Identifying Manufactured Gas Plant Tar in the Environment Using Chemical Fingerprinting

The United States Environmental Protection Agency (EPA) estimated that 3,000 to 5,000 manufactured gas plants (MGPs) were constructed in the United States (EPA, 2000). Companies located their MGPs near urban waterways due to the close proximity to cheap condensing liquid (water), improved site drainage, and easy access to delivery channels. However, these site selection criteria were shared by other industries, many of which generated PAHs or handled tar. Contemporary environmental forensic investigations must draw upon a detailed understanding of the relationship between MGP history and tar chemistry in order to differentiate between different types of MGP-derived tars and non-MGP impacts. This article describes the history of MGP operations in the U. S. and how chemical fingerprinting can aid in unraveling liability associated with MGP legacy sites.