Salt Lake Aqueduct Gets New Intake Structure

Metropolitan Water District of Salt Lake and Sandy facility improvement

December 11, 2000

Sheet pile excavation for the new intake structure on bank of tailrace pool on the Provo River. (Photo: Bowen, Collins & Associates)

The Metropolitan Water District of Salt Lake and Sandy (MWDSLS) is reconstructing a critical part of its water conveyance system in Provo Canyon, Utah. Part of the 1935 Provo River Project, the Salt Lake Aqueduct (SLA) is the means of conveying Deer Creek Reservoir water to eastern Salt Lake County. Water is diverted from the Provo River downstream from the reservoir and hydropower generating plant into the 69-inch pipeline and conveyed approximately 32-miles to MWDSLS’s Little Cottonwood Water Treatment Plant located near Little Cottonwood Canyon. Flowing at maximum capacity, it carries113 million gallons per day to the water treatment plant for purification. Once the water is treated it is discharged into the treated water reach of the SLA, then to the Terminal Reservoirs near I-215 and 3300 South.  The total length of the SLA from Deer Creek Reservoir to the Terminal Reservoirs is 41 miles. The SLA is constructed of reinforced concrete, precast in 20-foot segments with a wall thickness of 7.5 inches. Each segment weighs up to 23 tons.

Excavation of bedrock around existing Salt Lake Aqueduct for construction of new Ultrasonic Meter Vault. (Photo: Bowens, Collins & Associates)

The aqueduct was first put into operation in 1950, when chlorinated water was delivered into the Terminal Reservoirs. Untreated, the water was unsatisfactory for municipal use. The Little Cottonwood Water Treatment Plant was completed in 1961, and since then, fully treated water is conveyed to four hundred thousand people for municipal and industrial use.

According to Michael Collins, Bowen, Collins & Associates:

“The $3,314,000 SLA Intake Structure Project includes the construction of a new intake structure for the SLA, a new Operations and Maintenance Building, and associated improvements to the surrounding site.  The Operations and Maintenance Building will be a 2,600 square-foot single-story structure including a maintenance garage, a control room, and associated operations facilities. 

The new SLA intake will consist of a 28-foot deep reinforced concrete structure located on the bank of the Deer Creek dam tailrace.  The structure will contain two separate concrete channels, an automated debris removal system, two 96-inch sluice gates, and stop log isolation panels. A chemical storage vault will be located adjacent to the new intake structure containing two 3,000-gallon storage tanks, a metering pump, and associated equipment. Three existing hinged gates will be removed and replaced from an existing structure located adjacent to the new intake. 

Approximately 260-feet of 72-inch diameter pipe will connect the new intake structure to the existing SLA. A 29-foot deep concrete connection structure will be constructed at the point that the new pipe intersects the existing SLA.  A 32-foot deep concrete meter vault will be constructed around the existing SLA approximately 50-feet down stream of the connection structure.” 

Ellsworth Peck Construction Company is building the project. It is now approximately 40% complete, with final completion scheduled for June 1, 2001.

“One of the major challenges of the project was to drive the sheet pilings to dry up the excavation,” says Collins, continuing, “It was quite a job, but the contractor was able to overcome the problem and get a tight seal.”

Pouring concrete slab on grade for the new intake structure. The slab is approximately 20-feet below the existing surface grade. (Photo: Bowen, Collins & Associates)

The project is part of a larger master plan of improvements approved by the MWDSLS Board of Trustees in 1998. Capital improvements amounting to over $225 million are planned for construction, including a new water treatment plant at the Point of the Mountain in Draper City.

The SLA is currently running at capacity during the summer months, requiring new conveyance and treatment facilities to fully use MWDSLS’s water supply in Deer Creek Reservoir and water petitioned from the Central Utah Project. Enlarging or paralleling the SLA were evaluated, but it was decided to use the existing Provo Reservoir Canal (Murdock Canal) to bring the additional water to the Salt Lake Valley. Nevertheless, the SLA remains a critical means of delivering water to Salt Lake County residents and the new intake structure will ensure the continued dependability of this water supply.