CHAPTERII, SECTION 3 withstand expected overpressures. The buttress was formed of six concrete thrust blocks from which six 14-inch 142 #WF beams extended upward to the top of the wall. An equipment room of reinforced concrete 19’ x 32’ x12’ high with 1’-6” walls was added to each station. In this room was placed dehumidifying equipment, two generators, and a helium gas system using six User-supplied manifolds. The piping from helium bottles to manifolds was required to be approximately the same lengths, and criteria required that the leakage of helium not exceed 1 CFH of gas at standard pressures and temperatures during a 24-hour period. It was necessary to remove the old wiring and pull new wires. Holes were drilled through the heavy existing east wall for running hydraulic and electrical connections between existing structure and the new equipment room. A plywood dust cover was fitted in the chimney of the existing structure with removable plywood covers at one end of the dust cover to provide access. Two 14-ton electric hoists were mounted: one on the boom above the entrance to the station, the other above the hatch between Rooms 1 and 2. New doorlatch assemblies Figure 2-109. Page 2-116 were designed, fabricated, and installed for the blast doors of the 24” wide camera port. New type latches were required so that the blast doors would be gas-tight when closed. Work benches, access ladders and stairways, storage shelves, fuel tanks, compressed air systems for blast door operation, and salt water pumps were also required. Power for Station 2300 was furnished by two - 35 KW generators installed in the equipment room. Power for Station 2301 was furnished from the island distribution system through a 35 KVA transformer installed in the equipment room. Sixteen-pair timing signals were terminated in Station 2300 and six pair terminated in 2301. A telephone with an extension to a trailer was provided at each station. In Station 2301 there was a noticeable amount of spalling of the existing limonite caused by oxidation of the metal pellets. All such loose material was chipped out and the affected surface was treated with a coat of bitumastic for waterproofing. Completion of these stations was somewhat delayed because of late equipment delivery. Station 2300