CHAPTER If, SECTIONS 1-1A Aeld inspectors to the greatest extent possible. rhe weekly progress report detailed activity ‘n open construction work orders which reached a maximum number of 337 on the Eniwetok Atoll and 339 on the Bikini Atoll for a total of 676. SECTION IA SURVEYS Surveys by Holmes & Narver at the Pacific Proving Ground were initiated at Eniwetok Atoll in February 1949 with the topographic mapping of project islands for design purposes. As additional personnel arrived, the activities of the department expanded to include a hor- Atoll. This scheme was expanded in 1951 and 1952 to include the entire Atoll and consisted of primary network of second order triangulation stations supplemented with third order stations at locations of lesser importance. Test hydrography, construction layout, and special surveys to satisfy scientific requirements and to required, by tions of the are included ERATIONS izontal control network, additional topography, provide assistance to Users. Surveys at Eniwe- tok were a continuation and expansion of these activities to fit the special needs of three test operations. With the expansion of the PPG to include Bikini Atoll, a survey program was initiated in this area following the same general pattern of surveys previously performed in the Eniwetok Atoll area. The majority of the survey personnel were stationed at Bikini Atoll during the CASTLE program with a maximum of six field parties and supporting office personnel. The smaller program at Eniwetok Atoll was served by two field parties with some transfer of personnel between areas to meet peak work loads. The sequence of surveys at both areas was dependant on priorities for the services of the department. As construction layout proceeded simultaneously with design and control surveys, it was not possible to follow the normal procedure of first establishing horizontal and vertical control and then proceeding in sequence through design surveys and construction layout. This condition did not permit maximum efficien- cy in performing the design and control surveys, but as construction layout was kept on a current basis at all times, the procedures used were just- ified. The earlier surveys were covered in detail in reports of OPERATIONS GREENHOUSE and IVY, and the following is primarily a description of survey activities at Bikini Atoll through the CASTLE program. In view of the recoverability of the work and its probable future value in any use of the area, however, sufficient sistorical summaryis given to evaluate its cartgraphic significance. HORIZONTAL CONTROL — ENIWETOK ATOLL _A horizontal control scheme was establish- ed in 1949-50 covering the eastern portion of the Page 2-6 operations destroyed some of the original stations and new stations were established, as expansion from the remaining pornetwork. Records of these surveys in the completion reports for OPGREENHOUSEand IVY. PREVIOUS SURVEYS. A study of previous surveys within the Atoll was made and some features of these surveys were utilized in establishing the scheme. Theavailable records of these surveys are included in “The Report of the Engineer, Joint Task Force SEVEN, Part 2,” dated 1948. The earliest survey was completed in 1944 by the USS Bowditch to control the hydro- graphic mapping of the Atoll. This survey was of third order accuracy, and as most of the stat- ions were not on project islands it was not adaptable to requirements of this project. However, the Bowditch geographic position of Station North Base on Runit Island and the azimuth of the line Station North Base-Station Sand becamethe origin of position and azimuth for the later surveys. A survey was completed in 1947-48 by Joint Task Force SEVEN, consisting of a limited scheme covering the eastern portion of the Atoll. The scheme was reported to be of first order accuracy but it was only because of its limited extent that it could be considered to be of such high order. As the south end of the original (USS Bowditch) base line had been destroyed, a new base line, North Base-Runit, was established and the azimuth of this line was computed from its relation to the line North Base-Sand. Expansion of this scheme involved re-occupation of all of its existing stations and it became obvious that to meet project require- ments, a substantially new and stronger scheme was necessary which could be expanded as required. 1949-50 HORIZONTAL CONTROL SURVEY. This scheme was designed to meet the control requirements of OPERATION GREENHOUSEand to be adaptable to future expan-