For years a heavy oil used to power the plant leaked from storage tanks into the ground. The oil was "Bunker C" - a tar like substance. The oil has been "cleaned up." Really, some of it was cleaned up, the rest has been contained.
Sometimes I think America lives on top of a hazardous waste site. I think of the Silver Valley to the East in Idaho. The contaminated Spokane River. The contaminated Lake Roosevelt which is a part of the Columbia River upstream for Coulee Dam, the contaminated areas of Lake Coeur d'Alene, to name only a few.
In fact much of the area in and about downtown Spokane which has been rebuilt on old railroad yards is contaminated, but we will not say anything about that.