HMMH has worked at Denver International Airport (DEN) on noise issues since its planning. In 1988, The City and County of Denver and Adams County signed an Intergovernmental Agreement (IGA) dictating noise requirements that Denver was required to meet in return for the annexation of land to be used for construction of the new airport, including Noise Exposure Performance Standards (NEPS) for maximum annual noise levels at 101 points in around the airport. Since the signing of the IGA, HMMH has worked with DEN staff to support this requirement, including the development of software and the computation of annual noise exposure levels utilizing radar data to model the actual flight path and climb profile (critical at Denver’s 5,431 foot field elevation) for every individual aircraft in and out of the airport during each year of its operation. HMMH also recently analyzed radar data and calculated noise benefits resulting from a voluntary runway use program that reduced westbound departures of hush-kitted Stage 3 aircraft off of Runway 25, significantly lowering exposure levels over NEPS points in the area west of the airport. The firm has also contributed noise elements to an FAR Part 150 Noise Compatibility Program for DEN, designed an innovative noise and operations monitoring system (NOMS), and support in designing and evaluating Performance-Based Navigation (PBN) options at Denver International Airport.