SCI-Shawnee State Forest Bridge Hydraulic Report – Scioto County, Ohio

STONE completed bridge hydrology analysis, bridge hydraulic study and scour analysis, and prepared a Hydraulic Report. The Hydraulic Report focused on the abutment repair of the existing SCI-2SF-0034 along State Forest Service Road 2 over Nace Run, which was complicated by right angle turns at both the inlet and outlet. It evaluated the impacts the proposed structure rehabilitation was to have on existing channel hydraulics, with reference to the ODOT Location & Design Manual Vol. 2. HEC-RAS models were used (existing and proposed), and Manning’s “n” values were adjucted to account for dense brush on the banks. Manual correction of some cross-sections was also needed due to an anomaly in the Lidar base map (not present on the ground survey of the channel).

The existing bridge was a single span (24 feet), with a precast concrete box beam superstructure on stone abutments with a reinforced concrete beam seat and a low chord ranging from 567.93 to 569.22 feet. The bridge carried two lanes of traffic with a face‐to‐face of railing width of approximately 18 feet and an asphalt concrete wearing surface. The bridge abutments were to be refaced, which will reduce the clear span of the bridge measured face to face of abutments by one foot.

STONE concluded that the proposed improvements would not significantly change existing conditions, and that there would be no rise in headwater elevations between existing and proposed conditions.