Laserfiche WebLink
Mr,. Jim Herron January 30, 1984 Page 4 <br /> SEAL CJONSTRUCTION <br /> Before construction of the concrete seal at the proposed locations, the <br /> loose rock and crushed material will be removed. A small cut around the open- <br /> ing will be made to obtain the tapered plug shape. Also, the plug will be <br /> keyed into the perimeter of the opening using rebar or steel roof bolts. This <br /> keying of the plug into the openings will help increase shear strength around <br /> the seal. <br /> SUMMARY <br /> The permanent mine seals were designed based on the maximum possible <br /> hydraulic heads and the strength properties obtained from the Robbins and <br /> U. S. Bureau of Mines core samples. A safety factor of three was used in cal- <br /> culating the applied forces on the seal and the seal dimensions were estimated. <br /> All seals will be eight feet thick. Seals will be of tapered plug shape and <br /> they will be well keyed into the mine openings. <br /> It should also be noted that the maximum calculated stress on the seals is <br /> 661 psi and a safety factor of 3 is used. The concrete seal with compressive <br /> strength of 5352 psi and with a stress of 661 psi would yield a safety factor <br /> of 8.1. The designed seals will be able to withstand the applied forces with <br /> comfortable safety factors. <br /> As the mine is developed, additional geologic and hydrologic data will be <br /> collected and the seal design will be re-evaluated before construction. <br /> Yours very truly, <br /> i�,,,� 6-1)Ak,,_e� <br /> Environmental Coordinator <br /> DWBowma.n:ms <br />