Environmental Review Toolkit
Water, Wetlands, and Wildlife

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On IL 29 facing north – View of Miller Anderson Woods Nature Preserve. Narrow median with barrier designed to avoid impact to this resource. (IDOT)
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View of part of environmental mitigation land proposed to be purchased. The land includes high quality floodplain forest and backwater of the Illinois River. This land will be transferred to IDNR after purchase. (IDOT)

Illinois Department of Transportation

Illinois 29 improvements to protect ecosystems

A narrower footprint on the land--that's the future of planned improvements on IL 29 in Illinois' resource-rich Peoria Wilds.

The 35-mile Illinois Department of Transportation (IDOT) project corridor runs from IL 6 near Mossville in Peoria County to Interstate 180 in Bureau County, and the highway lies between bluffs and blufftop farmlands to the west and the Illinois River to the east. Two-lane IL 29 is being studied for expansion to four lanes.

An impressive array of natural resources are located within the IL 29 study area: Illinois Nature Preserves and Natural Areas, an Illinois Land and Water Reserve, and approximately 6,000 acres of the Illinois Department of Natural Resources' (IDNR) Fish and Wildlife Areas. These properties offer recreational opportunities and provide habitat for wildlife species like the bald eagle and plant species like the federal ESA-listed (threatened) decurrent false aster (a tall, aster-like plant which grows only along the Illinois and Mississippi Rivers) and the Illinois state-listed (threatened) arrowwood (a 4 to 10-foot high plant known for its peeling bark and large, reddish-purple leaves).

To minimize IL 29 construction impacts on surrounding ecosystems, IDOT partnered with the IDNR, U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Department of the Interior, and FHWA to develop these minimization and mitigation strategies:

Flexible Highway Design: A narrow, 22-foot-wide median with barrier wall will be constructed on two sections of the improved highway. Usually, medians are 50 feet wide. By narrowing them to 22 feet, IDOT will be able to reduce impacts to upland forests, natural areas, and the Miller Anderson Woods Nature Preserve and its associated high-quality wetlands and natural areas. Narrower medians and 2-foot-wide openings along the barrier wall will also help keep small animals moving as they cross the road.

Three miles of IL 29 have been designed as a "split profile" roadway. In other words, the southbound lanes will be 3 to 17 feet higher than the northbound lanes, avoiding impacts to upland forests and natural areas along the bluffs.

In addition, IDOT will use a "split interchange" design for a new IL 17-IL 29 interchange within the Village of Sparland. As the name implies, a split-interchange design divides an interchange in half. Half of this project interchange will be located at the southern end of Sparland and the other half at the northern end. Separating the ramps by nearly a mile is expected to reduce impacts to Sparland, nearby wetlands, an IDNR property, flood-buyout properties, and residential areas.

Land transfer: The IDOT will ultimately transfer approximately 734 acres to IDNR: a 15-acre buffer between the Root Cemetery Nature Preserve and a quarry, about 643 acres within the Illinois River floodplain that will connect 2 land segments currently owned by IDNR, and 91 acres of wooded bluffs which was threatened by residential development and is adjacent to a state Fish and Wildlife Area.

Wildlife Passages: Using data from a 2001-2002 roadkill survey along IL 29, IDOT has proposed about 30 wildlife passages for mammal and amphibian/reptile roadkill hot spots. The IDOT predicts the passages will reduce the high number of animal-vehicle collisions and remove barriers to wildlife movement. Bridge spans will be lengthened, opening an additional 10 to 25 feet to provide a sufficiently wide, dry-crossing area for large animals. Ledges will be installed in culverts for small animals to use during storms.

Upland Habitat Mitigation: To increase the amount of habitat restored during the project, IDOT will plant 64 acres of trees and 255 acres of prairie species on excess right-of-way and landlocked parcels. One planting location will be near a planned wildlife crossing. Another will be along a creek and could provide habitat for the arrowwood plant north and south of the parcel. Still other plantings will be on cropland adjoining streams where they will help reduce sediment flowing into the Illinois River.

Restore Existing Upland Sites and Prevent the Spread of Exotic Species: The IDOT will provide IDNR with funding to restore prairies at the Hopewell Hill Prairie Nature Preserve and the Marshall County Hill Prairie Land and Water Reserve. The IDOT will also provide IDNR with funding to restore 15 acres of an old farm at Miller Anderson Woods Nature Preserve and for control of non-native, invasive plants like Common Teasel and Canada Thistle.

For more information, contact Paula Green, Paula.Green@Illinois.gov

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