IN AUGUST 2016, an inspector from the U.S. Environmental Protection Agency arrived at Barksdale Air Force base in Louisiana, a nerve center for the U.S. military’s global air combat operations, to conduct a routine look at the base’s handling of its hazardous waste. Barksdale, like many military bases, generates large volumes of hazardous materials, including thousands of pounds of toxic powder left over from cleaning, painting and maintaining airplanes. For years, Barksdale had been sending a portion of its waste to an Ohio company, U.S. Technology Corp., that had sold officials at the base on a seemingly ingenious solution for disposing of it: The company would take the contaminated powder from refurbished war planes and repurpose it into cinderblocks that would be used to build everything from schools to hotels to big-box department stores — even a pregnancy support center in Ohio. The deal would ostensibly shield the Air Force from the liabililty of being a large producer of dangerous hazardous trash. The arrangement was not unique.