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~ I I I ~ It 1 . ~ . r' t' .-, .l.U 01 " . STEEL PIPE 75 ,-Onglnal ground j" gunife.-., ..WlTe mesh " ; 1 ? ~~ ~? f; . i ,. .: - ..t;;~ J ,,/j 0:/ P,}' hf;;:3 : ' " " '8Cklijll'\ :.:. ~ ; \ :'Ef. .. ~ I .~;-. IlI.*.'f;j: ! "jNmorfar, Steel pipe': .~ ."i-_.:..-;-.__~____:~_..::'_' i-~1 : c~nfn"(1J1a{ly 5pun .~\. y. <0..:.._ /i''''''~''', I ';;, '"enamr1co_fmgi"n areas MORTAR LINEO I . I E of high elrc!ric polrnliator ~: " ----,t'....-... r:..:; ~'.:: carrOSI'11! 5011. . :-l'gun/fe. WIre mesh": '" ~ .:: ""Fn.;~~~ i '" 0" )^,~! I, '.J-coil/lar ,,: I.' {J'.. .~_,. __--....:::s~ rniimeJ. Steel p!pe. Omd bQlfom .... "'." "1 ele'" EN'AMEL LINeO 6'Jn firm dry sod.." . CONe. CRADL~ NORMAL EXCAVATION SECTION Fig. 5. Welded steel pipe t Construction was performed by two separate crews. One crew started at the southern end of the contract and worked north on schedules 23SC and 22SC to Valley Boulevard. The other progressed from the northern end through schedule 21SC into schedule 22SC to connection at Valley Boulevard. Three types of equipment were used for excavation, the trenching machine, dragline, and crane with clamshell bucket. Most of the trench in th~ northern portion. because of hard ground and many large boulders, was excavated by dragline, while in the southern portion the trenching machine was operated advantageously. The clamshell crane excavated bell holes necessary for welding and guniting the pipe joints and did the miscellaneous work. In general a vertical trench section was used, 78 inches wide for the 55-inch pipe and 72 inches for the 51-inch pipe. The depth varied from 7 to 30 feet. Side lagging required was dependent upon the character of the ground. In some portions lagging was driven skin-tight as excavation proceeded; in others excavation was completed and 2" x 12" Jagging was then placed on 2- to 10-foot centers, using trench jacks in all cases to hold lagging in position. Crossing of existing underground utilities required special treatment in order not to disturb service while the construc- tion was being carried on. Railroad crossings were accomplished mainly by tunneling, 01' by jacking steel culvert pipe, aCl'OSS the line deep under the tracks. Then the steel pipe sections were welded together and pulled through the tunnel or culvert, after which the '~pace around the pipe was filled with concrete. '\ The three tunnels and ad it, totaling 2,701 feet, were excavated .to a diameter of approximately 6 feet using steel rib support in all