Abstract

DCI Environmental, Inc. (DCI), in cooperation with Iowa Power and Light Company and its affiliates (IPL) have implemented an innovative approach to manufactured gas plant (MGP) site remediation. In the late 1990s, with the regulatory change in the characterization of MGP waste as a hazardous material, DCI and IPL sought a cost-effective strategy for treating contaminated materials removed from IPL's MGP sites. It was ultimately determined that thermal desorption treatment using DCI's mobile and fixed-based Medium Temperature Thermal Desorption (MTTD) systems was the optimum solution. In cooperation with the Iowa Department of Natural Resources (IDNR), DCI established a fixed-base Soil Management Facility at the Cedar Rapids, Iowa (USA) Bluestem Solid Waste Agency Landfill in 2001. The DCI Cedar Rapids Soil Management Facility has successfully treated 308 000 tonnes (340 000 tons) of source materials and contaminated soil from over 25 MGP sites. The facility uses methane gas generated by the landfill to provide energy for the thermal des-orption treatment of MGP wastes. Thermally treated soil is used as daily cover at the landfill.

This paper describes the processes required to establish the thermal desorption facility, including facility siting, permitting and trial-burn requirements, fuel sources, material processing, treatment criteria, treated soil disposal, and the economies of scale. The merits of energy recovery through the use of methane gas to power the unit and landfill conservation by using treated waste as cover material are described.

Key words: manufactured gas plant, PAHs, remediation, thermal desorption