Timber Lane Bridge over Tributary No. 4, West Branch DuPage River

Wayne Township Road District

OBJECTIVE

Achieve Phase I design completion and NEPA Categorical Exclusion documentation for the Local Bridge Formula Program (previously known as STP-Br) funded project. The current structure, a reinforced, cast-in-place box culvert spanning approximately 33 feet and comprising four cells, exceeds flood thresholds for all events beyond the 5-year frequency.

PROJECT DESCRIPTION

The Phase I project involved the development of preliminary engineering, including environmental clearances, Preliminary Design and Hydraulic Report (PBDHR), Bridge Condition Report (BCR), and Project Development Report (PDR), design variance approval (BLR 22120), and state-approved categorical exclusion processing.

Phase I engineering work encompassed hydraulic, structural, and drainage designs, preliminary geometric roadway designs, public involvement via property owner letters, detour concepts, geotechnical analysis completed by HLR’s subconsultant, and engineers' estimates of probable cost. Hydraulic modeling was conducted using HEC-RAS. Preliminary designs were developed to minimize impacts on onsite and adjacent environmentally sensitive areas and to avoid adverse effects on any structures upstream or downstream of the Timber Lane structure.

Phase I environmental project work included wetland delineation of Tributary No. 4 of West Branch DuPage River and potential associated wetlands, jurisdictional determination, tree survey, structure bat habitat inspection, and Regulated Substances Screening.