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each of these samples. Because it is relatively uncommon for natural soils to have Ra -226 concentrations <br />lower than 1 pCi /g, and these values represent part of the overall statistical distribution of measurements <br />as calibrated against ELI results, these low end final estimates are considered valid. <br />The results of the above adjustments to raw onsite counting data indicate that in general, final estimates of <br />Ra -226 and U -nat based on onsite soils lab measurements had good statistical agreement with analytical <br />results from ELI (Figure 5, top). As normally expected for this field lab methodology, Ra -226 estimates <br />had stronger agreement with analytical results from a commercial laboratory than did U -nat estimates. To <br />better visualize numerical differences at the lower end of the scale, the correlative comparisons were also <br />graphed with axes truncated to show only the lower range of measured values (Figure 5, bottom). <br />800- <br />700 - <br />600- <br />500 - <br />400 - <br />300- <br />200- <br />100 - <br />0 <br />120 - <br />° <br />. • 80- <br />N . <br />N 60 <br />te 40- <br />w 20 <br />0 <br />Ra-226: Field Lab vs ELI Results U -nat: Field Lab vs ELI Results <br />y =0.993x+3.340 <br />R =0.998 <br />O 200 400 600 800 <br />Onsite Soils Lab Ra -226 (pCi /g) <br />y = 0.993x + 3.340 <br />R • 0.998 <br />• <br />• <br />•• <br />O 20 40 60 80 100 120 <br />Onsite Soils Lab Ra -226 (pCi /g) <br />7 <br />900 <br />m <br />& 600 <br />a <br />c <br />D 300 <br />J <br />W <br />250 <br />To 200 <br />c..) <br />�+ 150 <br />10 <br />f 100 <br />m <br />W 50 <br />0 <br />y = 1.00x - 0.00 <br />R =0.97 <br />300 600 900 <br />Onsite Soils Lab U-nat (pCi /g) <br />0 50 100 150 200 250 <br />Onsite Soils Lab U-nat (pCi /g) <br />Figure 5: Comparison of final onsite field lab estimates and results from a commercial <br />laboratory (ELI). Tog: Correlations between soils lab estimates and corresponding <br />analytical results from ELI. Bottom: Correlation data plotted with truncated axes to <br />better illustrate numerical differences in the lower range of values. <br />Unprocessed (bulk) aliquots of most samples sent to ELI for Ra -226 and U -nat analysis were also <br />analyzed by a Synthetic Precipitation Leaching Procedure (SPLP, EPA method 1312) to evaluate the <br />potential of this material to leach uranium and other constituents of potential concern. <br />