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Section 779.14(a) Continued. Rule 2.04.6 <br />foam, Revert, was found to result in SAR values 152 percent higher than <br />samples of the same material from holes drilled using air only or highwall <br />samples. Low-salt water injection during drilling yielded SAR values 172 <br />percent higher and high-salt water injection yielded values 259 percent <br />higher than the highball collected controls. Use of drilling mud was <br />found to result in SAR values 852 percent higher than the controls. <br />With respect to the Kerr samples, several of the holes are known to have <br />been drilled with foam, water, or mud. All of the USGS samples are from <br />holes drilled with water and foam. Therefore, almost all of the SAR <br />values are potentially subject to bias as a result of contamination. In <br />this analysis all of the values are presented. <br />A total of 67 Kerr samples and 55 USGS samples were analyzed with respect <br />to SAR. The Kerr SAR values ranged from 0.40 to 25.2 with a mean value <br />of 6.40. The weighted average is 8.74. Twenty-three or 38.6 percent of <br />the overburden samples have values above the limit of 15.0 set forth in <br />~. <br />the Myoming Guidelines. For the USGS samples the SAR values ranged from <br />0.43 to 41.4 with a mean of 14.57 and a weighted average of 15.33. <br />Initial examination of these data suggests that overburden SAR levels are <br />potentially toxic relative to revegetation. As previously noted, this <br />conclusion is probably not accurate due to sample bias resulting from <br />drilling fluid contamination. <br />Exchangeable Sodium Percentage (ESP). ESP values presented in the <br />original Kerr permit were not directly calculated but were determined <br />using the correlation graph from USDA Handbook 60 (Saline and Alkaline <br />Soils, 1969). Since they are not calculated values they are not addressed <br />in the present discussion. <br />Cation Exchange Caoacity (CEC). A total of 54 Kerr samples and 65 USGS <br />drillhole samples were analyzed with respect to CEC. CEC values for the <br />• <br />779-23 b Revised - Apr11,1990 <br />