East Zayante Road PM 6.22 Storm Damage Repair Project

East Zayante Road PM 6.22 Storm Damage Repair Project

The Project is limited to the replacement of one 48-inch diameter corrugated metal pipe culvert located on Tanaka Creek approximately 60 feet above the confluence with Zayante Creek. The County will replace the pipe with a bottomless arch culvert 44 feet long by 9 feet wide with precast footings and concrete headwalls at the channel interface sized to convey the 100-year flow and pass debris that have been recurring problems at the existing undersized culvert. The channel would be reconstructed for a length of 90 feet at a profile grade of 6.5 percent. The channel bed material would be constructed of engineered streambed material containing a well-graded mix of large and small rock to provide scour protection, grade control and channel complexity. A low flow channel approximately four feet wide and one foot deep would concentrate low flows and provide depths sufficient for upstream fish passage. The channel configuration would provide a wide distribution of velocities within the channel cross-section with lower velocities located near the channel banks and behind large rocks that protrude above the channel bed. Large rocks placed in clusters would direct the low flow channel to meander within the culvert thus reducing the channel slope at low flows. Two resting pools would be constructed within the profile, each having a minimum depth of two feet and da drop of six inches. A band of large boulders will be installed upstream of each of the pools to provide grade control and induce scour within the pools. The Project has been designed to pass both adult and juvenile salmonids. The California Department of Fish and Wildlife (CDFW) is executing a Lake and Streambed Alteration Agreement Number 1600-2013-0052-3 pursuant to Section 1602 of the Fish and Game Code to the project Applicant, Russell Chen/ County of Santa Cruz Department of Public Works.

Santa Cruz