The unloading process was interrupted by Lawrence city workers at the plant, but not before about 300 gallons of the chemical toilet waste was dumped into a carbon storage tank at the treatment plant.
The storage tank was not being used at the time, and there was no danger to the city's drinking water or plant facilities, said City Manager Mike Wildgen. The Lawrence Utilities Department notified the Kansas Department of Health and Environment.
"Our operators were responsive and attentive to the situation and responded quickly," said Roger Coffey, city utility director.
The Johnny on the Spot driver had been picking up waste from portable toilets in the area.
Deffenbaugh Industries, Kansas City, Kan., where the driver was employed, has agreed to pay an estimated $20,000 to cover costs in cleanup and repairs, city officials said.
-- Staff writer Mike Belt can be reached at 832-7165.