The October ACEC monthly meeting featured guest speaker Randy Fessler, Principal Engineer & Construction Branch Manager for the California Department of Water Resources (DWR). Randy began his presentation by welcoming all consultants in attendance and sharing that he has previously worked as a consultant and understands our business.
Randy’s presentation highlighted the Pajaro River Emergency Levee Repair Project that was performed by DWR. Shortly after midnight on March 11, 2023, the Pajaro River levee failed approximately 10 miles inland form the pacific coast, creating a 120-foot-wide breach, resulting in uncontrolled flows onto the adjacent farmland and ultimately flooding the town of Pajaro, where nearly 17,000 people were forced to evacuate.
Randy reviewed the sequence of events leading up to DWR’s presence on the site and how DWR assumed responsibility for the emergency repair. Prior to the levee failure, the local reclamation district had installed a muscle wall in an effort to stabilize the levee. As the water continued to rise, the muscle wall failed and the levee breeched. When the reclamation district requested help from the State, DWR was the first agency contacted to provide help. DWR assessed their resources and response time and determined they had the ability to support this emergency project.
The first order of work for DWR was to establish a stable point of access to the repair site. After reviewing the site, there was only one feasible access point that could be established, upstream of the breach. Once access was established, DWR could start attempts to close the breach. Their initial plan was to use the National Guard’s Chinook helicopters to place rock-filled super sacks. After two attempts, it was determined that the weather posed too great a risk for that operation.
DWR moved to Plan B, which was to bring in track mounted dump trucks that rotate on a turret like an excavator. This eliminated the need to back on-road trucks down the levee. The on-road trucks delivered rock to a staging area, where loaders loaded the track dumps. The track dumps traveled to the breach area, rotated 180 degrees, and dumped rock into the breach. Using this method in a 24-hour operation, DWR was able to close thebreach by March 14th. During that time, the breach would grow to a maximum opening of 325 feet. Once the breach was closed, they switched to 12-hour daytime shifts to place finer material that would hydraulically fill the remining voids in the placed rock.
On March18th cleanup of the site began, providing aggregate base along the levee, removal of excess stabilization material, repairs to private fencing, and replacement of the old access road with a new section of hot mix asphalt. DWR coordinated with local property owners to ensure that adequate cleanup was provided. Cleanup of the site and demobilization of equipment was completed on March 25th.
