UT NP ARCH100(2) Bridges on Delicate Arch Road Final Hydraulics Report_Signed.pdf

This is a Final Hydraulics Report for the Bridges on Delicate Arch Road project (UT NP ARCH 100(2)) within Arches National Park. The report provides technical analysis supporting the design and construction of three 100-foot span concrete bridges to replace inadequate culverts at Salt Valley Wash, Salt Wash, and Winter Camp Wash crossings on Delicate Arch Road. The project, managed by the Federal Highway Administration under the Department of Transportation, addresses critical infrastructure deficiencies that currently cause flooding, sediment deposition, unsafe visitor conditions, road closures, and high operational costs. The hydraulic analysis supports the roadway profile elevation to accommodate a 10-year design frequency flood event and provide equipment access to the wash areas, with the Salt Valley Wash crossing requiring roadway realignment to the north of the existing facility.

The project scope includes reconstruction (4R) work with one restoration (3R) segment, encompassing embankment construction (10,000 cubic yards), riprap placement (1,725 cubic yards), roadway aggregate installation (5,140 tons), and asphalt concrete pavement overlay (4 inches) for restoration sections. The hydraulics report provides the technical foundation for this design-build or design-bid-build reconstruction effort to restore safe operations and improve visitor experience at this principal park road, which serves as the primary access route to Delicate Arch within the National Park system.