On December 6, 2002, EPA Region IX issued an order pursuant to Section 106(a) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). The UAO directs the respondents, W-H Tanklines, Inc. and William Huhn, to remove and dispose of hazardous substances from six abandoned truck trailers in Corona, Riverside County, California. Three of the trailers are 5000-gallon tank trailers, each at least half full with waste oil and oily water. The other trailers are container trailers, one containing used tires, and the other two containing approximately 150 smaller containers. Labels and other marking on these smaller containers indicate that the contents include tetrachloroethylene, other solvents, ink, and various petroleum products. On December 3, 2002, EPA investigated and observed solvent leaking from two of the container trailers, and petroleum material leaking from one of the tanker trailers. Markings on the trailers and on individual container labels state that they belong to the respondents, which have indicated to EPA that they will comply with the UAO.