INVESTIGATION AND CLEANUP OF IOWA’S FORMER MANUFACTURED GAS PLANTS – THE INTEGRATION OF GEOLOGICAL, ENGINEERING, AND URBAN ARCHEOLOGICAL PRACTICES

The Iowa Department of Natural Resources (IDNR) is aware of 173 former manufactured gas plant (FMGP) sites in Iowa, and assessment and/or cleanup activities have been initiated at over 50 of them. We intend to use our experiences from assessment and clean up of these initial 50 sites to improve assessment and cleanup approaches for the remaining ones.

FMGP sites are very different from a majority of conventional contaminated sites administered by IDNR. These sites are typically 100 years old (or more) and are poorly documented. We often do not have site plans that show where the chemicals of concern were generated, stored, conveyed, or handled at each site. In addition, it is not readily apparent where underground piping or subsurface tanks were buried, and we do not know the condition of the site after typical plant decommissioning decades ago. Therefore, we will be trying to adjust our initial approach to site investigation by treating FMGPs more like archeological sites, which are thoroughly investigated using with backhoes and shovels rather than with soil borings or monitoring wells. Once the subsurface structures are exposed, we can develop an accurate site layout and identify those areas of the site where chemicals of concern were likely present. Soil borings, soil probes, and monitoring wells can then be efficiently placed to determine intermediate and deep site stratigraphy and hydrogeology, and complete plume delineation.

In this presentation, I will be presenting photographs taken during the exhumation and remediation of several Iowa FMGPs, along with some historical manufactured gas plant prints and photographs.