California Department of Transportation - Route 255 PM 4.74 Culvert Replacement

California Department of Transportation - Route 255 PM 4.74 Culvert Replacement

The purpose is to replace an existing 112-foot, 18-inch diameter reinforced concrete pipe (RCP) culvert that has separated at the culvert barrel, allowing a sinkhole to develop in the roadway above the culvert. The existing culvert will be replaced with a 112-foot, 24-inch diameter RCP. This project involves removing the existing culvert, creating a trench that is approximately 3 feet wide and up to 7.5 feet deep, filling the portion of the trench that is within the limits of the paved roadway with cement slurry and then re-paving. The applicant will backfill the trench on the shoulders of the roadway with a mixture of sand and gravel, and then compact the area. An area, approximately 6 x 3 x 3 foot, will be excavated in preparation for the new headwall and end wall, and to install 4 x 4 foot by 6-inch thick pre-cast concrete (PCC) head- and endwalls at the culvert inlet and outlet, respectively. Dewatering may be required for the construction of the head- and endwalls. Typically, water would not be present during the planned construction period, June 1 to October 15. The applicant will pump any water encountered at the inlet or outlet to an upland sedimentation basin, where the water will be allowed to percolate into the soil or will be pumped to a tank truck for offsited disposal. The intake for the pump will be screened, and a qulaified biologist will be onsite to facilitate rescue of any sensitive aquatic species. The project does not require the removal of trees.

Humboldt