20160939 Ver 1_610224_Project Description_20160929

3d. Explain the purpose of the proposed project:
The purpose of the project is to replace Bridge 224 along McCallum Pond Road (SR 1562) over
Big Creek with a single span (60’), pre-stressed cored slab bridge.
3e. Describe the overall project in detail, including the type of equipment to be used:
There is one proposed major structure involved with the bridge replacement. The existing
structure is a 1 @ 25'-5", timber deck on I-Beam, supported by timber caps, timber piles and
timber bulkhead. The existing bridge has vertical abutments on both sides. The proposed
structure, along McCallum Pond Road (SR 1562), is a single span 1 @ 60', 24" pre-stressed
cored slab with 4' deep caps with spill thru abutments on both sides. This structure has been
designed to have as little environmental and surface water impacts as possible. Excavation was
kept to a minimum and was kept outside of the existing stream channel. There are existing
roadside ditches which end at wetland boundaries with non-erosive velocities. There are no
proposed roadside ditches. This will promote sheet flow through grass shoulder areas to provide
storm water treatment for pavement runoff before entering the wetlands or stream with non-
erosive velocities. The bridge stormwater outlet was designed to the west side to avoid wetland
impact. The rip-rap pad at the pipe outlet was designed to dissipate energy and provide diffuse
(sheet) flow through the wooded area. This provides 50' +/- of diffuse flow through the wooded
area for treatment before it reaches the top of bank and enters the stream. 2:1 roadway fill
slopes were designed to minimize wetland impacts. Equipment to be used includes standard
heavy highway construction equipment (i.e. excavators, dump trucks, etc.). Traffic will be
maintained with an off-site detour.