. So, could the current activity at Redoubt develop into a cataclysmic explosion, like Krakatoa or the Mount St. Helens eruption in Washington state? Geologists believe that the summit caldera on Mount Spurr resulted from a Mount St. Helens-style explosion as recently as around 11,000 years ago.

Redoubt Volcano has never erupted as violently as that, John Power, a research geophysicist with the Alaska Volcano Observatory, said during a press conference March 31.

“There is a lot of overriding evidence that large eruptions such as … Krakatoa … were all preceded by very, very large earthquakes,” Power said. “… We’ve seen nothing like that currently at Redoubt. There’s no indication currently from our seismic monitoring that a larger event may be afoot.”