DETROIT (WWJ/AP) – Checks by the Michigan Department of Environmental Quality have found that hulking black mounds along the banks of the Detroit River in southwest Detroit don’t pose a threat to human well being.

The petroleum coke, or pet coke, mounds are a byproduct of oil refining used in vitality production. Petroleum Refinery Manufacturer The material has been introduced by trucks from the close by Marathon Petroleum Co. refinery. The pet coke is stored at a site off Jefferson Avenue in southwest Detroit, the place it’s loaded onto freighters.