Middle River Intake Project

Contra Costa Water District, 
California

Middle River Intake Project

Awards: 
2011 Engineering Excellence (Honor Award) - American Council of Engineering Companies, CA
2011 Outstanding Water Project of the Year - American Society of Civil Engineers, Region 9 (California)
2010 Outstanding Water Project of the Year - American Society of Civil Engineers, San Francisco Section
Service Type: 
Project Highlights: 
  •  Five 3,000-hp vertical turbine pumps (two pumps utilize variable frequency drives)
  • 12,500 feet of 72-inch conveyance pipeline
  • 90-foot directional-drilled river crossing
  • Site work and 275,000-cubic-yard setback levee with a clay core
CCWD aerial
This project addressed permitting for threatened and endangered species, and design considerations for difficult foundation soil conditions, high groundwater table, and active seismic zone.

The Sacramento-San Joaquin River Delta is a sensitive environmental resource that provides drinking water supply for about two-thirds of all Californians and irrigation water for millions of acres of farmland. Contra Costa Water District’s (CCWD) Alternative Intake Project (AIP) is the most significant Delta drinking water project to complete planning, permitting, design and construction in the past decade. The AIP is designed to improve delivered water quality, protect and improve health and aesthetic benefits to customers, improve operational flexibility, and protect delivered water quality during emergencies.

Carollo served as the program manager for the AIP and was the lead engineer for the setback levee and the intake and pump station projects. The AIP design provides for construction in three separate projects: (1) the Middle River Setback Levee and Sitework, (2) the Middle River Intake and Pump Station, and (3) the Middle River Conveyance Pipeline.

The first stage of the AIP project involved construction of the Middle River Setback behind the intake location to provide flood protection for Victoria Island. The setback levee was constructed from 275,000 cubic yards of on-site borrow material. The levee includes a clay core, drainage facilities, instrumentation to monitor settlement and groundwater, and permanent bulkhead walls along Middle River Canal.
The second stage involved construction of the Middle River Intake and Pump Station. The intake and pump station include five 3,000-hp vertical turbine pumps, debris screening, automatic screen raking, a surge suppression system, a 69KV substation, an electrical building, and 72-inch discharge piping.

Unique project features include:

  • Permitting for threatened and endangered species.
  • Difficult foundation soil conditions.
  • Design considerations for a high ground water table.
  • Design/construction within an active seismic zone.

The project includes a unique pump wet well design that uses submerged bells on the large vertical turbine pumps to overcome net positive suction head problems and reduce surface and wall attached vortices. Carollo also prepared a computation fluid dynamic model of the intake and fish screens to ensure proper flow distribution and pump entrance conditions while maintaining the smallest practical size of the structure.

The final stage of the AIP consisted of construction of the Middle River Conveyance Pipeline. The conveyance pipeline includes 12,500 feet of 72-inch-diameter pipeline and a 90-foot-deep tunnel crossing beneath Old River. The Middle River conveyance pipeline project also accommodated the requirements of the landowner to allow continued operation of a 7,000-acre farm while minimizing the impact on the threatened giant garter snake habitat.