Awards Category D: Environmental

LOCATION

DuPage County, Illinois

PROJECT DESCRIPTION

The North-South Tollway (I-355) Wetland Mitigation Project represents almost a decade of advancement in engineering and scientific understanding of palustrine wetland construction.  To mitigate for the 80 acres of wetlands directly lost from construction of 17.5 miles of the tollway, in 1984 the Illinois State Toll Highway Authority (ISTHA) proposed to construct or enhance 120 acres of wetlands across five sites on land owned by the Forest Preserve District of DuPage County.  Consoer Townsend Envirodyne Engineers, Inc. designed, permitted, and supervised construction of the new wetlands.  After the five year monitoring period, only 11 acres of re-created wetlands did not meet the performance expectations established by the regulators.  Christopher B. Burke Engineering, Ltd. was then retained to design and supervise construction of an additional 11 acres at the Greene Valley site - regulators accepted these final wetlands, thereby indicating that ISTHA had met its original mitigation obligation.  This has established ISTHA's credibility with the agencies regulating wetlands for mitigation of impacts related to highway projects.