VEN - 101 Culvert Replacement Project near la Conchita

VEN - 101 Culvert Replacement Project near la Conchita

Permittee activities shall not exceed temporary impacts to more than 0.50 acres of ephemeral streambed. The two streams carried through the culverts to be replaced are ephemeral carrying seepage and seasonal flows during storm-related events captured from the adjacent steep mountain slopes above the community of La Conchita. The culverts will be replaced with larger (and wing walls and aprons will be reconstructed) to prevent storm-related overtopping should debris-flows occur; however no additional water flow will be directed to these culverts as part of the replacement project. The culvert inlets, and associated wing walls and aprons, are on the mountain side of US 101 within Union Pacific Railroad (UPRR) right-of-way, and just a short distance (bare ground) from the culverts for the UPRR. When reconstructed, the wing walls and aprons will join the existing UPRR culverts (the bare ground between culverts will remain). Culvert outfalls are on the armored (rip-rap) embankment on the ocean-side of US 101 (close to the mean high water line). During replacement of the culvert outfalls, the rip-rap will be removed and replaced in-kind (approximately 240 cubic yards (c.y.) within the existing footprint, 15' along bank (from edge of highway to the outfall), and 16' high). Culvert replacement is proposed for staged "cut-and-cover" construction from the roadway surface during the dry season ( no water diversion). Some temporary disturbance of bare ground in the flow line, and adjacent areas will be required to remove and replace the inlets, aprons, and wing walls. The culverts will be removed and replaced as follows: 1) excavation will occur to remove the existing wing walls, aprons, and culverts (approximately 2210 cy total for the two culverts; each approximately 200' long, 24' at base of channel, 40' across top of channel); 2) precast reinforced concrete box culverts will be set in place and backfilled (approximately 1410cy); 3) the highway roadbed and surface will be reconstructed above the culverts; and 4) wing walls and aprons will be reconstructed (cast-in place concrete), and will join the existing UPRR culverts.

Ventura