existing portions of air conditioning units in these buildings should be salvaged for use in less important locations. lighting and communication repairs recommended for existing structures are described elsewhere in this Report. Realignment of Gamma Stations. The tubes in Gamma Stations are now aligned to a former sight point approximately 200 feet high at center of Zero Tower location. As it is now recommended to locate new Zero Towers 75 feet beyond former Zero tower location ami use a tower 100 feet higher, it will be necessary to change the alignment of the existing tubes. Analysis was made as to the possibilities of reaming out present tubes and installing new tubes but the vertical displacement necessary and the difficulty of field drilling through limonite concrete was such that this proposal was abandoned. Similarly, a study of cutting out the entire tube rack and in- stalling a new set of tubes properly aligned was discarded as possible but very difficult and expensive. 4s the realignment figured for Gamma A Structure on Engebi, as an example, required approximately 3-1/2" vertical lift to meet the new requirements, it is recommended that the following procedure be followed: of Gamma structure and install bearing pad. building to correct. vertical elevation. Excavate under front end Use screw jacks to raise front of Should horizontal change in alignment be considered necessary it is recommended that the Zero Tower be set on an extension of Gamma line instead of on Zero line extension. Dry packing or pres- sure grouting can be utilized to firm up this new alignment. Additional Structures. Should additional tubes be required at present Gamma locations, it is proposed that new buildings of similar design to existing structures be built alongside present buildings. Such blast structures and foundations as may be required for the