Branch circuits emanating from the power distribution panel in the spillway compressor house extend to the following equipment located in the house: (1) Two motor starters for two spillway radial gate hoists. (2) Motor starters for two air compressors. (3) Dry-type 480- to 120/240-volt, single-phase lighting service transformer for compressor house and deck. (4) Two 440-volt, single-phase power outlet receptacles for portable electric space heaters. (5) Dry-type 480- to 120/240-volt, single-phase lighting service transformer in diversion works access gallery. Branch circuits from the power distribution panel serve the following equipment outside the compressor house: (1) Dry-type 480- to 120/240-volt, single-phase lighting service transformer in diversion works access gallery, and a similar transformer in the piezometer well. (2) Distribution panel in penstock trashrack structure compressor room which feeds compressor motors, heating and lighting circuits, and the penstock bulkhead gate hoist motor. (b) Lighting Installation. --Dry-type transformers for lighting requirements are located in the spillway compressor house, the trashrack compressor room, diversion works access gallery, and the peizometer well. Each transformer is energized by a 460-volt branch circuit originating at the power distribution panel in the spillway compressor house. The transformers supply power to individual distribution centers consisting of thermal type circuit breakers for the control of branch lighting circuits. The use of dry type air-cooled transformers energized from the 460-volt power system eliminates the need for an extensive 115/230-volt feeder system for lighting requirements. Switching of lights is performed either by local wall switches or by the circuit breakers in the distribution panel. (c) Power System Controls. - (1) Spillway gates. --Each spillway gate is manually controlled by means of a separate momentary contact "Raise-Lower-Stop" pushbutton station located on the radial gate hoist deck. Motor starters provided with overload and undervoltage protection are located in the spillway compressor house. Limit switches are installed on the spillway gate hoists and are connected in the hoist motor control circuits. The limit switches stop the corresponding gate hoist motor when the spillway gate attains its fully raised or fully lowered position. (2) Penstock bulkhead gate. --The penstock bulkhead gate is raised and lowered by means of a 20-horsepower wound-rotor motor mounted on a hoisting frame rack structure. Three-phase power is supplied from the 460-volt power cabinet in the penstock structure air compressor room. Hoist operation is accomplished through a drum controller which controls the operation of the hoist motor starting equipment. The hoist is provided with a mechanical load brake and an electrical brake. A block-actuated limit switch limits the hoisting travel of the lifting eye. (3) Air compressor (for ice prevention). --An ice prevention, compressed air system located in the spillway gate house is used to prevent ice formation at the spillway gates. A similar and independent air system located in the penstock trashrack structure compressor room prevents ice formations at the penstock trashrack structure. Two motor-driven air compressor units are used for each system and the electrical operation of both systems is identical. Each compressor motor is provided with a combination air circuit breaker type magnetic starter and is controlled by means of a "Start-Stop" pushbutton control station contained in the starter enclosure. The control circuits of the two air-compressor motor starters are connected through a manually operable selector switch to alternate the operation of the compressors and also to prevent the operation of more than one compressor motor at any one time. Motor overload and undervoltage protection are provided in the magnetic starters. (4) Diversion works access shaft and piezometer well. --A 230-volt, 3phase branch circuit emanating from the power distribution panel in the spillway compressor house is extended across the spillway gate hoist deck through the spillway left training wall to the diversion works access shaft. This circuit supplies a dry-type 460 to 120/240-volt single-phase lighting service transformer located in the diversion works access gallery. This circuit is further extended to the piezometer well where a 3-kv. -a. dry-type transformer is energized to supply 115-volt, single-phase power to a distribution panel. Circuit breakers protect circuits to lights, space heaters, blower and sump motors. (5) 40,000-gallon water storage tank. --A thermostat-controlled magnetic contactor located near the base of the water tank controls the operation of the four 2-kilowatt, 230-volt, single-phase, immersion type heaters in the water tank. A power-service disconnect switch is connected ahead of the contactor and is located adjacent thereto. Heating circuit protection is provided by a circuit breaker on the switchyard power panel. Two control cables extend from the float switches on the water tank to the powerplant. One cable contains circuit conductors for the water tank high-low water level alarm system. The other cable contains conductors controlling the operation of the water pump starting and control equipment in the powerplant. (6) Reservoir level. --Self-synchronous transmitting equipment is located in the penstock trashrack structure for the remote indication of reservoir elevations. The transmitting equipment is float actuated and transmits forebay water level elevations to receiving equipment on the powerplant control board. The transmitting circuits are contained in a control cable routed through a duct line between the penstock forebay structure and the powerplant. PART III--CONTRACT ADMINISTRATION CHAPTER XI--MAJOR CONSTRUCTION CONTRACTS 85. Prime Contract--Specifications No. 1890. The construction of Boysen Dam and Powerplant (fig. 46) and relocation of Chicago, Burlington, and Quincy Railroad, which was the prime contract, was accomplished in accordance with specifications No. 1890. Two bids were received and were opened at Thermopolis, Wyo., on August 20, 1947. Contract No. 12r-17649 was awarded on August 29, 1947, to Morrison-Knudsen Company, Inc., of Boise, Idaho, the low bidder. The bids and the engineer's estimate were as follows: (1) Morrison-Knudsen Company, Inc., Boise, Idaho $13, 899, 999.30 $16,468, 523.00 $12, 644, 273.25 Notice to proceed was received by the contractor on September 30, 1947, a period of 1,475 days being allowed for the completion of the contract. The contractor began construction operations on September 16, 1947, which was 14 days prior to issuance of the notice to proceed. All work was completed and accepted by the Government on February 16, 1952. The pay item breakdown of work performed under this contract is given in appendix B. (a) Orders for Changes. --Order for changes No. 1, issued October 15, 1947, provided for construction of 710 feet of U. S. Highway No. 20 instead of 300 feet. This change was because of realinement of the highway and the addition of an entrance way to the Government camp. Estimated net increase in the contract amounted to $12, 323.65. Order for changes No. 2, issued on January 14, 1948, provided for replacing 1,523 linear feet of circular concrete pipe culverts with elliptical concrete pipe culverts under the railroad roadbed, to conform with railroad standards. Estimated net increase in the contract amounted to $2, 348. 00. Order for changes No. 3, issued May 27, 1948, provided for replacing 1,800 feet of unstable foundation material in the railroad roadway with rockfill. By means of a $20,000 bridge, the 178,000 cubic yards of excavated material from the east side of the river was moved to the west side and used in building the railroad embankment. This saved money because otherwise the excavation on the east side of the river would have had to be wasted at a considerable overhaul expense, and the fill material on the west side would have had to be excavated and hauled to the fill. Estimated net increase in the contract amounted to $10,916. 93. Order for changes No. 4, issued November 4, 1948, reduced the amount of work required in the railroad relocation. The changes permitted the roadbed to be settled by the traffic of the work trains, prior to final alinement and ballasting of the track. There was no adjustment in the amount due under the contract. Order for changes No. 5, issued on November 29, 1948, provided for (1) a revised and relocated north tunnel portal forming a cut-and-cover section, (2) a gravel zone with drains for the cut-and-cover section, and (3) open excavation to solid rock for the invert of the tunnel. This work stabilized the slope between the highway and railroad relocations. Estimated net increase in the amount due under the contract was $89, 224. 74. Order for changes No. 6, issued September 1, 1948, provided for flattening the backslopes of a railroad cut to produce a more stable slope. Estimated net increase in contract amounted to $3,734. 88. Order for changes No. 7, issued January 20, 1949, provided for placing new and salvaged structural steel invert struts in the railroad tunnel to furnish additional strength in certain reaches of the tunnel. Estimated net increase in the contract amounted to $221,015. 96. |