The "Removal Site" is located on the Apache Nitrogen Products, Inc. (ANPI) facility which is also a National Priority List (NPL) Superfund site under CERCLA known as the Apache Powder Superfund Site (Site). According to plant records, acquisition of property presently comprising the Apache Nitrogen Products, Inc. (ANPI) facility began in 1919. The Apache Powder Company officially began operation of its manufacturing processes in 1922. The primary products manufactured at the start-up were mixed nitric and sulfuric acids used for the production of nitroglycerin (NG). In 1968, the Apache Powder Company began manufacturing detonating cord containing pentaerythritol tetranitrate (PETN) at the Cord Plant. Manufacturing of detonation cord ceased in April 1994. In the mid-1950s, ANPI broadened its product line to include ammonium nitrate, nitrogen-based fertilizers, blasting agents, and nitric acid. Today, ANPI manufactures various forms of ammonium nitrate fertilizers, prill, liquid ammonia nitrate, aqua ammonia, nitric acid, and the agricultural product AN20.
Historically, the Apache Powder Company’s Curtiss Plant was the site of continuous industrial use related to the production of NG explosives from 1922 to 1981. It was the first explosives plant to be established in Arizona and was closely tied in terms of ownership and customer base to the copper mining industry in Arizona, New Mexico, and Sonora. Historical periods of construction occurred during the initial building phase in 1920–1922 and subsequent construction episodes between 1951 and 1954 in which additional NG production facilities were added.
