In the morning hours of August 10, 2008, a sudden pressure drop was noted on a 20-inch diameter pipe line owned and operated by Marathon Pipe Line. The pipe line transports crude oil (oil) from Patoka, Illinois, to Owensboro, Kentucky. The pipe line was shut down immediately as pressure sensors noted the pressure drop. Reconnaissance noted a pipe line rupture adjacent to a remote section of gravel road in a predominantly agricultural area south of the towns of Mt. Erie and north of Golden Gate, Wayne County, Illinois. The pipe line release occurred between MPL pumping stations located approximately 10 miles to the northwest and 8 miles to the southeast. The pipe line is buried approximately 5 feet below ground surface at the release location. It has been estimated that approximately 5,000 barrels of oil were released during the pipe line break. Over 3,260 barrels of crude oil have been recovered from the Site (through direct recovery, estimated evaporation, and estimated quantity contained within directly removed soils). To-date, over 6,000 tons of soil has been disposed off-site.

Immediately after the pipe line release, oil exited the ground and sprayed an area of foliage and trees immediately to the southwest of the pipe line rupture. Oil also flowed over the ground surface in the immediate vicinity of the release. In addition to the oil “spray” and surface flow of oil, oil migrated through the subsurface soil due to the pressure of the pipe line (i.e., pipe line pressure at the time of release was estimated to be 200 pounds per square inch (psi)).

The overland oil flow traversed east approximately 70 to 100 feet into a forested area and oil then flowed south to the pipe line right-of-way (ROW). An additional overland flow pathway of oil flowed southward from the ROW about 430 feet and stopped. At the ROW, oil flowed in a southeasterly direction, and pooled behind a slight hill in the ROW, resulting in backflow of oil northward approximately 100 ft in a narrow, seasonally dry swale. Once the pool in the ROW was large enough, the oil flow extended south of the ROW into forested woodlands. The oil flowed northward out of the forested area back to the ROW, and continued to migrate along the ROW to the southeast until it reached a drainage swale which directed the flow southward at the eastern edge of the woods. The oil flowed southward along a seasonally dry drainage swale to open surface water. Upon reaching the open water, the oil formed a layer on the water surface, and migrated down seasonally dry meandering creek beds and low flow capacity streams (i.e., the abandoned Elm Creek Channel). The oil was largely contained within the creek banks.