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 (www.adeq.state.ar.us.) 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.