in which A = area of gate leaf, at outside edges of gate seats, P = water pressure at centerline of gate, and W = weight of moving parts (gate leaf, stem, piston, etc.). A hoist was selected which has a capacity of 173,000 pounds when operated with an oil pressure of 750 pounds per square inch. A hydraulic gate hanger is installed on the cylinder head of the hydraulic hoist for holding the gate at any required opening. The hydraulic system is so connected to the hoist that the hanger jaws release the gate before oil pressure is applied to the hoist cylinder for moving the gate leaf. 74. Steel Outlet Pipe. - A 7-foot-diameter steel outlet pipe extends inside the downstream conduit from a transition at the gate chamber to a wye which leads into two hollow-jet valves. The pipe is supported by support rings, bearing plates, and bearing shoes. The bearing shoes are grouted in position on concrete piers in the concrete conduit. Provision was made in the design of the supports to permit axial movement of the pipe because of temperature changes. An expansion joint, located about halfway between the upstream and downstream ends of the pipe, compensates for changes in the length of the pipe. Manholes located near the upstream and downstream ends of the pipe provide access to the interior of the pipe. The materials used conformed to the following specifications or requirements: (1) Steel plates for the outlet pipe and support rings. --"Standard Specifications for Low Tensile Strength Carbon Steel Plates of Structural Quality for Welding, grade B, designation A 78-43" of the American Society for Testing Materials. (2) Forged and rolled steel. --Standard Specifications for Flanged or Rolled Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High Temperature Service, grade 1, with a carbon content not exceeding 0.35 percent, designation A 105-40 of the American Society for Testing Materials. (3) Bridge-bearing bronze for bearing plates. --Minimum physical properties: Ultimate tensile strength, p.s.i. Yield point in tension, p.s.i. 11 100,000 62,000 10 10 240 The pipe was designed, for the most part, in accordance with the 1943 edition of the API-ASME code for the "Design, Construction, Inspection, and Repair of Unfired Pressure Vessels for Petroleum Liquids and Gases. The minimum pipe shell thickness required to provide sufficient rigidity for handling and transportaion was the determining factor in selecting the pipe shell thickness. This thickness was greater than that necessary to resist design load stresses. A thickness of 7/16 inch was selected for the pipe shell. The pipe was fabricated from single plates and the plate edges were beveled for field welding. All longitudinal joints were double welded, and the girth joint was so designed that all field welding could be done from the inside of the pipe. Each section of completed pipe, including the wye and expansion joint, was given a hydrostatic pressure test. The test pressures were determined from the following formula: t = minimum plate thickness in inches of the pipe section tested, and D = internal diameter of pipe in inches. A test pressure of 60 pounds per square inch, equivalent to 150 percent of the design pressure, was applied to the wye. 75. Hollow-Jet Valves. A 60-inch hollow-jet valve is installed on each of the two downstream ends of the outlet pipe. Discharges through the outlet works are controlled by the valves, which have a combined discharge capacity of 1,448 second-feet with the reservoir water surface at elevation 3129.5. Each valve is bolted to the downstream end of the outlet pipe and also to a concrete pedestal. A hollow-jet valve consists of a body and a needle. The needle is moved along the centerline of the body by an electricmotor-driven control unit for opening or closing the valve. When the needle is moved to the upstream end into its seat, the valve is closed. When the valve is closed there is no water in the valve body except in the balancing chamber of the needle. When the valve is opened water flows past the periphery of the needle in the shape of a cylindrical ring along the inside surface of the valve body. Splitters which support the needle divide the ring into sectors as water is being discharged. Openings are provided for maintaining atmospheric pressure in the interior of the ring inside the valve. Each valve was designed for a maximum head of 231 feet, or 100 pounds per square inch. The axial thrust of the water on the valve is transferred to the valve body and to the outlet pipe upstream from the valve. Weight of the valve and its contained water is supported by the concrete pedestal. Model tests were used in the valve design to prevent subatmospheric pressure and cavitation at any valve opening. Eight 1-1/4inch-diameter holes are provided in the upstream face of the needle for admitting water to a balancing chamber inside the needle. Experiments indicated that this chamber permits a large percentage of the water thrust on the needle to be transferred directly to the needle support. The maximum unbalanced thrust occurs when water is flowing through the valve and the needle is about 20 percent open. The unbalanced thrust used in the design was determined by the following formula: The control unit of the valve was designed for the unbalanced thrust plus starting friction of the valve seat and parts. Normal working stresses were allowed for valve or other parts subjected to water pressure and normal torque of the electric motor of the control unit. Also, the stress in any part resulting from the maximum or breakdown torque of the motor was not allowed to exceed three-fourths of the yield point of the material in the part. For a plan and section of a standard 60-inch hollow-jet valve, the reader is referred to drawings 40-D-4009 and -4010 (not included in this technical record). (a) Control Unit.-- A two-speed, reversible, electric-motor-driven gear-reduction unit is provided for opening or closing each valve. This unit is connected to the valve control shaft by means of a special coupling which permits the motor to reach full speed prior to any movement of the needle. A position indicator, mounted on the gear reducer, is equipped with limit switches to reduce the motor speed and power output when the needle approaches either the fully open or closed position, and to stop the motor when the needle reaches the ends of its travel. Approximately 3.75 minutes are required to move the needle between the two limiting positions. The end of the motor shaft is squared for use with a short-handled crank for emergency operation. (a) 76. Miscellaneous. Trashracks. -- Six rectangular trashracks are installed vertically in grooves in the trashrack structure, and a round trashrack is installed horizontally on top of the trashrack structure. The rectangular sections are each 8 feet 3-1/2-inches wide by 12 feet 9 inches high, and the round section is 8 feet 8-1/2-inches in diameter. The trashracks consists of 2- by 5/8-inch trashbars spaced to provide clear openings 5-1/8 inches wide, which openings are considered adequate for protecting the outlet valves. The trashracks were designed for a differential head of 40 feet at a stress of 33,000 pounds per square unit. (b) Reservoir Level Gage.-- A direct-reading mercury gage, mounted in the valve house, is provided for indicating the elevation of the reservoir water level. The gage is marked at 1-foot intervals from elevation 3078.00 to elevation 3131.00, and each 1-foot interval is graduated in 20 divisions. The zero of the gage is marked as elevation 3052.00. The intake for the gage is located on the trashrack structure at elevation 3078.00. Connection between the intake and the gage is by means of 3/4-inch copper tubing and 1/4-inch brass pipe. (c) Ventilation System.-- A ventilation system is provided for personnel entering the gate chamber and the horseshoe conduit. This system consists of a fan mounted on a wall bracket in the valve house, and 8-inch outside-diameter, slip-joint duct extending from the fan through the conduit to the gate chamber, and an exhaust outlet in the gate chamber. The ducts are made of No. 20 gage copper-bearing galvanized sheets. The fan delivers 480 cubic feet of air per minute, which will provide one air change per hour for the combined conduit and gate chamber and three and three-fourths changes per hour for the gate chamber. (d) Heater. An oil-burning radiant heater having a capacity of approximately 70,000 British thermal units per hour is installed in the valve house. Oil for the heater is stored in a storage tank having a capacity of 275 gallons. The tank is connected to the heater with a 1/2-inch copper pipe and vented to the outside of the valve house. A test well, consisting of a 2-inch vertical pipe connected to the bottom of the tank, is provided for measuring the quantity of oil in the tank. The heater is vented by a 7-inch stove pipe which is connected to the valve house chimney. CHAPTER V--CONTRACT ADMINISTRATION A. General 77. Contract under Specifications No. 1410. The initial construction of Enders Dam and dike and the relocation of Nebraska State Highway No. 61 were accomplished in accordance with specifications No. 1410. Invitations for bids for this construction were issued July 30, 1946. Bids were opened at the office of the Bureau of Reclamation, Indianola, Nebr., September 4, 1946. The three lowest bids and the engineer's estimate were as follows: Wunderlich Contracting Co., Jefferson City, Mo. $4, 109, 927.00 The presidential moratorium of August 2, 1946, on construction work and the order limiting Federal expenditures on Reclamation projects to 85 million dollars for the fiscal year 1947 delayed the awarding of the contract. It was not until November 1946 that the Secretary of the Interior was able to delegate authority to the Chief Engineer to award and execute a contract under specifications No. 1410 with the Wunderlich Contracting Co. Award of the contract was made on November 1, 1946. The contractor acknowledged the notice to proceed on January 26, 1947, and this set the completion date of the contract as March 17, 1950. Stripping operations were started in March 1947, and the first embankment material was placed in the fill on May 3. The shortage of skilled and unskilled labor, late shipments of materials, and severe blizzard conditions during the winter caused the submission of three different construction programs. The contractor submitted his first proposed construction program based on completion of the work in 672 days, or by the last of November 1948, which was 15 months ahead of the specified completion date. Early in July 1948, he submitted a revised construction program which called for the completion of all work early in January 1949. Actual construction lagged behind this schedule, with the result that at the end of 1948 approximately 29 percent of the work remained to be completed. On March 23, 1949, the contractor submitted another revised construction program which called for completion of all work by December 31, 1949. As of the latter date, 98 percent of the work had been completed, with 93.5 percent of the allotted contract time having elapsed. It became necessary during the construction of Enders Dam under specifications No. 1410 to issue nine orders for changes and six extra work orders to supplement the contract. Several of these changes became necessary as a result of a change in the outlet works and spillway designs; whereas, others were issued in order that materials could be obtained to meet the contractor's advanced construction program. The scope of the orders for change and extra work orders is shown in appendix B. During the latter part of 1949, the Wunderlich Contracting Co. submitted a number of written protests pertaining to the spillway radial gates and repeatedly requested that they be relieved of this item of the work. The contractor had scheduled December 13, 1949, as the date that closure of the river would be effected by placing the concrete plug in the diversion intake in the trashrack structure of the outlet works. However, because of incomplete negotiations at that time regarding the aquisition of the Superior Hydroelectric Plant at Superior, Nebr., and its water rights, it was necessary that the Bureau delay the date of closure. Estimates of the time required to fill the dead storage pool of Enders Reservoir indicated that this period of storage, during which water releases could not be made, would extend into the next irrigation season and interfere with the water rights of the Frenchman Valley Irrigation District if an appreciable postpone ment of the closure date was made. During the early part of 1950, it was decided that it would be in the best interest of the Government if the contract with the Wunderlich Contracting Co. for the construction of Enders Dam, dike, and relocation of State Highway No. 61 was terminated before all of the work required under the contract was completed, and that the remaining work |