Revitalizing the Chicago Area Water System,
Over 100 miles of rivers and canals make up the Chicago Area Waterway System (CAWS), which connects Lake Michigan with the Mississippi River and includes the Chicago River, the Chicago Sanitary and Ship Canal, the Cal-Sag Channel, and the Calumet Rivers. This complex water system has a long history of industrialization, and today, is used for navigation and shipping, residential and industrial wastewater management, and recreation. With residential and commercial development on the rise over the last two decades along the waterway’s banks, there has been an increasing need to improve water quality.
A large part of improving water quality within the CAWS is addressing environmental pollutants left behind by historic industrialization such as former manufactured gas plant, or MGP, sites along the waterways. Cleaning up former MGPs—which left behind contamination in the form of tars, oils, coke, and ash—requires investigation and remediation work to address and resolve environmental impacts, while meeting regulatory goals, as well as preserving critical assets present at these sites.
Characterizing effects of former waterfront MGP sites
Since 2010, OBG has been leading development of a strategy to characterize the effects of former MGP sites on the CAWS. This has included technical and regulatory support to develop site-specific remedial strategies for sediments at eight sites located adjacent to MGP sites. These sites are enrolled in the Superfund Alternative Sites Program, with investigations consistent with the U.S. Environmental Protection Agency’s (EPA) sediment remediation guidelines.
For the highly urbanized environment encompassing the CAWS, a technical approach was developed for separating probable impacts on sediment due to the MGPs from other industrial sources. Potential background pollutant sources were researched and site sampling was conducted in river reaches near to, but outside of, the influence of the former MGPs. Background concentrations of pollutants were then established using statistical evaluation, and site impacts are defined as pollutant concentrations above background that have polycyclic aromatic hydrocarbon (PAH) signatures like those of MGP byproducts. Making this distinction improves the remedial footprint by focusing on MGP impacts only.
Efficiencies in remediating sediment at waterfront MGP sites
OBG has realized efficiencies while working through this portfolio of sites. Planning allowed for grouping sites and mobilizing investigations to address more than one site at a time, consolidating schedules and creating cost savings. In addition, lessons learned early in the work, such as how to overcome complexities of permitting and predict the location of weathered byproducts in the river bed within the CAWS, have been applied to subsequent sites to reduce uncertainties.
By working closely with local, state, and federal agencies, OBG developed an understanding of stakeholder interests in the work and are expediting the path toward closure by:
- Knowing and using agency guidance and precedence
- Understanding sensitive issues to mitigate related project stall outs
- Understanding local interests in risk reduction and redevelopment
OBG’s contaminated sediment site experience demonstrates the importance of understanding stakeholder concerns; expecting the unexpected; and planning means and methods, schedules, and budgets to accommodate reasonable contingencies.
About Sarah Meyer: Sarah is a senior managing scientist within OBG’s Applied Sciences group, and leads the company’s remedial investigation work on the CAWS. She has 22 years of experience as a marine scientist and program manager doing research, investigation, and environmental response work throughout the Great Lakes and nationwide. Sarah is based out of OBG’s Chicago, Illinois office and will be presenting on contaminated sediments at the 2019 Battelle Sediments Conference, taking place February 11-14, 2019 in New Orleans, Louisiana.
Sarah can be contacted at Sarah.Meyer@obg.com.