The Chevron Questa Mine site, formerly Molycorp, Inc., is located in Questa, New Mexico. The site includes a molybdenum mine and milling facility on three square miles of land and tailing ponds on about one-and-a-half square miles of land. A nine-mile-long pipeline running along State Highway 38 connects the milling facility to the tailings ponds. Mining operations began in 1920. Open pit mining took place from 1965 to 1983. Mining operations placed over 328 million tons of acid-generating waste rock into nine piles surrounding the open pit and disposed of over 100 million tons of tailings in the tailing ponds. Mining operations and waste disposal practices contaminated soil, sediment, surface water and groundwater. Site investigations, remedy design and cleanup are ongoing.