Since yesterday’s post on the Peterborough Oil case, a little birdie told me that MassDEP may be taking the position that MTBE 
is covered by the “oil exemption”, because it is a hydrocarbon. If so, that would be good news for PRPs, because most cleanups don’t involve third parties. If MassDEP says that MTBE is covered by the exemption, then a PRP cleaning up a site with an “oil” release containing MTBE could still close out the site based on the MassDEP interpretation.
However, I think that that interpretation is at best on shaky ground and if I were litigating a private action where the scope of an MTBE cleanup was at issue, I know which side I’d rather represent. EPA’s MTBE web site states that:
MTBE(methyl tertiary-butyl ether) is a chemical compound that is manufactured by the chemical reaction of methanol and isobutylene. MTBE is produced in very large quantities (over 200,000 barrels per day in the U.S. in 1999) and is almost exclusively used as a fuel additive in motor gasoline.
I don’t think anyone would dispute that the environmental concerns with MTBE relate to its use as an “additive” in gasoline to increase octane. The SJC decision certainly seems to take the position that additives are not subject to the oil exemption.
If MassDEP believes that MTBE in gasoline poses different risks of migration than lead in gasoline, and that those different risks justify different regulatory treatment, that would be excellent news for PRPs – but that’s not the exemption that MassDEP promulgated.
In fact, MTBE is typically much more mobile in the environment relative to lead so this distinction for one additive versus another does not appear to be based on migration/exposure potential.