The butterfly valves are operated by individual power units, each containing an oil tank, a set of hydraulic equipment, and a motor-driven grease pump. Electrical equipment for both control systems is housed in a single, independent electrical control center. All control equipment is located in the control house above the butterfly valves.

The estimated weight of two power units, complete with external piping is 14, 500 pounds, and that of one electrical control center for two valves is 2, 750 pounds.

(b) Design Valves. --The butterfly valves were designed to open or close normally under balanced, noflow conditions and to close, in an emergency under ruptured penstock conditions, with a flow of nearly 11,000 second-feet at a head of 295 feet. The bodies were designed to withstand a total head, including water hammer, of 485 feet, and the leaves were designed to withstand a total head of 350 feet, using normal safety factors. The 26-inch-inside-diameter cylinders for the operating units were designed for a maximum oil pressure of 3, 000 pounds per square inch with the cylinder wall stress limited to two-thirds of the yield point of the material. This maximum pressure would occur only with a ruptured penstock. The maximum oil pump pressure for normal operation or an ordinary emergency closure will not exceed 500 pounds per square inch. At this pressure, the operating units will develop approximately 572, 000 footpounds of torque at the drive shafts, which exceeds the torque requirement of 496, 000 foot-pounds for seating the leaves. The reactive forces from the operating units are transmitted directly to the bodies. The leaves were designed to limit the deflection angle at the trunnions to less than 6 minutes. The direction of rotation to the closed position was made so the slightly higher head on the lower half of the leaf would keep the valve closed. The leaf was designed to rotate 2° past the horizontal position to help hold the valve open with the small opening torque thereby developed.

The valve bodies and the expander pieces connected to the upstream flanges were proportioned to provide a nearly uniform rate of acceleration of the flow through the valves; i.e., from a velocity of 16.5 feet per second at the 138-inch-diameter inlets to 19.75 feet per second at the 126-1/8-inch outlets. This acceleration minimizes valve losses and provides a smoother flow. The bulkhead load on the closed valve is transmitted to the upstream penstock. The weight of the valves, including water, is carried by the valve feet into the concrete pedestals.

(c) Design Controls. --To provide the desired operating time of approximately 30 seconds for each butterfly valve, a pumping capacity of 200 gallons per minute is necessary for each valve. One hydraulic power unit containing two identical pumps driven by a single 40-horsepower, 1, 200-r. p. m., 440-volt, 3-phase, 60-cycle motor was selected for each power unit. Both pumps operate at pressures up to 200 pounds per square inch to obtain faster rotation of the leaf when only a normal torque is required. At 200 pounds per square inch, an unloading valve unloads one pump and the other continues to pump oil up to 500 pounds per square inch for seating the leaf at closure or when a high torque is required. This arrangement was used to reduce the size of the motor required and still obtain a closure time of 30 seconds.

A single electrical control center (fig. 158) of the valve structure was designed to contain the control transformers and rectifiers which provide reduced-voltage alternating and direct current for the electrical control equipment. A separate source of power was provided to operate the butterfly valves in case of an interruption of the normal supply from Clear Creek Powerplant. The controls for each butterfly valve were designed to open or close the valves from either the valve structure electrical control center or the Clear Creek Powerplant control board. Emergency closure was designed to be initiated manually at the Clear Creek Powerplant control board or at Keswick Powerplant, or initiated automatically by protective devices in the Clear Creek Powerplant. Transfer switches in the electrical control center were provided to permit control of the butterfly valves from either the control center or the remote operating stations at Clear Creek or Keswick Powerplants. A pressure switch in each control circuit prevents the valve from being opened unless the water pressure on opposite sides of the leaf is balanced. A motor-driven grease pump was provided for each valve to grease the trunnions automatically, whenever the valve operates. The grease pumps may also be operated by separate pushbuttons in the electrical control center. To provide balanced heads on the butterfly valve leaves during remote operation, the motor-operated bypass valves were designed to open automatically when the butterfly valve is opened from the powerplant control board, and close automatically when the butterfly valve is fully open. Separate pushbuttons were provided to open the bypass valves when the butterfly valves are opened from the electrical control center.

(d) Design Stresses. --The maximum stresses used for design were based in general on the following criteria:

(1) Tensile. --The allowable design stress in tension used for the following materials were the smaller value of the percentages of the yield and ultimate strength of the following material:

(2) Compression. --The allowable design stresses in compression used for the materials listed above were the same as for tension.

(3) Bearing. --The allowable design stresses used for crosshead or trunnion bearing were limited to 3, 500 pounds per square inch.

(4) Shear. --Allowable design stresses in shear were not more than 0.6 the allowable design stresses in tension.

(5) Hoist cylinders. --Allowable design stresses for hoist cylinders were based on the recommendations of the ASME Boiler and Pressure Vessels Code--Unfired Pressure Vessels--Section VIII.

194. Intake Structure Electrical System. Electric service for operation of electrical and lighting system equipment at the Clear Creek Tunnel intake structure is provided at a power distribution panel in the pump chamber of the structure by means of a service circuit in a conduit extending from a service pole located near the roadway abutment end of the structure access bridge. Lewiston Powerplant provides the source for the electrical service (fig. 121). Service is nominally 115/230 volts, 3-phase, 4-wire (groundedneutral), 60 cycles providing 230-volt, 3-phase service for operation of motors and 115/230-volt service for operation of the structure lighting system. Motor-driven equipment served includes a fishscreen wash pump, a screen hoist unit, and 10 slide gate lifts. The wash pump motor and the power and lighting system distribution panels are located in the pump chamber of the structure, and the screen hoist and the slide gate lifts are located on the hoist deck of the structure. The lighting system provides illumination in the pump chamber and on the hoist deck area; and 115-volt convenience outlets served by lighting system circuits are provided in the pump chamber and at the hoist deck area. Motors, the lighting distribution panel, and a 230-volt power outlet are served by branch circuits emanating from the power panel. Lighting fixtures and convenience outlets are served by branch circuits emanating from the lighting panel.

Branch circuits are afforded overcurrent protection by automatic-trip molded-case-type circuit breakers grouped in the respective power and lighting system distribution panels. The main service circuit to the structure is afforded overcurrent protection by a fused main service switch located on the service pole. The magnetic motor starters for the water pump and slide gate lifts are controlled by pushbutton station units. The various motors are afforded thermal overload protection by their associated starters. Pump chamber and hoist deck lights are controlled by lighting circuit switches located at the hoist deck.

195. Clear Creek Penstock Valve Structure Electrical System. Electric service for operation of butterfly valve equipment and lighting equipment in the penstock valve structure is provided nominally at 480 volts, 3-phase, 60 cycles, from two sources. The emergency source is obtained from the distribution system of the Pacific Gas and Electric Co. The normal source originates at a circuit breaker located at power board M1A in Clear Creek Powerplant. Both the normal and emergency service circuits enter the valve structure via conduits and terminate at an automatic transfer switch contained in butterfly valve control center HJA located in the structure.

A

All electrical equipment in the valve structure is usually supplied from the normal source through the transfer switch. Failure or loss of normal source voltage will cause the switch to transfer automatically the electrical equipment load from the normal source to the emergency source. Restoration of voltage to normal source will cause the switch to retransfer the load to the normal source.

The switch is such that it will not transfer load to a dead or unenergized source. Also, loss of normal source voltage for approximately 30 cycles or less will not initiate transfer of load to the emergency source.

Lighting system voltage for operation of valve structure lights is provided by a 480- to 120/240-volt, 5-kv. -a., single-phase, 60-cycle transformer located in control center HJA. The transformer serves a circuit breaker type load center distribution panel located adjacent to the control center. From the breakers in the load center panel, circuits emanate to serve lights and convenience outlets in and on the valve structure. Exterior lights on the structure are controlled by a time switch located near the load center panel. The control room lights are controlled by a single-pole switch located near the access door. The remainder of lights in the structure are controlled by circuit breakers in the load center panel.

The penstock valve structure is provided with a grounding system to which the electrical equipment enclosures, electrical conduits, and other metalwork items are connected.

GENERAL OPERATING INFORMATION
A. BASIC FUNCTION AND OPERATION:

The two 156-inch butterfly valves are operated by separate and
independent hydroulic power units which are controlled by a
common local electrical control center in the valve control house.
The butterfly valves are used to shut off the flow of water to
the turbines when taking the generator out of service for
extended periods of time; when unwatering the penstock, scroll
case, and draft tube for inspection or repair; and, when
emergency conditions occur requiring shutdown

2 The butterfly valves are normally to be opened or closed with
balanced pressures on the leaf and no flow through the penstocks
however, the valves are designed for safe closure, in an emergency,
under the turbine flow conditions of 2000 cfs and a maximum
reservoir head of 215 53 feet, or under ruptured penstock conditions
3 The hydroulic systems are designed to operate under a maximum
pumping pressure of 1000 psi, but normal operation requires o
maximum pressure of only 500 psi to open or close the valves
including emergency closure in addition, the systems are designed
to withstand a 3000 psi operating cylinder pressure which could
be developed by hydraulic forces acting on the leaf when closing the
volve with a totally ruptured penstock downstream of the valve

volve

-Penstock water pressure switch

---Oil pressure

goge

System relief

-Oil pressure
Switch

Angle check
valve

Oil pump

Unloading
valve

4. The valves may be opened or closed locally from the electrical control
center in the valve control house, opened or closed from the main
control board in the power plant, and closed, but not opened, remotely
from the control board of Keswick,

5 Emergency closure, which overrides all opposing signals, may be
initiated manually from the power plant control board and from
Keswick or may be initiated automatically from the power plant by
ony of the following conditions:

a. Loss of governor actuator oil pressure or level

b. Incomplete sequence of operations on shutdown of generating unit.
e Sustained overspeed of generating unit following load rejections.
d High water level in station sump.

e Continued ratation of turbine runner after unit should have stopped
f Undervoltage of station DC system from flooding or severed circuits.
6. The motor-driven bypass valves must be opened to balance pressures
on the leaf prior to opening the butterfly valve, and closed at the
completion of the butterfly opening cycle. The operational sequence is
automatic whenever the butterfly valves are opened from the power
plant control board; however, when opened locally at the valve control
house, the by-pass valve must be operated by independent push buttons
in the electrical control center

7 The grease pumps will operate automatically whenever the butterfly
valves are opened or closed, however, they may be operated independently

JIC HYDRAULIC SCHEMATIC

Angle check volve

3. During inspection or repair of o turbine, close Valves D and E of
the corresponding control system to prevent occidental opening of
butterfly valves. In addition, turn transfer switch 438VI or 438V2
to "OFF position and remove key

4 The butterfly valves may be closed during the opening cycle by
directly initiating the closing either from the local electrical
control center on the power plant control board, depending on the
position of the transfer switches (see Operating Instructions). Opening
of the volves during the closing cycle may be accomplished only
when operating from the local electrical control center by first
pushing the STOR then the OPEN push buttons.

5. When the opening or closing cycle is initiated the leaf will rotote
to the fully open or closed position where the oil pressure switch

opens to stop the motor-pumps automatically

6 The butterfly valve will not open until the downstream penstock
has been filled with water and the pressures balanced sufficiently

to actuate penstock water pressure switch. After putting valve
into service, bleed air from line by loosening tubing cop 2 of
penstock water pressure switch.

7 Coution: After completion of any local operation from the valve
control house, return the control transfer switch in the local
electrical control center to the REMOTE position.

C OPERATING INSTRUCTIONS:

1. Operation from local electrical control center Set oppropriate transfer
switch, 438V1 or 2, at electrical control center to the LOCAL position.
a. Opening-Assume valve is closed with full reservoir head on
the upstream surface of the leaf.

(10 Open by-pass valves, by pressing appropriate OPEN push
button, to allow filling of the penstock between the butterfly
valve and the turbine. The filling time will be opproximately
75 minutes.

(2) When filling is complete, press butterfly valve OPEN
push button.

(3) When the butterfly valve is fully open, as indicated by the

red indicator light, press the by-pass valve CLOSE push button

b Closing--Press CLOSE push buffon

Stopping-Press STOP push button.

d. Return transfer switch to REMOTE position.

2 Operation from moin control board.

Appropriate transfer switch, 438V1 or 2, at local control center
must be set in the REMOTE position. Transfer switch 43-1 or 2 of
main control board may be set in any position, LOCAL-MANUAL.
LOCAL-AUTOMATIC, or REMOTE-AUTOMATIC

a. To open valve, operate appropriate butterfly valve control
switch, BVICS (OPEN) or BV2CS (OPEN)

b To close valve, operate appropriate butterfly valve control
switch, BVICS (CLOSE) or BV2CS (CLOSE)

3. Operation from Keswick Power Plant.

Set appropriate transfer switch, 438V1 or 2, of the local electrical
control center to REMOTE position, and appropriate transfer switch,
43-1 or 2. of main control board to REMOTE-AUTOMATIC position

a To close valve, operate appropriate keyed switch handle,
220 BVIC or 2C, to CLOSE position and hold for approximately
3 seconds.

b Valves cannot be opened from Keswick.

416 0-2302

TEST GAGE ADDED PICTORIAL #TORAULIC SCHEMATIC

PARAGRAPH AZ FLOW AND HEAD CORRECTED

Figure 158. --Clear Creek Powerplant--Controls and operating diagrams for 156-inch butterfly valve. (Sheet 1 of 2.)

INSTALLATION AND SERVICING INSTRUCTIONS

All adjusting and testing procedures, except the emergency close test and
The operational test with butterfly valve open, shall be performed
either with no water in the penstock upstream of the butterfly valve
leof or under balanced no flow conditions with the turbine wicket gates
closed Use local contral for all servicing, testing, and maintenance
procedures except the checks for remote operation. If penstock is
unwatered, place a temporary jumper wire across terminals of
penstock water pressure switch At installation, remove and discord
pipe plug in diophragm to permit drainage of housing

A. GREASE PUMPS:

1. Fill grease pump crankcase to the proper level with SAE 20 oil.
2. Fill grease pump reservoir with water resistont grease having o
National Lubricating Grease institute No 0 or I consistency, and
comparable to Fiske Bros Lubriplate No 130-AA.

3 Fill grease lines and butterfly valve covities by removing grease
relief valves from upper and lower body halves of butterfly valve.
Run pump by pressing GREASE push button until grease appears
of relief valve tops Add grease to reservoir os system fills and
completely fill reservoir after grease lines are full Replace grease
relief valves.

B. FILLING THE SYSTEM WITH OIL:

The pressure devices have been shop set and should require no
further adjustment at this time

2 Approximately 285 gallons of new, clean, light, hydraulic oil will be
required to fill the system. The oil shall have a viscosity of about
150 SSU of 100°F and shall be similar to Texaco Regal Type A R &0
or conform to Military Specification MILL-17672A Grade 2110 TH
Special care shall be token to assure cleanliness and to vent all
air from the system during filling. Add oil to tank as required
during filling process

3. Physically place the butterfly leaf in the open position and close
oll hand operated valves except those on the oil sight gage

4 Provide and install auxiliary piping and volve C suitable for 1000
PSI service in place of plug y in lower cylinder head.
5 Open Valve S and slowly pour oil into tank allowing air to escape
bock through suction line while filling Fill until oil level in tank
reaches MAX mark on sight goge.

• Remove solenoid wiring access plate on 4-way valve and temporarily
disconnect solenoid wires. Place jumper wire across oil pressure
switch terminals and set relief valve at its minimum setting of
500 psi.
7. Open valves U end K. Press either the CLOSE or the OPEN push
button to start the pumps Pressure lines will fill and system relief
valve will by-pass entire flow to tonk. Press STOP push button.
8 Open Valves E and M, disconnect tubing on tank side of Valve M. With
piston at bottom of stroke and resting on cylinder head, connect
temporary oil supply to auxilliary piping of Valve C. Pressure on
the temporary supply may be applied either by pump or by gravity
means. Proceed to fill line b. When oil appears at Valve M, close
valve, reconnect tubing, and stop filling. Close Valve C and
disconnect temporary oil supply. Open Valve D.

9. Open Valves Q. v, and R. Press either the CLOSE or the OPEN push
button to start the pumps Allow line to oil pressure goge and oil
pressure switch to bleed and reclose Valve R Momentarily loosen
tubing fitting on pilot line of unloading valve to let trapped air
escope. Press STOP push button, reconnect 4-way valve solenoid
wiring, and replace wiring access plate.

10 Press CLOSE push button, the piston will raise and the butterfly
valve will close Reset relief valve to 750 psi in accordance with
Subparagraph E-1, removing jumper wire from oil pressure
switch terminals only

IL Press OPEN push-button when the butterfly valve is fully opened
the oil pumps should shut off automatically Run the valve through
several opening-closing cycles opening Valves M and N momentarily
during the opening-closing cycles to vent any trapped air Leave
the butterfly valve in the open position Add oil to tank until it
reaches MAX mark on sight gage

b Valve open--Adjust screws to operate four upper switches simultaneously which actuate as follows

(1) Two switches apen to turn green lights off at local control center, power plant control board, and supervisory control board at Keswick

(2) One switch closes to actuate by pass valve closure
(3) One switch closes for generator interlock control
3. Lightly grease gears in position indicator

D. CHECK REMOTE OPERATION:

From main control board (See Operating Instructions Porograph C-2)
a With butterfly valve fully closed, initiate opening cycle from
main control board and check for proper opening of butterfly
and by pass valves.

b When butterfly valve is fully open, check that by-pass valves
close outomatically

c. initiate closing cycle from main control board and check for proper closure of butterfly valve.

4 Initiate opening cycle and interrupt it by initiating closing cycle Check that valve closes

2. From Keswick control board (See Operating Instructions Paragraph C-3).

a. With butterfly valve fully open, initiate closing cycle from Keswick control board and check for proper closure of butterfly valve

E PRESSURE DEVICE FUNCTIONS, SETTINGS, AND ADJUSTMENTS:
Check volve settings by General Operating information, paragraph 8-1
1. The relief volve is set to limit the system pressure to 750 psi in
case of pressure switch failure Adjust as follows:

e Place a jumper wire across terminals of pressure switch
b. If butterfly valve is open, press OPEN push button, if closed,
press CLOSE push button.

c. Adjust relief volve as quickly as possible to maintain gage
pressure of 750 psi, then press STOP push button and remove
jumper wires. CAUTION At 750 psi motor is over loaded, and if
run for more than 1 minutes overload device will stop motor
2. The unlooding valve is set to divert discharge of one pump to
tank when system pressure reaches 200 psi which minimizes
horsepower requirements of seating pressures. Adjust as follows:
a. Close valve Q and press OPEN or CLOSE push button.
While leaf is moving, slowly build up gage pressure by
throttling with valve U until pressure suddenly drops. Moximum
goge reading represents unloading valve setting. Adjust
unloading valve to operate at 200 psi, then open Valves Q and U.
3. The sequence valve prevents butterfly valve from closing too rapidly
under emergency conditions by throttling flow of ail from operating
cylinder to tank until it equals pump delivery, and maintains a
pressure of at least 100 psi in pump discharge line. Adjust as follows
a. With the butterfly valve open, press the CLOSE push button
and check minimum gage pressure required to close leaf.

b. Adjust sequence volve to give a minimum goge reading of 100
to 125 psi.

4 The oil pressure switch is set to open contacts and stop motor pumps
on rising pressure of 500 psi and to remake contacts at 400 psi
on falling pressure Adjust as follows

a. Set relief valve slightly above its minimum setting of 500 psi
and partially open valve R

b if butterfly valve is open press OPEN push button, if closed.
press CLOSE push button, and start motor-pumps

c. Do not open valve R when gage reads less then unloading valve
setting of 200 psi because motor will be overloaded

d Slowly close Valve R and build up goge pressure until pressure
switch opens contacts and stops motor pumps Adjust pressure
switch to open contacts at 500 psi, then close valve R

e Close Valve v and almost close Valve Q Restart motor-pumps as
directed in b above, and as soon as pressure switch stops motor,
close Valve Q to trap pressure in pressure switch line
f Slowy crock Valve Q. ollowing pressure to drop until pressure
switch contacts remake and operate relay Adjust pressure
switch to remake contacts of 400 psi, then open Valves v and Q.
5. The penstock water pressure switch is set, using the calibrated
dials, to close contacts on rising pressure at 60 psi and to open
contacts on falling pressure at 40 psi. It is connected to penstack
by line and functions to prevent opening butterfly until
pressures on leaf are balanced

F MAINTENANCE.

The service and maintenance procedures prescribed by the
manufacturer shall be followed for the pumps, motors, and other
commercial components

2 The oil tanks and lower cylinder heads of operating units shall be
drained of accumulated water and sediment once a year. Also,
clean oil tank filler breather units.

3. The oil filters should be removed and cleaned immediately after
installation and testing of controls, and thereafter once a year
Carefully refill filter housing with hydraulic oil before reinstalling
to minimize admission of air to system.

4. Check oil level in grease pump crankcoses periodically, and grease
level every 25 operating cycles of butterfly Add oil and grease
as required.

,5 Butterfly valve mounting bedplates should be greased periodically
through fattings in valve feet

6. When butterfly valves are not operated for prolonged periods, grease
trunnions once a month using the GREASE push button

7. Check operation of entire control system including both hydraulic
and electrical equipment once a year

8 Every two years, check gages for accuracy and adjust pressure
devices as necessary.

9 Method of making operational test with butterfly valve open and
generating unit on the line.

a. With operators stationed at the local control center in the valve
house, the main control board in the power plant and the control
board of Keswick power plant, and at a prearranged time, initiate closure
of the butterfly valve from Keswick through the appropriate contact
220BVIC or 2C. (See Operating Instructions Paragraph C-3)

b. As soon as the green light turns on at the local control center, indicating
that the butterfly valve has started to close, the operator shall
immediately depress the STOP push button.

CAUTION: Valve closure must be stopped before it interferes with
power generation

c. Reopen the butterfly valve from the main control board using the appropriate OPEN switch BVICS or 2CS

10. Unbalanced closure tests

d Test procedure:

(1) Install test pressure goge at valve C.

(2)Set turbine wicket gates to produce desired flow thru unit to be tested,
but do not use a mechanical block to prevent closure of wickets, Hove
second turbine of speed-no-lood and, as output from test unit drops
during butterfly valve closure, manually odjust wicket gates on second
unit to pick up load and hold power output constant

(3) Initiate butterfly valve closure using BVICS or BV2CS at power plant control
board and record test goge pressure below operator piston vs volve
opening at every 1 degrees of leaf rotation Also, record closure time.
ail temperature, reservoir and tailwater level elevations and penstack
pressure goge reading at stort of tests.

I For seal and operating unit adjustment instructions see
Drowings 416-0-1205 and 1191 respectively.

The electrical control equipment for bath butterfly valves is housed
in a common control center in addition to the control equipment.
the central center also houses on automatic transfer panel for the
power supplies, ond a lighting transformer Te control is arranged
to provide outomatic operation of the valves when operation is
initiated remote from the valve house When control is initiated from
The valve house, sequence of operations is under manual electric
control by operator, using push buttons of local control center
(See Operating lestructions, Paragraph C-1)

8. OPENING VALVE NOI BY REMOTE CONTROL:
(Valve No 2 similor, see Schematic Diagram Drawing 416-0-1332)
Before initiating opening operation of main control board, local
transfer switch (438VI) must be placed in REMOTE position. Operole
Switch BVICS on control board to OPEN position. This will energize
auxiliary opening relay 428VIYO, which seals in and also energizes
contactors 428PIAO and 428PIBO to operate the by-pass valve
motors in the opening direction. At the end of by-pass valve travel,
the contactors 428PIAO and 42 BPIBO ore de-energized by limit
Switches and the motors stop. Penstock begins filling. When pressure in
penstock reaches 60 psi, pressure switch 63PW1 closes,energizing relay 63PWIX
Relay 63PWIx energizes moster opening relay 428VIXO, which seals
in. Relay 42BVIXO energizes 4-way valve solenoid 2008V1-0 and
oil pump starter 42BVI, which, in turn, epergizes grease pump starter
4261. Oil and grease pump motors start and 4-way valve shifts to
OPEN position, directing oil through line a to the topside of the
operator piston, rotating the leaf toward the open position, and
returning ail from the underside of the operator piston, through line
b. to the tank. When the leaf reaches the full open position, the piston
will be stopped by the cylinder head, and system oil pressure will
then rise to 500 psi, which will open pressure switch 6301.
de-energizing master opening relay 428VIXO, which, in turn, de-energizes
starters 42BVI and 4261 to stop pump motors, and de-energizes
4-way volve solenoid 2008VI-0. Four-way valve is spring returned
to neutral position. When leaf is fully open, limit switch BVILS will
close to energize contactors 42 8PIAC and 428PIBC to operate
the by-pass valve motors in the closing direction Valve motors are
stopped at end of trovel by motor limit switches. Operation of limit
switch BVILS of full open position of leaf also closes an interlock
circuit to permit starting of generating unit.

C. CLOSING VALVE NO.1 BY REMOTE CONTROL:
(Valve No. 2 similar, see Schematic Diagram Drawing 416-D-1332)
With local transfer switch 438vi in REMOTE position, operate switch
BVICS on main control board to CLOSE position This energizes
moster closing relay 42BvIXC which seals in. Reloy 428VIXC
energizes 4-way volve solenoid 2008VI-C and oil pump starter
42BVI, which, in turn, energizes grease pump starter 42G1. The oil
and grease pump motors stort and 4-way valve shifts to the
closing position directing oil to the underside of the valve
operator piston, (line b). rotating leaf toword closed position. When
leaf is stopped in the fully closed position by the seating of the seals,
oil pressure will rise to 500 psi and open pressure switch 6301, to
de-energize motor closing relay 428VIXC and, in turn, the oil pump
and grease pump starters to stop the motors. Emergency closing
is accomplished by energization of master closing relay 428VIXC
through contacts of remote protective devices, as listed under Bosic
Function and Operation, Paragraph A-5, above.

TRACES ... ECOMMENDED.

спесикоза. APPROVED.

DENVER, COLORADO, NOV 30, 1962
SHEET OF E

416-0-2676

Figure 158. --Clear Creek Powerplant--Controls and operating diagrams for 156-inch butterfly valve. (Sheet 2 of 2.)

B. Clear Creek Powerplant

1. Powerhouse Structure

196. General Structural Design. As stated in section 99, the general and structural layouts of Clear Creek and Trinity Powerplants were very nearly identical, but opposite hand. The structural design was therefore intimately related. It was decided that where the structures were comparable from a design standpoint, one design analysis would be made and the results used for both structures. The analysis used was based on composite critical design conditions from both structures. This decision was made as an economy move in the design office and to speed up the design which was tightly scheduled for the number of personnel available. The final structures were somewhat overdesigned in a few areas, but separate analyses were made where possible savings were indicated. Figures 159 through 163 show the general arrangement of Clear Creek Powerplant, and figure 164 shows a view of the powerplant.

197. Loading Conditions. Principal data pertaining to the structural design of Clear Creek Powerplant are shown on figure 165. Among the more important items shown are live loads on floors and decks throughout the plant including trailer loads, weights of generators, cranes, turbines, oil tanks, and transformers; and loading conditions for analysis including assumed loads for water, temperature, wind, earthquake, backfill, and uplift pressures. Working stresses and allowable increases in unit stresses for various loading combinations are also shown.

The original design was based on estimated weights and dimensions of equipment. When final manufacturer's data indicated that the equipment weight and size were in excess of estimated values, the design was reviewed and revised accordingly.

198. Basic Data and Codes. See section 101 for a listing of data and codes used in designing both the Trinity and Clear Creek Powerplant structures.

199. Stability Analysis. Loading conditions tending to cause instability and flotation of the structure were investigated for construction and normal operation of the powerplant as shown on figure 165. Allowable values of cohesion, friction, and bearing as determined from laboratory tests are also indicated. Full uplift pressures were assumed effective over the entire base area as outlined in present Bureau policy. Loads of primary importance considered include dead load, equipment loads, hydraulic thrust, water and backfill loads, and earthquake.

It was determined from stability studies that the powerplant would be stable for any forseeable construction and operation conditions with the exception of failure by sliding. The primary question was the amount of cohesion which would develop between the concrete and rock foundation. A key placed at the downstream toe of the powerplant was added to insure necessary stability against sliding.

200. Foundation Preparation. (a) General. --The location of Clear Creek Powerplant was changed several times to avoid major faults. Excavation, however, revealed the final site to be badly faulted. These faults crisscrossed and dipped in different directions and in a random manner. It was generally agreed that faults could not be avoided by minor shifting of the powerplant location. Necessary adjustments in the foundation preparation were therefore undertaken as the most feasible solution at the late date.

(b) Gas Collection System. --It was further determined during preliminary exploration and later during excavation that methene gas was seeping out of these faults under low pressure. This is a light, odorless, and flammable gas. It was feared that the gas would seep into the plant over a period of time and cause a serious fire hazard and might even be exploded by a mere spark. A method of venting this gas into the atmosphere and above the powerplant roof was therefore deemed necessary.

Since the gas was coming primarily from the faults, it was desirable to collect it in or at the faults before it spread under all areas of the plant. Accordingly, loose material in faults greater than 1 foot in width was gouged out to a depth of twice the width of the fault plus 6 inches. Coarse gravel covered with building paper was placed in the bottom few inches to provide a makeshift channel to collect the gas. top of this channel was maintained at near constant elevation but with slight slope to prevent pockets of gas collecting. Concrete backfill was then placed on top of this in the gouged-out area.

The

Where the faults were too narrow for the above treatment and where drill holes had been made during exploration, steel channels were provided in place of the gravel and building paper channels. These steel channels were placed on a gravel bed for leveling purposes.

All channels for the flow of gas terminated in a perforated clay pipe header embedded in gravel at the edge and base of the structure. Gas was then piped from this header to a point above the powerplant roof and vented to the atmosphere. The location of all channels was determined in the field at points where escaping gas could be detected. A maximum spacing of 25 feet was recommended, however. The gas collection system is shown as details on figures 166 and 167.

At first glance, the collection channels may not appear to form a positive collection system. It should be realized, however, that the gas will flow along the path of least resistance. Also, the channel barrier formed by the building paper needed to be little better than the surrounding foundation material, which was badly deteriorated. These criteria, coupled with the low pressure which the escaping gas was under and the submergence of the whole system, precluded more refined treatment.