ROCKFORD, Mich. (AP) — Federal environmental officials are resuming an investigation into contamination at a former tannery in western Michigan five years after the Environmental Protection Agency left the site under state control.

The Grand Rapids Press reports that the EPA says new testing will begin this month at the former manufacturing site where Wolverine World Wide used chemicals to waterproof shoe leather.

The EPA has requested Wolverine conduct extensive soil and groundwater sampling across the Rockford property. The site has been open to the community and used as a space for events since 2010.

Recent testing found extremely high levels of per- and polyfluoroalkyl substances at the site. But the EPA is focusing its probe on other contaminants as well.

Wolverine says it's working with regulators and expects to begin fieldwork this summer.