Approximately five acres southeast of Oakland Place Southeast and Fourth Street Southeast in the center of Austin was the site of a former coal gasification plant that served the city from 1905 to 1935. Residual gas generation equipment was removed and the site was subsequently used for a variety of retail and commercial uses, including an implement and automobile dealership, a roofing company, and, more recently, a pet and animal feed and supplies store. However, subsurface contamination from waste byproducts, such as coal tars, sludges, oils and other chemicals, remained at the site. Interstate Power and Light Co. (IPL), a subsidiary of Alliant Energy, purchased the Austin Gas Manufacturing Co. in 1924, making it responsible for the cleanup of the residual contamination.
Years of soil and groundwater investigations identified concentrations of polychlorinated biphenyls, polynuclear aromatic hydrocarbons, and benzene, toluene, ethylbenzene and xylenes in excess of the MPCA’s soil reference values. After completing land acquisitions, IPL removed all remaining above-grade structures in 2006 and then excavated and thermally treated contaminated soils with a permitted, mobile thermal destruction unit (TDU). Treated soils were then placed back in the excavation and covered with topsoil from an approved source. The area was then planted with native trees and prairie species.
Environmental issues and the cleanup process
- Debris was hauled to a permitted landfill.
- 74 tons of metal scrap were recycled.
- 1,039 tons of concrete and 592 tons asphalt were removed and recycled.
- 31,328 tons of soil were treated through the TDU, which operated 24/7 through the first quarter of 2008.
- 4,372 tons of topsoil were delivered to facilitate surface restoration as a public green space.
Site remediation utilized a permitted thermal treatment unit. (photo: MPCA staff)
Redevelopment of the site
Prairie Eco-Recreation greenway and trail, which connects to the adjoining Cedar River trail.
Environmental and economic benefits
- prairie and tree plantings, public parking with Cedar River trailhead for public recreation
- remediation of the Cedar River watershed and adjoining floodplain
- A No Further Action determination is being sought.
- An Institutional Control is in order.
- IPL – Cedar Rapids, Iowa
- MPCA VIC staff involved in the project: Ed Olson, Project Manager, and Mike Connolly, Hydrogeologist
- MWH – Des Moines, Iowa, consultant
- DCI Environmental, Inc., Savage, Minnesota, TDU operator
- City of Austin