Ohio Rev. Code Ann. § 3746.02
(A) Nothing in this chapter applies to any of the following:
(1) Property for which a voluntary action under this chapter is precluded by federal law or regulations adopted under federal law, including, without limitation, any of the following federal laws or regulations adopted thereunder:
(5) Any other property if the director of environmental protection has issued a letter notifying the owner or operator of the property that the director will issue an enforcement order under Chapter 3704., 3734., or 6111. of the Revised Code, a release or threatened release of a hazardous substance or petroleum from or at the property poses a substantial threat to public health or safety or the environment, and either of the following applies: