State agencies say preliminary reviews of soil and sediment samples in and around Lake Conway and the oil-fouled Northwoods subdivision in Mayflower show levels of hydrocarbons and metals below those necessary to constitute a public health hazard.

But a release from the Department of Environmental Quality and the Arkansas Health Department said the level of pollutants do “pose ecological concerns,” particularly in the cove of the lake, but not the main body of the lake. Further testing of samples is still underway.


The release said remediation needs to continue.

The release suggests more questions than it answers and we’ve sought input from some experts.


UPDATE FROM LINDSEY: Arkansas Department of Environmental Quality Deputy Director Ryan Benefield said today that ADEQ released preliminary analysis today because of pressure from the public and the media. He said it was important for the state to provide the initial take on what soil and sediment sampling around the area where oil spilled means.

“One thing [ADEQ] knows is that without putting out this information, someone will fill that void. So we think it’s important that the public hears from the department and the Department of Health on our review as opposed to not having something from their state government,” he said.


An Exxon contractor — overseen by ADEQ and using methods dictated by ADEQ and approved by the EPA — has been testing sediment in the spill area since Sept. 24. The process, outlined in this plan, requires the contractor to send the samples to an independent lab certified by ADEQ. The lab then tests the samples and provides ADEQ the raw data derived from the tests. 

This analysis is preliminary both because ADEQ doesn’t have all of the data required under its sampling plan and because it hasn’t looked at the data it does have as thoroughly as it plans to once it has everything. By Friday, ADEQ expects to have the remainder of the sampling data, Benefield said.

Asked how the levels of pollutants specifically mentioned in the release — Polycyclic Hydrocarbons (PAHs) and metals  — could be safe for humans but not for the surrounding ecology, Benfield said the ecological community is much more susceptible to chemicals.

“For all the different chemicals of concern out there, there are certain numbers that have been established that can pose a health risk to humans or ecological health risk. When you look at human health risk numbers or ecological risk numbers, it’s more of a probability. The way they are set is in a very conservative manner. They’re looking at the most sensitive population.”


ADEQ set its human risk levels based on recommendations from the EPA and the Arkansas Department of Health. The ecological risk levels came from recommendations from several federal agencies. (You can see them both at the bottom of this page).

In addition to Polycyclic Hydrocarbons (PAHs) and metals, ADEQ is also looking for Volatile Organic Compounds, total extractable hydrocarbons, mercury, total organic carbon and black carbon in the sediment sampling. Asked if focusing on PAHs and metals meant that ADEQ hadn’t found any of the other things that are being tested for, Benefield said no and called the release a “general statement.”

“Ultimately, when it’s all said and done, there’s going to be 300 samples. I don’t want to speak generically to all 300 samples.”

Once ADEQ has all of the data and has received analysis from Exxon’s contractor and done its own analysis, it may ask Exxon to test more sediment. Or the process will move into the next stage of remediation. It’s hard to predict what that’ll look like without knowing the full picture, Benefield said, but it could include more digging and hauling away soil or bioremediation.

“When you’re in remediation, we’re looking at extremely low numbers of all these constituents. Once you get to this level, removing that to a lower level can be very timely and difficult. Remediation can take an extended period of time,” he said.

The full news release follows:

The Arkansas Department of Environmental Quality (ADEQ) and the Arkansas Department of Health (ADH) have conducted preliminary reviews of soil and sediment samples pulled by ExxonMobil in and around Lake Conway and the Northwoods subdivision in Mayflower as part of ongoing remediation efforts following a March 29, 2013 oil spill.

The agencies’ preliminary reviews found that levels of Polycyclic Hydrocarbons (PAHs) and metals in the soil and sediment samples are below levels expected to be a public health hazard. However, the levels could pose ecological concerns, the reviews indicate.

“We’re reassured that the results don’t show a public health threat,” said ADEQ’s Hazardous Waste Division Chief Tammie Hynum, “but the results do show a need for continued remediation to eliminate ecological concerns, particularly in the cove. We have not seen an environmental impact to the main body of Lake Conway.”

ADEQ has asked ExxonMobil to submit a final data report to the department documenting the sediment, soil, and surface water sampling activities and summarize field and analytical data no later than Oct. 11, 2013.

In the meantime, ADEQ and ADH have been reviewing the soil and sediment data as the laboratory completes the analyses, a process that can take upwards of four or more weeks. The first samples were pulled in late July, and results were made available on ADEQ’s website ( The Arkansas Game and Fish Commission (AGFC) and its consultants are also conducting an independent assessment of the soil and sediment sample data.
Since shortly after March 29, when a breach in the 20-inch Pegasus Pipeline in Mayflower resulted in the release of approximately 5,000 barrels of crude oil, both agencies have monitored data being collected at the site. These data, which includes air, soil/sediment and water sampling, as well as related documents, are posted on ADEQ’s website.
Once submitted by ExxonMobil the final data report on all the sediment, soil, and surface water sampling will also be posted on the website. The data can be found on ADEQ’s website by clicking the “Latest Data from Mayflower Oil Spill” in the Hot Topics section of the home page.

The Downstream Areas Remedial Sampling Plan established the sampling locations and the sampling and laboratory analysis methods for characterization of sediment, soil, and surface water in five areas affected by the crude oil release. The breach occurred in the Northwoods Subdivision in Mayflower and crude oil flowed to the ditch alongside North Main Street, underneath highway 365, and into the Dawson Cove area of Lake Conway.

The plan called for the collection of sediment, soil, and surface water samples. In all, 134 sediment samples, 135 soil samples, and six surface water samples were pulled in five areas:
• Subsection A-Main: Shallow Ditch along North Main Street
• Subsection A-365W: Shallow Ditch between North Main Street and Highway 365
• Subsection A-365E: Shallow Ditch between Highway 365 and Interstate 40
• Subsection B-Dawson Cove: Open Marsh Area located between I-40 and Division B on Water
• Subsection B-On Water: Open Water Area located between Division B-Dawson Cove and Highway 89 Bridge

Additionally, 18 sediment samples were collected in Lake Conway north of Highway 89. As a reference, background samples were also collected in non-affected areas of Mayflower.

Sediment and soil is being tested for the presence of Volatile Organic Compounds (VOCs); PAHs; total extractable hydrocarbons; total metals; mercury; total organic carbon and black carbon. Surface water is being tested for VOCs, PAHs, total metals, total mercury, dissolved metals, dissolved mercury, total suspended solids, oil and grease.

All the samples are collected and shipped by Department of Transportation standards to an ADEQ-certified laboratory using Environmental Protection Agency (EPA)-approved methods.

Since early April, ADEQ and ExxonMobil have also taken surface water samples at 20 sites in and around the cove and main body of the lake. The sites were chosen with the input of ADEQ scientists as well as those at other state agencies, such as the AGFC.

The response to the spill has been a coordinated effort between EPA, ADEQ, the ADH, AGFC, Faulkner County, the city of Mayflower, ExxonMobil and many others.