Show HUGH DOLAN INC contractors pottsville spottsville POTTS VILLE PA hercules powder co wilmington del gentlemen you may be interested in some data on the driving of keffers geffers tunnel which is one of a series of three tunnels driven for the philadelphia reading coal iron co in the development of tower city colliery near tower city pa this tunnel driven by the undersigned undersigner under signed is 81 8 x 12 this letter received from in cross section with a drainage ditch at one I 1 side mr hugh dolan the one foot deep below sill and two feet wide the total contractor who drove the length of the tunnel is 2056 feet keffers geffers tunnel for the the single shift system was used viz one drilling and reading philadelphia shift and one mucking shift every twenty f four our hours coal and iron co each round consisted of twenty two holes nine and gives important details ten feet deep an average advance of 72 feet was concerning a noteworthy made for each round the maximum drive was made in achievement in tunnel june 1920 when feet advance was accomplished driving hercules ga L F gelatine and 8 electric blasting caps were used exclusively all holes were tamped camped HEP HERCULES CULES POWDER CO with hercules tamping bags f filled with sand the consumption per linear foot was pounds of gelatine or 43 pounds of explosives for each cubic yard of excavation in view of the hard conglomerate through which the tunnel was driven we consider this a very good berf performance or the writer has used hercules almost exclusively in all his tunnel and shaft work since this brand has been on the market and its performance has been consistently satisfactory the low freezing feature especially commends it for a job like the above which was electrically driven no powder was thawed during the duration of the work october 1919 july 1920 very truly yours hejka C EMES POWDER CO chicago chattanooga salt lake city hazleton pa pittsburg kan st louis pittsburgh pa joplin wilmington del york san francisco denver new |