The U.S. Army's Camp Ono existed from 1942 to 1947 in Southern California. It was used for housing Italian Prisoners of War and was later converted to a truck and munitions cleaning site. Several of the solvents used in the cleaning process were later discovered to be toxic. and the contaminated site is now part of the Newmark Ground Water Contamination Superfund site.
References
Camp Ono Wikipedia(Text) CC BY-SA