Evaluation of tertiary butyl alcohol (TBA) impact on groundwater: application to California

Abstract

Leaking underground storage tanks can contaminate the groundwater. Since the 1980s, California leaking underground storage tanks have released millions of gallons of petroleum containing tertiary butyl alcohol into the subsurface. This compound was banned in early 2000 due to human health concerns. The United States Environmental Protection Agency considers tertiary butyl alcohol an animal carcinogen and a potential human carcinogen. California has not established a maximum contaminant level for tertiary butyl alcohol. (1) Based on the documented health hazards, a maximum contaminant level should be developed for tertiary butyl alcohol in California. (2) The California Water Resources Control Board’s “Low Threat Closure Policy”, which is a tool to evaluate closure of leaking underground storage tank sites, does not require regulators to consider tertiary butyl alcohol contamination in soil or groundwater in their closure review. This practice should be revisited based upon tertiary butyl alcohol’s toxicity data, its biotransformation from methyl tertiary butyl ether, and its stability in the environment. This review summarizes toxicity, sources, and environmental transformation of tertiary butyl alcohol, aims to raise awareness regarding the magnitude of the tertiary butyl alcohol problem in groundwater, and urges California regulators to develop more stringent protocols for tertiary butyl alcohol treatment. The nine Regional Water Quality Control Boards regulate and oversee cleanup at leaking underground storage tank sites in California. This study will directly impact Regional Water Quality Control Boards regulatory practices and will help provide a framework for developing monitoring and cleanup strategy for tertiary butyl alcohol around the world.