This 640-acre (one square mile) site for hazardous and toxic materials opened in 1982. Laidlaw operated this facility for years, and it served as a dump site for the toxic ash from Laidlaw's incinerator, 15 miles away at Clive, one of a few waste sites Laidlaw acquired when it bought U.S. Pollution Control Inc. (USPCI), Union Pacific's toxic waste company, in 1994. USPCI had developed a few waste sites around the country in remote locations, but accessed by its railway, which was used to deliver the waste from all over the nation. Grassy Mountain is now owned by the Clean Harbors company, which bought most of Laidlaws waste sites, as well as others, and is now the largest hazardous waste disposal company in the nation. The site accepts waste from all over the country, trucked in directly, or from the company's rail transfer facility at Clive.
