Tropical Storm Isaac, projected to become a hurricane with 100 mile-per-hour winds when it makes landfall, may dredge up as much as 1 million barrels of oil buried in sediment in the Gulf of Mexico since the BP Plc spill two years ago, a Louisiana official said.
The state is adding about 50 experts to its hurricane response teams to identify new oil damage from the surge of sea water expected from the storm, said Garret Graves, chairman of Louisiana’s Coastal Protection and Restoration Authority.
Isaac is expected to batter almost three-quarters of the state’s coast with wave collisions that have the power to erode beaches and send sea water deep into coastal marshes, according to computer models from the U.S. Geological Survey. That may force debris from the Gulf, including oil, deep into Louisiana’s wetlands, according to Graves.
“We should be able to focus all our resources on search and rescue, and helping people repopulate,” Graves said in a telephone interview. The oil removal plans are a “frustrating necessity that would have been largely preventable had BP been more aggressive about removal efforts.”
Ray Melick, a Houston-based spokesman for BP, said the London-based company has been cleaning up the Gulf of Mexico since the 2010 Deepwater Horizon spill, and has seen a diminishing amount of oil picked up.
“We’ve gone through some hurricane seasons and that included a couple of tropical storms and the impact was minimal,” Melick said in a telephone interview. The company, he said, is still working under the direction of federal on-scene coordinator, and will follow the lead of government agencies in its response to Isaac.
“If a response is needed, we have the people and the equipment to do that,” he said. “We’ve always responded as appropriate and will continue to do so.”
Isaac will be the first hurricane to hit the area since the worst spill in U.S. history, which started with an April 20, 2010, explosion on the Deepwater Horizon oil rig in the Gulf. The storm, moving at about 12 miles an hour last night, is expected to have a storm surge of as high as 12 feet as it hits land, according to the U.S. National Hurricane Center.
Jeff Masters, co-founder of the Weather Underground forecast website based in Ann Arbor, Michigan, said Isaac’s slow speed may increase the damage it does at the coast. The current projection is for the winds to peak at 100 mph as it comes ashore, according to the Hurricane Center.
The storm surge will be particularly bad from Louisiana to Mississippi simply because the storm is so big, Masters said in a telephone interview yesterday. Federal officials said last night that Isaac stretched almost 400 miles wide.
As the storm passes, any oil carried by its power will probably end up clogging marshes as the water retreats to the Gulf, according to Graves.
In June, Brian Silliman, of the department of zoology at the University of Florida in Gainesville, published a paper in the Proceedings of the National Academy of Sciences that found oil from the spill may have more than doubled the rate of shoreline erosion by killing the roots of salt-marsh grasses. His group will go to the area after Isaac to see how much the storm affects erosion, he said in a telephone interview.
“I’m not pulling all the alarms here,” Graves said. “But the oil is absolutely an added disaster threat in the middle of all this other mess. It’ll delay and frustrate recovery efforts.”
A hurricane wouldn’t be able to disturb any oil remaining on the floor of the Gulf, Chris Vaccaro , a spokesman for the National Oceanic and Atmospheric Administration.
“This was a question that was raised during the oil spill,” Vaccaro said in a telephone interview. “If there is anything on the floor of the Gulf of Mexico it won’t be churned up by Isaac at all.”
Masters said the risk is if any oil remains in the wetlands at the shore.
“If there is still oil stuck in those marshlands when the surge goes over it is going to liberate that oil,” said Masters, who used to fly with NOAA’s Hurricane Hunters from 1986 to 1990. “There is going to be sheen in the water.”
Isaac won’t be the first storm to hit the area. In September 2011, Tropical Storm Lee was found to have remobilized tar mats along the Alabama coast, according to research from Auburn University in Alabama.
When scientists tested the tar mats, they were found to contain about 17 percent oil by mass. That suggested that “every kilogram of oil that reached the Alabama shoreline had the potential to create 5 kilograms of submerged tar mat,” the research concluded.
Michael Blum, an ecologist at Tulane University in New Orleans, said it’s not clear whether or how much submerged oil may surface during a hurricane, since this is the first since the spill. Much depends on Isaac’s power and speed, he said.
“There’s a lot of oil that’s not accounted for, and there’s good evidence suggesting a significant proportion of it is submerged or in sediment,” Blum said in a telephone interview “As it is now, it’s stable under the water, but if the environment is stirred up, it may resurface and the question then is where.”
With the increasing storm surge and the movement of the water, erosion is another major concern, Blum said. There could be severe losses along the shoreline, with tens of square miles in a single event, he said. The extent of damage will depend on how fast the storm is moving and where it hits.
In addition, the salty flood water could kill plants and animals in cypress swamps and other marshes, Blum said.
“Those are the most at-risk ecosystems in the area,” Blum said. The area was predominantly freshwater marshes until the sea level rise and erosion contributed to their disappearance.
The U.S. Geological Survey has increased the number of storm-surge sensors located in the northern Gulf to measure the water level and barometric pressure every 30 seconds as Isaac washes over the region, according to the agency’s website. The findings will be used to help pinpoint emergency responses to communities, and operating flood control reservoirs.
“Beaches along the Gulf of Mexico are extremely vulnerable to erosion during hurricanes, in part, because of low elevations along the coast,” said Hilary Stockdon, a research oceanographer for the geological survey who in May presented a study about the potential for damage among Gulf Coast beaches in the event of a hurricane.