Report on the water supply system at Basic Magnesium, Inc.
hln000934. Union Pacific Railroad Collection, 1828-1995. MS-00397. Special Collections and Archives, University Libraries, University of Nevada, Las Vegas. Las Vegas, Nevada. http://n2t.net/ark:/62930/d14m9499r
BASIC MAGNESIUM, INCORPORATED WATER SUPPLY SYSTEM CLARK COUNTY, NEVADA DESCRIPTION This system is for transmission of water from Lake Mead, a distance of 15.15 miles, with a static lift of 806 feet from the highest surface level of the lake to the Water Treatment Works at the Magnesium Plant, and the softening and filtration of the water before its distribution to points of consumption, The raw water is of low turbidity, palatable and free of contamination, but is relatively corrosive and hard. The hardness of the untreated water is always in excess of 380 ppm as CaCO3. PHYSICAL COMPONENTS The component units of the system are as follows: Intake Pumping Plant. Pressure Pipe Line from Intake Pump Station to Booster Pump Station. Booster Pump Station. Pressure Pipe Line from Booster Pump Station to Terminal Reservoirs. Terminal Reservoirs. Water Treatment Plant. Electric Transmission and Controls Lines. Distribution Mains to Points of Consumption. INTAKE PUMPING PLANT The Intake Pumping Plant consists of the following units: 1 Steel Truss Cantilever Structure. 1 Pump House. 6 Deep Well Turbine Pumps. 1 Concrete Control House. Electrical Control Equipment. CANTILEVER STRUCTURE The Cantilever Structure is of trussed steel construction, 386 feet 9 inches long with a clear projection of 233 feet, 0 inches. The deck of the structure is 13.23 feet above the high water level of Lake Mead. The location is on the deep water side of an island, which was separated from the main shore by shallow water when the lake level was high. The pump housing and pumps are located at the extreme end of the cantilever structure. The cantilever structure was fabricated and erected by the American Bridge Company, sub-contractors under Engineers Limited. INTAKE PUMPS Intake pumps consist of six Peerless deep well turbine pumps, powered by 400 HP, 4130 volt General Electric motors. Pump columns are 18 inches O.D. with flanged joints, and measure 196 feet 4-1/2 inches from motor base to bottom of strainers. Pumps are set in two rows of three, and each three discharge through 16 inch pipes to a 28 inch manifold. The two discharge manifolds connect to the 40 inch W.S.P. pressure main. An 8 inch Pelton Surge Suppressor is mounted at the discharge of each pump. Motors are controlled by float switches located at the Booster Station Reservoir. The discharge capacity of the intake pumps will vary in accordance with the lake level, and can operate between the following maximum and minimum ranges. Number of Pumps Lake Level at Lake Level at Operating Elev. 1050.00 Elev. 1229.00 1 4,120 gpm 5,500 gpm 2 8,180 " 10,930 3 12,040 * 16,320 " 4 13,380 21,480 " 3 19,040 * 26,380 " 6 22,100 * 31,010 " These two elevations represent the highest possible and lowest probable elevations of the lake surface. Within my knowledge the lake surface has not been lower than Elevation 1150.00. INTAKE PUMP-HOUSING The Intake Pump Housing is constructed of A.P.M. siding and roof mounted on steel frame. The pump house la equipped with a 13 ton motor operated hoist, mounted on a hand operated bridge crane for pulling the pump columns and handling the motors. CONTROL HOUSE The intake control house is a one-story, concrete building, 19 feet 11 inches wide by 80 feet long. It is divided into a circuit breaker room, a battery room and storage apace. Control panel for the intake pumps is located in this building. PRESSURE PIPE LINE The pressure Pipe line consists of the following principal parts: Pipe. Air Relief Valves. Blow-off Valves. Expansion Joints. Anchorage. Number of Pumps Operating Lake Level at Elev. 1050.00 Lake Level at Elev. 1229.00 1 2 4,120 gpm 8,180 * 12,040 * 13,380 ' 19,040 " 22,100 * 3,300 gpm 10,930 * 16,320 ' 21,480 ' 26,380 * 31,010 * The pressure pipe line is of 40" welded steel pipe throughout its entire length. The line is divided into two sections; from the inlet pumps to the Booster Pump Station Reservoir; from the Booster Pumps to the Terminal Reservoirs. The total length of the pipe lines from the inlet pump station to the terminal reservoirs is 79,990 lineal feet. The pipe wall thicknesses range from 9/16" to 1/4". Joints of the heavier sections are banded and butt welded. Joints of the lighter sections are lap welded. Interior coatings are of spun coal-tar enamel, and exterior coatings are of #26 coal-tar saturated rag felt wrapping. This pipe was fabricated in accordance with Standard Specifications for Electric Fusion Welded Steel Pipe for Sizes 30 Inches and Over, No. 7A.3-1940, of the American Water Works Association. The minimum cover is not less than 2-1/2 feet throughout the length of the line, with the exception of two short lengths which are exposed and supported on concrete and steel bents. Exposed sections are anchored at each end with an expansion Joint between the anchors. There are 23 18* manholes in the line. For vacuum relief there are 12 6" Simplex Vacuum Relief Valves, and 9 6" Pelton Dash Pot Valves, which also serve as surge suppressors on the line. For air relief at the create there are 12 3/4* Fisher Air Relief Valves. Blow-off valves are located at each low point and range in size from 4 inches to 12 inches. BOOSTER PUMP STATION The Booster Pump Station consists of the following units: Reservoirs, Pumps. Building. Electrical Control*. Electrical Sub-Station. The Booster Station Reservoir has a capacity of one million gallon*. It is constructed within an earth work cut in fill, with a 2" Gunnite lining, laid on a shallow layer of statbilized earth. It is circular in shape with a 90 foot diameter, flat bottom and sloped sides rising 12 inches on 36 inches. The diameter at the top of the slope is 162 feet. The normal depth of the water is ten feet with a 2 foot free-board. The reservoir is completely covered with a timber roof supported on wood columns and with composition roofing. A float well for the Intake pump float switches is connected to the reservoir. There is a separate float switch for each of the intake pumps, set at varying levels so that the pumps will start and atop in measured sequence, thus eliminating excessive starting and stopping surge. Main booster pumps consist of six Byron-Jackson, 2-stage, horizontal, centrifugal pumps. They are powered by 1250-HP, 4150 volt, Westinghouse synchronous motor*. The booster pumps take auction from a 48 inch auction manifold, which is connected with the booster station reservoir. They discharge into a 40" discharge manifold, which is connected to the 40 inch pressure pipe line to the terminal reservoirs. A six inch Pelton surge Suppressor is installed at the discharge of each pump. The discharge from these pumps is against a constant static head of 635 feet. Their capacities are as follows: Number of Pumps Discharge Gallons Total Dynamic Operation _Per Minute Head. 1 5,580 645 feet 2 10,800 677 ' 3 15,375 717 " 4 19,180 781 * 5 22,290 802 ' 6 24,813 839 * The Booster Pump Building is one story and of reinforced concrete construction. It is divided into a pump room, circuit breaker room, battery room and supply and storage space. The pump room is equipped with a 10-ton, hand operated hoist, mounted on a hand operated bridge crane. All of the electrical controls are located in the circuit breaker room. The booster station transformer bank is located in the grounds adjacent to the booster pump house. The transformer bank is 750 KVA, Allis Chalmers 69/4.16kv. TERMINAL RESERVOIRS The Terminal Reservoirs consist of the following units! Two Reservoirs. Waste Water Pipe Line. Gates Algae Control Equipment. The Terminal Reservoirs are two separate units with a combined capacity At normal high water level of 31,517,600 gallons. Their maximum capacity, with the water surface at the lip of the emergency waste way is 36,582,900 gallons. These reservoirs* are of the same type of construction as the reservoirs at the Booster Pump Station. They are constructed within a shallow out, completely surrounded by fill. The bottom of each reservoir is flat and 200 feet square. The sloping walls have a total rise of 30 feet on 90 feet. At the top of the sloped sections each reservoir is 380 feet square. The lining is 2 inch Gunnite laid on a shallow layer of stabilized soil. The over-flow spillways empty into a concrete shaft, from which a 36 inch, reinforced concrete pipe extend* to a point on the north aide of the state highway. This pipe line conveys waste water and sludge from the Water Treatment Plant. On the north aide of the highway the 36 inch pipe line empties into an earthwork ditch which conveys the waste water out on to the desert to an evaporation area. A 40 inch, welded steal pipe line discharges from the bottom of each of the two reservoirs to the Water Treatment Plant, with a geared slide gat* at the inlet end of each. The inlet of the reservoirs from the 40 inch pressure line is at elevation 2035, which is also the normal high water level in the reservoirs. At the head of this inlet is located an automatic copper sulfate feeder for the control of algae. These reservoirs are not covered. Number of Pump* In Operation Discharge Gallons Per Minute Total Dynamic 1 3,380 645 feet 2 10,800 677 * 3 15,375 717 " 4 5 19*180 22,290 781 * 802 " 6 24,813 839 ' WATER TREATMENT PLANT The Water Treatment Plant consists of the following principal units: Two Reaction Tanks. Chemical Feed Equipment. Eight Rapid Sand Filter*. Four Zeolite Softeners. Chlorination Equipment. Two Clear Well*. Building. Reaction Tanks are of the up-flow variety, using Dorr Hydrotreator Equipment. The tanks are 65 feet square, with a 14-1/2 foot side water depth. Retention at maximum flow is approximately one hour. The reaction tanks are identical and operate in parallel. The Rapid Sand Filters consist of eight separate units, with a total surface area of 5,080 square feet and a three foot sand depth. The design maximum rate of application is three gallons per square foot per minute. The back-wash rate is fifteen gallons per square foot per minute. The plant does not have a back-wash tower, back-wash water being pumped direct from the filtered water clear well through the filters. W&stewash water is reclaimed and pumped back through the reaction tanks. Water to be Zeolite softened is conveyed directly from the filter overflow to four Zeolite cell*. The total surface area of the Zeolite bed* is 528 square feet, with a media depth of four feet. Synthetic Zeolite is used. Zeolite treated water overflows to the smaller of the two clear wells. For the domestic water supply, filtered water and Zeolite treated water are blended to the desired hardness by an automatic tempering valve. Three small booster pumps are used to raise the pressure in the domestic water distribution system. All water is chlorinated after treatment, the chlorine being applied at each of the clear wells, which provide a brief contact period before the water is discharged to the distribution mains. The entire plant, including building, tanks and clear wells, is of reinforced concrete construction. It is completely fireproof and of excellent design. ELECTRICAL TRANSMISSION & CONTROL LINES Electrical Transmission and Control Lines consist of Electric Transmission Line, Telephone Control System and Transformer Bank. The electrical transmission line to the Booster Pump Station is 69 kv, is 62,770 feet long with 100 structures, and with 2/07-strand copper cables. From the transformer bank at the Booster Pump Station to the intake control house is 2.3 miles of 300 m.c.m., 5 kv, Parkway Cable laid under ground. The telephone control cable ha* an approximate total length of 84,000 feet with 438 poles, ranging from 25 to 75 feet in length. The cable is 6-pair, pulp insulated, 19 gauge, non-coated 3% lead sheath. The transformer bank at the Booster Pump Station has been described under "Booster Pump Station Equipment*. DISTRIBUTION MAINS Distribution Mains from the Water Treatment Plant consist of: Stabilized Water Main. Zeolite Treated Water Main. Domestic Water Main The stabilized water main from the Water Treatment Plant clear well to the distribution system at the Magnesium Plant is 40 inch, welded steel pipe. This pipe was fabricated, coated and laid under the same specifications as those for the booster pressure pipe line. The zeolite treated water main is 10 inch diameter, welded steel and extends from the Zeolite treated water clear well at the Water Treatment Plant to the Boiler Plant in the Magnesium Plant area. This pipe is coated in accordance with American Water Works Association specifications No. 7A.16-1940. The domestic water main between the housing booster pumps and the domestic water distribution system is 12 inch cast iron bell and spigot pipe with lead joints. CAPITAL INVESTMENT IN WATER SUPPLY SYSTEM INTAKE PUMPING STATION Structures, including Cantilever Structure, Pump House and Buss House Equipment Power Line from Sub-station near Booster Pump Station Grading and Excavation Roadway-Park Service Highway to Inlet Works Causeway Mainland to Island Fencing Protective Works for Pump Columns $ 366,122.32 239,728.00 118,090.31 73,237.93 231,422.92 233,963.18 9,489.26 243.91 Total $ 1,294,322.23 BOOSTER PUMPING STATION Structures Equipment Grading and Excavation Reservoir $ 112,316.53 331,484.44 13,461.68 77,858.25 Total 333,120.90 PRESSURE PIPE LINE Complete from Intake to Terminal Reservoirs & Terminal Reservoirs to Magnesium Plant $ 2,221,131.83 TERMINAL RESERVOIRS Total $ 428,331.37 WATER TREATMENT PLANT Structures Equipment Caustic & Brine Pipe Lines from Chlorine Plant Construction Items Added After Completion of Contract $ 364,748.92 288,369.08 22,713.43 11,954.99 Total $ 687,986.44 Total Capital Investment $ 3,167,112.81 OPERATING COST DATA In August, 1944, the cost of electrical energy for pumping was approximately $7.29 per million gallons. Average total cost of water at point of use for the first seven months of 1944 was as follows: Cost of Water Purchased $ 1.688 per million gallons Supply and Transmission 10.200 " " * Storage and Treatment 17.045 " ' * Distribution 3.129 * * " Sub-total $ 32.062 ' " " Evaporation & Operating Waste 0.434 * " a Total $ 32.496 " a a NOTE: Depreciation and replacement not included. 8 OPERATION OP WATER SUPPLY SYSTEM The Intake Pumps at Lake Mead are completely automatic and require no attendant. Pumps are started and stopped by float control from the Booster Station. Reservoir. The starting and stopping of the pumps is in measured sequence which is governed by the setting of the float switches to prevent excessive surge. Should all pumps stop at the same time due to power failure the capacity of the surge suppressors is sufficient to prevent a dangerous strain on the pressure pipe line. These pumps require little maintenance work, and the installation Is as simple and no different than that of any other deep well pump installation. At the booster reservoir, in addition to the six float switches for the control of the six intake pumps, there is a float switch for the protection of the Booster pumps. Should the Intake pumps fail this float switch would cut out the booster pumps before water in the Booster Station Reservoir became dangerously low. The booster pumps were designed for either float control from the Terminal Reservoirs, remote manual control or manual control at the pumps. The remote manual control board is now located in the electrical control house at the Magnesium Plant. These pumps are equipped with every electric and hydraulic protection whioh may ever be necessary, a complete description of which would be too lengthy for this report. Unlike the intake pumps, when starting or stopping, the timing relays for all the pumps in service are energized simultaneously with the time setting being set to effect the desired starting and stopping sequence. For our normal operation but three pumps have been in service at one time; however the true maximum capacity of this station is reached when five pumps are in regular service and the sixth is used as a standby. In the discharge pipe from the Booster Pumps, just outside the building, there is a venturi tube with a 17 inch throat connected with a meter in the pump room. The meter ia a Buildera Providence lnatrument of the recording, indicating and integrating type. Payments to the Colorado River Commission are based on readings taken at this meter. About four miles below the Terminal Reservoirs a 12 inch O.D. line takes out of the 40 inch pressure main for water supply to Maganese Ores Company. The Manganese Ores supply is stored in a one million gallon tank, whose water surface if 47 feet six inches lower than the inlet to the Terminal Reservoirs. The connecting pipe line and storage tank are the property of Manganese Ores Co. At present the Manganese Ores Company use about 1.25 million gallons per day. At the Terminal Reservoirs the 40 inch pressure pipe line enters a reinforced concrete box which is bifurcated to divided the flow between eaoh reservoir. There is a gate at each entrance to permit taking either reservoir out of service whan necessary for cleaning or repairs. It has been found that algae grows rapidly in these reservoirs if it is not controlled. About three pounds of CuSO4 per million gallons of water will keep the algea under control. The designed capacity of the Water Treatment Plant is twenty million gallons per day. Proper operation requires the services of the following personnel: 6 - Shift Operators 3 - Relief Operators 1 - Chemist 1 - Superintendent The chemicals used for treatment are as follows: Caustic Soda Sulfate of Alumina Sodium Hexametaphosphate Activated Carbon - (occasionally) Caustic soda is mixed with the incoming water to the reaction tanks for the purpose of converting the calcium and magnesium becarbonates to an insoluable state, thus permitting its removal by sedimentation. The caustic soda used is produced on this project at the chlorine plant and pumped to the water treatment plant through 13,100 lineal feet of 2 inch pipe line. About 1000 pounds of NaOH is required for the treatment of one million gallons of water. No addition of soda ash is made. For coagulation, sulfate of alumina is added to the water ahead of the reaction tanks. Floc is built up in the lower part of the tanks by a mechanical slow stirring device. The incoming raw water is distributed at the bottom of the tank and reses vertically through a floc blanket. The precipitated sludge is thickened on the floor of the tanks and swept to a sludge pocket near the center from which it is pumped to waste on the desert. About midway between the bottom and the water serface is located a large receiver to which the excess sludge overflows. The sludge pumps operating on program switch control pump sludge from these receivers periodically. From the reaction tanks the water passes directly to the battery of eight rapid sand filters. Before entering the filters it is dosed with sodium hexametaphosphate at the rate of about five pounds per million gallons. This disage is to stabilize the water sufficiently to prevent calcium carbonate scaling of the filter sand. Rate of flow controllers regulate the flow of water from the filters to the stabilized water clear well in proportion to the deman. All gates and valves connected with the operation and backwashing of the filters are hydraulically operated by pilot switches from the operating tables. Filters are back-washed from the stabilized water clear well by two 12" 50-HP, 4000 G.P.M. centrifugal pumps, at the rate of 13 gallons per square foot per minute. Backwash water is reclaimed and retreated. At this point the total hardness of the water has undergone about 67% reduction, and it is distributed for general use at the Magnesium Plant, and into the fire protection system. A portion of the water leaving the filters is admitted through controllers to four Zeolite softening beds. The controllers are actuated from floats on the water surface of the Zeolite treated water clear well, and admit enough water through the beds to always satisfy the demand. The synthetic Zeolites are hydrous silicates of sodium and aluminum. They absorb the calcium and magnesium from the water and release an equal amount of sodium. When the capacity of the Zeolite to absorb calcium and magnesium is exhausted the beds are regenerated with salt brine to restore the sodium and carry off the absorbed calolum and magnesium. Salt brine for regeneration Is pumped through a 3 inch pipe line a distance of 13,100 feet from the Chlorine Plant. At the Water Treatment Plant the brine is passed through a pressure filter and stored in a concrete tank until used. The Zeolite treated water is distributed to the Magnesium Plant Boiler House, the Hospital boiler and laundry, and is used for tempering all of the domestic supply. Stabilized water to be blended for the domestic supply is drawn from behind a weir at the entrance to the stabilized water clear well. The lip of this weir is about three feet higher than the surface of the water in the Zeolite water clear well. The pipe line which conveys stabilized water to the auction header of the domestic water booster pumps is equipped with a hydraulically operated control valve, and a venturi tube. The pipe which conveys Zeolite softened water from the Zeolite clear well to the pump suction header is always completely open. The total flow of mixed water passes through another venturi tube at the discharge of the booster pumps. Between the stabilized water and mixed water venturi tubes and hydraulically connected to them la a differential transmitter with pilot valve and a regulating valve, The regulating valve can be set to proportion the soft and stabilized water in any desired ratio. The pilot valve at the differential transmitter operates the controller on the stabilized water supply line. There are three horizontal centrifugal pumps to supply pressure in the housing system. The normal operating head is 39 pounds. One pump discharges 500 g.p.m., one 750 g.p.m. and the other 1300 g.p.m. against that head. Capacity of the pumps working in various combinations: Pump No. Discharge at Design Head 1 300 g.p.m. 2 750 g.p.m. 3 1500 g.p.m. 1 & 2 1240 g.p.m. 1 & 3 1940 g.p.an 2 & 3 2270 g.p.m. 1, 2 & 3 2770 g.p.m. The housing booster pumps are controlled by an automatic float switch located in redwood tanks which serve as a standpipe for the domestic water distribution system. The are six standard redwood tanks of 30,000 gallon capacity each, which provide a total storage of 300,000 gallons. The tanks are inter connected with two 10 inch welded steel pipe connections to the domestic water system. To supplement this storage in case of a power failure of long duration, there is a vault near the water treatment plant. At a moderate operating speed this pump will deliver as much water as all of the electric powered booster pumps combined. Pump No. Discharge at Design Head 1 300 g.p.m. 2 730 g.p.m. 3 1300 g.p.m. 1 & 2 1240 g.p.m. l & 3 1940 g.p.rn^ 2 & 3 2270 g.p.m. 1, 2 & 3 2770 g.p.m. PRINCIPAL ELEVATIONS THROUGH WATER SUPPLY SYSTEM Maximum possible water level in Lake Mead 1229.00 Minimum probable water level in Lake Mead 1030.00 Suction inlet of Intake Pumps 1043.88 Base of Intake Pumps (Deck of Cantilever Structure) 1242.23 Surface of water in Booster Station Reservoir l4oo.oo Maximum surface elevation In Manganese Ores Reservoir 1987.30 Water surface and inlet elevation at Terminal Rearvoirs 2033.00 Water surface in Stabilized Water Clear Well 2007.00 Water surface in Zeolite Mater Clear Well 2003.00 Water surface domestic water standpipes 2067.30