Response lessened impact of toxic spill

Short-term air and water quality impacts from last month’s spill of thousands of barrels of gasoline product into the Houston Ship Channel appear to be limited, an outcome that experts credit to a rapid response that contained and removed the toxic product.

A tugboat pushing two barges — each with a capacity to hold up to 25,000 barrels — collided May 10 with a 755-foot tanker, the Genesis River, carrying liquefied natural gas. The tanker’s hull punctured two of the smaller vessel’s four storage tanks, leaking what turned out to be 11,276 barrels of a gasoline product called reformate, a highly flammable chemical that’s mixed with gasoline and can have high concentrations of the carcinogen benzene.

Aerial footage showed a gash in one of the barges and a sheen floating on the water. The other barge capsized but did not leak any product. The tug, which had four crew aboard, was undamaged.

What happens after a spill like this depends not only on the amount leaked into the water or the toxicity of the product spilled, said Erin Kinney, a coastal ecology research scientist for the Houston Advanced Research Center. Another factor, Kinney said, is whether the product breaks down immediately through air or wind action,

or if it takes longer and requires the use of dispersants.

“In this most recent spill there were volatile compounds that quickly got into the air,” she said. “It has the potential to affect air quality — I believe that’s what people could smell — but tends to quickly dissipate as you move away from the incident site.”

“It seems like at this point, the risk dissipated fairly quickly for this one,” she added. “The response was very rapid, they were able to get out there and boom off most of the spill fairly quickly and it was well-coordinated. I think we are getting better at responding quicker and at containing.”

It’s too soon, however, to predict the economic effects of the spill, which forced the closure of the ship channel for a couple of days, or to assess the cumulative impacts to Galveston Bay of this spill and others. The bay, which covers about 600 square miles, provides critical habitat for oysters, shrimp, fish and tens of thousands of migratory birds.

An average of 264 spills a year were reported from 1998 to 2018, according to HARC. The group tracks the spills in Chambers, Harris, Brazoria and Galveston counties reported to the Texas General Land Office.

After this latest spill, officials used seven skimmers to recover product-water mixture and placed about 20,000 feet of boom around the barges and surrounding sensitive shoreline areas to help contain and absorb the gasoline product.

A contractor took thousands of air monitoring samples for benzene, hexane, toluene, volatile organic compounds and xylene. The Centers for Disease Control and Prevention and Galveston County Health District determined the air sampling data was below levels of health concerns.

The Texas Commission on Environmental Quality, assisting with air monitoring in the beginning, detected a benzene reading 14 times higher than the level of concern for short-term health effects about seven hours after the collision. This reading wasn’t replicated, however, and no highlevel detections were made after that.

Water sampling data from some areas showed some elevated levels of levels of benzo(a)pyrene, a polyclic aromatic hydrocarbon — which the Environmental Protection Agency has determined it is probably a human carcinogen — and for m,p xylene, a form of benzene.

After the spill, a raccoon and three birds were found dead on the barge. A fish kill was reported on the property of the Galveston Bay Foundation in Kemah. Workers were still cleaning up the shoreline at the group’s property this week.

“Winds out of the northeast pushed the product toward Seabrook and Kemah. We saw sheen on the water and product out there,” said Bob Stokes, the bay foundation president.

The highest concentrations of the toxins probably occurred on Saturday, May 11, he said, but testing was not started until Sunday. “As the days went on, the concentrations went down because they had skimmers and had been cleaning out the product at that point.”

“It could have been worse, of course it could have been worse,” said Stokes. “It doesn’t mean there weren’t impacts in the short term; every spill is different and every spill has its own impacts.”

The Texas Department of State Health Services issued a temporary seafood consumption advisory for portions of Galveston and Trinity Bays. It lifted the advisory on May 24 after water testing showed contaminants from the accident no longer presented a risk to human health from consuming fish or shellfish, it said. It also reopened private oyster harvesting on May 25.

The department did not collect any tissue samples because volatile organic compounds do not accumulate in fish tissues once they evaporate, said Lara Anton, a spokeswoman for the Texas Department of State Health Services.

“Overall, I don’t think it looks that bad, especially compared to some of the spills we’ve had,” said Stephanie Glenn, a research scientist at HARC who specializes in ecology and hydrology. “It looks like response was quick.”

In March 2014, a collision closed the channel and caused a spill of 168,000 gallons of bunker fuel oil. The oil was described floating in patches as far as the Galveston Channel and an area of East Beach on Galveston Island.

Even though the amount was much smaller than the roughly 473,000 gallons spilled in May, “I believe it was a different type of fuel oil, heavier, than what spilled in this most recent collision,” said Kinney.

The 2014 spill also happened at an especially sensitive time and place, with the potential to affect tens of thousands of wintering birds still in the area. Changing currents, winds and weather conditions also forced responders to extend the containment and oil recovery plans into the Gulf of Mexico and south along Galveston Island.

If the latest collision had happened next to shore in shallower water, or closer to where people live and work, “you might have seen a very different cascade of impacts,” Kinney said. “This is, unfortunately, still part of the cost of doing business for the large shipping traffic and volume Houston experiences. What’s encouraging about this is the speed of the response.”