Post-Construction Quality Assurance Testing for RCC at the San Vicente Dam Raise Project

The San Diego County Water Authority (Water Authority) has raised the original San Vicente Dam to provide both emergency and carryover storage to increase local reservoir supplies in San Diego County, California. The $1.5 billion Emergency Storage Project (ESP) and Carryover Storage Project (CSP) will also provide a more flexible conveyance system, and increase water supply reliability in case of catastrophic failure to the delivery system due to a major earthquake. The San Vicente Dam Raise (SVDR) project is a major component of the last phase of the ESP and consists of raising the existing 220-foot high concrete gravity dam with 90,063 acre-feet of storage, by 117-feet to increase reservoir storage capacity by 152,000 acre-feet. The dam raise itself is now complete and is the tallest dam raise in the United States and tallest roller-compacted concrete (RCC) dam raise in the world. The reservoir capacity will be more than doubled, making it the largest single increase in water storage in the region’s history.
This paper introduces the post-construction quality assurance (QA) program for validation of in-situ RCC properties. The discussion also includes the RCC structural design intent, mix design and construction placement. A key aspect of the RCC QA is a post-construction coring and testing plan. The paper will present a discussion of the basis of this program to validate design assumptions. A key to this program is testing RCC at various locations, including interfaces between lift surfaces, at rock contacts and critical contact between the 70-year-old conventional concrete with the new RCC. The design and construction of this Project were developed and executed in close cooperation with the dam safety regulatory offices of the State of California, Division of Water Resources, Division of Safety of Dams (DSOD).