ENGIN. LIB.

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TRINITY RIVER DIVISION

FEATURES

OF THE

CENTRAL VALLEY PROJECT

Technical Record of Design and Construction

Volume I--Design

Volume II--Construction

VOLUME I

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

A Water Resources Technical Publication

TC

424 C2

A522 General Information

1965

CENTRAL VALLEY PROJECT
Trinity River Division, California

The Trinity River division is the name given to a group of structures all of which are either physically
or hydraulically interconnected for the purpose of transmountain diversion of Trinity River water. The
Trinity River division is in the Bureau's Central Valley project and is located in Trinity and Shasta Coun-
ties of northern California. The Trinity division plan provides for the regulation and control of Trinity
River, and for the transbasin diversion of surplus Trinity River water to the Sacramento River to aug-
ment the supply and utilization of water in the Central Valley project.

Utilization of the power potential is accomplished at four generating stations, consisting of Trinity,
Lewiston, Clear Creek, and Spring Creek Powerplants. Operation of the power system is integrated
with the Central Valley project through the facilities of Keswick Powerplant. Energy generated at Trinity,
Clear Creek, and Spring Creek Powerplants is conveyed to the Keswick Switchyard for distribution in the
Central Valley project transmission system. Power generated at Lewiston Powerplant is intended pri-
marily for local utilization.

Trinity Dam

Location: About 8 miles (13 kilometers) north of Lewiston, Calif., on the Trinity River

Type: Zoned earthfill

Constructed: 1957-1962

Reservoir: Clair Engle Lake

Total capacity to top of active conservation level, elevation 2370 (722.4 meters): 2, 447, 654 acre-feet (3, 019, 181, 000 cubic meters)

Active capacity: 2, 135, 023 acre-feet (2, 633, 551, 000 cubic meters)

Surface area: 16, 400 acres (6, 637 hectares)

Maximum reservoir elevation: 2387 (727.6 meters)

Dam dimensions:

Structural height: 537.5 feet (163.8 meters)

Top width: 40 feet (12.2 meters)

Maximum base width: 2, 680 feet (816.9 meters)

Crest length: 2,600 feet (792.5 meters)

Crest elevation: 2395 (730 meters)

Volume: 29, 250, 889 cubic yards (22, 364, 000 cubic meters)
Outlet works:

The outlet works has a design capacity of 7, 200 second-feet (204 cubic meters per second) at a water
surface elevation 2370 (722.4 meters). It consists of a concrete intake structure with diversion inlet,
a concrete-lined 28-foot-diameter (8. 5-meter) tunnel with a gate structure and shaft housing a 10-foot
(3.05-meter) by 20-foot (6.1-meter) fixed-wheel gate, a 28-foot-diameter (8.5-meter) concrete con-
duit, a concrete control house for two 84-inch (2. 1-meter) ring-follower gates and two 84-inch (2.1-
meter) hollow-jet valves, a concrete stilling basin and an outlet channel. A 16-foot-diameter (4.9-
meter) steel penstock extends from the gate structure to the powerplant manifold, and an 11-foot 3-inch
diameter (3.4-meter) steel outlet pipe extends from the powerplant manifold to the outlet works con-
trol house manifold where the manifold branches to two 84-inch-diameter (2.1-meter) pipes.
Auxiliary outlet works:

The auxiliary outlet works has a capacity of 2, 520 second-feet (71.4 cubic meters per second) at a water
surface elevation 2370 (722.4 meters). It consists of a concrete intake structure, a 7-foot-diameter
(2.1-meter) concrete conduit, a concrete-lined 7-foot-diameter (2. 1-meter) tunnel to the gate chamber,
which houses an 84-inch (2.1-meter) ring-follower gate and an 84-inch (2.1-meter) jet-flow gate, and a
concrete-lined 8-foot (2.4-meter) ovate tunnel from the gate chamber to the spillway tunnel.

The intake structure has embedded stoplog guides and seats to provide for future installation of stoplogs. Because of the probable excessive depth of water, it is very unlikely that the intake structure will ever be closed with stoplogs.

Spillway:

The spillway has a capacity of 22, 400 second-feet (634 cubic meters per second) at a water surface elevation 2387 (727.6 meters). It consists of a 54-foot-diameter (16.5-meter) uncontrolled morning-glory concrete crest structure, a concrete-lined 20-foot-diameter (6. 1-meter) inclined shaft and tunnel, a concrete chute, and a concrete flip bucket. The auxiliary outlet works discharges into the spillway tunnel approximately 1,000 feet (305 meters) upstream from the lower portal of the spillway tunnel.

Trinity Powerplant

Location: Immediately downstream from Trinity Dam about 8 miles (13 kilometers) north of Lewiston,
Calif.
Constructed: 1960-1963

Structure: Indoor type; reinforced-concrete substructure and intermediate structure; superstructure of

structural-steel framing with reinforced grouted brick masonry walls and metal siding;
built-up roofing on wood sheathing; metal doors and windows; 300-ton (272-metric-ton) over-
head traveling crane. The structure is about 141 feet (43 meters) long, 122 feet (37 meters)
wide, and about 126 feet (38 meters) above the lowest point in the foundation.

Generators: Two 55, 555-kv. -a., 90 percent power factor, 13, 800-volt, vertical-shaft, 200-r. p. m.,
alternating-current, hydraulic-driven generators. The two generators are paralled at
generator voltage, and connected to three 23, 220/30, 960/38, 700/43, 333-kv.-a., 13.2- to
230-grounded wye/132. 8-kilovolt, single-phase, outdoor power transformers through gen-
erator voltage circuit breakers.

Turbines: Two vertical-shaft, Francis-type, each 85,000 horsepower at 426-foot (129.8-meter) head, with high-head runner; 70, 000 horsepower at 334-foot (101. 8-meter) head with low-head

Lewiston Dam

runner

Location: On Trinity River, approximately 1 mile (1.6 kilometers) north of Lewiston, Calif.
Type: Zoned earthfill

Constructed: 1961-1963

Reservoir: Lewiston

Total capacity to active conservation level, elevation 1902 (579.7 meters): 14, 660 acre-feet (18,083, 000 cubic meters)

Active capacity: 2, 890 acre-feet (3, 565, 000 cubic meters)

Surface area: 750 acres (303. 5 hectares)

Maximum reservoir elevation: 1902 (579.7 meters)

Outlet works: Located in left dam abutment and consists of a concrete intake structure, a 4-foot-diameter (122-centimeter) conduit, a gate chamber, and an 8-foot-diameter (24.4-meter) horseshoe

conduit

Capacity: 320 second-feet (9.06 cubic meters per second) at elevation 1902.0 (579.7 meters) Spillway: Located in right dam abutment and consists of a concrete-chute-type structure 65 feet 6 inches (199.6 meters) wide, controlled by two radial gates

Capacity: 30,000 second-feet (849. 5 cubic meters per second) at elevation 1902.0 (579.7 meters)

Lewiston Powerplant

Location: Immediately downstream from Lewiston Dam

Constructed: 1961-1963

Structure: Indoor type, reinforced concrete; structure also contains river outlet regulating gates. The structure is about 27 feet (8.2 meters) in length, 23 feet (7 meters) in width and 37 feet (11.3 meters) above lowest point in foundation

Generator: One 438-kv. -a., 480-volt, 80 percent power factor, 600-r. p.m., alternating-current, vertical-shaft, hydraulic-driven generator

Turbine: Vertical-shaft, Francis-type, nameplate rating of 525 horsepower at 60-foot (18. 3-meter) head Clear Creek Tunnel

Location: Between Lewiston and Whiskeytown Reservoirs

Constructed: 1957-1962

Length: About 10.8 miles (17.4 kilometers) or 56, 668 feet (17, 272.4 meters)

Diameter: 17 feet 6 inches (5.33 meters) circular--concrete lined throughout except for 385 linear feet (117.3 meters) of 15-foot 8-inch diameter (4. 8-meter) steel plate lining at outlet end Capacity: 3,200 second-feet (90.6 cubic meters per second)

Clear Creek Powerplant

Location: At downstream end of Clear Creek Tunnel, approximately 15 miles (24 kilometers) northwest of Redding, Calif.

Constructed: 1960-1963

Structure: Indoor type, reinforced-concrete substructure and intermediate structure; superstructure of structural-steel framing with reinforced grouted concrete block masonry walls and metal siding; built-up roofing on wood sheathing; metal doors and windows; 300-ton (272-metric-ton) overhead traveling crane Generators: Two 74, 444-kv. -a., 90 percent power factor, 13, 800-volt, vertical-shaft, 225-r.p.m., alternating-current, hydraulic-driven generators. The two generators are paralleled at generator voltage and connected to three 35, 000/46, 667/58, 333-kv. -a., 13.2- to 230grounded wye/132.8-kilovolt, single-phase, outdoor power transformers through generator voltage circuit breakers. Turbines: Two vertical-shaft, Francis-type, each with a nameplate rating of 93, 500 horsepower at 535foot (163-meter) head

Clear Creek Switchyard

Location: About 340 feet (104 meters) southeast of Clear Creek Powerplant

Initial installation: Terminal facilities for a 230-kilovolt single circuit from Trinity Powerplant; a 230

kilovolt single circuit from Clear Creek Powerplant, and for two 230-kilovolt circuits to Keswick Switchyard, utilizing four bay positions and a bus tie bay; power circuit breaker in bus tie bay, and disconnecting switches in others Ultimate installation: Switchyard area is sufficient to accommodate seven 230-kilovolt bays, three 115kilovolt bays, and a 230- to 115-kilovolt transformer bank

Whiskeytown Dam

Location: On Clear Creek, approximately 10 miles (16 kilometers) west of Redding, Calif.
Type: Zoned earthfill

Constructed: 1960-1963