Primera was retained for Phase I engineering services for the replacement of the Illinois Route 102 Bridge over Ryans Creek in unincorporated Will County, Illinois. This rural site is surrounded by wooded residential lots, open farmland, and the Kankakee River State Park. Ryans Creek has an upstream watershed of 6.6 square miles and the crossing is located approximately 1600 feet upstream from its confluence with the Kankakee River.

A full hydrologic and hydraulic study was completed including a stream survey to create the HEC-RAS base model. A HEC-HMS critical duration analysis was completed to determine the peak flow rates for storm events ranging from the 2-year to the 500-year storm events. A HEC-RAS model was then completed to determine if the existing structure meets current design criteria. An alternatives analysis was completed with proposed modeling to determine the best fit structure which met the design criteria and reduced the occurrence of roadway overtopping and scour. Significant environmental resources were identified at the site which required special design and considerations during construction. This project required the preparation of culvert/bridge technical memorandums, hydraulic reports, geometric studies, crash and safety analysis, scour analysis, transportation management plans, environmental permitting coordination, public involvement documentation and project report, including multiple proposed geometry alternatives.