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Show ff ( v , v -: ? - '. ' : - . " 7 "T - LEFT SPILLWAY tunnel inspection, Glen Canyon Dari CRSP, Upper Colorado Region. Personnel from the E&R ?5''' Center and the Upper Colorado Region check the approx- 'd imate 100 feet within the outlet tunnel. Note the large at amount of debris they have to climb over. i;'c(es jten Repair work starts on Jstrii Glen Canyon spillway J The Bureau of Reclamation is boring bor-ing an access tunnel into the left spillway to remove accumulations of debris prior to repairing the damaged damag-ed spillways at Glen Canyon Dam, Reclamation's Upper Colorado Regional Director Clifford Barrett announced an-nounced this week. The tunneling machine, which started from the machine shop parking park-ing lot, is 70 feet into the canyon wall and 110 feet from intersecting the spillway tunnel. The drilling, expected to last another 2 weeks, is progressing " at a rate of 20 to 40 feet a day. While the drilling is continuing, the contractor also is installing drainage pipes to extract the remaining water, and hooking up utilities, such as compressed com-pressed air and electricity, prior to moving in heavy equipment to remove the eroded pieces of sandstone and reinforced concrete. The current contract con-tract calls for the left spillway debris removal and repair to be completed by mid-April 1984. The right spillway repair is expected to be completed by June 15, 1984. Damage in the right spillway is estimated to be only about one-third the magnitude of the left spillway. Total costs could run into the $5 million range to $10 million range. Guy F. Atkinson, the prime contractor, is expediting ex-pediting the repair in time for next season's runoff in late June to July. "Despite the damage, which first had been observed early in June, neither the dam nor the spillways were in danger of failing," said Barrett. "And while there was serious damage to the spillway lining, it was confined to a small area and at no time would it have caused us to shut down the spillways. Considering all the water that was spilled (4.4 million acre-feet including the bypass tubes), it was remarkable how well the spillways performed," he added. The work in the left spillway will in- ;E1 elude the removal of approximatf- itS 1,000 cubic yards of debris "Veh, several holes that have to be backrl ed," noted Barrett. About 4,000 to;' T cubic yards of concrete is estimated., , be needed to fill the holes, plus m :en 4,000 cubic yards of concrete to reL i the damaged reinforced concrete 1 ing. "To better appreciate the enorri. :lain ty of the work to be done, a largecos-struction largecos-struction truck has a capacity of fro 8 to 10 cubic yards," he said. At the right spillway, catwalks a. jies being constructed along the canya ! rdidi wall to allow access to the downstrK-1 itove end of the spillway. Then, pumps-; c be installed to get out as muchwa t as possible. The powerpha on transformer deck will be used by the je I boring machine for access to theotber im spillway to drill an access tud rye-similar rye-similar to the one currently beingtl j( u ed on the left. The power plant is etc- rter tinuing to operate at full capan despite the widespread constnicia r Bo effort. The boring machine has i round, rotary auger head, with cutfci teeth mounted on an arm positkri hydraulically to dig into the canyr wall from several angles. i n Atkinson currently has about &jpe- sonnel actively engaged at the rj, IH, with expectations of another 70 eve; Soto tually joining them. Assisting thece- Apply tractor are 4 Reclamation persona Paten from the Upper Colorado Region a spiciK 6 from other Reclamation regios (rise In addition to the repair, an air Li will be cut into the inclined portio-.i m('a-each m('a-each spillway to counteract futureef- ver fectsof cavitation, a condition in holes are eroded into the spillway h f 5 P ing. Cavitation occurs when ski x u waves are created from swiftly Qo- Hlli ing water traveling over 100 rr.iles aaj :ere' hour, passing over irregularities in ie m'es concrete, and cutting away bit mR pieces of the lining. The air slot wfej troduce air bubbles which prevent is formation of the destructive stoi Otv waves. |