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<br />Review of the standards used to compare against baseline <br />ground water chemistry at the Yoast Mine resulted in discovery <br />that the drinking water standard for mercury is 2.0 ug/1 <br />(CDOH, 1994), not .05 ug/1. Also, the review resulted in <br />finding the livestock standard for mercury is 10 ug/1. <br />Further review of the standards used to compare against all <br />water quality data resulted in SCC rerunning comparisons of <br />all revised standards against ground, spring, and surface <br />water quality data. Tables 7-19 (Domestic Drinking Water <br />Standards), 7-21 (Agricultural Standards), and 7-23 (Livestock <br />Standards) have been revised based on the review. Also, the <br />tables which present the comparison results have been revised <br />(Tables 7-20, 7-22, 7-24, 7-27, 7-28, 7-34, 7-35, and 7-36). <br />Where necessary, text changes have been made in order to <br />address the revised list of standards or the comparison <br />results. Because of the revisions to the mercury standards, <br />the discussion of mercury concentrations and detection limits <br />referenced on Page 66 is no longer applicable and has been <br />deleted. <br />23. Table 7-9 in Tab 7 has been expanded with several notes to <br />explain why there are some unreported hydraulic conductivity, <br />discharge, and storage coefficient values for certain wells. <br />24. As was explained by SCC in Denver (February 1, 1995), the text <br />on Page 26 in Tab 7 is correct as worded. A small "q" always <br />means a discharge through a unit width of the aquifer. The <br />small "q" is adequately defined and the modification of <br />Darcy's equation is clear. The large "Q" in Table 7-9 is <br />correct as used. It has nothing to do with the small "q" on <br />Page 26. All hydrology texts use a large "Q" for representing <br />pumping rates in aquifer test equations. The only value from <br />Table 7-9 used on Page 26 is K. <br />25a. Table 7-9 has been revised to include water levels in feet <br />below top of casing (ft btoc) at the time the pumping tests <br />were performed. <br />b. In Appendix 7-3, negative drawdowns are used because the <br />spreadsheet program employed treats drawdown as values <br />increasing in the negative direction (downward) in order to <br />correctly plot the best fit lines from which the slope of s/Qw <br />is determined. Excepting the slug tests for YGAL17 and <br />YGAL18, all drawdowns were measured using air lines and <br />pressure gages. In the case of the two slug tests, electric <br />tapes were used to measure the drawdowns. In some instances <br />(YAAL14, YOV30, YW30, YWU29, etc.), the initial drawdown <br />measured when the air line is loaded is positive. The values <br />are obviously incorrect and are never among those used to <br />calculate the slope of the drawdown data. <br />c. YHAT is an estimate of the regression equation of the latter <br />part of the drawdown data. The r2 used in this instance is <br />5 <br />