Terracon was retained by the City of Cheyenne to assist with the challenge of siting, permitting, and designing a new landfill for the City of Cheyenne and western Laramie County. The existing City of Cheyenne Landfill, which services approximately 75,000 residents of Cheyenne and western Laramie County, was scheduled to reach capacity in approximately 2009. The mayor of Cheyenne appointed a Landfill Advisory Committee (LAC) to study the issue and provide recommendations to the city for a future course of action. Terracon worked with the LAC in a series of public meetings to evaluate several options. After careful consideration and input from the Wyoming Department of Environmental Quality (WDEQ), the LAC recommended the city site and design a new landfill to replace the existing landfill, and to increase recycling efforts. The Terracon team utilized a geographic information system (GIS) approach to site the new landfill. The approach systematically mapped and eliminated areas within Laramie County that were not suitable for siting a new municipal solid waste landfill based on landfill siting criteria established by the U.S. Environmental Protection Agency (EPA) and the WDEQ. The Terracon team then assisted the LAC in a series of public meetings to evaluate and rank the suitable sites. Once the site was selected, Terracon performed a biological resource survey, cultural resource survey, and subsurface geotechnical and hydrogeological assessment at the site. Terracon utilized a unique sonic drilling method to advance borings to depths of more than 300 feet through dense material to obtain continuous core recovery. Terracon assisted the city with landfill design negotiations with the WDEQ. Based on the relatively transmissive subsurface conditions and groundwater resources at the site, the WDEQ requested an enhanced cell design, more pro-tective to groundwater than Federal RCRA Subtitle D requirements. The project is currently in the design and permitting phase. The leachate system design includes two gravity-flow, double-wall un-derground pipelines that flow to one of two lined leachate evaporation ponds. Due to the estimated high cost of developing the site as a landfill, the city placed the project on hold while new options, including waste-to-energy, are considered.