Public works . ets on tangents, making a rightangle at the Western ave. gate shaft and having theinvert about 140 to 155 feet below the surface of theground. It has a cross-sectional area of square feetand a perimeter of feet, and involves a rockexcavation of cubic yards and a concrete lining cubic yards per Hnear foot. It has a capacityof 800,000,000 gallons per 24 hours at a velocityof feet per second. The total average force employed in the four headingsis about 400 men. The tunnel is being ex-cavated simultaneously atfour headings, two drivenfrom the foot of a c
Public works . ets on tangents, making a rightangle at the Western ave. gate shaft and having theinvert about 140 to 155 feet below the surface of theground. It has a cross-sectional area of square feetand a perimeter of feet, and involves a rockexcavation of cubic yards and a concrete lining cubic yards per Hnear foot. It has a capacityof 800,000,000 gallons per 24 hours at a velocityof feet per second. The total average force employed in the four headingsis about 400 men. The tunnel is being ex-cavated simultaneously atfour headings, two drivenfrom the foot of a con-struction shaft at Woodstreet 4,000 feet from theWestern ave. gate shaftand two from the footof the 61 St street shaftabout 8,000 feet from theWestern ave. gate shaft. The work was com-menced by sinking, in1919, of the two con-struction shafts describedin Public Works, page477. The excavation wascommenced in the firstheading, dri\en in thefoot of the Wood streetshaft, in May 1920, andon the fourth heading in. June 1920 and the excavation was 33 per cent com-pleted November 15, 1921. It is estimated that the two construction shafts, twogate shafts, tunnel excavation and pumps will re-quire a total amount of 200,000 yards of excavationand 53,000 yards of concrete, will cost about $4,000,-000 when completed and that the tunnel will be readyfor service in November 1923. The work is beingdone on force account by the city of Chicago underAlexander >Murdock, City engineer and Myron , designing engineer, and the WaterworksDepartment, James J. Versluis, constructon engineer,and E. P. Scotc and G. S. Samuels, resident engineers. MINING AND MUCKING The work is executed under atmospheric pressureand is carried on continuously with two 8-hour shiftsin each of the four headings. The miners enter threehours after the muckers in each heading and for bothheadings, a total of 44linear feet daily with amaximum record of 46feet is secured. The work is done bythe regular top heading
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmunicip, bookyear1896
