Pipeline’s oil lingers in places near lake

More than nine months after Exxon Mobil’s Pegasus pipeline ruptured in a Mayflower neighborhood, oil remains in a Lake Conway cove and drainage areas.

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Mayflower oil spill

The Arkansas Department of Environmental Quality has given Exxon Mobil until Jan. 17 to recommend ways to correct the problems, which include the presence of more metals and chemicals than normal and increased oil-sheening in those areas.

The agency still does not believe that the March 29 oil spill, estimated at 210,000 gallons, contaminated the main body of the popular fishing lake, Tammie Hynum, chief of the department’s Hazardous Waste Division, said in a series of email and phone interviews this week.

A company hired by Exxon Mobil most recently took samples from Dawson Cove, three drainage ditches and the main part of the lake in November and December.

Among the oil-related chemicals and metals found at levels exceeding established ecological-screening values in one or more areas were lead and nickel, Environmental Quality Department spokesman Katherine Benenati said.

While some of those could have been in the areas before the spill because of motorboats, drainage or for other reasons, Hynum said, “Based on the investigation … there is evidence that there are some residuals remaining in the drainage-ways as a result of the spill.”

Hynum noted that samples can vary from one area to another. “Lead may be high in one area for a couple samples but not exceeding it in another area,” she said, for example.

The roughly 850-milelong Pegasus pipeline, built in 1947 and 1948, runs from Patoka, Ill., to the Gulf Coast in Texas. Exxon Mobil has said the pipeline - a common carrier that also shipped oil belonging to other companies - was transporting Wabasca Heavy crude from Canada at the time of the rupture, which has been blamed in part on manufacturing defects.

In a related development, Exxon Mobil spokesman Aaron Stryk confirmed that the federal Pipeline and Hazardous Materials Safety Administration has granted the company another 90-day extension before it must file its remediation work plan. That means the plan is now due April 7, more than a year after the rupture. The line has been shut down since the rupture.

The type of oil that was flowing through the line is so thick that it is blended with other ingredients before it is transported.

According to a sheet Exxon prepared and that the Pipeline Administration posted online, the oil blend contained the following “hazardous” constituents: benzene; cyclohexane; ethyl benzene; hydrogen sulfide; n-hexane; naphthalene; polynuclear aromatic hydrocarbons; sulfur; toluene; and xylenes.

In a Dec. 13 email to Jeff Bunce, project developer for Exxon Mobil Environmental Services Co., Hynum wrote that a “thorough investigation” had been completed.

Hynum’s email said Exxon Mobil’s report must include recommendations on how it proposes to remediate areas“that contain crude oil constituents in levels exceeding the established ecological screening values.”

“The next step is to mitigate these areas,” she added. “Exxon Mobil should evaluate several (minimum of 3) remedial alternatives for factors including, but not limited to, overall protection of human health and the environment, compliance with applicable and relevant rules and regulations, reduction of toxicity, mobility, and volume, effectiveness (short and long term), cost, and implementability.”

Hynum also wrote that weekly “reports have been showing a movement and increase of sheening in all the drainage areas.”

The cove is considered a drainage area.

Exxon Mobil should include in its report measures to correct the sheen, Hynum wrote.

“Sheening isn’t uncommon after a major spill such as this [one] particularly after a rain,” Benenati said. “You’ll often see sheening reoccur after rain because the sheening will resurface.”

Asked if Exxon Mobil thought dredging might be needed or what other remediation was needed, Stryk replied, “We continue to evaluate the data to develop remedial options as requested by” the state agency.

Sediment samples taken in Dawson Cove and the other drainage sites also found that some chemicals were higher than established ecological screening values for “benthic receptors,” which are organisms living on or in the water’s bottom.

“Benthic organisms are a major food source for smaller fish,” Benenati said. The kinds of such organisms in the Lake Conway area would include aquatic worms, blood worms or midge larvae, scudders, burrowing mayflies and several other insect larvae, she said.

“Concentrations above [established ecological screening values] do not necessarily imply that ecological risk exists; only that further evaluation is warranted,” Hynum said.

Hynum gave an example of the findings. Among 54 soil samples taken from 15 locations in Dawson Cove, four samples had a polycyclic aromatic hydrocarbon, or PAH, concentration above established screening levels and warrant further evaluation, she said.

Polycyclic aromatic hydrocarbons are “a group of chemicals that are formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances, such as tobacco and charbroiled meat. There are more than 100 different PAHs,” according to the federal Agency for Toxic Substances and Disease Registry’s website.

The federal agency says these hydrocarbons “generally occur as complex mixtures … as part of combustion products such as soot,” for example. They also can be found in substances including coal, coal tar pitch and asphalt used in road construction, it adds.

Further, the website says, “PAHs in general do not easily dissolve in water. … Some PAHs evaporate into the atmosphere from surface waters, but most stick to solid particles and settle to the bottoms of rivers or lakes. In soils, PAHs are most likely to stick tightly to particles. Some PAHs evaporate from surface soils to air. Certain PAHs in soils also contaminate underground water.

“The PAH content of plants and animals living on the land or in water can be many times higher than the content of PAHs in soil or water. PAHs can break down to longer-lasting products by reacting with sunlight and other chemicals in the air, generally over a period of days to weeks. Breakdown in soil and water generally takes weeks to months and is caused primarily by the actions of microorganisms.”

Some polyaromatic hydrocarbons are “known animal carcinogens,” the U.S. Department of Health and Human Services has determined, according to the website.

It was unclear if any of those specific carcinogensor other chemicals described on the website were among those found in Mayflower.

Front Section, Pages 1 on 01/09/2014

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