Control was established by placing brass-capped concrete monuments about six inches below the ground surface on axes radial and normal to ground zero. These monuments were then tied in to the local plane coor- dinate system. Locations for the points were laid out roughly; drive-it pins or drill holes were placed in the structures and then located in three planes by the use of a transit and tape and an engineer's level. During the pre-blast survey, considerable difficulty was experienced be- cause of construction equipment, wind , and dust. As the work progressed, however, the men became more proficient in working with equipment and under conditions not usually associated with surveying. All work was completed prior to "E" day, including extra points requested by the Users. The second phase of the work was started as soon as radiologically possible after "E" day. All momuments and bench marks were checked by re-establishing their position with respect to one another. All avail- able men were used on this re-survey, and the work was completed on the last working day prior to "G" day. Because of lack of time, it was not feasible to re-establish the precise chaining bucks for a further check of the control monuments; however, within their own system there was no observed movement of the monuments either vertical or horizontal. The results of the two surveys were assembled in tabular form and the differences in location of each point were obtained. It should be noted that while the notes indicate differences to 0.001 feet, it is believed that the accuracy of the survey does not exceed plus or nimis 0.01 feet. The azimuths and distances of each station built on the experiment islandsare shown in Appendix C of this report. SURVEY RECORDS In setting up survey procedure, one objective was to provide permanent horizontal and vertical control which could be recovered for future surveys and make possible the avoidance of duplication of effort, All primary control points were set up as concrete monuments with an established elevation. When practical, reference monuments were set at these locations, Local control on the experiment islands consisted of concrete monuments whose interrelation was determined. Most of these monuments can be considered permanent or replaceable from other remaining monunents. Field notes were kept in duplicating field books and are available covering all field surveys. Maps were made from these notes, showing the horizontal and vertical control layout for each location. Records of the primary horizontal control survey were made up on transparancies in order that duplicate copies could be prepared as required. PERSONNEL The survey personnel in the original group arriving at the Jobsite in’ February 1949 consisted of a department head and one instrumentman, 5-73