Appendix A Memorandum for: CTU 3.1.7 From: CTU 3.1.1 Subject: CRATER SURVE YS— ALL SITES LESS E+ Reference: SDF-649 The crater surveys being conducted by Holmes and Narver will consist of detailed surveys of the tower areas to determine the shape and size of the craters and determinations of the amount of material removed and the earth movement produced by the blasts. To facilitate the latter, a number of reference points will be required which will consist in part of existing structures to which should be affixed a ceference mark, and the remainder are to be steel survey stakes. , Iron structures imbedded in the concrete of existing structures can serve as the reference, or in case this is impractical, a gun-driven slug flush with the surface may be used. Any markings on the metal or concrete should not be depended on to remain after the shot. The steel stakes are to be of solid steel stock approximately 2 in. in diameter and 4 ft long with a pointed end. These should have an identity mark at about the mid-point of the stake. They are to be driven flush with the ground surface and such that the deflection from the vertical may be measured to +5 degrees, by use of gunner’s quadrant or leveling protractor when the stake has been driven at least 2 ft into the ground. The position and elevation from Ground Zero are to be measured to +0.01 ft. On the postshot surveys, the distance by which the stake protrudes is also to be measured to estimate the earth removal. As some time will elapse between shot and survey, during which time there may be some erosion, the exposed portion of the stake should be painted as soon after the shot as possible and the painted length measured at a later date. The inclination of the stakes from the vertical is to be measured on postshot surveys. , The approximate positions of the stakes together with existing structures which may be useful in the surveys are: : SITE C 4 Stake positions: On a line 113° to Ground Zero: at 25, 50, 75, 100, 150, 200, 250, 300, 400, and 500 ft On a line 293° to Ground Zero: : at 25, 50, 75, 100, 150, 200, 250, 300, 400, and 500 ft On a line 210° to Ground Zero: at 25, 50, 75, 100, 150, 200, 250, and 300 ft On a line 348° to Ground Zero: at 25, 50, 75, 100, 150, 200, 250, 300, 400, and 500 ft ss Oy 23