Del Valle Dam Stilling Basin Dewatering and Repairs

Del Valle Dam Stilling Basin Dewatering and Repairs

Dam Safety Branch staff will oversee repairs on the Del Valle Dam stilling basin by a contractor to repair the spillway to original design conditions and specifications. DFD staff will dewater the Del Valle Dam spillway and stilling basin to perform repairs per Dam Safety Branch requirements. The spillway and stilling basin are located immediately downstream of Del Valle Dam. Two six-inch trash pumps with a 100-150 ft hose, working in tandem, will be used to dewater the basin. The flow will be directed into the routine downstream discharge, which is Arroyo Valle Creek. Scaffolding will be erected onsite to allow personnel access from ground level into the spillway work area. A heavy lift crane will be onsite to hoist equipment and material into the spillway work area. A generator will be onsite to provide power. The contractor will core 17 inches into the spillway at eight locations and drill 3/4 inch holes through the entire concrete slab at eight locations. Core samples will be logged and taken offsite to a lab. The contractor will use a water truck to wash the holes via high pressure to allow a latex bond to be applied. The holes will be filled with non-shrink cement grout. Any damage to reinforcing steel will be repaired by mechanical means. The contractor will demolish portions of the invert using an air jack hammer or concrete saw to remove deficiencies. Material will be removed using a skid steer and the crane. Spoils will be hauled to a nearby waste facility by dump truck for proper disposal. Primary staging areas for equipment and vehicles will be located on pre-existing paved and unpaved raods near the dewatering site. The project footprint which includes work area and staging is approximately 1.3 acres. The entire project within the DWR right of way. Upon completion of the project, the spillway and basin will return to normal operations.

Livermore

Alameda