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.i~i8 150 METROPOLITAN WATER DISTRICT Original conclusions as to the economy of full-capacity tunnel construction having been thns confirmed, succeeding advertisements called for bids on full-capacity tunnels only. On April 10, 1933 specifications for the East Eagle, West Eagle, Hayfield Nos. 1 and 2, and Mecca Pass Nos. 1, 2, and 3 tunnels were .~~ issued, followed on April 24th by specifications for Colorado River, 'I Copper Basin Nos. 1 and 2, and the Whipple Mountain tunnels. By June 16, 1933 the construction of all tunnels, excepting East Eagle, bids on which had been rejected, and Schedules 7 and 8 of the West Coachellas, had been provided for either by contract or by District forces. On December 27, 1933, specifications were issued for this remaining work. On February 2, 1934 a contract was awarded for the East Eagle tunnel, but the bids on the Coachella schedules were rejected, these two schedules aggregating 7.1 miles of tunnel being later added to the adjoining work being done by District forces. Tunnd-driving operations In general, contractors, upon receiving notice to proceed with their work, were diligent in organizing forces, assembling equip- ment and materials, erecting camps, and proceeding with all pre- paratory work even before power and water were available from the District systems. The mess accommodations and dormitories in contractors' camps were in some cases operated by the contractor; in others were sub- contracted to commissary and catering companies. In the Coachella tunnel camps such operations were carried on by the District, with a steward in charge of all mess halls. The most common entry to the tunnels was through one or both portals. Five tunnels, however, were driven from horizontal adits, the total length of adits amounting to 10,327 feet. The east por- tion of Iron Mountain tunnel was driven entirely from one vertical shaft and Valverde from three vertical shafts and one inclined adit. At San Jacinto there are two vertical shafts and three in- clined adits, of which the one at the west end has been discon- tinued with the opening up of the west portal of the tunnel. Standard methods of excavation have been employed with im- provements to take full advantage of modern equipment. In be- ginning tunnel driving at any point a top heading followed by ex- cavation of the bench was customary for the first few hundred feet. In bad ground small drifts are driven in the top heading ,