Union Oil Co Of Calif Sia is a superfund site located at N1/2 Of Sec6 T6s R7e, Mayberry Twp, IL 62817. The Environmental Protection Agency (EPA) identifies sites such as Union Oil Co Of Calif Sia because they pose or had once posed a potential risk to human health and/or the environment due to contamination by one or more hazardous wastes. Union Oil Co Of Calif Sia is currently registered as an Archived superfund site by the EPA and does not require any clean up action or further investigation at this time.