The San Vicente Pipeline Tunnel Project involves construction of an 8.5-foot diameter water pipeline in an 11-mile tunnel. Excavation takes place in variable geologic conditions consisting of strong granitic and volcanic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. One 5,200-foot mixed face reach included Friars Formation Conglomerate overlying granitic rock. The excavation in this reach employed drill-and-blast and NATM methods.