California Department of Fish and Wildlife, Northern and Eureka Region 1
Cold Creek Tributary Culvert Replacement Project (Lake or Streambed Alteration Agreement, EPIMS-SIS-28017-R1I)
NOE - Notice of Exemption
The project is limited to the replacement of a culverted stream crossing associated with the City of Mt. Shasta Sewer Interceptor Improvements Project. The existing 48-inch circular pipe culvert will be replaced with a compressed pipe arched culvert measuring 57-inches by 38-inches and spanning forty linear feet. The slope of the new culvert will be corrected so as not to shotgun at the outlet, improving upstream passage for resident fish and other aquatic species. The existing headwall will be retained but raised by two feet. The existing outlet headwall will be replaced and set 5-feet deeper than the existing headwall. The voids behind the improved headwalls will be filled with slurry backfill and compacted base. Rip-rap 24-feet wide, 11-feet long, and 2-feet deep will be placed at the outlet. Approximately 150 square feet of the rip-rap will be installed within the ordinary high-water mark.
A temporary water diversion will be required for the culvert replacement. Sandbags will be placed upstream and downstream of the work area, and a bypass pump will be used to divert the water around the work area while the culvert is being replaced. The pump will be used for approximately 25 days. A temporary culvert may be used to divert water beyond the proposed concrete headwalls during construction. When construction is complete and the concrete is sufficiently cured, the temporary culvert and/or the bypass pump will be removed. The temporary water diversion is not expected to produce any negative effects on water quality or flow volume in the perennial stream.