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~\ <br />u <br />u <br />Section 779.14(a) Continued. Rule 2.04.6 <br />Montana's Guidelines set a suspect limit of 6.0 mmhosycm. Of the samples <br />from the proposed mine plan area only five (5) samples exceed the more <br />stringent 6.0 mmhos/cm standard. These samples amount to 10.65 percent <br />of the overburden volume for the Kerr samples and 0.69 percent of the <br />overburden volume for the USGS samples. Given the finding of Power and <br />Sandoval (1976) regarding potential bias in EC values due to contamination <br />by drilling fluids, Kerr submits that these values may be elevated as a <br />result of contamination. There are no significant indications that <br />toxicity or potential topsoil suitability problems with exist with EC. <br />Saturation Percent (SP). A total of 67 Kerr samples and 54 USGS samples <br />were analyzed with respect to saturation percent. The saturation percent <br />of all the Kerr samples were within a range of 24.20 percent to 167.7 <br />percent with a mean value of 56.17 percent. The USGS samples ranged from <br />20.3 percent to 122.9 percent with a mean value of 61.0 percent. <br />Montana's Guidelines doe not specify maximum or minimum values for <br />saturation percent, although Wyoming sets a minimum limit of 25 percent <br />and a maximum limit of 80 percent. On a volumetric basis, 6.53 percent <br />of the USGS samples and 4.97 percent of the Kerr samples exceed the <br />Wyoming suspect value, The nine (9) CSU samples collected by Striffler <br />and Rhodes (1981) from regraded spoils had a mean of 36.0 percent with a <br />range of 28.5 percent to 48.8 percent. The USGS samples were analyzed for <br />SP in the CSU Soils Lab as were the samples of Striffler and Rhodes. <br />Comparison of the results from these two (2) sample sets indicates the <br />impact of mixing on relative analysis values. It is anticipated that SP <br />will have no direct effect on groundwater quality. With respect to <br />suitability, most of the samples fall within the piddle of the suitability <br />range. Extensive mixing of overburden during removal and replacement <br />operations as demonstrated by the Striffler and Rhodes data will result <br />in an overall SP value well within the acceptable range. Therefore, no <br />toxicity or other problems are anticipated with respect to SP. <br />Sodium Adsorption Ration (SAR). The work of Power and Sandoval (1976) <br />graphically demonstrates that no overburden sampling parameter is more <br />prone to bias by contamination than is the SAR. Their study shows that <br />the use of drilling fluids dramatically increases SAR values. A drilling <br />779-23 a <br />Revised -April , 1990 <br />