The exterior dikes of the Indiana Harbor and Canal (IHC) confined disposal facility (CDF) are being expanded to increase storage capacity.
Dredging and disposal of dredged material to the CDF began in 2012. Through 2020, the backlog volume of approximately 1.7 million cubic yards of dredged material was placed into the CDF. The CDF includes two interior cells separated by a center dike that is approximately 16 feet high surrounded by exterior dikes that are approximately 20 feet high. Consistent with the original project authorization and plan, the US Army Corps of Engineers (USACE) is expanding the CDF exterior dikes (designated Phase 2 dike project) by 11 feet to maintain sufficient storage capacity for the intended project life.
The dike expansion includes reconfiguring access ramps; replacing utilities, outlets, piezometers, and roads; adding seepage control and an emergency overtopping area; adding venting for methane at one location; and other related work to extend the containment dikes vertically while maintaining the functionality of the remaining site operations. The construction of the dike expansion will ensure that a proper disposal facility is available for IHC sediment for many years to come.
The 11-foot dike expansion is expected to occur from 2021 through 2024. The current plan includes no dredging and dredged material placement into the CDF during the dike expansion. CDF operational activities such as groundwater extraction and water treatment continue during dike expansion.
The CDF dike expansion will have an insignificant impact on air quality since the construction is being done with clean material, and the contents of the CDF will not be disturbed during construction.
During the dike construction period, air monitoring equipment from the existing pads on top of the dikes will be moved to temporary gravel pads in the northeast corner, southeast corner, and southwest corner of the site. Air monitoring during the dike construction period will include:
This monitoring is consistent with the single ambient air monitoring location on the site during CDF construction. The additional particulate monitoring will support the traditional visual dust monitoring conducted at construction sites. Throughout the period, the ambient air monitoring at the East Chicago High School will continue.
After completion of the dike expansion, air monitoring equipment, except for the real-time naphthalene monitors as discussed below, will be re-installed on top of the dikes, and the current air monitoring program will restart.
Four real-time naphthalene air monitors (UV-DOAS) operated continuously at the four corners of the CDF dikes since the spring of 2012.
These naphthalene units recorded data every 15 minutes. Average levels are computed for a 24-hour period and are compared to Action Levels. From 2012 to 2021:
The levels of naphthalene and other chemicals of concern in the IHC sediments have decreased significantly in the last several decades. These levels are expected to continue to decrease in the future due to legacy contaminated material being removed by dredging, regulation of uncontrolled discharges, improved sewage systems, and changes in land use practices. Since naphthalene has been infrequently detected at the onsite real-time air monitors, the anticipated lower future concentrations of naphthalene in the sediment are expected to result in even fewer detections by the real-time naphthalene air monitors.
For these reasons, USACE stopped operating the real-time naphthalene air monitors when the dike expansion began, and it will not restart when dike construction is complete.
Real-time particulate air monitoring, and ambient air/high volume air monitoring will continue through the dike construction/interim dike period at temporary locations off the dikes. When dike construction is complete, they will be re-installed on top of the dikes and monitoring at those locations will resume.
See the Photo Gallery for photos of the dike expansion activities.