... Work starts on Blue Mesa Dam
On the Gunnison River in western Colorado, the Tecon Corp. has started work on the first dam of the Curecanti Unit of the Bureau of Reclamation's Colorado River Stor age Project. The 342-ft. earthfill dam will contain 3,000,- 000 cu. yd. Reservoir storage will be 940,800 ac. ft. and the powerplant will have a 60,000-kw. capacity.
CONSTRUCTION of the Bureau of By GRANT BLOODGOOD The darn embankment will consist Reclamation's Blue Mesa Darn and Assistant Commissioner and Chief Engineer of three zones of selected material, Powerplant on the Gunnison River in Bure1u of Recl11m11tion each distinguished by its particular western Colorado began in late Ap Denver, Colorado structural and permeable properties ril. The darn and powerplant are the and by the method of placement. De major features to be undertaken on Blue Mesa Dam is to be construct tails are provided in the caption of the Curecanti Unit of the Colorado ed about 25 mi. downstream from the cross-section drawing. River Storage Project. The $13,706,- Gunnison and about 1 Y.2 mi. down 230 contract for construction of the stream from the town of Sapinero. Powerplant 342-ft. earthfill darn and 60,000-kw. Principal dimensions and characteris powerplant is held by the Tecon Cor tics of the darn and powerplant ap The Blue Mesa Powerplant, to be poration, Dallas, Texas. Work under pear in the accompanying table. constructed at the downstream toe of the contract is required to be com Geologically, the darnsite is favor the darn, is to house two 30,000-kv. pleted by February 1966. The power able for a high earthfill structure. generators, each driven by a 41,500- plant is expected to begin operation Foundation and both abutments con hp. turbine. The powerhouse will be in June of the same year. sist of very hard, moderately jointed a reinforced concrete structure 114 The Curecanti Unit is one of the granite gneiss, quartz-mica schist, and ft. long, 89 ft. wide, and 116 ft. high four initial units of the Colorado quartzite. Exploration of the river above foundation. River Storage Project. The other three channel and abutments by drill holes Construction of the powerhouse storage units are in advanced stages has revealed no dominant foundation will be carried out in two stages. of construction. They are Glen Can defects. First-stage construction is part of the yon, Ariz.; Flaming Gorge, Utah; and Profile of the darnsite along the prime contract for the dam. Second Navajo, New Mex. The primary pur centerline of the crest of the dam stage construction, which will be car pose of the Curecanti Unit is to de is nearly V-shaped, and after over ried out under a separate completion velop the water storage and hydro hanging rock is removed it will slope contract, is to begin in the summer electric power generating potentiali on either side at 0.6: I. An estimated of 1965. ties along the 40-mi. section of the 190,000 cu. yd. of material will be Gunnison River below Gunnsion, and excavated from the dam's foundation Hydraulic features above the Black Canyon of the Gun to assure a completely competent and Gunnison River floodwaters will be nison National Monument. Other pur tight contact with bedrock. A grout passed through a tunnel-type spillway, poses of the unit are irrigation, rec curtain will extend from the bottom 1,245 ft. long, extending through the reation, and flood control. of the cutoff trench into bedrock. right abutment of the dam: The con-
LOCATION MAP showing Blue Mesa Dam on the Gunnison River in National Monument. Some of the necessary highway relocation is relation to the towns of Gunnison and Montrose in western Colorado. indicated. Note the locations of the Morrow Point Dam and the Also shown are the upper limits of the Black Canyon of the Gunnison Crystal Dam site (under investigation) referred to in the text.
66 WESTERN CONSTRUCTION-August 1962 Facts on Blue Mesa DAM Type . Earthfill Height above riverbed 342 ft. Volume: hrth and rockfill .. . . 3,000.000 cu. yd. Concrete (spillway, outlet works, and related structures) 37,460 cu. yd. Crest length .. 800 ft. Crest width .. .. 30 ft. Bue width 1,600 ft Crest elevation 7 ,528 Maximum dischorge through spillway 33,700 ch Freeboud 8.6 ft. RESERVOI~ Capacity 940,800 ac. ft. Area ... 9, 180 ac. Efevation m•ximum water svrhice 7519.4 length 19 mi. POWERPLANT Capacity 60,000 kw. Number of generating units ...... 2 Capacity of each generator 30,000 kw. ARTIST'S drawing of dam and reservior superimposed on aerial photograph of the site. The Capacity of Heh road running across the crest of the dam will connect Colorado State Highway 92 on the left turbine ...... 41,500 hp. and U. S Highway SO on the right. The powerplant at the toe of the dam will contain two 30,000 kw. generators.
crete-lined tunnel will have a ma,i crctc lined and will link with the chor block. Maximum discharge capa mum capacity of 33,700 cfs. and will \pill\\ay tunnel about 908 ft. down city of the outlet works will be 5, l 00 be :?4 ft. 8 in. in diameter near the stream, near the intersection of the cfs. The tunnel will also convey wa upstream portal and :? I ft. at its inclined section with its horizontal ter to the main power penstock in dO\\nstream portal. The initial section section. Closure of the diversion tun the anchor block. of the tunnel will be inclined at an nel will he made by concrete plugs. Two steel penstocks will branch off angle of 55 deg. with the horizontal. The contractor has completed the main penstock. Each will have a Minimum thickness of the tunnel lin open-cut excavalion for the upstream diameter of 11 ft. 3 in. A wye ing will be :? I in. at the upstream portal of the diversion tunnel and has branch, having two 7-ft.-diameter section and 18 in. at the :? 1-ft.-dia had three shifts working 7 days a steel pipes, will connect to the mani meter section. The spillway intake wcel.. on open-cut excavation for the fold assembly downstream from the structure will be controlled by two downstream portal. A subcontractor penstocks to conduct the outlet works 25x33.5-ft. radial gates. has three \hifts working 7 days a discharge to a stilling basin. The in During construction, the river will week on the e,cavation of the tunnel. take structure of the outlet works will be diverted through a 21-ft. diver The outlet works will consist of an contain a l 6x 18-ft. fixed-wheel gate sion tunnel, to be driven through the intake structure, a 16-ft.-diameter, for emergency closures. right abutment, and the spillway tun 973-ft.-long tunnel through the dam's A metal enclosure at the intake nel. The diversion tunnel will be con- right abutment, and a manifold an- structure is to be provided to pro-
Contractors coff,rdo,,.
CROSS-SECTION of Blue Men Dam indicating the general dimen cu. yd. of semi-impervious fill. This is selected clay, silt, sand, g ravel sions and the zones of fill material. The impervious Zone 1 (880,000 and cobbles and is to be compacted by 12 passes of a tampin9 cu. yd.) consists of selected clay, silt and gravel compacted by a roller over Heh 12-in layer. Zone 3 (990,000 cu. yd.) represenh minimum of 12 puses of a tamping roller over each 6-in. layer. the pervious outer zone of rock fill to be placed in 3-ft. laye rs. The Zone 2 on either side of the impervious zone will contain 1,100,000 upstrHm slope of the dam will be surfaced with a 3.ft. layer of riprap.
WESTERN CONSTRUCTION-August 1962 67
/ prove the economy of the Curecanti Unit over that which would be pro vided by only the Blue Mesa and Mor row Point features. However, should detailed studies show the Crystal de velopment to be unfavorable, the ,,~ Blu: Mesa and Morrow Point features ,,' ,•, , together would comprise the most fa. ,.,,,,• vorable plan for the Curecanti Unit. The Blue Mesa and Morrow Point features together will develop 760 ft. of the 1,000 ft. of potential power head along the 40-mi. reach of the river canyon. Substations and transmission Jines will be constructed to connect the Cu recanti Unit powerplants with main lines of the power system of the Col DIAGRAM show ing t he relation of diversion and o utlet works to the intoke and spillway orado River Storage Project and with strvcturH and the powerplant at the downstream toe of tho dam. other systems for the delivery of power to load centers. Flows of the Gunnison River will tect the outlet works fixed-wheel gate 92 and a timber bridge, an addition be largely controlled by the Blue hoists and controls from low air tem al 1.4 mi. of permanently relocated Mesa Reservoir, wliich will provide peratures (temperatures at the dam State Highway 92 running to the dam, the greater part of the capacity for site during winter months average and 1.33 mi. of a service road to the Curecanti Unit. Water released about minus 15 deg. F), and will the powerplant. through the Blue Mesa Powerplant, be made removable to facilitate the In April 1961 the Colorado State together with minor downstream in handling of stoplogs and removal of Highway Department began work on flows, will receive short-item regula the gate and hoists by a tru:k crane. the relocation of 6.5 mi. of U. S. tion at the smaller Morrow Point A compressed air system is also to Highway 50 around the damsite. The Reservoir. Releases through the Mor · be provided to prevent the formation highway relocation, financed primar row Point Dam and Powerplant will of ice at both the spillway and outlet ily by the Bureau of Reclamation, is be relatively uniform during the irri works intake structures. under contract to the H-E Lowder gation season to maintain flows need milk Co., Englewood, Colo. The state ed for downstream water rights. A Road construction highway department prepared the flow of 200 cfs. or more will be plans and designs and is supervising maintained at all times in the river U. S. Highway 50 is the principal the work. The relocation includes through the Black Canyon of the Gun transportation artery of the area in construction of two structural steel nison National Monument to preserve which the Curecanti Unit is located. bridges, each about 270 ft. high - scenic and recreation attractions. The highway's route includes the west the highest such bridges in Colorado. The two reservoirs and intercon ern Colorado cities of Gunnison, nected powerplants will permit con Montrose, Delta, and Grand Junction. Curecanti Unit developmmt siderable flexibility in daily and From Gunnison, the highway paral monthly power production operations. lels the Gunnison River through the To accomplish the objectives of the The power output of the Blue Mesa major portion of the Curecanti Unit Curecanti Unit, the Bureau consider Powerplant will fluctuate to meet area. It leaves the river canyon at ed a number of plans for develop variations in load requirements; the the town of Sapinero and crosses ment. These embraced a series of Morrow Point Powerplant will be op mesas south of the river. The high two, three, and four dams, reser erated largely for base loads during way is joined at Sapinero and at voirs, and powerplants along the sec the irrigation season to permit release Delta by Colorado State Highway 92. ti on of the Gunnison River below of near-uniform flows for down The Blue Mesa damsite is present Gunnison and above the Black Can stream water uses. During t!Je re ly accessib!e over a secondary road. yon of the Gunnison National Monu mainder of the year, the Morrow This road has been constructed along ment. The two most favorable de Point plant will be operated on a an abandoned railroad bed in the velopments were found to be the two variable production basis for integrat river canyon and joins Highway 50 dam plan at the Blue Mesa and Mor ed operation with other plants in the at the towns of Cimarron and Sa row Point damsites and the three system in meeting load requirements. pinero. Montrose, the railhead near dam plan, including those two sites Floyd E. Dominy, whose offices est major features of the Unit, is and a third site, the Crystal dam are in Washington, D. C., is Com served by a branch line of the Den site. (see map). Detailed feasibility in missioner of the Bureau of Reclama ver and Rio Grande Western Railroad vestigations have been completed at tion. The Colorado River Storage extending from the main line at the Blue Mesa and Morrow Point Project is in the Bureau's Region 4; Grand Junction. sites, but investigations have not yet F. M. Clinton, at Salt Lake City, Utah, Contract for construction of the been completed at the less accessible is Regional Director. J. D. Seery is dam also calls for construction of Crystal damsite. Project Construction Engineer for the earthwork, structures, and surfacing Preliminary investigations indicate Curecanti Unit; his office is at Gun for 6.5 mi. of three access roads in that the Crystal damsite, through its nison, Colorado. All designs for the the vicinity of Sapinero. Included in own power production and its effect Unit are under the direction of 0. L. this roadwork arc 3.85 mi. of tem in increasing power values at the up Rice, Chief Designing Engineer of the porary relocation of State H ighway stream Morrow Point site, would im- Bureau.
68 WESTERN CONSTRUCTION- August 1962