THERMAL-TREATMENT AND NONTHERMAL TECHNOLOGIES FOR REMEDIATION OF MANUFACTURED-GAS PLANT SITES

More than 1500 manufactured gas plant (MGP) sites exist throughout the U.S. Many are contaminated with coal tar from coal-fueled gas works w hich produced 'town gas' from the mid-1800s through the 1950s.(1,2) Vi rtually all old U.S. cities have such sites. Most are in downtown area s as they were installed for central distribution of manufactured gas. While a few sites are CERCLA/Superfund, most are not. However, the co ntaminants and methods used for remediation are similar to those used for Superfund clean-ups of coal tar contamination from wood-treating a nd coke oven facilities. Clean-up of sites is triggered by regulatory pressure, property transfers and re-development as well as releases to the environment - in particular, via groundwater migration. Due to ut ility de-regulation, site clean-ups may also be triggered by sale of a utility or of a specific utility site to other utilities. Utilities h ave used two approaches in dealing with their MGP sites. The first is 'do nothing and hope for the best'. History suggests that, sooner or l ater, these sites become a bigger problem via a release, citizen lawsu it or regulatory/public service commission intervention. The second, f ar better approach is to define the problem now and make plans for was te treatment or immobilization. This paper describes recent experience with a high capacity/low cost thermal desorption process for this was te and reviews non-thermal technology, such as bio-treatment, capping, recycling, and dig and haul. Cost data is provided for all technologi es, and a case study for thermal treatment is also presented. (C) 1997 Elsevier Science Ltd.