Heavy equipment at work
Heavy equipment operators fill in the first subgrade sulfate reactor at Travis Air Force Base, Calif., in the summer of 2016 with a mixture of gravel and crushed drywall, creating the right conditions for naturally occurring microbes to use fuel contaminants as food. The reactor is powered by a solar panel array, making this cleanup technology nonintrusive and environmentally friendly. (Courtesy photo/Jordan Ollanik)