Cross Cut Hydro Plant, North Side of Salt River, Tempe

Source document Quoted word for word from HAER ARIZ,7-TEMP,4-. Not written, edited or summarised by this site.

On the north side of the Salt River in the city limits of Tempe, Maricopa County, Arizona UTM: Dates of Construction: Original construction - Desilting basin built and conversion to 60 cycle - Engineers: Construction in 1913-1914supervised by the U.S. Reclamation Service Supervising Engineer: William S. Cone Chief Electrical Engineer: 0. H. Ensign

Source document Quoted word for word from HAER ARIZ,7-TEMP,4-. Not written, edited or summarised by this site.

This was the largest low-head hydro plant in the SRP system. From about to it represented a large percentage of the SRP generating capacity. Historians: Fred Anderson and Carol Noland Salt River Project Archives MAP 1 CANALS OF THE SALT RIVER VALLEY: NORTHSIDE (PAST & PRESENT) ~ c .J :r ~ ~ .. .. .J ~ > .. . ~ Ill lltEENWAY llO. .. ~ LEGEND ... TMINDEll8lRO RO. l&N ..J ..J ..~ > ~ ~ - HISTOIUCAL CANAL ... ~ ~ lC ~ :r _/ N ..J EXISTING CANAL CACTUS RO. ~~~ - ~ ~ ... ~ 3- " >II .. ~(. .. N - = ~ t! ..J ... POWEil PLANT/ ~ ~ <I;" .. I'El IRJA ~ ~ PUMPING PLANT PEORIA AYL L ~ :;; . .. lS ... u ... l ,. :n :n. :w 1 2' OUYE AVE. / . " D ORIGINAL TOWNSITE I W t- ~a.,. ., .., .," w -" M "' h - :lC tlORTHERll AYL ~ ~ : ,.: ,.: ,_: ,_: i! & & I I ' W M In "" In d .. 7 f I '9 Z (.

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AZ-30 3 Although the Salt River Valley and the Phoenix Metropolitan area lie within a semi-arid, desert-like region of central Arizona, modern farming and urban development were made possible by the damming of the Salt and Verde rivers by the U.S. Bureau of Reclamation during the early While the Salt River Valley was developing as a result of successful efforts to control the river's flow for irrigation, the young cities of the Valley were experiencing the social and technological changes of the late century. One of these was the coming of the electrical age. The first widespread use of electricity in the Valley was to increase the amount of the irrigated acreage by pumping groundwater.

Due to a lack of readily accessible fuel, valley citizens soon realized the importance of hydroelectric generation, and the Salt River Project realized the importance of developing it. The Crosscut Hydro plant was the largest and most important low-head hydro plant built on the SRP canal system. It was also the center of the SRP electrical distribution system for many years. The hydro plant was built at the head of the Grand Canal (see HAER No. AZ-17) and has always been operationally dependent on the flow of water through the Grand Canal to generate power. Early Hydropower Development The first Arizona hydro plants were located on falls in canals.

By there was a plant located at Arizona Falls on the Arizona Canal operated by the Phoenix Light and Fuel Company, and another plant at the site known as Chandler Falls where the Tempe Crosscut dropped off the mesa into the Tempe Canal. A third plant was under construction by Phoenix Light and Fuel on the Salt River Indian Reservation about two miles west of Granite Reef Dam, where water from the Arizona 1 canal was diverted to a drop and then back into the river bed. The earliest plans for Roosevelt Dam included hydro generation of electricity which would be used in the construction of the dam and later used for Project pumping plants, or sold. The sale of power was a very practical way to reduce the construction and operation costs of the project.

After the irrigated acreage of the Valley was expanded by the dam, electricity for pumping took on a new importance. The application of irrigation water to larger areas of land resulted in the raising of the water table to a point where thousands of acres were nearly waterlogged. Thus the most important use of pumping in the first two decades of SRP operation was not for increasing agricultural acreage per se, but for saving existing 1 Earl Zarbin, "The Salt River Project: Generating Electricity," (manuscript, SRPA), p. 3. Crosscut Hydro Plant HAER No. AZ-30 4 acreage by draining it. Of course this drainage water was quickly put to use by farmers outside the Project boundaries. Power was generated at Roosevelt from two different heads.

A 19 mile long power canal took water from the Salt River above the upper end of Roosevelt Lake, and delivered a constant head of 220 second/feet. In addition, an intake at the dam provided a variable head when water was discharged from the dam for irrigation. The two sources entered the power house below . Roosevelt Dam through separate penstocks, and each drove three 900 kilovolt turbines. Commercial operation of the plant began with the first transmission of power to Phoznix in and slowly increased to KW capacity by It soon became apparent that electrical demand would grow far beyond the capacity of the Roosevelt plant, and that there were numerous other feasible hydropower sites on the Project water delivery system.

The Reclamation Service was responsible for building the Project, and in many ways exercised its powers not only to direct the construction, but to determine the ultimate size and purpose of the Project. This was particularly true of the power system which, as Zarbin says, remained "firmly in the hands of the Reclamation Service, and not the Water Users' Association," at least until In the government acquired the Arizona Falls and Indian Crosscut plants from Pacific Gas & Electric, and agreed to provide the company KW for retail sale in Phoenix. The government promised not to enter into retail sales its3lf, but reserved the right to serve large industrial customers. The government also built an electrical distribution system.

The main artery was the volt (44 KV) line from Roosevelt to the Mesa Switchyard and the Phoenix Substation. The first branch off this line was the Sacaton 44 KV line, completed in to supply the pumping plants on the Gila River Indian Reservation for which a power supply contract was signed in as well as the Chandler pumping plants. Over the next several years, 44 KV extensions were built from the Mesa Switchyard to the South Consolidated Power Plant (built in from Phoenix to Glendale, mainly to supply the South-Western Sugar & Land Company; and from Roosevelt to Miami to supply the Inspiration Consolidated Copper Company.

In addition, 11 KV lines were built connecting the canal hydropower stations and pumping batteries, and a few 4.5 KV lines to supply smaller customers in Phoenix and 2James M. Gaylord, "Power and Pumping System of the Salt River Project, Arizona," (manuscript, SRPA), pp. 3 zarbin, "Generating Electricity," p. 23; Geoffrey P. Mawn, "Phoenix, Arizona: Central City of the Southwest, diss. Arizona State University, p. Crosscut Hydro Plant HAER No. AZ-30 5 Glendale. The layout of these main lines shows the importance of commercial cu~tomers and pumping plants in establishing the SRP power system.

The Agreement Although the Water Users' Association saw the advantages of power generation, the overall cost of the project was already soaring far above the original estimate of about $3 million, and there were no other funds available from the Reclamation Fund for expansion of power generation. In October with the anticipated completion of Roosevelt Dam still two to three years away, Association legal adviser Joseph Kibbey proposed to the Board of Governors that the Water Users' Association build hydropower plants on the canals and sell the electricity to reduce the repayment costs. According to this plan, Association members would assess themselves about two dollars per acre for three years to pay for the plants.

The sale of electricity would produce revenue of to per year, which, it was assumed, would reduce Project repayment charges from about per acre per year, to about per acre per year, once the 10 year repayment period began. By May this idea had been formed into a definite proposal for the consideration of the Interior Department. Under this proposal, the Water Users' Association would: 1. Build a new crosscut canal from a point on the Arizona Canal one mile above Arizona Falls to a point near Hole-in-the-Rock northwest of the Mill Avenue Bridge in Tempe. 2. Extend the Grand Canal approximately two miles east to meet the new crosscut, and enlarge the upper end of the existing canal. 3. Build a horsepower hydro generating plant at the fall between the new Crosscut and the Grand extension. 4.

Build a HP hydro plant on the South Canal at the junction of the Consolidated Canal, with a transmission line to the Mesa Switching Station. 4 Gaylord, "Power and Pumping," pp. 5 under Reclamation law, the 10 year repayment of construction costs began when the project was declared "open" by the Secretary of Interior. Kibbey hoped to build and pay off the hydro plants before these repayments began, which was easily accomplished. The project was not declared open until (by which time the repayment period had been extended to 20 years). Crosscut Hydro Plant HAER No. AZ-30 6 5. Refurbish the existing Arizona Falls plant to generate 700 HP.

The estimated cost of this work was about The proposal was approved by the Interior Department, and a contract was executed which also provided that the Salt River Project would not be declared open at least until the power plants were completed. The work was to be directed by the Reclamation Service, and when completed would be turned over to the federal government to become part of the Salt River Project. On July 21, Association shareholders approved the contract in a special election, and the Board levie~ an assessment on member lands of per acre for two years. These power projects required acquisition of rights of way, designing of facilities and specifications, solicitation of bids and letting of contracts before construction began.

The bidding on hydropower equipment was particularly cumbersome, since all the equipment suppliers were located far from Phoenix, and many of the installations were custom-made. Furthermore, almost all correspondence related to power construction was routed through Chief Electrical Engineer O.H. Ensign at the Reclamation Service office in Los Angeles. Work on the South Canal plant began in and operation of the plant began in November Work on spillways at Arizona Falls began in January and work on a new powerhouse began in June. The plant went into operation in May Work on the Crosscut project began with the building of the three and one-half mile long New Crosscut Canal.

The reasons for relocating the interconnection between the Arizona and Grand canals had to do entirely with power development rather than irrigation. By moving the crosscut east, it was possible to take advantage of a 112-foot drop (the maximum flow of the canal was 720 cubic feet per second), at the point where the Crosscut would meet the new head of the Grand. Also, the Crosscut power station would act as the central distribution station for the entire system, connecting Arizona Falls with th7 southside system and the main line from Roosevelt to Phoenix.

Despite the primacy of power generating considerations in the development of the Crosscut project, the fact remained that the first purpose of the Salt River Project was irrigation, and therefore, the plant was "designed not to vary the water to suit 6 zarbin, "Generating Electricity," pp. Project Director to Director, USRS, August 31, Contract of August 30, (both SRPA). 711 Power Situation on the Salt River Project, Arizona," by Chief Electrical Engineer, Los Angeles, California, (SRPA). Crosscut Hydro Plant HAER No. AZ-30 7 the demands of power but to vary the water to suit the delivery of the water, and to get every pound of power out of that water." Thus the plant 8 was designed to achieve maximum efficiency under varying loads.

Bids on the new canal were opened on March 28, with Grant Brothers Construction the successful bidder. The first three thousand feet of the canal below the Arizona Canal crossed a depression which at its lowest point was eleven feet below the required grade for a canal. The Reclamation Service produced designs for both an underground pipe and an elevated, lined canal in this stretch before deciding to build the latter (see photo AZ-30-18). The lower end of the canal crossed a 500 foot ravine in a concrete flume supported on concrete bents, to a saddle between two hills, where it emptied into a long concrete forebay 380 feet long by 58 feet wide.

The purpose of the forebay was to hold a steady head of water for power generation, and more important, to allow the water to settle and drop its silt and sand to the floor of the forebay. The spillway wall contained small gates which c~uld be opened periodically to flush sediment out of the forebay. At the lower end of the forebay were the mouths of two parallel seven-foot wide concrete penstocks, feet long which conveyed the water to the power plant (see photo AZ-30-7, AZ-30-9). The penstocks were reinforced with longitudinal 1 1/4 inch steel bars and circumferential rods. Every 300 feet the penstocks were anchored into concrete pads which were poured with the pipe. The penstocks were covered with earth and broken rock to a depth of twelve inches above the crown.

The work on the penstocks was done under contract by Martin & Gillis from March to December This company also built the 1 Benstock entrance and installed the butterfly regulating valves. Construction of the Crosscut Hydro Plant Contract for the construction of the power plant building was let to Martin and Gillis July 21, (see Table 1). Construction began in late September, and was completed in November, (see photo AZ-30-1). The equipment consisted of six HP Pelton Turbines connected to six vertical shaft Westinghouse volt generators of 700 KW capacity. Each penstock drove three main water wheels and an exciter unit 8 chief Electrical Engineer to Water Users' Association, February 2, (SRPA). 9 sRP Annual History lOibid., Crosscut Hydro Plant HAER No.

AZ-30 8 (photos AZ-30-19, AZ-30-20, AZ-30-21 show the layout and relationship of the equipment). The main units were each turned by six nozzles, each with a maximum capacity of 20 cubic feet per second, which could be opened and closed individually by hand-operated needle valves. A governor, driven by pulleys from the top of the generator, controlled the opening and closing of deflectors in front of each nozzle. This affected the force of water striking the water wheel blades. This governor and deflector system was the mechanism by which electric load was derived from variable heads of water.

The water wheels were custom-made to handle the expected large amount of sand and silt in the water: the number of parts most susceptible to wear was reduced, and they were designed for cheap replacement (see photo AZ-30-2 for a view of the original generators and exciters, including the governor pulleys and belts; and photos AZ-30-20, AZ-30-21, AZ-30-22, AZ-30-25, AZ-30-26, AZ-30-27 for drawt gs of the details of the water wheels, deflectors and nozzles). The generators were connected to the water wheels by a straight shaft with split clamp couplings. The weight of the rotating parts of the wheel and generator totaled 23 tons, and was suspended from the top of the generator by a single Kingsbury thrust bearing twenty four inches wide.

The lower end of the water wheel-generator shaft was held in place by a spider bearing (See photos AZ-30-23, AZ-30-24). The transformers, switches and bus bars were housed in adjacent rooms east of the generator room. The twelve transformers, produced by Allis-Chalmers Manufacturing, were oil-insulated and cooled by circulating water. They were connected to double and main bus lines through Westinghouse switches (photo AZ-30-3). By spring the building was largely complete, and installation of machinery had begun. The most critical part of the process was the placement of machinery which had to be set in concrete or grouted in position. All summer long a flurry of correspondence between Chief Electrical Engineer Ensign and Superintendent of Construction William S.

Cone in Phoenix was generated by the concerns over placement of the needle valves and nozzles, and the alignment of the water wheel, shaft, bearings and generator. The specifications for the placement of the generator sole plate, which was to be grouted into position, were detailed as to the method of shimming and bolting to be used, and the tolerances needed: "Extreme care should be taken by the man using the engineer's level (transit) to be certain that the rod is held absolutely vertical, and that he is looking for a difference less than the diameter of his cross hairs." Specifications also called for a variation of less than one 11 sRP Annual History, 12 Gaylord, "Power and Pumping," pp. Crosscut Hydro Plant HAER No.

AZ-30 9 one-hundredth of a~ 3 inch in the centering of the needle valve shaft in its seat. By September all the water wheels and generators were installed, and the pipes and chambers were filled with water to test for leaks. When small leaks caused by shrinkage cracks were found, the pipes were refilled with "as dirty water as we could get," mixed with sawdust, to fill in the hairline cracks. In testing the needle valves, a serious vibration was discovered during the opening of the valves. These valves were intended to be operated only in a full open position, but had to be opened and closed slowly enough to prevent abrupt changes in water pressure in the pipes.

The problem was that when operated slowly under a full head of water, the valves were subject to a vibration or "chattering" which could damage the valve seats and stems, and even crack the concrete around the stem guides. Ensign calculated that if the valve could be opened and closed so that it passed through the vibration zone in three to five seconds, the water pressure rise would be acceptable. During October and November, the Pelton Company and the Reclamation Service Engineers experimented with several ways to alleviate this problem, and in November installed new valve guides wit~ 4 vanes which prevented the eddies which caused the vibration.

There were also problems with the butterfly valves at the penstock entrances, and with the efficiency of the water wheels, which at first seemed to be "drowning" in the backwash of water from the nozzles, so that the turbines were operating more efficiently with four jets open than with all six. Work on all these problems was complicated by the operation of one penstock and three turbines for generating purposes, beginning December 19, This was done to take advantage of the flood flows of the Verde River, which allowed the Roosevelt plant to be shut down to store water. This operation of the untested plant resulted in damage to several of the needle valves and water wheels.

Eventually so many of the valves were damaged that the specif ications for Erection of Apparatus for Crosscut Plant," c. June 25, by O.H. Ensign; Ensign to Superintendent of Construction, Phoenix, Arizona, June 26, (both SRPA) . 14 chief Electrical Engineer to Superintendent of Construction, October 14, October 19, Superintendent of Construction to Chief Electrical Engineer, October 8, November 23, (all SRPA). Crosscut Hydro Plant HAER No.

AZ-30 10 TABLE 1: SPECIFICATIONS, CROSSCUT HYDRO PLANT, Water Wheels (6) Maximum capacity HP Speed 94 RPM Guaranteed maximum efficiency 75% Exciter Water Wheels (2) Maximum capacity 300 HP Speed 150 RPM Guaranteed maximum efficiency 75% Governors (6) Speed regulation 2% Speed fluctuation, full load off 10% 11 11 full load on 12% 11 " half load off 6% 11 11 half load on 8% Price of complete hydraulic equipment, FOB San Francisco Generators (6) Rated capacity 875 KV-A 700 KW @ 80% PF Rated temperature rise (guaranteed) 40 deg. c. 2-hour overload capacity KV-A Overload temperature rise 50 deg. c. Full load efficiency Weight lb. Price FOB Pittsburgh Exciter Generators (2, 200 volt) Rated capacity 200 KW Temperature rise 50 deg. c.

2-hour overload capacity 250 KW Overload temperature rise 65 deg. c. Full load efficiency 90% Price FOB Pittsburgh Transformers oil insulated, water cooled) Rated capacity 500 KV-A 2-hour overload capacity 625 KV-A Full load efficiency Regulation 100 PF Weight lbs Cooling water required 2.5 gal/minute Primary voltage ratio v Secondary voltage v Price FOB Norwood, Ohio ea. SOURCE: Gaylord, "Power and Pumping System of the Crosscut Hydro Plant HAER No. AZ-30 11 TABLE 2: CONSTRUCTION COSTS, CROSSCUT HYDRO PLANT, Forebay Concrete and materials $ Grant Bros.

contract Butterfly Valves (Penstock) Machinery & materials Martin & Gillis contract Penstocks and Water Passages Concrete and materials Martin & Gillis contract Supplemental work Water passages Concrete and materials Martin & Gillis contract Steel Building Excavation Martin & Gillis contract Miscellaneous Water Wheels Generators Freight Testing Installation (Water Wheels, electrical, etc.) Source: USRS Correspondence, SRPA. valve stem 1 ~as redesigned and strengthened (see photo AZ-30-28). Through the rest of work continued on the various problems with the plant. Most of this work was done by the Pelton Company under the fulfillment of their contract to achieve required efficiency and reliability.

The contract between the Water Users' and the Reclamation Service called for a thirty day 15 Super1n . t end ent o f Construction . to Ch'1e f E1 ectr1ca . 1 Engineer, January 8, (SRPA). Crosscut Hydro Plant HAER No. AZ-30 12 test of the plant before acceptance by the Water Users' Association. This test was not begun until December 15, Although not considered fully operational, the plant generated a total of KWH in operating on only one penstock at a time. This was the second largest production of any SRP hydro plant that year, 1 15 per cent less than the output of the Roosevelt plant. A summary of costs issued June 1, showed a total cost of not counting changes requested by the Water Users' Associati~9 (see Table 2).

The original estimate had been Freight costs were high, undoubtedly due to the remoteness of Phoenix from industrial suppliers. The combined installation and testing cost of over reflects the fact that there was a great deal of work done in modifying and adjusting the equipment. This is reflective of the innovative nature of the plant, as summed up by Ensign: The designing of a plant of this kind to meet the peculiar conditions of water flow and hold the efficiency and all other desired characteristics, without interfering with the water flow, such as we are doing at the Cross Cut Plant, requires a considerable concentrated skill and experience.

Yet, it being quite radical in some features from previous plants, little things are likely to develop that are annoying and perhaps more or less costly to the contractor . . . but I am still confiden1 8 that the plant will come through high in efficiency. Growth of the SRP Power System At the time it was put into service, the Crosscut Hydro Plant supplied about 40 per cent of the generating capacity of the SRP system. For the next twenty-four years the plant operated as a generally reliable power source, despite increasing evidence that some features of the plant were less than ideal. The Pelton water wheels did not operate well on the low head available, and numerous problems were experienced with the transformers and distribution equipment at the plant. 16 sRP Annual History, pp.

44, 47. 17 chief Electrical Engineer to Chief of Construction, Denver, Colo., June 1, (SRPA). 18 chief Electrical Engineer to Superintendent of Construction, February 18, (SRPA). Crosscut Hydro Plant HAER No. AZ-30 13 Nevertheless, this was a period w 9n the Crosscut experienced "many repairs but little change." . The Association's operation of the power system, however, underwent great change (the Salt River Water Users' Association took over operation of the Salt River Project by contract with the Federal Government dated September 6, Project pumping and wholesale and industrial power sales both increased greatly during the World War, but the power supply remained dependent on the flow of water, and the flow of water was determined primarily by the weather and irrigation needs.

This meant that during the winter months, when the water stored behind Roosevelt Dam was not needed for irrigation, those generators were not available. At those times, power could be generated by the canal hydro plants using Verde River water, but even these sources could be cut off by a general drought on the watershed. The SRP hydroelectric facilities lay within easy reach of some 80 per cent of the electric load of the state of Arizona, and that load was growing rapidly. While this represented an opportunity, it also represented a threat. If the Association did not take steps to expand and firm up its electrical capacity, some competitor was sure to expand into the Project area.

The Water Users' had an investment of million in electric generating plant to protect, and the opportunity to further reduce per-acre assessments on Association farmers through increased power revenues. As Association President Frank Reid put it: We are in the power business. We cannot afford to stay out of the power business with the large and growing demand for pumping on our project and power needs on the farm. Never in the history of the Valley has there been a greater need for vision on ~he part of the ~em~ers 20 . . to see this great opportunity of our Association. Association management considered the best solution to this problem to be the expansion of hydro generating capacity by building more power generating dams on the Salt River.

Between and three hydroelectric/storage dams were built on the Salt River between Roosevelt Dam and Granite Reef Dam. They were Mormon Flat Dam (begun Horse Mesa Dam (begun and Stewart Mountain Dam (begun This allowed water to be run through the upper dams for power generation and still stored 19 Grasmoen and Hudson, "Cross Cut--Forty Years of Power Plant Progress" (conference paper, AIEE Pacific General Meeting, August, 2 F.A. Reid to the Members of the Council, Salt River Valley Water Users' Association, November 16, (SRPA); David M. Introcaso, "Mormon Flat Dam," Historic American Engineering Record Report No. AZ-14 Chapter 2. Crosscut Hydro Plant HAER No. AZ-30 14 behind the lower dams for irrigation.

It also expanded the total hydro generating capacity of the Association from about KW to KW. The dams were financed by bond issues based on contracts to deliver power to industrial users, especially the mines in Globe, Miami and Superior, and to Central Arizona Light and Power Company (CALAPCO). A contract to deliver KW of firm power to CALAPCO, added to KW previously contracted for, brought the minimum annual revenue from that source up to This increased revenue made possible the million bond issue to finance Stewart Mountain Dam. million of this financing was used for the Association's rural electrification program.

The construction of 712 miles of 4 KV line and eight substations made it possible to bring electric power to Association members, making the Salt River Project "the largest completely electrified rural area in the world." Sales.to.farm customers add2~ approximately to Association power revenues. In continued drought endangered hydropower generation and led to power supply contracts with CALAPCO and the Inspiration Consolidated Copper Company.

CALAPCO agreed to build a steam generating plant in Phoenix primarily to supply Association commitments, in return for guaranteed minimum payments through The Association also paid the total cost of the expansion of the Inspiration Consolidated steam turbine capacity in return for availability on demand of the expanded capacity through In addition, the Association was able to purchase as much as KW from the Arizona Power 22 Company's plants in Childs and Prescott ("wheeled" by CALAPCO). Expansion and Modernization of the Crosscut Facility With the pending expiration of the CALAPCO and Inspiration Consolidated contracts, the Association made plans to build its first non-hydro generating plant, and to modernize the Crosscut Hydro Plant.

A report by a consulting engineer recommended the purchase of diesel generating units to provide KW of standby power and the testing of the canal hydro units to determine whether upgrading these plants was feasible. Construction of the diesel plant began in October and in two KVA, 25 cycle diesel generators were installed. Over the next 12 years, the Crosscut complex added and removed at different periods a total of three more diesel units and added 21 Barry Dibble, "Engineering and Economic Examination of SRVWUA, Salt River Project, Arizona," SRPA), pp. the rural electrification claim is made in Grasmoen and Hudson, "Cross Cut." 22 Dibble, "Engineering and Economic Examination," pp. Crosscut Hydro Plant HAER No. AZ-30 15 four steam turbine units.

The hydro, diesel and steam units were all connected, and the changes at Crosscut were almost continuous over this period (as this report was being written, plans were underway for a Historiz 3American Engineering Record report on the Crosscut Steam Plant). To this point all the generating capacity of the Project had been 25 cycle frequency, but the eventual conversion of the system to 60 cycle was recognized. The first step in this direction was taken primarily to serve a single large customer, the City of Mesa, which had a 60 cycle system powered by an obsolete and inadequate frequency changer. The Association desired to begin supplying 60 cycle power directly.

In hydro units 4, 5 and 6 were decommissioned, and the penstock to unit 4 was reworked to accommodate a HP, 327 RPM water wheel built by James Leffel & Co. This was attached to KVA, 60 cycle vertical shaft generator, KW capacity, produced by Electric Machinery Manufacturing Co (see photo AZ-30-5). In a KVA frequency changer was installed in the space formerly occupied by hydro un~~s 5 and 6 to convert between 25 and 60 cycle (photo AZ-30-6). Also as part of this project, a 21 acre-foot desilting basin was built on the east side of the forebay, to further reduce the entry of sand into the penstocks. This was created by a concrete dam 30 feet high and 300 feet long (see photos AZ-30-7, AZ-30-8, AZ-30-9).

The dam was built of arches on 25 foot centers, designed not as a multiple arch dam, but as a structure of "heavy horizontal piers with expanded upstream ends acting as corbells and meeting in the center." This was the first use of "low-water-cement-ratio" concrete on an Association construction project, and "went far toward breaking down a residual feeling among some Association concrete men in favor of the old wet mixes." The new generator had a contract price of the Leffel water wheel (see photo AZ-30-4) had a contract price of including governor system; the desilting basin dam was designed by consulting engineer Raymond A.

Hill, with a contract price of Other less-expensive designs for the dam were rejected because they were less well suited t~ 5 the capability of the Association workforce, in Hill's opinion. 23 Elliott to Lin Orme, October 4, (copy in Engineering Section, SRP Annual History, SRP Annual History, 24 File: Crosscut Conversion, Box 6-4 (SRPA). 25 sRP Annual History, File, Crosscut Conversion, Box 6-4 (SRPA). Raymond Hill was the son of Louis c. Hill, the Supervising Engineer who oversaw the original construction of the (Footnote Continued) Crosscut Hydro Plant HAER No. AZ-30 16 In the Salt River Power District (as the electrical department of the Project was then known), began a concerted effort to convert all its facilities to 60 cycle power (except service to the mines).

Also that year the District began construction of the Kyrene steam generating plant, a modern, outdoor type facility which vastly increased the generating capacity of the Project. The three remaining 25 cycle units at Crosscut continued to be used through the mid-1950s, then were decommissioned and removed. The 60 cycle unit continued to be used as a small peak-load unit during the summer. The building was used for storage and part of it was converted into a hydrology laboratory. After several years disuse, the 60 cycle unit was renovated in and has been used ever since (through As always, the generation is dependent on surface water irrigation flow of the Grand Canal.

The unit is run continuously from May to September at extremely low cost and displaces up to KW of the most expensive power source then operati~g, realizing considerable savings in SRP generating costs. (Footnote Continued) Salt River Project, including the Grand Canal extension and the Crosscut Hydro plant. 26I nterv1ew . . h Tom Kouts ( SRP Power Operations wit . Department, August 21, Crosscut Hydro Plant HAER No. AZ-30 17 Bibliography I. Books and Articles Introcaso, David. "Mormon Flat Dam." Historic American Engineering Record No. AZ-14, II. Dissertations and Theses Mawn, Geoffrey P. "Phoenix, Arizona: Central City of the Southwest, dissertation, Arizona State University, III. Manuscript and Archival Collection Tempe, Arizona. Salt River Project. Research Archives. IV.

Unpublished Papers Gaylord, James M. "Power and Pumping System of the Salt River Project," Manuscript at Salt River Project Archives ( SRPA). Grasmoen, and Hudson. "Cross Cut -- Forty Years of Power Plant Progress." Conference paper, AIEE Pacific General Meeting, (SRPA). Zarbin, Earl. "The Salt River Project: Generating Electricity," n. d. ( SRPA) .