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` �~ r",kN2,��Y�5 <br /> MEMORANDUM <br /> TO: Doug Bowman <br /> r <br /> ._ <br /> FROM: Tom Johansen ' J85-046 <br /> /SUBJECT: Rock Tunnel Sealing plan <br /> - <br /> Attached is the additional information requested <br /> by Jim Pendleton in his memo of 5/20/85 to Candace Thompson' <br /> The concrete seals will be keyed 24 inches into the <br /> 'bedrock around the perimeter' <br /> Groundwater head and seal design calculations are <br /> attached. The maximum water head pressure occurs against <br /> seal no. 1 . Calculations were made on the assumption that <br /> the full length of tunnel , behind the bulkhead , will* fill <br /> with water. Calculations 'for seal strenght were based on <br /> the assumption that the concrete and steel bulkhead would <br /> fall in shear in a horizontal plane. <br /> A �6 inch concrete wall can support a total force of <br /> 4 , 200,000 lb. before failure. The maximum head is 143 feet , <br /> creating a force of 1 ,5001000 lb. The factor of safety is <br /> - <br /> ' <br /> ` <br /> ` <br /> � . <br /> ` <br />