IN THIS CANYON section of the the grade will be improved to serve a s t he access road will be built near the location of the abandoned to the site. The dam and re s ervoir are upstre am from railroad bridge shown in the picture. The railroad the Black Canyon of the Gunnison National Monument.

Construction starts at Morrow Point

Proiect in on Gunnison River include-s several 11firsts" for the Bureau of Reclamation: double curvature, thin arch dam, underground power plant and free-fall spillway. The $15A36,- 000 contract went to ioint venture of Al Johnson Construction Co. and Morrison-Knudsen Co., Inc.

CONSTRUCTION of the Bureau downstream from , of Reclamation's first double­ a large earthfill structure under curvature. thin-arch dam began construction by the Bureau as part in June. The concrete structure is of the Cw·ecanti Unit. (The article Morrow Point Dam, a major fea­ ··work Starts on Blue Mesa Dam" ture of the Bureau·s Curecanti. Unit by Grant Blooctgood, published in of the Storage the August 1962 issue of Western Project m west-central Colorndo. Construction. describes the earth­ The 515,436.066 contract for f'ill dam and plan of development construction of the dam wa~ of the Curecanti Unit.) awarded to the joint venture firm The Bureau's thinnest arch dam, of Al Johnson Construction Co. By 8. P. BELLPORT on the basis of width to height, and Monison-Knudsen Co., Inc. Chief Engineer Morrow Point will have a top Time allowed for completion of Bureau of Reclamation width of 12 ft. and a base width construction is 1,460 days-by Ma~· Denver, Colorado at the crown section of 52 ft. It 1967. will be 465 ft. high above founda­ The contract for construction of tion and will have a crest length the dam includes another Reclama­ of 720 ft. and a volume of 360,000 tion first-an underground power­ Morrow Point Dam i:; on the cu. yd. Capacity of the reservoir plant to be built in the left abut­ Gunnison River, a major tributary to be impounded by the dam will ment a short distance downstream of the Colorado River. It is near be 117,000 ac. ft. from the dam. The plant will house the village of Cimarron, about 22 The dam's powerplant will con­ two 60,000-kw. generating units. mi. east of Montrose and 12 mi. sist of two 60,000-kw. generators.

WESTERN CONSTRUCTION- August 1963 Over two million pounds of rein­ replaced by an 86-ft. span steel­ Geologically, the damsite is forcing steel will be required. beam, concrete deck hridge. Re­ situated on the downstream limb placement of a second bridge will of a small transverse synclinal Access problems be obviated by a high fill. The re­ fold which plunges gently into the A major consideration in con­ maining bridge will be abandoned left abutment. The dam will abut struction of the dam is access to as a crossing is not required. against the upstream-dipping rock the damsite for the contractor's The access roads will be 20 ft. sequence comprising this limb of use. At present, existing access to wide and have a 4-in. gravel sur­ the fold. Rock in the damsite the site from U.S. Highway 50 is facing. The road running to the foundation is competent, consist­ along an abandoned narrow gauge powerplant will have a maximum ing of alternating lenticular and railroad grade going downstream grade of 10~. Maximum grade of irregular beds of micaceous quartz­ along Cimarron Creek (a tributary the road branching to the crest ite, quartz-mica schist, augen of the Gunnison River), then up­ of the dam will be 12 't. Steel-bin gneiss, and biotite schist, all of stream along the river about J/4 mi. retaining walls are to be installed which have been irregularly in­ to the darnsite. The abandoned in certain sections of the road to truded by pegmatite. The only railroad grade includes three 1- the crest of the dam to reduce significant foundation defect is a lane pin-type truss railroad bridges deep cuts in the canyon walJ. shallow system of stress relief which have been satisfactory for joints. access during preconstruction ac­ Geology of the site The dam and powerplant sites tivity but which are to be re­ Design of the dam and power­ were explored by approximately placed or removed to carry heavy plant is strengthened by one of 7,500 ft. of NX (3-in.) core drill traffic loads during construction. the most intensive geological in­ holes and 685 ft. of 6- by 8-ft. The contract for the dam con­ vestigations ever made by the exploratory tunnels. One explora­ struction calls for removal of the Bureau at a darnsite. The in­ tory tunnel was driven 100 ft. into three bridges and construction of a vestigations embraced five dis­ each abutment in the direction of road beginning at U.S. Highway tinct but correlated methods of maximum thrust from the dam, 50 and running 1.7 mi. to the pow­ testing the foundation and abut­ and a third tunnel was driven the erplant. An additional 0.6 mi. of ment rock---core drilling, labora­ full length of the underground access road is to be constructed to tory tests of drilled cores, in-situ powerplant. Most of the power­ branch from the powerplant road jacking tests, seismic investiga­ plant investigations, including 17 and continue to the crest of the tions, and bore hole observation vertical and angled drill holes, dam. One of the bridges will be with closed-circuit television. were conducted from the power­ plant exploratory tunnel. Several small di'ameter holes were drilled in conjunction with the in-situ---~--~­ rock properties tests and seismic measurements completed in the -f tunnels. Observation of the 3-in. drill­ hole sidewalls was carried out by T a Bureau-owned, 21h-in. diameter, closed-circuit television probe. This direct examination included a study and correlation of the de­ gree and extent of jointing, fault­ ing. folding, and foliation that ex­ MORROW POINT Dam is between Montrose and Blue Mesa Dam. ist in the foundation rock.

Diversion plan Diversion of the Gunnison River at the Morrow Point site during construction is to be closely allied with the construction of the Blue Mesa Dam. Closure of the Blue Mesa Dam diversion works is ex­ pected to take place in December 1964. After that closure date, the flows of the river will be con­ trolled by the Bureau to such an extPnt that not more than 5,000 cfs. will be released from the dam in 1965 and not more than 8,000 cfs. will be released during the remainder of construction of Mor­ row Point Dam. Any damage to any part of the permanent work or to any part of the contractor's diversion or pro­ UNUSUAL DESIGN features of Morrow Point project are the free-fall spill­ way shown in action in this artist's sketch and the underground power­ tective works caused. by flows in house In the abutment, with discharge indicated. The thin concrete arch excess of 5,000 cfs. in 1965 and will be 465 ft. high, 52 ft. thick at the base and 12 ft. thick at the crest. 8,000 cfs. thereafter will be the

WESTERN CONSTRUCTION-August 1963 responsibility of the Bureau. Any 1965. The Bureau anticipates the the freshly placed layers of con­ damage to the contractor's con­ placement of concrete will be crete. The gang vibrators .may be struction plant or equipment which completed within two construction used only if they can be readily may occur from flows in excess seasons. raised and lowered to eliminate of 5,000 cfs. in 1965 and 8,000 To assist in construction of the dragging through the fresh con­ cfs. thereafter will remain the re­ dam, Bureau designers, using an crete and provided all other place­ sponsibility of the contractor. electronic computer, have pre­ ment and consolidation require­ The contractor has the option pared data on the coordinate points ments are met. of at least two methods of diverting for each lift of concrete in each Concrete is to be cooled by river the river during construction. He block. The coordinates can be water, supplemented by refrig­ may divert the flow of the river used by the contractor to set forms erated water, circulated through through a concrete-lined diver­ for concrete placement. 1-in. embedded cooling pipe placed sion tunnel in the right abutment, Placement will be in 7 12-ft. lifts. on top of each 71h -ft. lift. About or he may construct diversion Maximum differential levels of 59 mi. of cooling pipe will be em­ channels or flumes in conjunction adjacent blocks during construc­ bedded in the concrete. Placing with diversion conduits through tion are not to exceed 30 ft., and temperature will be limited to 60 the dam. The final closure struc­ the highest block is to be not more deg. maximum. After the tempera­ ture or structures, whether for than 52.5 ft. above the lowest ture of the concrete has been low­ conduits through the. dam or for a block. The differential between ered to 40 deg., the transverse con­ tunnel, are to be designed to with­ adjacent blocks is to be reduced traction joints will be grouted. The stand a 300-ft. head of water. to not more than 15 ft. prior to concrete will be successively cooled If the contractor elects to divert the cessation of concreting at the and grouted in 60-ft. lifts. When through a tunnel, the tunnel is to end of a construction season. This the proper cooling temperature has be located not closer than 75 ft. requirement will reduce the ex­ been attained and the contraction from the dam. Permanent closure posed concrete surfaces to a prac­ joints grouted, the cooling pipe of the tunnel is to be made by a ticable minimum during the severe will be filled with grout. concrete tunnel plug immediately cold winter weather at the dam­ after contraction joint grouting is site where temperatures may drop Concrete mix design completed in the dam. as low as - 40 deg. Rate of place­ The thin-arch structure will re­ Should the contractor elect to ment in any block will be re­ quire concrete designed to obtain ciivert through a diversion con- stricted so that not more than one a compressive strength of 4,500 1~uitor conduits through the dam, horizontal lift can be placed in psi. at 1 year's age. Tests in the the maximum diameter of any 72 hr. Bureau's engineering laboratories conduit is to be 10 ft. Any such The contractor has the alterna­ in Denver indicate that about four 'ts used are to be backfilled tive, where practicable, of using sacks of cement per cubic yard with concrete, coo1ell, and-grout~ ang vibiators to consolidate mass used with a water-reducing, set­ after the dam is completed. concrete in the dam. As m ny-as­ ret~ admixture (water-re­ The profile of the dam will be five vibrators may be mounted ducing agent) will meet this nearly symmetrical upon comple­ on a tractor which can travel over tion of excavation for the abut­ ments. Shallow holes will be drilled on 20-ft. centers to depths of 50 to 70 ft. and grouted under low pressure over the full area of the foundation. Following con­ -IO"D,o.o,r,rift crete placement in the dam, a CO•'l)rtfJOf" C/IOtflblr-...... I main grout curtain will be formed Foct of ct,,,L _ _...... f • J by grouting holes drilled on 10-ft. .,. 4 1,t o, ws t1.1JU ··, I c ~--' centers from the foundation gal­ I Nor w t Ct ftl O· - ~ -. - I 1' lery and tunnels in the left abut­ .. ,,~rf ..'J ' Futd •flffl (JOit ment to depths as great as 200 ft. A line of drainage holes on • J.. 10-ft. centers will be drilled to .. \ • • ··lms o( do,,, depths of from 40 to 150 ft. down­ p ~:,i.. ,01inib ·l•rii, 91:1 ,,,,,s stream from the main grout cur­ tain. SECTION THRU S ...ILL WAY The dam is to be divided into blocks by vertical transverse con­ traction joints radial to the axis of the dam to confine shrinkage openings to predetermined planes. OvUt t ,,ostiroct 1t,uc.t11,..., With the exception of one 30-ft. block, spacing of the joints will be 40 ft. The joints will be keyed and grouted to assure watertight­ ness and monolithic action of the dam.

Concrete placing MAXIMUM section showing outlet works and spilling basin for the free-fall Placement of concrete is ex­ spillway. Fall from the spillway openings will be 350 ft. Into the 60-ft. pected to begin in the spring of depth of the pool.

WESTERN CONSTRUCTION--AuJust 1963 blasting" technique to minimize to maintain the 60-ft.-deep pool MORROW POINT DAM fracturing of the rock. A cable which will reduce the impact and (Continued from page 57) tunnel will provide access to the turbulence of the water falling crown of the powerplant chamber from the great height. The stilling strength requirement. Approxi­ and thus permit excavation of a basin floor will have a maximum mate mix proportions for the mass pilot drift down the crown of the thickness of 5 ft. and will be about concrete, now under considera­ opening. After the arch above the 160 ft. wide. Study of models of tion, are: springing line is excavated, bench­ the spillway in the Bureau's hy­ Portland cement (Type type excavation may be used. The draulic laboratory confirmed de­ II, low alkali) ...... 4 sacks access and draft tube tunnels will sign studies that there will be no Coarse provide additional accessibility for possibility of damage to the dam aggregate .... 2,760-2,820 lb. excavation of the powerplant or afterbay channel by the falling Sand ...... 660-680 lb. chamber. water. Vlater ...... 145- 155 lb. Grouted, expansion anchor-type The spillway will have a com­ Tests on samples taken from near­ rock bolts are to be used as the bined maximum capacity of 41;000 by deposits show that aggregates primary and permanent support cfs. Each opening will be con­ of suitable quality are available. for the arch roof and sidewalls trolled by a 15-ft. wide by 16.83- Maximum size of aggregate speci­ of the chamber. The bolts will be ft. high fixed-wheel gate. fied is 4 ~2 in. installed and tensioned as close to the excavation heading as prac- Outlet works Underground powerplant ticable. Vlire mesh will be pinned The dam's outlet works will Morrow Point Powerplant is be­ to the roof arch to prevent small comprise one 4- by 4-ft. stainless ing constructed as an under­ rock spalls from dropping out. steel-lined conduit through the ground installation for economic A tunnel to be used to ventilate dam. Control of the flow through and engineering reasons and to the powerplant was constructed the conduit will be maintained by provide year-round construction at under a previous contract for ex- 3.5- by 3.5-ft. slide gates in tan- the damsite. (A conventional sur­ ploration purposes. Under the dem. Capacity of the outlet works face plant would have necessitated prime contract, a short length of will be 1,500 cfs. Discharges will shutdown of construction during concrete lining will be constructed be directed into the stilling basin the long, cold winter season.) To at each portal. A transverse con- at the toe of the dam. achieve economy in the lengths crete bulkhead will be constructed Two 13.5-ft.-diam. steel-lined of the penstocks, the powerplant in the tunnel near the powerplant penstocks are to be installed in was placed as close to the intake chamber and a louver will be in- tunnels excavated in the left abut- structures as possible. stalled in the bulkhead. ment rock. The penstocks will The underground powerplant Access_ to the completed power- convey_ wa_l~ ir:Q_m t.he...~e plant w1lL !bro.ug!.i. ..a 204t:--- ti·asnrack structures in the left chamber, to be excavated in rollli.;. q_e. -si\te. :'()(;k about 4110 Tt. below the w1ae, 150-ft.-long tunnel extend- abutment to the powerplant tur- ground surface, will be about 231 ing from the approach area to the bines. ft. lo!1g and 57 ft. wide and will underground chamber. The floor The: contractor is not required vary in height from approximately of the tunnel will be lined with to construct camp facilities at the 65 to 134 ft. Reinforced concrete concrete; the roof and sidewalls damsite. However, if he elects to will be placed within the chamber will remain as . expose? rock. provide such facilities, he will be to support the generating equip­ Grouted rock bolts and wire mesh permitted to use for construction ment. will support the roof of the tun- camp purposes and for construction A metal ceiling will be installed nel. . plant, storage, and incidental pur- the entire length of the power­ The transformers are to be poses any land available in the plant chamber. Howeve,, the walls placed underground in a vault vicinity of the damsite which is of the chamber above the elevation provided by the extension of the the property of the Government, of the generator floor will remain powerplant chamber at the level except such areas that have been as exposed rock. A structural steel of the generator floor. High-volt- reserved for special purposes. The runway will be installed for the age (230-kv.) cable will carry the contractor is required to have a plant's 300-ton overhead traveling power to the switchyard which is fully equipped infirmary at the crane. to be constructed adjacent to the job-site. Construction of the powerplant approach area and access tun­ Pe rsonnel will be carried out in two stages. nel. The fin1t stage of construction, Floyd E. Dominy, whose of­ which is part of the prime contract F r ee-fall spillway fices are in Vlashington, D.C., is of the dam, will include excava­ A feature of the Morrow Point Commissioner of the Bureau of tion of 45,400 cu. yd. of rock for Dam construction, unique in Bu­ Reclamation. The Curecanti Unit the powerplant chamber, place­ reau experience, is the dam's free.­ is in the Bureau's Region 4; F. M. ment of 3,700 cu. yd. of concrete, fall, orifice-type spillway. Four Clinton is Regional Director at 315,000 lb. of structural steel, 15- by 1.5-ft. openings are to be Salt Lake City, Utah. 460,000 lb. of reinforcing steel, and constructed in the top central part J. D. Seery is Project Construc­ installation of the traveling crane. of the dam to serve as the spill­ tion Engineer for the Curecanti Second-stage construction, ex­ way. Vlater flowing through the Unit. His office is at the Unit head­ pected to begin in January 1966, openings will fall more than 350 ft. quarters on U.S. Highway 50, 19 will be carried out under a sep­ to a pool retained in a reinforced­ mi. west of Gunnison. Howard E. arate completion contract. concrete stilling basin at the toe Smith is the Bureau's Resident Excavation for the powerplant of the dam. A 65-ft.-high weir is Engineer for Morrow Point Dam chamber is required to be done to be constructed 320 ft. down­ construction; his field office is at by the "smooth bore" or "cushion stream from the axis of the dam Cimarron.

WESTERN CONSTRUCTION-Aucust 1963