On July 11, 1990, the Michigan Department of Natural Resources (MDNR) promulgated administrative rules to implement a uniform hazardous waste site cleanup program in Michigan. These MDNR Administrative Rules (Act 307) establish a process for calculating risk-based cleanup levels for soil and groundwater affected by carcinogenic and noncarcinogenic hazardous chemicals which pose a threat to human health and the environment.

The MDNR periodically publishes guidance documents that provide interpretation and procedures for implementation of the Act 307 Rules. The MDNR recently published a guidance document which presents generic risk-based cleanup criteria for industrial sites. The purpose of this paper is to provide background on the Act 307 rules, and to describe the algorithms used to calculate this cleanup criteria. In addition, this paper provides background on the MDNR's selection of standardized exposure variables for industrial land use.