Sandy Bar Invert Repair

Sandy Bar Invert Repair

The California Department of Transportation (Caltrans), using state funding only, is proposing a bridge repair project on state route (SR) 96 in Siskiyou County at post mile (PM) R9.11 at Sandy Bar Creek. The purpose of the project is to repair the inverts in order to protect the bridge and extend its life. The project is needed because the bridge's PCC inverts show significant derogation that if left uncorrected could eventually lead to undermining of the structure's foundation and potentially compromise its structural integrity. The proposed improvements include: • Reconstructing select areas of the two inverts by removing the invert slabs and replacing them with stronger, thicker invert slabs that are lower in the center of the spans thus protecting the footings from the abrasive effect of stream flows. The inverts will be sand blasted and then 3-inch-thick blown mortar will be applied over the exiting surface. • Reconstructing the apron and center support at the downstream end of span 2. Temporary Water Diversion A temporary water diversion would be installed in Sandy Bar Creek at the upstream side of the bridge and would be in place for approximately 30 working days to facilitate the repair. The temporary water diversion would divert water into span 1 while span 2 is being worked on and would divert water into span 2 while span 1 is being worked on. Upon completion of repairs, the temporary water diversion would be removed. Dewatering A pool below the concrete apron on the downstream side of the bridge would need to be dewatered and then filled with clean gravel to form a work pad. Upon completion of repairs, the fill gravel would be removed from the pool to the extent practicable. Construction Access Construction access to the downstream side of the bridge would be from an existing gravel/dirt road with a driveway entrance along the southbound lane of SR 96. Construction access to the upstream side of the bridge would require constructing a temporary construction access road that is approximately 150 feet long and 15 feet wide that would begin at an existing pullout along the northbound lane and lead down to the stream channel along its north bank. Upon completion of repairs, the topography along the temporary construction access road that leads to the upstream side of the bridge would be restored to pre-construction conditions to the extent practicable and replanted with native vegetation. Construction Equipment Concrete would be broken into small pieces to haul away (no jack-hammering would be needed). A bobcat front end loader would be utilized to remove concrete from span 2. A haul truck would be utilized to transport concrete away from the site for disposal. Equipment used for the water diversion and dewatering would be determined by the contractor. Ground Disturbance/Tree Removal Approximately 0.096 acres of soil would be disturbed by the work and maximum excavation depth would be approximately 3 feet deep (most ground disturbance would be associated with construction of the access road on the upstream side of the bridge). Because the project is considered routine maintenance and would not add any impervious surface within the project limits where it previously did not exist, the project is exempt from post-construction stormwater treatment best management practices (BMPs). A minimal amount of blackberry/tree removal would be needed for construction access to the upstream side of the bridge. No tree removal is anticipated for construction access to the downstream side of the bridge. Traffic Management The project would not utilize traffic controls or detours during construction. Schedule The project would be completed in one construction season. The work is anticipated to begin and end in summer 2025, although the exact start and end dates could change depending on a variety of factors, including permit conditions that dictate the in-water work period. Borrow/Disposal Sites No borrow or disposal sites would be utilized. Staging/Stockpiling Staging/stockpiling would occur within Caltrans’ right-of-way within the project limits away from streams and riparian areas. Staging/stockpiling buffer distances from streams and riparian areas would likely be specified in permits obtained from regulatory agencies. Utilities An existing underground telephone cable and an underground pull box are present within the project limits. These utilities would be protected in place during construction. No new utilities would be installed and no existing utilities would be relocated to accommodate the proposed improvements. Right-of-Way Most of the work would occur within Caltrans’ right-of-way. Some work associated with use of an existing construction access road along the southbound lane of SR 96 would occur outside Caltrans’ right-of-way on private property. A temporary construction easement would be needed for work occurring outside Caltrans’ right-of-way. Federal land owned by the Forest Service and managed by the Six Rivers National Forest is present within Caltrans’ right-of-way on the east side of SR 96. A letter of concurrence from the Six Rivers National Forest would likely be needed for work inside Caltrans’ right-of-way on Forest Service land. Construction of the project would not require the permanent acquisition of additional right-of-way.

Siskiyou

Northern California