MtBE in Groundwater: The Maine Experiment
Statement of Critical Regional Problem: Water Quality
Motor fuels, and particularly gasoline with oxygenates, pose a threat to water quality because of their widespread use and the high water-solubility of oxygenates (Squillace et al., 1999; Johnson et al, 2000), in Maine alone there were over 2,000 fuel-storage tank leaks in 1999 (Maine DEP, 2000). Nationally, MtBE has been detected in 3.4% of rural wells and 16.9% of urban wells according to USGS NAWQA. (Squillace et al., 1999). Although the US EPA has proposed a ban on MtBE, a national ban will not happen for at least three years according to EPA. MtBE will pose a tremendous risk to drinking water quality on a national scale for many years. Maine opted out of reformulated gasoline (RFG) in 1999, reducing MtBE content from 12% v/v to 2% v/v. Maine is the first state to act on MtBE and thus we have a unique and timely natural experiment ready for analysis. California is planning to ban MtBE after December 31, 2002, but the US EPA has denied the mandated oxygenate waiver request. This waiver request is now to be decided by federal court. The impact of these fuel changes on water quality was examined in 2001 and MtBE was detected in concentrations equal to or greater than in 1999 (Peckenham and Nielsen, in prep.). This project will quantify the occurrence of MtBE in groundwater and assess if fuel policy changes have worked. The results will be valuable to a broad variety of participants in the on-going debate about MtBE use in the US.
More than 35 states have used gasoline with MtBE (USEPA, 1999). On March 21, 2000, EPA proposed to phase out MtBE within 3 years (Browner, 2000). Maine banned RFG in 1999, and California and New York have enacted similar bans. This effect of policy change on water quality may be negligible and the results have not been assessed. For instance, will banning MtBE save money by reducing mitigation costs over a period of several years? It is assumed that there will be a residual cost to clean-up drinking water due to past or recurring MtBE contamination (Johnson et al., 2000). We will quantify the costs posed by MtBE and other oxygenates relative to persistence in water supplies. If MtBE concentrations in water supplies drop rapidly and mitigation costs are low, then a multi-year phase-out schedule would be justified. If not, then a faster phase-out may be justified. In Maine, our analysis will assess the value of reduced MtBE content. This economic assessment of the cost-benefits of the change will provide case-study data to support policy decisions regarding oxygenate (especially MtBE) use in gasoline formulation.