The scope of construction activities authorized by this Agreement (Project) is limited to the replacement and improvement of an existing stream crossing damaged in the 2021 Salt Creek Fire that provides access to PG&E electric transmission line facilities. The existing crossing consists of two defunct culverts (24 and 18-inch) at an unnamed intermittent spring-fed tributary to Coal Creek. The stream is not finfish-bearing, but demonstrates Class II habitat values for amphibians and mollusks. The culverts will be replaced with a rock-armored vented ford designed by an engineer to overtop during >two-year flood events and to withstand 100-year stormflows without diverting the stream. An 18-inch culvert will be installed to pass baseflows. The culvert inlet will be armored with six-inch rock slope protection (RSP) and the outlet will be armored with 12-18-inch RSP.
The project also includes the installation of bioengineered bank stabilization upstream of the inlet to support culvert functionality, reduce erosion and sedimentation, and improve aquatic habitat. To improve bank stabilization, large woody debris (LWD) consisting of root wads will be buried in the bank and incorporated into the RSP at the culvert inlet.
Project work will take approximately 15 days to complete and will include a crew of three-six individuals, two-three crew trucks, one excavator, one dozer, one dump truck, one water truck, a backhoe, and miscellaneous hand tools. All work will be conducted during the dry season, however, dewatering via a clear water diversion will be implemented if the spring-fed flows or standing water are present at the Project site.