Operating Industries Inc., Landfill  The former Operating Industries Inc. Landfill is a Superfund site located in Monterey Park, California at 900 N Potrero Grande Drive. From 1948 to 1984, the landfill accepted 30 million tons of solid municipal waste and of liquid chemicals. Accumulating over time, the chemical waste polluted the air, leached into groundwater, and posed a fire hazard, spurring severely critical public health complaints. Recognizing OII Landfill's heavy pollution, EPA placed the financial responsibility of the dump's clean-up on the main waste-contributing companies, winning hundreds of millions of dollars in settlements for the protection of human health and the environment. The Monterey Park Disposal Co. first utilized the landfill in 1948, later selling business rights to OII in the 1950s. Two decades later, the construction of the Pomona Freeway split the OII landfill into two parts: the North Parcel (45 acres) and the South Parcel (145 acres). Out of the North Parcel's , only served landfill purposes and collecting primarily construction and debris (C&D) waste such as: wood, glass, metal, paper, cardboard, brick, asphalt, concrete, and plastic. Shouldering the majority of wastes, the South Parcel received industrial and residential refuse, liquid chemicals, and hazardous materials. Close to 4,000 companies disposed of millions of gallons of waste during the landfill's operation time. Roughly 300 million gallons were liquid industrial wastes. The culmination of these wastes led to contaminated air, groundwater, and soil as well as a fire risk. All of these factors caused great concern for the well-being of nearby residents. According to the 2000 US Census, 2,151,372 people lived within of the landfill, while 23,000 people drank water from wells from the landfill. In January 1984, the State of California placed the OII landfill on the California Hazardous Waste Priority List, shutting down the landfill within the same year. In May 1986, EPA officially listed OII Landfill on the National Priorities List for remediation. Conducting studies, the Los Angeles County Sanitation District, the California Department of Health Services, South Coast Air Quality Management District and OII discovered carcinogenic chemicals such as tetrachloroethylene, benzene-type compounds, chloroform, lead, and toluene leaching into the groundwater. Tests also confirmed the presence of methane and vinyl chloride in subsurface soils and the air surrounding the landfill.