Overview
A confined disposal facility (CDF) was constructed to store the backlog of dredged sediment on a USEPA Resource Conservation and Recovery Act (RCRA) site in East Chicago, Ind., located on the
Lake George Branch of the IHC. Over a 7- to 10-year period, an estimated 1.8 million cubic yards of sediment backlog will be dredged and placed in the CDF. The CDF construction consisted of
multiple features that work together to complete the facility, including:
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A slurry cut-off wall approximately 40-ft deep around the perimeter of the CDF on the north, east, and west sides to hydraulically isolate the groundwater at the site from the rest of the
Calumet aquifer.
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A sealed sheet pile cut-off wall at the canal on the south side of the site to hydraulically isolate the groundwater at the site from the Lake George Branch of the IHC.
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A groundwater gradient control system to pump groundwater from the CDF site to an on-site water treatment facility. The gradient control system consists of 88 vertical extraction wells which will,
in combination with the slurry cut-off wall and sheet pile cut-off wall, prevent contaminated groundwater from the former refinery site from migrating off site.
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Approximately 20-ft tall clay dikes to contain the dredged material, and a 14-ft high center dike to aid sediment and water management. Dikes may be raised in the future to accommodate more dredged
material.
Dredging off-load facilities, an administration building and parking lot, security features, storage facilities, decontamination stations, and other support features have been constructed
as necessary to facilitate dredging.
The sediment will be hydraulically off-loaded into the IHC CDF, primarily using re-circulated groundwater from the CDF site. The CDF will operate as a "ponded" facility to reduce the risk of
potential air-emissions. Both real-time and ambient air monitoring will be conducted to ensure the safety of staff and the community.
A limited volume of sediment which is regulated by the Toxic Substances Control Act (TSCA) which may hold elevated levels of PCB's will be dredged from the canal and placed within the CDF
in future years. After removal, those areas of the canal will be capped with geotextile and stone to prevent further migration of sediment from those areas. TSCA dredging is currently
not scheduled, and coordination is on-going with USEPA and the Indiana Department of Environmental Management (IDEM) regarding TSCA permitting.
Photos of the CDF are available for viewing on the Photo Gallery page.