From the Lawrence Daily Journal-World for March 5, 1988:

Lawrence firefighters had been called on the previous morning to the Kansas Turnpike east of the city to help clean up a toxic chemical spill which had occurred the night before. The chemical, a toxic and flammable herbicide called Sonolan, had spilled when a truck carrying it had run into a ditch and overturned about 7 miles east of the East Lawrence turnpike entrance. Freezing rain and snow overnight had masked the spill, which was not detected until a Kansas Highway Patrol trooper had visited the scene the next morning. “One of our troopers went out to take some pictures, and that’s when he detected it,” a turnpike dispatcher said today. “It was just leaking out of one corner of the trailer.” The leaking substance had made two large pools near the truck, but Lawrence Fire Chief Jim McSwain emphasized that despite a press report to the contrary, none of the chemical had spilled into a nearby creek which eventually emptied in the Kansas River.