This $19 million project constructed eight miles of new concrete overlay over the significantly deteriorated northbound lanes of TH 169 from St. Peter to Le Sueur, replaced the northbound bridge over Robarts Creek and improved the failing drainage system.
Located at the bottom of the Minnesota River bluffs and within the Minnesota River floodplain, the project corridor had a long history of sediment clogging roadway cross culvert, resulting in sediment-laden water overtopping TH 169. A key aspect of the project was designing a long-term solution to extract sediment from off-site drainage prior to entering cross culverts under TH 169. Alliant’s solution was to construct two diversion weirs that, during significant storm events, diverted excess sediment-laden runoff from the natural creek bed and into off-line sedimentation traps constructed by the project. The sedimentation traps provide time for sediment to settle out prior to entering the roadway cross culvert.
Another unique aspect of the project includes our design of a context sensitive approach to guardrail warrants and placement throughout the corridor that improved safety while maintaining the beauty of this 8-mile section of the Minnesota River Valley National Scenic Byway.
As Prime Consultant, Alliant was integral in defining the project scope and developing preliminary layouts to assist MnDOT in obtaining management and functional group buy-in. Alliant generated the final plans, specification, and construction cost estimates for the project, in addition to authoring the project Traffic Management Plans, CATEX, and all associated permitting exhibits.