Mountain Dell Dam, Parley's Canyon, Northwest side of I-80, West of State Route 39, Salt Lake City

Source document Quoted word for word from HAER UTAH,18-SALCI,22-. Not written, edited or summarised by this site.

T. Allan Camp, HAER UT-16 "THE MOUNTAIN DELL DAM"* "For the past five years the city engineering depart- ment has been engaged, under the direction of the City Commission, in preparing plans for, and carrying out, exten- sive water supply improvements for this city. At the time the plans were first undertaken, the city was in a serious condition for want of sufficient supply during certain seasons of the year particularly in the late summer and in the middle of winter. At other seasons of the year the supply was generally ample for all purposes.' A careful study was made of the city's available supply with a view of conserving a portion of the surplus supply and of securing additional water.

This study, embraced in a report, resulted in the bond issue of whereby a certain portion of the improve- ments recommended were undertaken. Since that time detailed plans have been prepared and contracts let for most of the units included in the program. The Mountain Dell dam is the last of the storage and distributing reservoirs contemplated in the bond issue. With the completion of this unit the city has an available storage reservoir capacity of gallons, as com- pared with nothing at all prior to :-u * Sylvester Q. Cannon, Monthly Journal- Utah Society of Engineers. September 3 HAER UT-16 In the matter of distributing or equalizing reser- voirs, the city now has a total capacity of gallons as compared with gallons previously.

The location of the Mountain Dell dam is relatively so near to the city that it can serve as an equalizing as well as a storage reservoir. In preparing the plans for this improvement, the question of stability and cost were carefully considered. Plans for three types of dam were prepared and bids obtained on each type. These three types were: Arched solid dam, gravity type* reinforced concrete dam of the Ambursen type' and the multiple arch reinforced con crete dam of the Eastwood design. After a careful consideration of the various types the multiple arch type was accepted. One of the factors influencing this decision was the bedrock condition at the site. The bedrock is a calcareous shale not entirely water- tight and of a nature to decompose somewhat under exposure to air and water.

The advantages of the multiple arch type in this connection were considered to be the practical elimination of upward pressure, the practical impossibility of overturning or sliding on its base and the ready facili- ties for internal inspection of the dam at any time. By making the arches and buttresses of suitable thickness, the unit stresses in the concrete are kept low (the concrete being entirely in compression); and by placing suitable and sufficient strut tie beams the buttresses are thoroughly braced and supported. HAER UT-16 The dam is designed for a full projected height of >; 145 feet above the rock foundation. A provision was made, .

however, for the building of the dam only to the partial height under the present contract, because of the city's lack of means for the completion of the structure. The partial height brings the top of the dam 105 feet above the foundation. The cost of the structure was considerably increased because of the necessity of going 43 feet below ground level in the bottom of the canyon to secure the bed- rock foundation. The spillway level is 4 feet below the top of the dam, so that the maximum depth of the reservoir is 58 feet to the crest of the spillway. The dam as planned and as constructed consists of 11 buttresses and 11 arches. The maximum base width of the dam is 132 feet from the face of the arch to the down- stream end of the buttresses.

The maximum thickness of the buttresses is 8 feet with a batter of approximately 3 inches in 10 feet vertically. The maximum thickness of the arch rings is 4.1 feet. The thickness at the present top of the dam, 15 inches. The arch rings are 120 degree arcs of circles, with a slope of 10 on 12. The spacing between buttress centers is 35 feet. Three hinges are formed in each arch one at the springing line and one at the crown. These hinges were formed by pouring the concrete at the buttress corbels, using curved metal forms for the same, and by the use of the sanr forms for building up one side or the other of the crown of the arch. "% HAER UT-16 At each of these joints the concrete face was painted with asphalt before pouring the concrete adjoining it.

Also, a water stop of galvanized iron was placed in each hinge along the slope. The arches are reinforced with two layers of Clinton Electrically Welded Mesh No. 2xl8-inch, for temperature changes. The buttresses are reinforced with 1-inch twisted bars for the same purpose, and the strut tie beams are heavily reinforced with 1-inch bars and stirrups for tension. The strut tie beams run through the dam from end to end continuously. The two sets of outlet gates each consists of two 24-inch pipes with a suitable grating entrance, and with a butterfly and a double-disc gate valve on each pipe. The spillway has a capacity of 580 second feet, or twice the maximum flood flow of record. The capacity of the outlet gates with the dam full is nearly twice the maximum flood flow of the stream.

The maximum compression in the buttresses for the full height of dam (40 feet higher than the present height) is 146 pounds per square inch; and in the arch rings 300 pounds per square inch. Frequent tests made of the concrete during construc- tion showed a strength at the end of 28 days of approximately pounds for the buttresses mix) and of 2000pounds per square inch for the arches mix). Since practically everything is in compression, the factor of safety is approximately 7. & UT-16 The contractor used the gravel and a considerable part of the sand excavated from the foundation for construc- tion purposes. The total quantity of concrete in the dam is cubic yards. The cost of the dam was The storage capacity at the present height is slightly over gallons.

The general design and supervision was handled under the direction of /Sylvester Q. Cannon, City Engineer, Salt Lake City_7, John S. Eastwood acting as consulting engineer. Parrott Bros. Co. were the contractors." *m& -0- RAER ^ UT-16 1 John Eastwood Mountain Dell Dam was one of nineteen multiple arch dams built by John S. Eastwood in his lifetime; none of them has ever failed. "The dams are a series of concrete half-cylinders, each fitted to the contour of the ground at its base to compensate for irregularity of the earth surface. The half cylinders are placed with their convex sides upstream and are so sloped that the impounded water forces the cylindrical bases more firmly against their foundations as the volume of water, and consequently its weight, increases.

It was an application of the principle of the lever to dam design. It made possible economic con- struction of dams in remote areas otherwise impractical and : <& on terrain unsuitable for conventional types." While it is one of his lesser accomplishments. Mountain Dell bears the mark of both Eastwood's genius and his acquired experience. John Eastwood was born in Minnesota in Des- cended from the family of Arent van Oosterhont, the Royal Dutch Engineer, Eastwood grew up in a family well-versed in the problems and properties of water. He attended the State Normal School at Mankato, Minnesota, and graduated in going from there directly to a position as assistant con- struction engineer on the Pacific extension of the Minneapolis and St. Louis Railroad.

He worked there for five years, but in he decided that a supervised position was HAKK -yC UT-16 unsuited to his personality and he left Minnesota for ^^ California. At the age of twenty-six he went into "private practice" in Fresno, a town of citizens. In he became Fresno's first city engineer and his main concern in that situation, as well as in his role as chairman for the Club" (its goal being to promote that popula- tion limit) was to find an adequate water supply for that city. He solved that problem in when he developed a hydroelectric power plant which transmitted electricity thirty-seven miles to Fresno.

In he completed the largest chain of hydroelectric installations in the United States (the Big Creek Project, in California) which included a tunnel twelve miles long straight through the mountains. .Mk ., When Eastwood died in French Strother, editor ^g0 of World' s Week, wrote: "Los Angeles owes its very exis- tence, in large measure, to this man..." Though he prac- tically singlehandedly made the Southwest habitable, and though his innovations preceded similar electrical engin- eering feats by many years, Eastwood realized very little profit from his endeavors. In at the age of fifty-five, he began a new venture: he attempted to design the "perfect dam." The result of this experiment was the multiple arch dam, of which Mountain Dell is an example.

Before his death in he built nineteen such dams; they can be found in British Columbia, Idaho, Utah, Arizona, and California. The design was used after his death and Eastwood's dam can be seen abroad as well as over the continental United States, a tribute to the foresight and engineering skills of this very unassuming man. T. Allan Comp Project Historian August Bibliographical Note: The foregoing article on Mountain Dell Dam was the only source encountered in research. For Eastwood, the following was most helpful. Charles Allen Whitney, "John Eastwood: Unsung Genius of the Drawing Board," Montana Magazine of Western History, Summer 5 <R Addendum to: HAEH Ho. Mountain Dell Dam Interstate Higltmy- 80 Skit Lake' City, Utan Salt Lake County

Photographs Written Historical and Descriptive Data

Historic American Engineering Record National Park Service Department of the Interior Washington, HAER No. UT-16 UNA. u 7 x ^ THE JOURNAL ^ OF THE SOCIETY wnm INDUSTRIAL r TIr n ARCHEOLOGY John S. Eastwood and the Mountain Sell D&IU by Donald C. Jackson For further information on John S. Eastwood and multiple arch dams, it is suggested that researchers refer to HAER No. CA-8, the Littilerock Dam. Volume 5, Number 1 HACK NO. UX-iO VP'ii^ and immediately went to work on railroad construc- John S. Eastwood tion projects in the Pacific Northwest.1 In he moved to Fresno, California, where he established a private office and the Mountain Dell as a civil engineer and surveyor. At this time, California was barely thirty years removed from the heyday of the Dam by Donald C.

Jackson gold rush, and Eastwood was among the second wave of pioneers who came not merely to extract mineral wealth, but also to develop the region's resources in a more lasting manner. At first engaged primarily in surveying, he became Fresno's first City Engineer in but he discov- Throughout the history of Western America, the key to ered he was not suited to the life of a bureaucratic engineer sustained development has always been the ability to store and soon resigned. His attention focused on the Sierra water. Water is the basic resource required for all human Nevada east of Fresno, where he recognized the great activity, and in many regions, it is utilized for power and potential of the swift-flowing mountain streams. Begin- irrigation, as well as for domestic purposes.

Unfortunate- ning with the construction of a seventy-mile-long wooden ly, precipitation in the West can be extremely intermittent, lumber flume, he became involved in controlling the and some means of storing water for future use is essential mountains' water resources. Soon afterward, he com- for any kind of long term economic endeavor. menced work on the first major project of his life.1 This paper discusses the Mountain Dell Dam (Figures 3 and 4) near Salt Lake City, Utah, an early reinforced con- crete multiple arch dam, and places it within the context of its designer's career.

In addition, the basic structural con- cepts used in multiple arch dam design are explained and a comparison is made with the two other types of dams con- sidered by the Salt Lake City Engineer's Office for the Mountain Dell dam site. I Developed in the early century, the multiple arch dam was intended to provide a safe and economic means of im- pounding water through the use of reinforced concrete as a structural material. Reinforced concrete presented the engineering world of the early century with a struc- tural medium of unprecedented versatility. However, it demanded engineers of imagination and vision to demon- Figure 1. Hume Lake Dam as it looked in June Constructed in strate its capabilities in useful structures.

In this respect, for the Hume-Bennett Lumber Company, it, along with the John S. Eastwood of Fresno and Oakland, California, surrounding forest land, came under the control of the U.S. Forest Serv- ice in (Courtesy of Water Resources Center Archives, Berkeley, was one of Western America's most innovative builders. Calif.

Huber Collection) Eastwood built the world's first reinforced concrete multi- ple arch dam on bedrock foundations at Hume Lake, Cal- ifornia, in (Figures 1 and 2), and the structural form has since been employed throughout the Americas, Europe, and Asia.' Because of the material economies inherent within its design, the multiple arch dam played a signifi- cant role in the development of the world's water resources during the first half of the century and, perhaps of equal importance, demonstrated the capabilities of rein- forced concrete construction to engineers involved in many aspects of structural technology.

As this account bears out, Eastwood first developed his reinforced con- crete multiple arch dam in direct response to the problems encountered in finding a durable and economical means of storing water high in the Sierra Nevada. Figure 2. Downstrean side of the Hume Lake Dam as it looked in June The building on the right was part of the original mill complex. It Born of Dutch ancestry in Eastwood graduated burned in Except for a recoating of the dam's upstrean face in the from the University of Minnesota as a civil engineer in late the structure has remained unaltered. (Water Resources Center Archives, Berkeley. Calif, Huber Collection) HAER NO.UT -16 (p. 12) Figure 3. Downstream face of Mountain Dell Dam. Covered spillway is on left and water treatment facilities are in foreground.

(Courtesy of Jack E. Boucher) Figure 4. Upstream face of Mountain Dell Dam wiih reservoir filled. Spillway opening is visible on the far side of dam. (Courtesy of Jack E. Boucher} HAER No. UT-16 In early Eastwood became chief engineer of the San stock to pay this assessment.1 Following this abrupt Joaquin Electric Company, and responsible for the design separation from the Big Creek Project at the age of 53, land construction of one of California's early hydroelectric Eastwood was left practically penniless and, as a means of plants. As described by George Low in the April survival, he began actively pursuing a career devoted to the Journal of Electricity, Eastwood employed the nascent design of multiple arch dams.

technology of long-distance alternating current power transmission in creating a hydroelectric power system for In the early century, Salt Lake City regularly ex- the Fresno area.4 Unfortunately, the financial capabilities perienced severe water shortages in mid-winter and late of the company proved insufficient to meet the great cost summer. To alleviate this condition, bonds were floated in of constructing a dam in the remote reaches of the moun- to finance the construction of three storage dams. tains, and, as a result, Eastwood was forced to rely on an The largest of these was to be the Mountain Dell Dam in undammed, natural supply of water to drive the turbines Parley's Canyon, a site about ten miles east of the city.1 In and generators.

It was this inability to impound and store the summer of Eastwood received a letter from the runoff that led to the demise of the San Joaquin Electric Salt Lake City Engineer, Sylvester Q. Cannon, inviting Company in after a long drought dried up the North him to submit a design of a multiple arch dam for their Fork of the San Joaquin River and brought the company's consideration. Included was a large amount of pertinent power production to a standstill.1 geological data gathered from test borings made at the dam site.

The letter explained that the Park City branch of Shortly after the San Joaquin Electric Company went the Denver and Rio Grande Railroad passed adjacent to bankrupt, Eastwood became engaged with the Pacific the site, and that sand and gravel deposits in the vicinity Light and Power Corporation as engineer in charge of were readily available for use in the dam's construction. designing a large hydroelectric project on the South Fork Cannon also stated that delivery of construction materials of the San Joaquin River.

This has since become known as by gravity would be possible and that the nearby transmis- the Big Creek Complex.6 The Pacific Light and Power sion lines of the Utah Power and Light Company could Corporation was controlled by the famous financier and supply electric power for construction purposes. In de- electric railroad magnate, Henry Huntington. Eastwood scribing the proposed project, Cannon stressed that the had great hopes for the project, and he planned it to in- reservoir would be ".. .about 8 miles above a portion of clude storage dams to insure that a drought could not stop the city that is rather thickly settled..." and that safety its power production.

would be a concern of paramount importance in the selec- tion of a design.' Although Big Creek was for the most part designed prior to financial difficulties precluded its construction Earlier, Eastwood had built four dams in California, and for several years. During this time, Eastwood developed his reputation as dam designer was growing. He had writ- an inexpensive type of reinforced concrete dam design in ten several articles in Western Engineering describing his which the water face consisted of a series of arches sup- Big Bear Valley Dam, Los Verjeles Dam and Kennedy ported by buttresses resting on bedrock.

This was a design Dam, and had also published a four page promotional which minimized the amount of material required and, "supplement" distributed with copies of the March consequently, reduced the transportation costs. In Western Engineering.' His primary source of income was while waiting for construction of Big Creek to begin, he from dam design commissions, and he sought work any- designed and built the Hume Lake Dam for the Hume- where he could get it. Bennett Lumber Company. This structure is located about forty-five miles south of Big Creek, and it demonstrated Eastwood knew that reinforced concrete could resist both the practicality of multiple arch design.

Shortly thereafter, compressive and tensile forces; however, he also knew that Eastwood received the contract for the design of a multiple if reinforced concrete is placed in sufficient tension, the arch dam to supersede the Big Bear Valley Arch Dam concrete surrounding the reinforcement will crack. In a near San Bernardino in Southern California. dam, this could precipitate disaster, as cracks in the dam's face could allow water to penetrate the structure, rust out Eastwood envisaged the use of multiple arch dams in the the steel reinforcement, and in time destroy the dam. Con- construction of the Big Creek project, but these hopes sequently, it was his object to design a structure subject were dashed when, in November he was dismissed only to compressive loadings.

Because the concrete would from all association with the project. He still held stock in be placed only in compression, the danger of serious the Pacific Light and Power Corporation, but even this cracks occurring in the dam would be entirely removed. financial interest disappeared when Huntington, as ma- Eastwood was also aware of the tensile stresses set up in jority stockholder, assessed all owners of Pacific Light concrete structures due to temperature fluctuation, and he and Power Corporation stock to pay for the construction realized that some steel reinforcement to resist these of Big Creek. Eastwood was, in essence, forced to sell his stresses was essential, especially in the concrete comprising HAER No.UT _16 (p. 14) Figure 5.

Upstream face of the Mountain Deli Dam as it looked in (Courtesy of the Utah Historical Society) r^ AOUNT4IN DCU. ISESCAW>K i i 5CUIU CIEVATICN Figure 6. HAER drawing of plan and downstream elevation. HAER No, UT-16 (p. 15) the dam's water face. For maximum conservation of ma- shown in Figure 8, it may be seen that a vertically-faced terials, Eastwood used the structural form of the arch, or dam is not acted upon by any vertical component of water more specifically, the arch ring." pressure. Consequently, the resultant 'R* for this dam in- tersects the foundation much closer to its downstream Figure 5 shows the Mountain Deli Dam shortly after com- edge. If the resultant falls beyond the downstream edge of pletion of construction.

The series of reinforced concrete the foundation of a gravity dam, then the dam will fail by arch rings which form the structure's water-face can be overturning. There is a greater chance of this occurring in clearly seen. These arch rings vary in thickness from four a vertically-faced dam. Eastwood was by no means the feet at the bottom of the dam to one and a quarter feet at first person to build dams with inclined upstream faces, as the top, and are inclined upstream at an angle slightly many century mill dams used this structural feature to greater than fifty degrees.

To calculate the arch thickness great advantage.11 needed at various elevations, Eastwood used what he re- ferred to as Rankine's Ring Formula, an equation relating As a result of the Mountain Dell's inclined face, the but- thickness to pressure, radius, and allowable stress.13 tresses are placed in compression, and this stress is Usually expressed as "thickness equals pressure times distributed over the entire width of the dam. Eastwood radius divided by allowable stress" or T the for- calculated the maximum stresses to be 146 pounds per mula provided a mathematical basis for determining the square inch in the buttresses, and 300 pounds per square dam's structural dimensions. inch in the arch rings.

Tests made on the original concrete used in the dam indicated an average strength of about The dam is 145 feet in height, but, as shown in Figure 6, pounds per square inch, which prompted Cannon to only the arch rings near the middle of the canyon have this proclaim the dam had a safety factor of seven.14 A recent great a depth. The canyon walls are sloped, and the arch structural analysis of the Mountain Dell Dam by Glenn L. rings at the end of the dam are only about twenty feet Enke, consulting engineer and Professor Emeritus of Civil deep. Each of the arch rings has a span width of thirty-five Engineering at Brigham Young University, confirms the feet with the extrados (upper curve of the arch) encom- accuracy of Eastwood's calculations in terms of average passing a 120 circular arc.

The vaults formed by these stresses within the dam, though modern mathematical arch rings are supported by trapezoidal shaped buttresses analysis indicates some parts of the dam to be stressed firmly anchored into bedrock. The buttresses vary in slightly more than 300 pounds per square inch.'s thickness from eight feet at the foundation to two feet at the top, and carry the thrust of the water load to the dam's In deference to the great height-to-width ratio of the but- foundation. When the reservoir is filled with water, the tresses, they were reinforced laterally to prevent any possi- hydrostatic pressure is exerted directly on the cylindrical ble buckling or toppling (Figures 9 and This reinforce- vaults.

Through their "arch" action, the water pressure is ment is supplied by strut-tie beams which connect all the concentrated on the buttresses which support them. Be- buttresses. The twenty-three strut-ties (thirteen are visible, cause the spans of the arches are all equal, their respective ten are below grade) in the Mountain Dell Dam each con- sideward thrusts due to water loadings cancel one another tain steel reinforcement approximately four square inches out, and the only forces the buttresses are required to sus- in section, run continuously through the buttresses, and tain are those perpendicular to their upstream faces. are grouted into bedrock on both sides of the canyon.

They were specifically designed to reinforce the dam Because of the upstream inclination of the dam's facing, against stresses resulting from earthquakes and other the resultant of the water pressure combined with the vibrational shocks.'6 structure's weight passes almost directly through the center of the dam's foundation. Figures 7 and 8 show A spillway exists at the west end of the dam with a capacity cross-sections of dams which use the force of gravity to re- of approximately 400 cubic feet per second. According to tain water. In Figure 7, the inclined upstream face of such the Salt Lake City Water Department, the spillway, in con- a dam is represented in black.

It inclines into the stored junction with the outlet gates, has always proved sufficient water, signified by the light and dark gray areas. The hori- in handling floods, and the dam has never been over- zontal component of the water pressure is represented by topped. the light gray triangle. Because of the inclined face, there is also a vertical component of water pressure pushing down In September City Engineer Cannon gave notice on the dam, as represented by the dark gray triangle. that bids from contractors would be accepted for East- Together, the weight of the dam, the vertical force exerted wood's Mountain Dell Dam design.

Eastwood's design by the water, and the horizontal force exerted by the water was to be placed in competition with a concrete curved form a resultant force ' R' which acts on the dam's founda- gravity design and a reinforced concrete Ambursen flat tion. In this case, it intersects the foundation almost at its slab buttress design. Both of these types of structures had centerpoint. Comparing this to the vertically-faced dam been built previously in many parts of the United States. HAER No. UT-16 (p. 16) ^ 1 '-a 1 '-/ * D - TAfeight of structure Wj, - Horizontal thrust of water D - Weight of structure Wv Weight of water above inclined face W^-Horizontal thrust of water R R Figure 7. Crass Section: Gravity or Buttress Dam with inclined Figure 8.

Cross Section: Gravity or Buttress Dam with vertical upstream upstream face. face. W- Figures 9 and 10. Detail of buttress walls and strut-tie beams. Impressions of form work on the concrete are clearly visible. (Courtesy ofJackE. Boucher) HAER No.yrp -16 A curved gravity dam, often referred to as a "gravity Stony River Dam in West Virginia, as it appeared in arch" dam, is a structure built with such ample dimensions January Due to faulty construction work, this Am- that the hydrostatic thrust of the stored water can be re- bursen dam failed, and the flat slab facing is clearly evi- sisted solely by the great weight of the material in the dam.

dent.21 In an Ambursen dam, the upstream facing is sup- In essence, it is a gravity dam which is built on an upstream ported on triangular buttresses which carry the hydrostatic arc, or curve, supposedly to provide it with greater thrust to the foundation. The only difference between the strength. In certain instances, like the Buffalo Bill Dam flat slab dam and the multiple arch dam is in the structural (formerly Shoshone Dam) shown in Figure 11, it is pos- shape of the dam's water-face. Both are buttress dams, sible to build a "true arch" dam with such slender dimen- but Ambursen designed the upstream facing as a series of sions that the' 'arch action" of the dam is required to resist flat slabs instead of arch rings.

the hydrostatic thrust, i.e., its cross section is less than that required for a gravity dam.17 True arch dams can be built In a letter sent to City Engineer Cannon in July of safely only where there are strong foundations, not at Eastwood outlined the advantages of his design over that relatively porous sites like the location of the Mountain of Ambursen.24 He related it directly to the arched up- Dell Dam. At these sites it is impossible to depend on the stream forms of his design and their necessarily compres- "arch action" of the structure. Consequently, Cannon sive loadings. A dam must retain standing water for long asked for bids on a conservatively designed, curved gravity periods of time, and it is imperative this water be kept dam.

from corroding the steel required to reinforce against ten- sile stresses. When a series of flat slabs supported by but- Eastwood had reservations about this kind of design be- tresses is uniformly loaded, the section of the slabs at mid- cause of the possibility of its failing as a result of "up- span will necessarily deflect away from the loading. In the thrust ."' * Upthrust is a hydrostatic phenomenon affecting case of an Ambursen dam, this would mean that the slab dams which, because of its complex nature, has come to be facings would deflect downstream.

Consequently, the only vaguely understood since the beginning of the concrete on the downstream side of the slab would be century." Essentially, it is the result of water seeping placed in tension, and cracking in the concrete resulting under a dam and then pushing upwards on the founda- from these conditions could allow moisture to seep in and tion. If sufficient water "percolates" under the dam and corrode the steel reinforcement. This water could seep pushes up, the dam will float free of its foundation and, through from the reservoir, or it could result from conden- because of the horizontal component of the water pres- sation; in either case, the structural integrity of the dam sure, slide downstream, thus destroying the integrity of the could be seriously threatened.

Eastwood stated that the structure, and possibly everything below the dam as well. only way to prevent this cracking was to reduce the loading on the concrete, and the only way to do this was to increase The solid base of the curved gravity dam makes it suscepti- the amount of concrete in this dam. Because of this, East- ble to upthrust, unless special means of draining the foun- wood predicted that the cost of an Ambursen dam would dations are provided. The solid base does not allow for a be much greater than an equally secure multiple arch dam. natural and convenient means of seepage dispersal.

Be- cause a multiple arch dam is buttressed, the effect of such On November 24, the bids on the Eastwood, Am- pressure is, in almost all cases, negligible.:o Any water bursen, and curved gravity designs for the Mountain Dell seeping under a buttressed dam will harmlessly rise to the Dam were opened in the Salt Lake City Engineer's Office. surface in the area between the buttresses. Over ten different contracting firms submitted bids, and most bid on all three designs. The results clearly bore out Eastwood believed arch dams were only suitable for nar- the validity of Eastwood's claims concerning the economy row canyons with strong rock wails capable of withstand- of the multiple arch dam for the Mountain Dell Dam site. ing the compressive thrust of the dams' arch.

The Buffalo For the 145-foot-high structure, the low bids (rounded off) Bill Dam site is a perfect example of this.;i For a wide were as follows: Eastwood multiple arch dam: valley with porous foundations, such as the site of the Ambursen flat slab buttress dam: concrete Mountain Dell Dam, he believed the amount of material curved gravity dam: Breakdowns of the con- required in a curved gravity dam, and consequently its ex- tractors' bids indicate Eastwood's multiple arch design was pense, would be excessive, and because of upthrust, could more economical because it required less excavation and be dangerous as well. less concrete than its competitors.26 The second design competing with Eastwood's was an Following opening of the bids, final approval of East- Ambursen flat slab buttress dam.

First built by Nils F. wood's design by the State of Utah was required before Ambursen of New York in the Ambursen dam may construction could begin. Utah Governor Wells be regarded essentially as the application of reinforced received an endorsement of Eastwood's designs from concrete slab construction to dams.22 Figure 12 shows the McGillicuddy, president of the Los Verjeles Land JriAtiK NO. ux-10 K? Figure II. Buffalo Bill Dam (formerly Shoshone Dam) near Cody, Wyoming, built by the Reclamation Service between Over 300 feet tall, its crest length is only 200 feet. This was one of the first arch dams built by the Reclamation Service (later Bureau of Reclamation). (Courtesy of Jack E. Boucher) Figure 12. The Stony River Dam in West Virginia following collapse.

Investigators blamed the catastrophe on a failure to properly key the dam into its foundation. January (Courtesy: "The Reconstruction ofthe Stony River Dam," Scheidenhelm, ASCE Transactions, Paper No. page HAF.R No. UT-16 and Water Company, of California, stating that his com- with carbon dioxide in the atmosphere to form a calcium pany had obtained excellent service from Eastwood's Los carbonate deposit. Eastwood was aware of this phen- Verjeles dam. Going so far as to say, "For weeks at a time omenon and believed the solely compressive loading last winter, flood waters had to pass over its entire crest within the arch ring rrummized its occurrence and effect.

If length to a depth of three feet, carrying over logs and efflorescence is excessive, it can seriously weaken con- debris with no injury or cost for repair, * * McGillicuddy ex- crete. On the Mountain Dell Dam, it is not extensive and pressed complete satisfaction with Eastwood's work and the structure's integrity is not impaired.1' recommended his dams without reservation.27 In mid- December, Eastwood made minor alterations in regard to the dimensions and reinforcement of the buttresses, per re- quest by Cannon, and by the end of the month, the initial contract had been let to Parrot Brothers Contractors of Salt Lake City." For construction of the fust 105 feet of the dam, Eastwood was to receive an amount slightly less than five percent of the initial contract price, for his services.

Upon construction of the final forty feet, Eastwood was to receive an additional Construction of the dam was a straightforward operation using standard methods of placing concrete in wood forms. For the buttresses and the outsides of the arch rings, sectional panel forms approximately five feet square and built up on 2" x 4" umbers were used. The inner forms for the arch rings consisted of trussed liners eight feet apart supporting vertical 2" x 4" ribs spaced every two feet around the arch. Two layers of heavy sheeting were then laid horizontally over these ribs to provide the I contact surface for the poured concrete.

To insure that the outside panel forms did not bulge during a pour, cables were attached to the buttresses, strung around the outer forms, and then cinched tight with a turnbuckle. The concrete in the arch rings has a cement: sand :gravel Figure 13. Detail of buttresses, strut-tie beams, and the downstream face of arch-ring wails. Efflorescence is evident in the white patches and ratio of while the concrete in the buttresses has streaks on the arch rings. (Courtesy of Jack E. Boucher) ratios of and The porosity of concrete is in large part determined by the amount of cement within the In the dam was constructed to its initial height concrete mix. Because concrete with a higher percentage of 105 feet above bedrock.

Figure 14 shows the down- of cement is more watertight, it was specifically stated that stream side of the dam as it looked upon completion of the the arch rings be constructed using a richer mix than the initial construction. The buttresses were stepped to insure buttresses. Reinforcement of the arch rings consists of a tight bond upon completion of the final forty feet. Clinton wire mesh, while some reinforcement of the but- tresses is provided by one-inch twisted eyebars.

The pour- ing of the concrete was facilitated by the use of a 125-foot- Following the initial construction, Eastwood continued his high distributing tower which delivered the concrete career in water resource development and dam design, through chutes directly to the forms.'0 becoming involved in projects in California, Idaho, Arizona, Mexico, and British Columbia. Figure 15 is a pho- Some struts have required patching due to deterioration, tograph of Eastwood, his wife, and associates taken during and the concrete in the structure can only be considered, at an inspection of the 117-foot-high Murray Dam near San best, average in quality.

A small amount of efflorescence, Diego in late He was not an "armchair" engineer, and a phenomenon often affecting concrete, has deposited on he spent much of his life in the field working on practical the dam. This is evident on the whitish patches of calcium problems of water control. Figure 16 shows him around carbonate which have formed on the downstream face of involved in gauging the flow capacity of a stream in the the arch rings (Figure Because concrete is slightly por- Sierra Nevada Mountains during the design of the Big f ous, water from the reservoir has, over the years, seeped Creek hydroelectric project. He worked as a practicing through the facing and in the process dissolved lime pre- engineer until the end of his life, when, in August at sent in the concrete.

When this water subsequently evapo- the age of 67, he drowned attempting to save a woman rates upon reaching the downstream face, the lime reacts swept into the Kings River." ILTiijlV , \f * *-V / Figure 14. Downstream view of dam prior to construction of the top 40 Figure 15. Eastwood (foot on rail), his wife, Ella (on his right), and a feet. This photo group indicates the targe amount of excavation re- group of associates inspecting the Murray Dam in San Diego County. quired to facilitate construction of the buttresses on bedrock. March ca. (Courtesy of Charles Allen Whitney) (Courtesy of Utah Historical Society) Figure 16. John Eastwood involved in gauging the flow capacity of a stream high in the Sierras, ca.

(Courtesy of Charles Allen Whitney HAER No.UT -16 Late in Salt Lake City decided to complete the Although he considered himself the primary and most Mountain Dell Dam, and with Eastwood not available to prolific designer of reinforced concrete multiple arch supervise the construction, an alteration, simplifying his dams, Eastwood never claimed he had "invented" the design, was made. Figures show other dams de- multiple arch form for dams. He was aware of antecedents signed by Eastwood, and it can be seen that the upper 10 to to his structures, including the vertically-faced masonry, 12 feet of these structures' upstream faces is vertical.

In us- Meer Allum Dam in Hyderabad, India, built by European ing Rankine's Ring Formula, Eastwood determined the engineers at the beginning of the century, and the late thickness of the arch rings according to their elevation. century, brick and plain concrete, Belabula Dam in Near the top of the dam, he felt this formula to be inappro- Australia, as well as prior theoretical propositions such as priate, as he believed a minimum "mechanical" arch ring Henry Goldmark's design for the Pioneer Power thickness was required regardless of the possible water Plant near Ogden, Utah, and George Dillman's loading.

In other words, there was a practical limit to how paper on economical dams." However, Eastwood was the thin the arch ring should be built, regardless of water pres- first to construct a reinforced concrete multiple arch dam sure. Given a minimum "mechanical" thickness, the con- on bedrock foundations and the first to demonstrate the struction of a vertical top to the arch rings provided an economic advantage of doing so. economy of material compared with construction of slop- ing arch rings to the same elevation. The vertical top In the years following Eastwood's death, labor costs rose shortened the length of the arch rings, and, consequently, sharply in relation to material costs, and the multiple arch the concrete required in their construction was reduced.

dam never received the widespread use Eastwood believed The original plans for the Mountain Dell Dam included a it warranted. Nevertheless, the structural form has con- vertical top, but they were changed prior to completion in tinued to be employed in locations where material trans- Many other engineers built multiple arch dams port costs are great and a materially-efficient design is after he introduced the form, but the vertical top facing highly desirable.

Perhaps the most spectacular example of was an almost exclusive design feature of Eastwood's.54 this has been the 703-foot-high Daniel Johnson Dam After his death, the Salt Lake City Engineer's Office chose (formerly Manicouagan Five) in Northern Quebec, built to continue the inclined facing to the top of the dam and between and After consideration of all types of assume any structural effect resulting from this would be dams, engineers on the project chose a multiple arch de- insignificant." By doing so, they simplified the construc- sign because of the economic advantages it afforded.39 tion of the form work, though the amount of concrete re- quired was increased.

Finally, it is appropriate to recognize the exemplary safety records that Eastwood's dam and all multiple arch dams It is important to recognize that Eastwood was a practical, have compiled. The recent Grand Teton Dam fail- innovative construction engineer and not a theoretical re- ure in Idaho, and the near disasters of the Lower San Fer- searcher into the properties of reinforced concrete. He nando Dam and the Baldwin Hills Dam near considered himself an engineer, not a scientist, but he was Los Angeles, have provided startling proof that dam safe- proud to declare that he had developed a "scientific" dam ty is not something which can be taken for granted.

Al- design, i.e., one which would provide the safest, most though alteration of some Eastwood dams has occurred in practical, and most economical means of water storage.36 the last half century, none has failed in any manner or He understood that every dam site presents a unique set of been the cause of any loss of life or property. Dramatic geological conditions, and, consequently, every site re- evidence of the strength of Eastwood's dams is provided in quires a dam especially designed forit.

In his multiple arch Figure 20, which shows the Anyox Dam in British Colum- dam designs, Eastwood varied the span of the arch rings, bia, Canada, in Following forty-eight hours of heavy the arc enclosed by the arch rings, the upstream inclination rains, the reservoir behind the Anyox Dam filled up before of the arch rings, the downstream batter of the buttresses, the final fifteen feet of one arch ring had been constructed. and the maximum allowable stress within the concrete in Though water poured through the structure and, upon hit- determining the specific form of each structure, and, of ting the strut-tie beams, sprayed for over 200 feet, the struc- course, these factors were interrelated.

For example, the tural integrity of the dam remained uncompromised.''0 Mountain Dell Dam was originally to have the arch rings inclined upstream at an angle of 45 with a maximum Eastwood's reinforced concrete multiple arch dam was a allowable stress of 350 lbs per square inch (psi); however, design created to meet a need considered to be inadequate- Cannon later requested the allowable stress to be lowered ly met by other contemporary dams. The Mountain Dell to 300 psi. Consequently, Eastwood increased the angle of Dam is representative of the seventeen dams built using his inclination to 50 11' because, with a greater percentage designs.

The critical role played by economics in Salt Lake of concrete in the dam, less water was needed to provide a City's decision to build Eastwood's dam reflects a major vertical Component of weight.37 concern of all who attempt to use water in the West. All MAKK MO. UT-1D iFigure 17. The 117-foot-high, 900-foot-long, Murray Dam in San Diego County, California. Built for the Cuyamaca Water Company, it was one of 'four Eastwood dams built in the county during March (Courtesy of Water Resources Center Archives, Berkeley, Calif. Huber Collection) Figure 18. Built for the Bear Valley Mutual Water Company in this was Eastwood's second dam and the first to include strut-tie beams. It replaced the famous single-arch masonry dam designed by F.E. Brown, visible inihe foreground.

The photo is of Eastwood. (Courtesy of Water Resources Center Archives, Berkeley, Calif., John S. Eastwood Collection) HAER No. UT-16 human activity depends on reliable sources of water, and by far the most expensive, as well as vital, component of any water storage system is the dam. Eastwood's primary objective in developing his multiple arch dam was to min- imize the expense of water storage and allow maximum use of available financial resources. The Mountain Dell Dam was built to serve a small, but growing, mountain community.

Though the site was not located in the remote reaches of the mountains, East- wood's multiple arch design was chosen because of the economic savings it promised local taxpayers.41 At the time, few in Salt Lake City appreciated the theoretical nature of the design, or the experiences which led to its de- velopment, but many appreciated its low cost. Today, the dam (Figure 21) continues in its original capacity as an im- portant component of Salt Lake City's water supply system.'2 Figure 19. In the Little Rock and Palmdale Irrigation Districts built the 175-foot-high Little Rock Creek Dam in the San Gabriel Mountains north of Los Angeles. The tallest of Eastwood's dams, it was the only design feasible to construct, given the limited Figure 20.

Following severe flooding, the reservoir behind the IS3-foot- financial resources of the irrigation districts. (Courtesy of Donald C. high Anyox Dam filled up before completion of construction and water Jackson) gushed through an open arch-ring. No damage occurred to the dam. December (Courtesy of Charles Allen Whitney) HAfiK NO. UT-AD Figure 21. Downstream face of Mountain Dell Dam with water treatment facilities in foreground. (Courtesy of Jack E. Boucher) Sast-Publicatian f&te: Footnotes ' Edward Wegmann with Fred Noetzli, The Design and Construction of Though tjlis article underwent a gestation period of ever 36 ;nacitfas Dams (New York, Lars R. Jorgensen, "Multipie-Arch Dams on between sutmittal and publication, there was little inpuc the Rush Creek, California," Paper No.

Transactions of the American journal's editor accept in a vary negative sense. As printed, the Society of Civii Engineers, 81 pp. These publications article Lacks a conclusicn that conveys to the reader the conplex role of aoananics in waatern water rasouiLes develoanent. The point is provide clear evidence of Eastwood's claim to be the first builder of rein- clearly sod* that multiple arch dans often provided the most aconcntical forced concrete multiple arch dams on bedrock foundations. Wegmann solutions to water storage problems, but what are not elaborated ucon states on page VII, ".. .it was not until when the late John S.

are the reaacns why oar* cities, towns, and ^wmanmat agencies did nat Eastwood, a California engineer, proved in competitive bids and by ac- build norm multiple arch 'dams in the early century. 'Sm Mauntaia Cell DOB was the first Sastucod dan built* by a city government, and tual construction the economy of building multiple arch dams that a out of the 17 built between and using his designs, only tso number of structures of this type reaching in heights upward of 250 feet were contracted for by a aimicipai, state, or federal aroanization.

have been built, both in this country and abroad." Construction of the Apparently, private ware more interested in saving money than governmental entities were, perhaps because the latter T"lri count an Hume Lake Dam was first reported in "The Hume Lake Dam," Journal the taxpayers to "cough vp" as much money as desired. The author also of Electricity, Power and Gas, 23 (October tends to believe there were wealthy interests involved in -water development that ware displeased with the idea of inexpensive dans because this would allow acre people to build dams, and, ccnseauantly, centralised control of water wnuM be mare difficult to implement.

For axaifile, if the people in the evens valley had been able to pay far of dans to control the water of the Cwens Siver", than Lty of Los Angelas being able to gain centred and transport Stater ever 200 miles south would have been less, this article should not be considered the last word en mltiple arch dans, it has presented a large amount of basic data en this type of structure but, in terms of historical analysis, much mere rsnains, and is needed, to HAER No. UT-16 1 "Application by Eastwood for membership in the American Socie- * S. Q. Cannon to Eastwood, June 10, JSE papers, ty of Civil Engineers," Marguerite Eastwood Welch Notebook on John WRCA. S. Eastwood, Bancroft Library, University of California, Berkeley. Eastwood's niece.

Marguerite Eastwood Welch, donated a notebook of "* John S. Eastwood "The New Big Bear Valley Dam," Western personal memorabilia, assorted newspaper clippings, and magazine ar- Engineering 3 {December pp. John S. Eastwood, "The ticles to the Bancroft Library, the contents of which relate to her uncle. Los Verjeles Dam," Western Engineering 5 (July pp. John S. Though Eastwood was selected for ASCE membership in Sept. he Eastwood, "The Kennedy Dam," Western Engineering 5 (April never participated in the society's activities. pp. 1 Charles Allen Whitney, "The Life and Times of John S. Eastwood," " Multiple Arch Dam Folder, John S. Eastwood Papers, Water unpublished manuscript; Charles Allen Whitney, "John S.

Eastwood, Resources Center Archives, University of California, Berkeley (hereafter Unsung Genius of the Drawing Board," Montana, the Magazine of cited as MAD, JSE papers, WRCA). Western History, 19 (Summer Mr. Charles Allen Whitney of Santa Monica, California, is an engineer " MAD, JSE papers, WRCA. and a leading contributor to many technical and professional publica- tions. In the late M.E.Welch hired him to write a biography " James Leffel, Construction of Mill Dams (Springfield, Ohio, of John S. Eastwood. This partially complete manuscript, which utilized reprint ed.. Park Ridge, New Jersey, also in J.A.

Garcia-Diego's, many personal sources including Ella Eastwood's (John's wife) diary, has "The Chapter on Weirs in the Code of Juanelo Turriano," Technology not been published, though Mr. Whitney did publish a short biography of and Culture 17 (April pp. designs for century Eastwood in the Montana Magazine of Western History, Mr. Whitney Spanish diversion dams are illustrated with inclined upstream faces. was very kind in assisting the author in the investigation of Eastwood and his multiple arch dams. Many illustrations accompanying this article are "Cannon, "Mountain Del!,*' p. from Mr. Whitney's private files, which he allowed to be photocopied by 15 the Historic American Engineering Record. The author is extremely Dr. Glenn L.

Enke, "Investigation of Elastic Behavior of a Multiple grateful for his help. Arch Dam," dissenation, Utah State University, (hereafter cited as Enke, "Investigation"). To insure that the horizontal thrust of ' George P. Low, "The Fresno Transmission Plant," Journal of Elec- the water did not destroy the buttresses by "shearing" action, Eastwood tricity, 2 (April pp. Operation of the transmission plant calculated the area A (in square feet) of a buttress and two half arches at commenced in April A 4,020-foot-long steel penstock supplied various elevations and divided this by the horizontal hydrostatic force P water under a head of feet. High-speed Pelton turbines powered (in pounds) acting at that elevation.

He then made sure that the dam was General Electric generators, and electricity was transmitted to Fresno proportioned so that the ratio P/A was less than 100 per square foot. over thirty-four miles away. The AC current was three phase with a This was a simple, straightforward way to approximate the shearing potential of volts. Low stated that the plant operated under the stress in the buttresses, and the use of a conservative allowable stress highest head in the world at the time and transmitted power farther than psi) insured its reliability. JSE papers, WRCA. any other commercial enterprise. " Big Meadows Dam Folder and Big Bear Valley Dam Folder, JSE ' Whitney, "Life and Times," Chapter one, pp. Chapter three, p. Papers, WRCA.

50; James Dix Schuyler, Reservoirs for Irrigation, Power, and Domestic Water Supply (New York, p. " Savage. "The Shoshone Dam, U.S. Reclamation Service, near Cody, Wyoming," Engineering News 62 (9 December pp. 'David H. Redinger, The Story of Big Creek {Los Angeles, Calif.. Readers interested in arch dams are referred to Nikalaus Schnit- pp. ter's "Evolution of the Arch Dam" published in the October and November issues of International Water Power and Dam Construc- 1 Charles Allen Whitney, "Dollars and Genius Built Southern California; tion. The Story of Henry Huntington and John S. Eastwood," unpublished manuscript on file at the Water Resources Center Archives, University of " Eastwood toS.Q. Cannon, November JSE papers, California, Berkeley, la The Story of Big Creek.

Redinger writes (page 8), WRCA. "According to Eastwood, he (John S. Eastwood) received only a small salary just sufficient for living expenses during the several years ' William P. Creager, Julian Hinds, and Joel D. Justin, Engineering for he spent on the preliminary work of the Big Creek Project (for the Pacific Dams, 3 vols. (New York, Light and Power Co.) because the future seemed bright. At last he lost ;o everything." Today, Big Creek is owned by the Southern California Ibid. p. Edison Company and supplies approximately six percent of the com- pany's total power production. "JohnS. Eastwood, "An Arch Dam Design for the Site of the Shoshone Dam," Engineering News 63 (9 June pp. In this letter, ' Sylvester Q.

Cannon, "The Mountain Dell Dam," Monthly Journal: Eastwood criticizes the Reclamation Service's Shoshone Dam for con- Utah Society of Engineers, J (September p. 223 (hereafter cited as taining excessive amounts of concrete, most of which does not provide Cannon, "Mountain Dell"); Mountain Dell Dam Folder, John S. any additional safety. In questioning the economic validity of the Eastwood Papers, Water Resources Center Archives, University of Shoshone Dam's "constant radius" design, Eastwood proposed an California, Berkeley (hereafter cited as JSE papers, WRCA). Ac- equally safe "constant angle" design which would have required less than cording to records in the archives, Eastwood's business papers and darn half the concrete.

In the final years of his life, Eastwood designed multi- design data were sold after his death by his widow to Mr. Chester ple arch dams which utilized conic or "constant angle" arches. He built Loveiand. In these papers, minus some material which had been in- only one of this type of dam, the 90-foot*high Weber Creek Dam in advertently discarded, were donated to the Water Resources Center Ar- Eldorado County, California. chives. The assistance of head librarian of the Archives, Mr. Gerald Giel- :I fer, his head reference librarian, Ms. Mary Deane, and their staff was of Wegmann, Design and Construction, p. Early Ambursen dams in- great value in the preparation of this paper. Special thankN are due Ms.

clude the 10-foot-high dam at Theresa Falls, New York the Deane for her unfailing good humor and kind help. HAER No. UT-16 65-foot-high dam in Ellsworth, Maine and the 135-foot-high La " Other designers of multiple arch dams include Lars Jorgensen of San Prde dam in Douglas, Wyoming Francisco, Fred NoetzJi of Los Angeles, Mclntosh of San Francisco, and Gardner S. Williams of Ann Arbor, Michigan. The Bureau of " Scheidenhelm, "The Reconstruction of the Stony River Dam," Reclamation has built only two complete multiple arch dams in its Paper No. Transactions ofthe American Society of Civil Engineers history. These are the 24-foot-high, Three Mile Diversion Dam on 81 pp.

Failure was blamed on an improperly con- the Umatilia River in Oregon, and the 287-foot-high BartJett Dam structed upstream cutoff wall, which allowed water to undermine the in Arizona (United State Department of the Interior, Reclamation Pro- dam's foundation. ject Data (Washington, " J. S- Eastwood to Cannon, 26 July JSE papers, " In the Engineering News-Record 93 (October 20, p. it was WRCA. reported that Fred Noetzli had recommended to the Salt Lake City Engineer's Office that completion of the Mountain Dell Dam to a 11 JSE paper, WRCA; "High Multiple-Arch Dam for Salt Lake 145-foot height was safe. City Water Supply," Engineering News-Record 78 (March 7, Some slight confusion exists concerning the height of the Mountain Dell " MAD, JSE papers, WRCA. Dam.

Its ultimate height is sometimes given as 145 feet and sometimes as 150 feet. Dam height is measured from the deepest bedrock foundations " Eastwood to Cannon, November 7, JSE papers, to the highest part of the structure. Utilizing the geologic data provided by WRCA. Cannon, Eastwood designed and proportioned the dam for a maximum height of 150 feet, but apparently bedrock was not as deep as originally " Wegmann, Design and Construction, p. Schuyier, Reservoirs, pp. thought and the structure was built only 145 feet high. Norman Smith, A History of Dams Secaucus, New Jersey, pp. The concept of a multiple arch dam dates at least to " JSE papers, WRCA. the century as described by J.A.

Garcia-Diego in "The Chapter on Weirs in the Codex of Juanelo Turriano," Technology and Culture 17 " McGiilicuddy to Governor Wells, December 9, (April pp. There is evidence in the Multiple Arch Dam JSE papers, WRCA. Folder, JSE papers, WRCA, that Eastwood prepared a draft patent for his multiple arch dam design ca. but there is no record of his ever " Eastwood to Cannon, December 21, JSE filing an actual patent application. It has been stated that Henry papers, WRCA. Goldmark's dam was constructed (Carl Condit, American Building Art, As reported in the Engineering News-Record, March 7, the war- 2 Vols. (New York, however, as stated in Wegmann (p. it time shortage of lumber increased the cost of wood used for formwork to never was.

the extent that the cost of the 105-foot-high dam was approximately as opposed to the original low bid of This cost increase " William W. Jacobus and Lilli Rathi, Manic 5: The Building of the would also have been incurred for the Ambursen and curved gravity Daniel Johnson Dam (Garden City, New York, p. 11. designs. '" Wegmann, pp. " JSE papers, WRCA. " The author thanks Professor Thomas Hughes of the University of 10 Engineering News-Record 78 (March 7, Though an accepted Pennsylvania for pointing out that this is a case of factor endowment. practice at the time, chuting of concrete long distances is now considered inadvisable because of the separation of aggregates and cement which can " Enke, "Investigation." occur.

The relatively low strength of the dam's concrete is prob- Following a thorough examination of the Mountain Dell Dam in ably the result of chuting. both physically and theoretically, Enke determined that the design was remarkably safe. His recommendations were that the upstream face of " Stephen BranauerandL.E. Copeland, "The Chemistry of Concrete," the dam be resurfaced with 1 /32 inch nylon-reinforced butyl rubber and Scientific American 210 (April pp. that all concrete showing signs of deterioration be throughly cleaned and The author thanks Mr. Howard Newlon of Charlottesville. Virginia. then coated with a moisture barrier type of sealant. He also recommended for his help in explaining the chemical nature of concrete.

that a permanent set of benchmarks and alignment discs be installed in the walkway across the top of the dam at each buttress, and at each abut- " Whitney, "Unsung Genius of the Drawing Board." p. 49. The follow- ment, to allow a periodic survey check capable of detecting any differen- ing lists Eastwood's known dams with completion dates (compiled by the tial foundation rotation or settlement. With such measures taken, Enke author): I. Hume Lake Dam, California, 2. Big Bear Valley Dam. declared the dam to be a safe and adequate structure with many years of California, 3. Big Meadows Dam, California (only partially service ahead of it. built and never completed), 4. Los Verjeles Dam, 5. Kennedy Dam, California, 6. Argonaut Dam, California, 7. Mountain Dell Dam, Utah, 8.

Eagles Nest Dam, California, 9. Murray Dam, California, 10. San Dieguito Dam, Califor- nia, II. MaladDam, Idaho, 12. Lake Hodges Dam, Califor- nia, 13. Cave Creek Dam, Arizona, 14. Fish Creek Dam, Idaho, 15. Anyox Dam, British Columbia, 16. Weber Creek Dam, California, 17. Little Rock Dam, Califor- nia. k" Cannon, "The Mountain Dell Dam." Accompanying this article are prints of Eastwood's originaldraw- ings, which clearly show ihe vertical top sections. Addendum to: MOtfKTAIN DELL DAM BAER No.

Interstate Highway 80 } , Salt Lake City Hfk Salt Lake County '' Utah f is] y-SAL^i 22 PHOTOGRAPHS WRITTEN HISTORICAL AND DESCRIPTIVE DATA Historic American Engineering Record National park Service Department of the Interior Washington, DC 2O013-7I27 HISTORIC AMERICAN ENGINEERING RECORD WRITTEN HISTORICAL AND DESCRIPTIVE DATA Addendum to: MOUNTAIN DELL DAM HAER No, UT-16 Interstate Highway 80 Salt Lake City Salt Lake County Utah Data pages 1 through 26 were previously transmitted to the Library of Congress. This is data page 27. INVENTORY OP

Photogrammetric Images

The glass photogrammetric plates listed below are not reproducible except with special permission. However, reference prints and film copy negatives have been made from the plates indicated by an asterisk (*) and are included in the Library of Congress collection of formal HABS/HAER photographs. 5" x 7" glass plate negatives (one stereopair) produced by Perry E. Borchers of the Ohio State University in One survey control contact print from each plate; survey control information for each pair. LC-HAER-GS05-B-1971-1101L * VIEW FROM WEST BELOW THE DAM LEVEL LC-HAER-GS05-B-1971-1101R

View from West Below the Dam Level

Left and right overlap: 75%

Project Information Statement

Photogrammetric images were incorporated into the HABS/HAER collections in the summers of and Inventories of the images were compiled and filed as data pages for each structure recorded. Since the glass photogrammetric plates are not reproducible except with special permission, a reference print and film copy negative were made from one plate of each stereopair and from the most informative plates in sequential sets. The reference prints and copy negatives were then incorporated into the formal HABS/HAER photograph collections. MOONTAIN DELL DAM HAER NO. OT-16 Data (Page 28) The Photogrammetric images Project was a cooperative endeavor between the HABS/HAER Division of the National Park Service and the Prints and Photographs Division of the Library of Congress.

The reference prints and film copy negatives of the original plates were made by the Library of Congress Photoduplication Service with funds provided by the Library of Congress Flat Film Preservation Fund. Additional reproductions were made by HABS/HAER. The project was supervised by HABS/HAER Architect John A. Burns, AIA, and completed by HABS Historians Jeanne C. Lawrence (University of London) in and Caroline R. Alderson (Columbia University) in ADDENDUM TO: HAER UT-16 MOUNTAIN DELL DAM HAER UTAH,18-SALCI,22- Parley's Canyon, Northwest side of I-80, West of State Route 39 Salt Lake City Salt Lake County Utah COLOR TRANSPARENCIES HISTORIC AMERICAN ENGINEERING RECORD National Park Service U.S. Department of the Interior C Street NW Washington, DC