Laserfiche WebLink
<br />ROCKY FLATS SOIL PLUTONIUM792A0 SURVEYS FROM 1970 TO 1991 <br />' Samples were taken yearly from 1970 through 1978, though not all of the 13 sectors were <br />analyzed each year. Surveys were conducted in 1980, 1981, 1986 and 1989. In 1989 two of the <br />sectors within the eastern hemisphere of the two-mile radius, Sectors 1 and 2, were sub-divided <br />into nine sectors each and sampled individually. The average of the nine sub-sector's results were <br />used to rE:present the results for Sector 1 and 2 in 1989. The last survey was conducted in 1991 <br />' similarly to the survey of 1489. Areas within the original Rocky Flats Plant Boundary are not <br />included in these surveys. <br />' Methods <br />All soil samples were taken from the surface according to Colorado Department ojHealth, <br />' Radiation Counting Facility, Operating Procedure, Soil sample collection-surface, version I.0 <br />/0-Jul-89. The sampling collection method underwent minor modification in years 1970 through <br />1974 and was standardized in 1975. (CDHe) Preparation of samples was conducted according to <br />' Colorado Department ojHealth, RadiationCornrtingFacility, Operating Procedure, <br />Preparation ojSolids, Air Filters, and Aqueous Samples for Ac[irride Analysis, Counting was <br />performed on Tennelec LB 5100 according to Colorado Department ojHealth, Radiation <br />Counting Facility, Operating Procedure No. QC-17, Temre%c LB SI00 Calibration, QC limits <br />memo and other internal procedures. The results are reported as Plutonium 792°0 . <br />Results <br />The data resulting from these surveys are presented in a series of tables, graphs and maps <br />described below. Where values are reported as less than values, the data has been censored, <br />converted to a numerical value equal to one-half the reported less than number. <br />' Table I presents the yearly results of the soil surveys. Table II presents the same results with all <br />less than values converted to half the reported less than value. Table III, Table IV and Table V <br />presents 1989 and 1991 data for each of the sub-sectors in Sectors 1 and 2, respectively. <br />~ ' Descriptive statistics are provided for censored data. <br />Box and V~/hisker plots are provided for the censored data by sector or sub-sector identified in <br />t map 1. Each graph shows the range, maximum and minimum, the 25th and 75th percentile of the <br />data record, the mean, median, geometric mean and the number of observations for each sector <br />with the state standard for plutonium793°0 superimposed on the graph. Graphs showing yearly <br />t data for Sectors ], 2, 6 and 7 and comparisons of 1989 and 1991 data are provided. <br />' Several geographical information system, (GIS) maps using ARC software have been prepared to <br />demonstrate the spatial distribution of the results. Maps show a measure of central tendency <br />(median) using the entire data set and variations of the data set to highlight areas of higher <br />' resolution and change over time. <br />2 <br />' ~,n.~ <br /> <br />