Oil Terminal Under Redoubt Volcano

Why build an Oil Terminal right under Redoubt Volcano?
The oil tanks at Drift river. The dark lahar mud spilled over the edge of the dike before this photo was taken on March 23. Photo from the Alaska Volcano Observatory.
Since its completion in 1968, The Drift River oil terminal has provided temporary storage for oil from wells in Cook Inlet. A pipeline brings oil from offshore wells to the storage terminal on the west side of the inlet. When enough oil has accumulated, a tanker removes the oil and brings it across to the east side to the Tesoro oil refinery at Nikiski, where it is processed (along with imported oil and oil from the North Slope) into fuel for Alaska markets.
Most of the platforms in Cook Inlet cannot pipe oil directly to the refinery on the east side of the inlet, they instead store the oil at the Drift River oil terminal (southwest corner of the map) until there is enough to ship across the inlet. Click on the map pins to see the name of the platform or facility that is marked.
At first glance, any spot on the west shore would work as well as any other. But most of the shore is too shallow for large ships to approach it closely. So Chevron sited the facility near the mouth of the Drift River, to take advantage of the steep delta left by thousands of years of volcanic mud flows (lahars) from nearby Redoubt Volcano. Unfortunately, this placed the facility right where it was vulnerable to these same lahars, and to other volcanic hazards.
This sort of compromise between feasibility and risk is common in large resource extraction projects like the oil drilling in Cook Inlet. In theory, risk is carefully weighed against benefits of development. However, the corporations developing a resource receive a greater portion of the benefits than the public with whom they share the risk. This conflict of interest between the public and industry muddles the issues involved and leads to a reactive policy of handling hazards, like we see at the Drift River Terminal. The lahars that are now lapping up against dikes that protect oil tanks could have been anticipated long before they arrived, and less likely but more severe volcanic hazards should have been considered as well. We rely on regulatory agencies to resolve conflicts between industry and the public, but as yet the process has not risen above the politics that inevitably surround major resource development projects.
A history of lahars on the Drift River
During the winters between eruptions, snow accumulates on the north slope of Redoubt, forming a glacier that flows five miles down into the Drift River valley. During eruptions, hot ash dumps onto this glacier. The glacier melts and mixes with the ash to form a great flood of mud that carries boulders and anything else in its path. Even as the Drift River facility was being built, the volcano erupted, leaving workers stranded by volcanic mud. In addition to worker safety, lahars could unleash a large oil spill, if any of the tanks were ruptured or torn from their foundations.
Lahar deposits from the 1989-90 eruptions as seen in 2001. This photo is only 2-3 miles upstream of the terminal, and even here boulders four or five feet in diameter are common.
1989-90 eruptions
A series of eruptions in late 1989 and early 1990 sent lahars flowing down the Drift River, flooding the oil storage facility. At the time, around 38 million gallons of oil were being stored at the terminal. All the tanks survived the flood, and no oil was spilled. In response, Chevron built a 25-foot earth and gravel dike (with concrete on the river side) to protect the tank farm from future eruptions.
Current (2009) eruptions
Oil production in Cook Inlet has declined greatly since 1990, and at the beginning of this eruptive episode, approximately 6 million gallons of oil remained, in just two of seven tanks. This information was not initially available to the public. Although the Alaska Volcano Observatory (AVO) had been warning of increased activity at Redoubt since late January, Chevron initially declined to release information about the oil stored there, citing homeland security concerns.
The first eruption at Redoubt happened on March 22, sending a lahar down the Drift River and around the terminal. Several eruptions followed including a violent explosion on April 4 that sent another large lahar down the Drift River. Mudflows have overtopped the dikes and surrounded the tank farm, swamped the airport, and caused damage to some equipment. But so far, major flows have not breached the dikes, and no oil tanks have been damaged.
The April 4th Lahar on the Drift River flooded the entirety of the upper Drift River valley, and spread out to be 8 miles wide. Source
On April 6, the volcano had quieted somewhat, and it was determined to be safe enough for a tanker to dock and offload approximately 60% of the oil. 2.53 million gallons of oil and sludge remain in the tanks, and in the pipeline between the facility and one of the oil platforms in the inlet. Reversing an earlier decision by the Coast Guard, 840,000 gallons seawater was used as ballast to refill the partially-drained tanks, lessening the chance that they could spill oil by being floated and torn from their foundations in a future lahar. The oil-water mixture is hazardous, and will eventually need to be disposed of. The Drift River facility is currently shut down for the duration of this episode of unrest, forcing the shutdown of ten nearby oil rigs in the inlet. AVO speculates that the eruptions could last for weeks to months.
Future Eruptions?
Even if the facility escapes this episode of eruptions unscathed, as sediment accumulates in the floodplains and channels around the facility, but not within the diked areas, it becomes progressively more vulnerable. In time, the area within the dikes will become the lowest spot in the valley, and mud, like water, will seek that lowest spot.
Bigger eruptions
Volcanoes don’t follow any rule that says every eruption must be the same. Stratovolcanoes like Redoubt build massive mountains over thousands of years, and can destroy the whole edifice in an eruption thousands of times larger than we have seen in Redoubt’s current episode of unrest. These giant eruptions can leave a hole where before there was a mountain. During such a caldera forming eruption, it is possible that an avalanche of hot ash, pumice, and rock (called a pyroclastic flow) would reach all the way to Cook Inlet, and in the process overrun and destroy the Drift River Terminal.
For an example of an eruption of this sort, we can look southwest of Mt. Redoubt to Aniakchak Caldera on the Alaska Peninsula. This volcano exploded catastrophically 3500 years ago, sending a pyroclastic flow 20 miles to the Bering Sea, where it then continued into the water, generating a tsunami that was likely over 30 feet high even after crossing over 75 miles of the shallow Bristol Bay. Along the Bering Sea coast the deposits of the pyroclastic flow are tens of feet thick.
The bluffs along the coast near the village of Port Heiden are composed of packed pumice from the 3500 year old Aniakchak eruption. Here, over 20 miles from the center of the caldera, they are 15-20 feet thick, and in some places along this coast they are twice this thick.
If a similar eruption occurred at Redoubt, the flow might well be strong enough to rupture the tanks, and could be hot enough to ignite the oil in them. Cleanup in a vast plain of porous pumice would be an unprecedented problem, and likely impossible, leaving the oil to leach into the environment in an uncontrolled fashion. This sort of worst case scenario is left out of analyses that are done when development is considered even now, since they are historically rare enough that it’s easily dismissed.
This map shows a cartoon of a hypothetical giant caldera forming eruption at Redoubt Volcano. An eruption of this scale is very rare, but not unheard of. Zoom out and look southwest to see the caldera and pyroclastic flow of an eruption at Aniakchak for comparison.
Designed for hazards?
Despite its proximity to Redoubt, the Drift River Terminal was not designed to be quickly evacuated of oil. If eruptions had been factored into its design, this would provide very good protection against oil spills, especially for extreme cases such as a caldera forming eruption. For an eruption as large as Aniakchak to happen, many cubic miles of magma would have to pool beneath the mountain, presumably causing easily detected swelling of the volcano and swarms of earthquakes prior to the eruption. Smaller eruptions can often be predicted somewhat in advance as well. This current cycle of lahar-producing eruptions was predicted months in advance by the Alaska Volcano Observatory. However, the outlet pipes from the tanks are set several feet above the bottom of the tank, so it is very difficult to remove all the oil.
Privatized gains, socialized losses
The natural resource extraction industry often finds itself in a conflict of interest with the public. The Drift River terminal faces what is for Chevron likely a financially acceptable risk of destruction by volcanic catastrophe. In cases like this, the industrial operator of a facility need only multiply the probability of destruction by the cost of the facility and cleanup. If that is less than the profits from having the facility, then the risk is financially acceptable.
From a public perspective the calculation is very different. The potential costs are many and difficult to quantify: destruction of subsistence, recreational, and commercial fisheries; damage to a regional reputation for pristine wilderness that draws visitors; and moral concerns over destruction of ecosystems. And the benefits are smaller and less direct. Some stakeholders receive almost no benefit from Chevron’s success, and many only gain tertiary benefits through increased economic activity.
If everything goes well, Chevron profits. If things go badly, everyone loses.
Questions for the future
The Drift River Terminal might survive the lahars from this eruption, as it has before. We all hope so. However, there is a growing public perception that Chevron is being cavalier about volcano hazards. Perhaps in the end it will be that perception that dooms The Drift River Terminal.
However, this is not how the system should work.
There should have been a facility built with a detailed assessment of volcanic hazards in mind. Instead we got a facility protected by dikes only after inundation by a lahar. We got tanks that cannot be drained in an emergency.
The operation of the facility should have been reconsidered after it was built, taking into account a new understanding of the hazard posed by Redoubt. Instead we see public outcry as a more important force than an understanding of hazards.
We should have easily understood information for the public about the vulnerabilities and mitigation measures at the Drift River facility. Instead we see a corporation unwilling to share information with the public, and a public correspondingly surprised when they learn about the situation.
Next time, will we do better?