Environmental protection: cleanups; cleanup standards; require. Amends secs. 20101, 20107a, 20112a, 20114, 20114b, 20114c, 20114d, 20114e, 20119, 20126, 20126a, 20137 & 20139 of 1994 PA 451 (MCL 324.20101 et seq.); adds secs. 20113a & 20139a & repeals secs. 20114a & 20114g of 1994 PA 451 (MCL 324.20114a & 324.20114g). TIE BAR WITH: SB 392'25, SB 385'25

SB 391 updates Michigan's environmental cleanup rules by establishing clearer standards for determining natural background levels of hazardous substances in soil. It defines "background concentration" as naturally occurring levels in soil, allowing property owners to demonstrate contamination is not due to human activity using specific soil surveys or studies. The bill directly affects developers, property owners, and environmental agencies involved in site cleanups by reducing unnecessary cleanup requirements when contamination matches natural background levels. Key provisions include adding new definitions (like "background concentration" and "baseline environmental assessment") and revising cleanup criteria to align with state soil surveys, making it easier to distinguish natural soil levels from pollution requiring remediation.