Laserfiche WebLink
JOHN F. ABEL.JR. <br /> MINING ENGINEER <br /> 17 7 3 7r 310 LOOKOUT VIEW COURT <br /> GOLDEN.CO 80401 <br /> 303.279-4901 <br /> FAX 278$163 <br /> '� nuary 31, 1994 <br /> Mr. Larry Perino <br /> Sunnyside Gold Corp. <br /> P.O. Box 177 <br /> Silverton, CO 81433 <br /> Dear Larry: <br /> This is the letter report you requested concerning my <br /> observations made during the filling of the first F- <br /> Level/Brenneman bulkhead on January 27-28, 1994 . <br /> My insgectio of the bulkhead preparations prior to filling <br /> indicated that the site had been prepared in accordance with the <br /> design specification for all loose rock to be removed prior to <br /> filling. The obvious ribside irregularities grossly exceeded the <br /> magnitude necessary to prevent displacement down the drift if <br /> subject to the design maximum thrust. The #10 rebar tensile <br /> reinforcement cage at 9-inch spacing was- properly positioned 3 . 5 <br /> inches from the downstream (air side) face of the form. The #6 <br /> rebar shrinkage and temperature cage at 12-inch spacing was <br /> properly positioned 3 inches from the upstream (water side) face <br /> of the form. The forms were rigidly braced to positively prevent <br /> both leakage and movement during filling. <br /> The filling took place continuously over the twelve hour <br /> period from approximately 1: 30 PM Thursday January 27th to 1: 30 <br /> am Friday January 28th. The only delays that occurred resulted <br /> from temporary blockages of the concrete slick-line as the result <br /> of the presence of small pre-set pieces of concrete in a few of <br /> the pre-mixed bagged concrete, loosening of a hydraulic fitting, <br /> loss of an 0-ring, replacement of the V-belts for the compressed <br /> air driven screw feeder and temporary blockage of the injection <br /> pipe resulting from back-pressure during final filling of the top <br /> of the form at the back of the tunnel. None of the delays <br /> exceeded one-half hour, considerably less than the allowable <br /> three hours at the ambient tunnel temperature of 44°F. <br /> Additional setting time was available throught the delay setting <br /> agent added at the mixers. The additi onal time for setting was <br /> not required because of the continuity of the filling operation. <br /> The water/cement ratio was maintained between 0.45 and 0.49 <br /> by metering the water to each batch at the concrete mixers. <br /> Twenty 6-inch diameter by 12-inch long concrete test samples were <br /> taken, four for every 5 cu yd starting after 2.,5 cu yd had been <br /> filled into the bulkhead form. The final four test samples were <br /> taken of the maximum water/cement ratio concrete:- The design <br />