Environmental Assessment: Lockport Approach Dike Stage 2 Repairs, Will County,Illinois

摘要

For the past 20 to 30 years, the Lockport approach dike has experienced seepagefrom the Chicago Sanitary and Ship Canal to the Des Plaines River. Repairs have been made, but a subsidence occurred in May 1990 with two subsequent events, the most recent in November 1990. In the interest of safety and integrity of project operation, the U.S. Army Corps of Engineers is finalizing emergency repairs to stop the subsidence problems. These emergency repairs are considered Stage 1 of a project to raise the safety level of the approach dike. Stage 2 repairs, although not considered to be emergency in nature, are needed to maintain the dike's safety and operation. The dike is experiencing ongoing erosion to its canal side due to canal level fluctuations and tow prop wash at the various water levels. Site investigations have revealed tension cracks on the landward side of the dike. The Corps proposes to reconstruct these slopes to prevent further erosion and rectify deficiencies in the existing approach dike.