A loader pushed a heap of garbage ever closer to a 40-foot-deep pit at Spokane’s Waste-to-Energy plant Tuesday afternoon, its effort punctuated by the echoing “pop” of a tire bursting and the tumbling of a child’s blue plastic swimming pool to the floor.

This trash, and the refuse waiting in a line of trucks idling outside the 26-year-old facility on the West Plains, represent not only the landfill space saved through burning but also millions of dollars of income for the city. This week, Spokane signed an extension of its deal with Avista Utilities Corp. to sell excess electricity generated at the plant, a deal valued at between $5 million and $5.5 million in each of the next five years.

“It’s a good chunk of revenue,” said Ken Gimpel, business services director for Spokane’s public works division.