Rosebud County Commission approves floodplain variance for MDT bridge project after engineer review

At its Jan. 20 meeting, the Rosebud County Commission voted to approve a floodplain variance requested by the Montana Department of Transportation for a bridge replacement project shown as Project Site 05511.

Kevin Bergle, who presented the county staff summary and the engineering findings, said the Montana Department of Transportation contracted with Robert Peshen Associates (RPA) to replace existing bridges with reinforced concrete box (RCB) culverts. Bergle said RPA and a hydraulic analysis by CDNH concluded the work "should be no no adverse impact to the floodplain during this production process," and that raising the freeboard to meet the regulation would substantially change the road surface elevation.

Bergle described the existing structure as having been constructed in 1937 and located on an unnamed stream within the mapped flood hazard area on FEMA FIRM Panel 3000690023A. He said the variance request seeks a deviation from section 9.422 of the Rosebud County floodplain regulations related to freeboard/road elevation requirements.

Commissioners asked clarifying questions about the analysis and timing for placing the item on the agenda for formal action. After discussion, a commissioner moved to approve the variance. The motion was seconded and the commission voted in favor; the chair stated the motion carried.

The commission did not record additional conditions in the transcript beyond the engineering findings. The item will proceed under normal implementation steps for MDT projects and county permitting; no further deadlines or reporting requirements were specified in the record.