Equipment and та terials

(a) Quality. All installed equipment and mate­rials shall be new except the discharge header system which may be either new or ‘like new” used pipe.

(b) Power units. Each of the 64 deep wells shall be equipped with a direct drive diesel power unit. The engines shall be certified to produce a minimum of 115 continuous net horsepower at 1800 revolutions per minute to the gear drive and shall be a Caterpillar Model 3304 T, Detroit Diesel Model4-71N, or equiva­lent as approved by the Contracting Officer. The unit shall be skid mounted with clutch power takeoff, have hood and side panels, fan shroud, muffler, high tem­perature and low oil pressure shutdown, battery, and fuel supply. Any additional item to make the unit function on a continuous 24-hour-per-day operation shall also be included. Engines shall be operated with­in the revolution-per-minute limits of the manufactur­er’s recommendations. The unit shall be leveled and mounted on a 6-inch-thick concrete base. Prior to oper­ation, each unit shall be started and serviced by a manufacturer’s factory trained representative, or equally qualified mechanic. The power units shall be operated and maintained in accordance with the manufacturer’s recommendations. Each power unit shall have an independent fuel tank with a capacity of at least 500 gallons. Fuel lines shall be provided with an approved screen or filter and shall be attached to the tank so that rain or contaminants may not enter the tank. The tank shall be properly vented and equipped with a drain plus and filler port. All fuel tanks shall be new and cleaned prior to being placed in service. At the commencement of pumping, the Con­tractor shall have at the jobsite five new complete die­sel power units. During the pumping period, the Contractor shall have a minimum of five (new or re­manufactured) diesel power units, complete with all components, available as standby. The Contractor shall also keep in stock on thejobsite other miscellane­ous spare parts essential to routine maintenance of the engines, pumps, gear heads, flexible couplings, valves, etc., as considered appropriate and approved by the C. O.R.

(c) Pumps. Deep-well turbine pumps, similar or equivalent to such pumps manufactured by Layne- Bowler, Fairbanks-Morse, Johnston, Jacuzzi, or other qualified pump manufacturer, shall be designed for pumping clear water at a rated capacity of 1500 gal­lons per minute at a total dynamic head of 200 feet and pump speed of 1800 revolutions per minute with a bowl efficiency of about 80 percent. The pump bowl as­sembly shall be of close-grained cast iron porcelain enamel-coated inside and fitted with replaceable bronze wear rings and sleeve-type shaft bushings, Im­pellers shall be cast iron or bronze and designed for nonoverloading. The bowl shaft shall be high-chrome stainless steel of sufficient diameter to transmit the pump horsepower with a liberal safety factor and rig­idly support the impellers between the bowl or case bearings. The pump column assembly shall consist of thirteen lo-foot sections of lo-inch steel threaded pipe with line pipe couplings. Bronze spiders with rubber bearings shall align the shaft bearings in each section. Line shafts shall be of Grade 1045 (ASTM A 108) steel ground and polished with Type 304 (ASTM A 743) stainless steel sleeves to act as a journal for each rub­ber line shaft bearing. A lo-foot section of lo-inch threaded suction pipe shall be screwed into the bottom of the pump bowl. The discharge head shall be provid­ed for mounting the gear drive and supporting the pump columns, bowls, and suction pipe. The design shall permit the drive shaft to be coupled about the stuffing box to facilitate easy removal and replace­ment of the driver. The stuffing box shall be of the deep bore type with a minimum of six rings of packing and a steel case. The packing gland shall be the bronze split-type and secured with stainless steel studs and silicone bronze nuts.

(d) Gear drive and flexible coupling. A right angle gear drive with a gear ratio of 1:1 shall be in­stalled on each pump. Horsepower rating shall be based on American Gear Manufacturers Association standards for spiral bevel gears. Ball and roller bear­ings shall have a capacity to carry the horsepower and thrust loads for a minimum of 20,000 hours. The hous­ing shall be a rigid semisteel casting properly propor­tioned to insure correct alignment of the gears under full load. Case-hardened spiral bevel gears shall be held in position by antifriction bearings selected to

Подпись: 12 0.22 18 0.25 24 0.25 30 0.25 36 0.28 42 0.28 convey the loads over a 4-year period of operation. A large stream of oil shall be pumped to the gears and bearings by a pump located in the base of the housing. The vertical shaft shall be hollow to allow for easy ad­justment of the pump shaft. Provision shall be made for circulating water through a copper coil installed in­side the case. A flexible drive shaft, Watson-Spicer WL-48, or equal, shall be provided with each gear drive. The shaft shall be a minimum of 36 inches long and provided with drive flanges to fit the engine and gear drive. A protective cover made of galvanized sheet metal or expanded metal shall be permanently attached between the engine and gear drive to shield the drive shaft.

(e) Standby equipment. At the commencement of pumping, the Contractor shall provide and have in stock at the jobsite three new complete standby tur­bine pumps. During the pumping period, the Contrac­tor shall continue to have a minimum of three (new of rebuilt) pumps available as standby units, which shall be complete with column, shafting, pump head, gear drive, and flexible coupling.

(/) A minimum of 20 feet of each size of header pipe and two of each size of Dresser couplings (or equivalent) shall be on site for emergency repair if nec­essary. Twelve S-inch flanged nipples shall also be kept on site for adding S-inch rubber or plastic cloth dis­charge hose for emergency pumping of the deep wells in event of discharge pipe failure. Sixty-five hundred feet of S-inch rubber or plastic cloth hose shall be kept on site for pumping of individual wells.

(gj Operation and repair or replacement. The pumps shall be operated so that the water level in the wells is not lowered below the pump bowl. The pumps and engines shall remain in operable condition at all times with no more than two wells or pumps being in­operative at any one time. No two adjacent wells or pumps shall be inoperative at the same time. The Con­tractor shall take immediate steps to repair or replace any well, pump, gear drive, or engine which is inopera­tive. Should the efficiency of a dewatering well show any significant reduction from its initial efficiency, the Contractor may, at the direction of the C. O.R., be required to redevelop and/or chemically treat the well as directed by the Contracting Officer, the cost of which will be paid for under paragraph 3 (Changes) of the General Provisions of the Contract.

(h) Riser pipe. The riser pipe for the wells shall be 16-inch diameter, 0.250-inch or thicker wall, steel pipe.

(i) Well screen. The well screen shall be John­son, Houston, or equal, wire-wrap type 304 stainless steel screen with a minimum inner diameter of 15 inches (16-inch pipe size) with a nominal length of 100 feet. The width of the slots will be 0.040 inch. The (keystone or trapezoidally shaped) screen wire shall be
wrapped and welded on 0.177-inch round rod. The well screen shall be furnished in lengths of 10 or 20 feet. One section of screen for each well will be provided with a stainless steel bottom plate.

(J) Filter sand. The fdter around the well screen and riser pipe shall be an approved washed (clean) sand or crushed stone composed of hard, durable, uniformly graded particles free from any inherent coating. The filter sand shall contain no detrimental quantities of vegetable matter, nor soft friable, thin, or elongated particles, and shall meet the following gradation re­quirements:

Filter Sand A

U. S. Standard

Percent by weight

Sieve No.

passing

1/4

100

4

95-100

6

85-100

10

55-85

14

28-65

16

20-55

20

10-32

30

0-18

40

0-10

If blending of two or more sands is required to obtain the specified gradation, the blending shall be accom­plished so as to achieve a uniform mix approved by the C. O.R.

(k) Discharge system. The discharge piping is for the purpose of conveying the water from the dewa­tering wells to the flotation channel on the south side of the cofferdam area. Under no conditions shall the Contractor discharge water from the dewatering sys­tems outside of the cofferdam dike other than at the specified location. The header pipe installed at the specified locations shall be standard structural grade pipe with the following minimum wall thicknesses:

Pipe diameter, inches Minimum wall thickness, inches

The diameter of the pipe will vary from 12 to 42 inches. Connections may be made either by welding or by Dresser couplings with tie rods. The pipe shall be laid straight, on approved blocking, in a workmanlike manner. Where crossing a road or ramp, the pipe shall be laid in an open separate culvert. The discharge pipe through the cofferdam dike shall have welded joints and be provided with “seepage” fins. A 42-inch Calco, or equivalent, flap gate shall be installed on the end of each discharge pipe. The discharge line from the well to the header shall be 8 inches in diameter and include a gate valve that can be locked or will remain in a fixed position while partially closed, a positive check valve and a pitometer cock for insertion of a pitot tube to
measure well flow. Certain wells shall be provided with a tee and blind flange for connection of an 8-inch discharge hose in event of damage or failure of the main discharge header pipe. The Contractor shall con­struct splash facilities for discharge water at the dredge channel. The Contractor shall maintain the dis­charge splash facilities so as to prevent erosion or dam­age to the channel slopes and to modify such if found necessary.