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<br />!1G??24
<br />
<br />27<&
<br />
<br />COLORADO MAGAZINE
<br />
<br />excavation at West Portal had been idle for repairs sixteen out
<br />of thirty-six days. The moist adobe and gravel encountered had
<br />entailed heavy timbering, and frequent cave-ins delayed the
<br />work."" '
<br />
<br />The contract was finally suspended, and on May 27, 1905,
<br />the Reclamation Service assumed the job of completing the
<br />tunnel project.:';; At this time 436 feet of 8x8 undercut drift
<br />on the tunnel grade at east portal had been driven, 135 feet
<br />of this' had been enlarged to full size (about 10xlO), and a
<br />power plant had been installed here to operate two air drills.
<br />an air hoist, and a pump. At West Portal. 574 feet of full-sized
<br />tunnel and 108 feet of 8x8-foot drift had been excavated.""
<br />
<br />The excavation of the tunnel under the supervision of the
<br />Reclamation Service was to continue for the next four years,
<br />with the actual work carried out by Service engineers when
<br />no satisfactory bids could be obtained from private concerns."
<br />Eventually, the work progressed on four headings: east from
<br />the Cedar Creek Portal, west from River Portal. and east and
<br />west from a shaft sunk into the mesa about a mile from River
<br />Porta1.'6
<br />
<br />The hazards accompanying the construction were closely
<br />related to the character of the rock material encountered dur-
<br />ing excavation. Starting from West Portal there was the fol-
<br />lowing geologic sequence: (1) 2.000 feet of heavy, water-
<br />bearing alluvial clay, graveL and sand beds; (2) 1,200 feet
<br />through a zone of hard shale below and gravel above, with
<br />much seepage: (3) J 0.000 feet of black shale, with fossil de-
<br />posits and pockets of combustible gas: (4) 2,000 feet through
<br />a badly shattered fault zone characterized by high tempera-
<br />ture, hot and cold water, coal, marble, hard and soft sand-
<br />stone, limestone, and concentrations of carbonic-acid gas; and
<br />(5) ] 5.455 feet of metamorphosed granite with many water-
<br />bearing seams.57
<br />
<br />Some of the adventures of the subterranean diggers
<br />equalled'those experienced by the earlier runners of the river
<br />and scalers of its chasm walls. On one occasion excavators
<br />from the west end tapped a cavern charged with carbonic-acid
<br />gas. Rushing and hissing. the gas drove workers helter-skelter;
<br />and the ventilating machinery had to be turned off until the
<br />confusion subsided."' In December of 1906 such a large under-
<br />ground stream was intercepted that jets shot forty feet into
<br />
<br />~ u. S. Geologica\ Sun'ey. 4th A.nnual R-e.port. op. c-it.... 11!=!, On September
<br />26. 1905, three bic10ers .submitted proposals tor completion of the tunnel. all of
<br />which were rejected.
<br />M U. S. Reclamation Servle~. 5th A nnual Re~oTt of the Re.clamation Service,
<br />1006 (1007), 109; U. S, Reclamation Servl<.-e, otlt' .{nnua! Revort.. op. cit" 96,
<br />Zl1U. S. Reclamation Service, 9th A.nnual Jeeport, ap. cU,. 96-97.
<br />5Spage, op. cU.~ !l325. It seem~. Tlrobable that slIghtly different descrIptIons
<br />of simtlar events in popular periodical articles may actually have l,een variations
<br />on a sing-Ie event. Newspapers and the annual reports of the Reclamation Service
<br />represe-nt tlH~ most "Valid SQurc(>s ot' information.
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