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I I I I I I I I I I I I I I I, I I I I .. butlt to the maximum elevation which available volumes of materials will permit. It will be about 30 feet long and we envision that it will be constructed of. sand bags. The lower 24"1 out-let is currently buried by an estimated five feet of concrete and rock rubble and is partially blocked. The outlet opening will need to be cleaned and a 18";1 pipe connected and extended to the cofferdam. Temporary control works will be required. Dam Preparati on Prior to placement of any shotcrete, the dam faces should be free of deteriorated and spalling concrete to provide a fresh and clean face for the adherence of shotcrete. The dam faces should be chipped by hand, sand blasted, and finally cleaned by high pressure water jets. Shotcrete Holes and deteriorated zones would be patched and returned to the origi- nal dam thickness with shotcrete; then, an additional 14"-thick shotcrete face would be placed on the upstream side, and a four inch thick face on the downstream side. Two vertical construction joints with waterstops would be placed in the upstream shotcrete face at locations of theoretically high tensile stresses. The upstream shotcrete would be placed in two lifts. An eight inch thick lift would be placed first and then reinforced with a grid of #4 rein- forcing bars on one foot centers. After the first shotcrete layer has cured, bolts will be tensioned and then the final six inches of shotcrete would be p 1 ac ed . The upstream shotcrete will act as an impermeable membrane. It also reduces stresses in the existing dam by increasing the section thickness, and helps prevent further temperature deterioration of the existing dam. Cracking in the new upstream shotcrete face would be controlled by the reinforcement, tensioned bolts, and the vertical construction joint. The purpose of the four- -25-