Construction workers lay down asphalt for a parking lot at Peterson Air Force Base, Colo., Oct. 27, 2011. The asphalt is a mix of recycled asphalt shingles, recycled concrete, rock and sand, and reduces waste sent to landfills. The recycled shingles and concrete come from the local area. The remnants of the old parking lot are being used in other projects around base. (U.S. Air Force photo/Lea Johnson)