Bituminous Pavement Constructed with Municipal Solid Waste Combustor Ash: Construction, Performance, and Economic Issues

摘要

The Polk County Solid Waste Department, located in Polk County Minnesota, participates in a complete integrated solid waste management program that includes four other counties in northwest Minnesota. One component of the integrated solid waste management program includes the operation of a municipal waste combustor (MWC) that combusts approximately 65 tons per day of processed solid waste. The starved air design of the combustor causes low turbulence in the primary burning chamber minimizing particulate carryover through the system. This results in generation of approximately 12 tons per day of combined ash comprised of 98 to 99 percent bottom ash and 1 to 2 percent fly ash, by weight. In 1996 the facility installed an up-front separation facility, or materials recovery facility (MRF), that removes recyclable materials as well as non-processible or objectionable materials prior to combustion. The energy produced is sold in the form of steam to businesses adjacent to the facility. The ash generated by combustion prior to the 1996 installation of the MRP is referred to as "old ash" and was landfilled in a MWC ash landfill permitted by the Minnesota Pollution Control Agency (MPCA). The ash generated since installation of the MRF is referred to as "new ash", and is also placed in the permitted landfill. The chemical and physical differences between the new and old ash are important enough to warrant the two ashes being addressed separately for purposes of this utilization demonstration project. In 2000 and 2001, Polk County performed a demonstration of the feasibility of utilizing combined MWC ash as a partial replacement of aggregate in bituminous paving materials. The demonstration consisted of building and evaluating a section of county road using the MWC ash-amended bituminous. This paper presents the performance, construction and economics issues and results of this demonstration. The up-front environmental evaluations performed as part of this demonstration were previously presented by Lucido and Wilson. The final environmental evaluations of this demonstration are presented in this paper. Therefore, after a summary of the following relevant publications, the remainder of this paper will focus on the structural performance, construction and economics issues and results of this demonstration. The project was approved by the MPCA and supported by the Minnesota Resource Recovery Association, the Association of Minnesota Counties, the Minnesota Office of Environmental Assistance, the Minnesota State Representative for District 2A, the four partner counties adjacent to Polk County, the Polk County Board, the Polk County Highway Department, and the citizens of Polk County.