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PROPOSED INTERGOVERNMENTAL AGREEMENT
Department: Department of Planning and Development
Other Part(ies): Illinois Department of Transportation ("IDOT")
Request: Authorization for the Forest Preserves of Cook County (the "Forest Preserves") to enter into an Intergovernmental Agreement regarding emergency repairs to the Big Bend Lake Spillway in Des Plaines
Goods or Services: The Forest Preserves and IDOT would like to cooperate in the planning, design, construction and maintenance of emergency repair of the Big Bend Lake Spillway.
Agreement Number(s): IGA #24-0467
Agreement Period: Five (5) years or completion of construction, whichever comes first
Fiscal Impact: Not to exceed $165,000.00 to be fully reimbursed by IDOT
Accounts: Professional Services 51010.520830; and Land Improvements 51010.560060
District(s): 17
Summary: Late last year, Forest Preserve staff discovered signs of instability and undermining at an existing water control structure at the south edge of Big Bend Lake. The existing spillway from this man-made lake accepts drainage from a 96" IDOT storm sewer at the north edge of the lake and empties into the Des Plaines River via a concrete spillway structure built by IDOT in the 1970s. The spillway structure was originally built as part of a license agreement between IDOT and the Forest Preserves in 1977 (License #1078). Portions of the area around the spillway were filled with rip rap material by the Forest Preserves in 2015, but that has since eroded away along with erosion of soil under the spillway slab. Sandbags are currently in place to reduce the flow of water and prevent further erosion. The spillway is now in immediate need of stabilization and repair to avoid collapse and flooding of downstream areas.
An Intergovernmental Agreement ("IGA") is needed at this stage to authorize the immediate repair of the spillway structure, including engineering design, construction and funding by the parties. The F...
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