to stop leakage in the manifold system. It required considerable pumping before all of the entrapped air in the tubes and tips was removed. Weekly readings were taken on the master gage and separate gages until all the entrapped air was removed from the system. The installation along station 43+00 was similar to the one at station 49+00 . Two of the extension pipes were 1-1/2 inches, and the remainder were 3/4 inch. In the drilling of the holes for tips No. 5 and 9, the first layer of clay encountered was only 1 foot thick. An additional tip was placed in the coarse gravel below the 1-foot clay stratum and above the next layer of clay, Gages and valves were ordered for this tip and numbered 31. In the terminal well at station 43+00, the manifold system was fabricated in the same manner as at station 49400, except that the pipe connections were soldered. The valves and gages were mounted as shown in figure 73. This method required 48 fewer holes to be drilled in the concrete wall and made it easier to connect the tubes from the tips to the gages and the tubes from the gages to the valves. Here again the kaires had to be ground and the bonnet seats smoothed before the leaks in the system were supped. After pumping was started, a break in the tube for tips No. 23 through 30 was noted because water could not be circulated through them. A timbered pit was excaxaled on he slope of the dam at a location determined by the residual pressure shown De gages The breaks in the tubes were found and repaired by making spliced COMEETEUS and Den testng under air pressure. Water was etrelated through the tubes decore Me 2x was backÒlled Most of the tube markings were near the break, and very moting the tubes from the terminal well with the |