Cascade Canyon Trail Bridge Project (Lake or Streambed Alteration Agreement No. EPIMS-MAN- 52367-R3)

Cascade Canyon Trail Bridge Project (Lake or Streambed Alteration Agreement No. EPIMS-MAN- 52367-R3)

The California Department of Fish and Wildlife (CDFW) has executed Lake and Streambed Alteration Agreement (EPIMS-MAN-52367-R3), pursuant to Fish and Game Code section 1602, to the project Applicant, County of Marin. The Project is limited to construction of two bridges and minor grading of two ford crossings. The construction of Bridge 1 at Location 1 includes a 90 foot-long, 6-foot wide bridge and the construction of Bridge 2 at Location 2 includes a 60-foot long, 6-foot wide bridge; both bridges constructed above 100-year flood elevation. Both bridges are prefabricated weathered steel connector style truss bridges with reclaimed redwood decking. The bridges will be constructed offsite in segments, then assembled at the Project site, respectively. The concrete bridge footings for each bridge will be located outside of the top of the stream bank. There will be no piers for Bridge 1 or 2 in the channel. The existing rock slope protection (RSP) on the north side of the stream at Bridge 1 and the south side of the stream at Bridge 2 will be repaired as needed to provide the required bridge abutment protection. Additionally, 40 cubic yards of new RSP will be placed at each bridge location, totaling 80 cubic yards of new RSP. At Location 1 One 8-inch diameter at breast height (DBH) madrone (Arbutus menziesii) will be removed, and there will be thinning and removal of some brush vegetation. At Location 2 there will be no vegetation removal. Large equipment (excavator, trucks, compactor, etc.) will temporarily ford the stream during the dry season to access the bridge sites. Tree roots may be impacted during the excavation of the bridge footings for some of the larger trees. Minimal excavation will be employed to avoid any unnecessary impacts to tree roots. No water will be present during construction. There will be minor grading and temporary fill placement at existing rock ford crossings 2 and 3, ford crossing 2 is located upstream of Bridge 1 and ford crossing 3 is located downstream of Bridge 2, to reduce the approach angle of construction equipment access. Temporary fill will be sourced from onsite excavations or from a CDFW approved location. Temporary fill will be placed on top of CDFW approved erosion control fabric to avoid mixing with the native and existing channel bed material. At the conclusion of project implementation, an excavator will remove the temporary fill, which will be spread on-site in upland areas at a CDFW approved location, and erosion control measures would be applied. The erosion control fabric will be disposed of at an approved landfill. The bridge and RSP permanent impacts at Location 1 total 776 square feet (0.018 acre) and the vegetation permanent impacts total 776 square feet (0.018 acre). The bridge and RSP permanent impacts at Location 2 total 356 square feet. There are no temporary impacts from the bridge work. The combined permanent impacts at Locations 1 and 2 total 1,908 square feet (0.044 acre). The ford crossing will result in temporary impacts from minor grading totaling 750 square feet (0.018 acre) including temporary fill of 25 cubic yards for both rock ford crossings 2 and 3.

Unincorporated Fairfax

Marin

San Francisco Bay Area

Marin