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• Larry Perino Page 2 May 28, 1994 <br /> The initial startup Tuesday morning resulted in a plugging of <br /> the slickline at 120 feet, due to segregation of the mix. It was <br /> decided to increase the slickness of the mix by adding one 94 lb <br /> bag of Type 5, sulfate resistant Portland cement to the 1:2 .5: 3.5 <br /> specified mix, resulting in a slicker mix for pumping. The <br /> resulting mix was approximately 1:2. 1:3.0. This increased the mix <br /> from a 5.7 bag/yd mix to a 6.4 bag/yd mix. The resulting concrete <br /> should not only be slicker, but should also be somewhat stronger. <br /> Pumping started at about 12: 30 PM, with the slurry preceding <br /> the transitional high cement sand and the adjusted mix. Slurry <br /> started to bypass the form into the plastic drain line at about <br /> 1:00 PM and concrete entered the bulkhead at 1:31 PM. Concrete <br /> pumping was continuous until the form was completely filled under <br /> nearly 600 psi pump pressure at 5:02 PM. This was the first time <br /> that a bulkhead has been completely filled without a single <br /> shutdown. Continuous concrete pumping and filling of the bulkhead <br /> form has always been the goal, but this was the first time, to my <br /> knowledge, that it has been accomplished. <br /> The shorter pumping distances that will be required for the <br /> Terry Tunnel (-- 100 feet) and American Tunnel (� 50 feet) bulkheads <br /> should permit utilization of the original concrete mix. However, <br /> it would be wise to consider slightly increasing the cement content <br /> of the mix for assurance that segregation will not occur in the <br /> slickline. <br /> Congratulations on a very difficult job well done. <br /> Sincerely, <br /> John F. Abel, Jr. <br /> Colorado P.E. 5642 <br />