UPDATE ON THE 'PIPELINE/TUNNEL OPTION' FOR THE DELTA HABITAT CONSERVATION AND CONVEYANCE PROGRAM

摘要

In order to improve the environmental sustainability of California's Sacramento-San Joaquin Delta region, and ensure the reliability of water deliveries throughout the state, the California Department of Water Resources has proposed multiple alternatives for water conveyance under the Delta Habitat Conservation and Conveyance Program (DHCCP). Each of the proposed alternatives will convey water from the Sacramento River north of the Delta to existing state and federal pumping plants south of the Delta. This paper describes recent developments to the conceptual engineering analysis of the "Pipeline/Tunnel Option," one of the proposed DHCCP options. The update to this analysis addresses revised anticipated system hydraulics, operational criteria, site conditions, and state-of-the-practice tunneling methodologies. The main features of the "Pipeline/Tunnel Option" consists of river intake structures, sedimentation basins, intake pump plants, forebays, and tunnels capable of diverting gravity flows up to 9,000 cfs. The main twin-bore tunnels will span approximately 35 miles consisting of 40-foot diameter tunnels with a precast concrete segmental liner constructed at depths up to approximately 150 feet below grade.