The Site consists of two adjacent landfills, each comprising approximately 80 acres. The Marshall Landfill, located to the north, began official operation in 1965, when the Richland Company, under contract Boulder County, began solid waste composing and disposal operation at the Site. Although the contract specified composting operations, landfilling comprised the majority (80%) of waste handling activities. In 1969,the operation was sold to Salvage, Inc, which was later acquired by a group of local investors and renamed Urban Waste Resources. Between 1969 ant 1974, the Marshall Landfill accepted municipal waste, unstabilized sewage sludge and many unknown and potentially hazardous wastes. In 1974, the Marshall Landfill was abandoned when Urban Waste Resources, along with Mesa Sand and Gravel, opened the Boulder Landfill to the south. Landfill, Inc, a wholly-owned subsidary of Browning-Ferris Industries, purchased the landfill operation in 1975. The Boulder Landfill closed in January 1992.