In Case of Emergency
Oroville Dam River Outlet Diversion Tunnel No. 2 - Removal of Baffle Ring and Concrete Repair
Under emergency contract, Syblon Reid was selected by the California Department of Water Resources to rapidly and surgically remove a deteriorating baffle ring within the river outlet tunnel at the Oroville Lake Dam. The baffle ring was located approximately a ½ mile inside the outlet tunnel underneath Lake Oroville. Syblon Reid followed strict tunnel safety orders as well as all necessary confined space requirements due to the use of heavy equipment within the tunnel.
Responding in short order, Syblon Reid first mobilized and began to establish tunnel ventilation utilizing over 1 ½ mile of dam galleries to provide a safe and adequate air supply for the workers within the confined space tunnel. The baffle ring was constructed of a trapezoidal concrete ring that was lined with a T1 steel plate around the circumference of the 35’ diameter tunnel. The baffle ring and tunnel were half submerged throughout the work requiring Syblon Reid to incorporate barges and floating platforms in order to perform the work. Additionally, a team of specialized divers was brought in to perform all the work that had to be performed under water. All work had to be performed within a critical 10 day outage period.
Syblon Reid worked around the clock from atop a 120’x30’ floating platform to remove 60 cy of concrete. The concrete above the water line was chipped and dropped on to the platform. Concrete that was submerged had to be chipped and placed by the divers into buckets reaching below the water line in order to place it on the platform. The barge would then move the platform out of the tunnel to a location to remove and dispose of the concrete. Additionally, the steel band that circumferenced the tunnel had to be cut and removed.
Once all concrete and steel was removed, the tunnel liner was repaired. In addition to removal of the baffle ring, Syblon Reid also built and installed a new pressure relief wall to protect the powerhouse from catastrophic failure of the low level outlet valves. All critical work was completed within the 10 day outage period without a single loss time accident or OSHA recordable incident.
Project Photos
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