LaGrange County Small Structure Replacement

JPR provided full design, construction administration, and inspection services for the replacement of a deteriorating 1940s reinforced concrete box culvert at County Road 600, spanning the channel between South Twin Lake and North Twin Lake. The project involved replacing the aging structure with a new reinforced concrete culvert designed for enhanced safety, longevity, and serviceability. Scope of work included topographic survey, geotechnical investigation, utility coordination, structural design, environmental permitting management (via subconsultant), bid phase support, construction documentation, and oversight throughout construction.

A key challenge emerged during the geotechnical investigation, which revealed very soft underlying soils, raising serious concerns about long-term settlement and public safety. JPR addressed this through a cost-effective deep foundation solution using helical piers to support the structure, ensuring long-term stability. Additional coordination was required to relocate conflicting utility lines and to re-route a planned sanitary sewer force main to prevent overlap with the culvert project limits. The project also included roadway widening, updated guardrails with reflectors and signage, improved cross slopes, and riprap for erosion control at the channel corners. Careful coordination with the County and Contractor ensured timely winter and early spring construction to avoid traffic impacts during fall harvest and peak boating season.

The completed project provides the community with a safer, wider crossing and a robust, low-maintenance structure built for long-term reliable service and life.