discretion of the EG&G scientist and as the need exists. After the data is processed in the IMP, it is stored on a cassette tape and sent to Enewetak. The data are transferred to a floppy disk for use in data evaluation. The cassettes of raw data are stored as a permanent record.* Vv. Typical OperatingSequence Figure A-2-1 shows a block diagram of the typical operating sequence for detection and removal of contaminated soil. Initially the heavy vegetation is removed** to allow the IMP to maneuver between measurement locations. A regular grid pattern is then surveyed (typically a square 25 or 50 meters on a side). The in situ van makes a measurement at each location and determines the 241 Am concentration. The americium data are converted to plutonium concentration and then processed through a statistical routine which provides area-averaged concentration values. In areas where the concentration exceeds the cleanup criteria, the top layer of soil is to be removed. The grid pattern is then reestablished. Those locations within and immediately adjacent to the areas where soil has been removed are remeasured. These new data are processed and the new area averages computed. If they still exceed the cleanup criteria additional soil will be removed. This process continues until the entire island complies with the established cleanup criteria, VL Technique to Locate Contamination Boundaries It is sometimes of value to establish more accurately the location of high concentrations of 24l14m. One technique readily accomplished is to limit the radiation detector's field-of-view by simply lowering the detector from the standard 7.4 to 4.5 meter height (half mast), Although there are greater errors in this position (from van shadowing), the data are useful to determine contamination boundaries, i.e., the ground surface diameter field of view is decreased from 25.6 to 15.6 meters. In the half mast position, the 12.5 meter grid survey is preferred over the normal 50 or 25 meter grid. *Cassettes were erased and reused after the data thereon had been transferred to magnetic tape in Las Vegas. **Brush removal prior to grid survey was limited to Janet. LANE CLEARING : [ > SOIL SAMPLES SOIL SAMPLE ANALYSIS SURVEY IN GRID IMP ENITIAL SURVEY - DATA PROCESSING RESURVEY BY IMP ERDA/ERSP | } CERTIFICATION REMOVALIF NECESSARY PATTERN FIGURE A-2-1. TYPICAL OPERATING SEQUENCE FOR DETECTION AND EVALUATION OF CONTAMINATEDSOIL A-2-2