Peoples Natural Gas Co.

Overview

The Peoples Natural Gas Co. site in Dubuque, Iowa is a former manufactured gas plant that operated from the 1930s to 1954. It left behind coal tar, cyanide-bearing wood chips, benzene, polycyclic aromatic hydrocarbons (PAHs), and other industrial residues in both soil and groundwater. The EPA added it to the National Priorities List (NPL) in August 1990 after contamination turned up during highway construction preparations. The site is also known as the Dubuque Coal Gas or Key City Coal Gasification Plant.

The EPA identified 34 contaminants of concern across soil and groundwater. These include benzene, toluene, ethylbenzene, xylene, naphthalene, cyanide, and numerous PAHs such as benzo[a]pyrene and chrysene. Carcinogenic PAHs were found only in soil, while most other contaminants appear in both soil and groundwater. Cleanup is organized under Operable Unit 1, which covers all remedial activity at the site.

Soil cleanup involved excavating and incinerating 6,850 cubic yards of contaminated material, completed by 1998. Groundwater treatment ran from 1996 to 2003, including an ozone sparging system from 2000 to 2002, but could not meet cleanup standards in certain areas. In 2013, the EPA determined that complete groundwater cleanup was technically impossible in those areas and amended the remedy to focus on containment and monitored natural attenuation. A pumping system between the site and the Mississippi River now captures contaminated groundwater to prevent it from migrating toward the river. MidAmerican Energy operates this system and monitors groundwater. Environmental covenants on all three property parcels restrict use to commercial, industrial, or transportation purposes, ban residential use, prohibit water well installation except for EPA-authorized monitoring wells, and require vapor intrusion safeguards in any new enclosed buildings. The site was declared ready for anticipated reuse in June 2015.

The site has been redeveloped as the Jule Operations and Training Center, a transit facility for Dubuque's local bus system. The 6.8 million dollar project was built with a raised foundation and a full-floor vapor barrier to address remaining subsurface contamination. One on-site business employs 22 people there as of December 2024. The EPA's Five-Year Review completed in December 2020 found the remedy protective in the short term because controls prevent exposure to remaining contaminants. A new Five-Year Review began in December 2024 and is scheduled for completion by December 2025. Sources differ on the date of the most recent Five-Year Review, citing both December 2020 and December 2025, so both are noted here as stated.

Community members with questions about the site can contact the EPA Community Involvement Coordinator or the Remedial Project Manager.