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For stream sites, monitoring at YSS2 (Sage Creek below Pond 012) have been changed from monthly to tri- <br />annual (spring runoff, post -runoff and baseflow). For spoil springs, monitoring has been changed from semi- <br />annual to annual (May — July). Three new spoil springs ( #2, 3 and 4) have been included into the <br />monitoring program. Table 15 -9, Surface Water Monitoring Frequencies (page 24, Tab 15), has been <br />revised to reflect these changes. <br />Yoast Technical Revision 39 (2009) Monitoring Program Changes <br />This technical revision assigned ground water points of compliance for the Yoast Mine. Details for this <br />revision are found in Attachment 15 -1. <br />Yoast Technical Revision 47 (2010) Monitoring Program Reductions <br />Additional reductions of the monitoring plans were requested. Table 15 -8 and 15 -9, Ground Water and <br />Surface Water Monitoring Frequencies, has been revised to reflect these changes. In addition, the <br />Surface and Ground Water Parameter lists (Tables 15 -5 and 15-4) have also been changed. The <br />details of the changes are provided below. <br />In regards to changes to the parameter lists, the following changes were made. Parameters without <br />CDPHE standards were removed from the 'long' lists. In addition, arsenic, boron, cadmium, chloride, <br />chromium, copper, lead, nickel, silver and zinc were removed from the Surface Water Long Parameter <br />List, since no (or very few) exceedances of those parameters occurred from 2005 to 2009 at stream <br />and NPDES sites (see Table 15 -10). Likewise, aluminum, arsenic, boron, cadmium, chloride, chromium, <br />copper, lead, mercury nickel and zinc were removed from the Ground Water Long Parameter List, since <br />no (or very few) exceedances of those parameters occurred from 2005 to 2009 at the monitor wells <br />(see Table 15 -11). On Tables 15 -4 and 15 -5, those parameters are indicated with a single <br />strikethrough. One year prior to final bond release, those parameters will be added back onto the <br />parameter lists. Likewise, lab pH and lab conductivity will also be temporarily suspended. Finally, the <br />'Potentially Dissolved' analytical technique (on the Surface Water Long Parameter List) will be changed <br />to 'Dissolved' as recommended by the CDPHE. <br />Short Ground and Surface Water Parameter Lists (Tables 15 -4a and 15 -5a) have been added to the <br />monitoring plan. These lists were derived from Section 2.05.6(3) of the Colorado coal mining <br />regulations, 2 CCR 407 -2. They consist of pH, TDS, iron, manganese (for both ground water and <br />surface water sites) and total suspended solids (TSS, for surface water sites only). <br />The 'short' parameter lists will be used for sites that display stable or decreasing TDS trends, as <br />indicated in 2008 AHR, and as discussed with CDRMS personnel in February 2010. Sites that display <br />increasing TDS trends will use the long parameter lists. TDS trends are determined by a statistical <br />method known as LOWESS (locally weighted scatterplot smoothing). The advantage of LOWESS is <br />that it fits a trend that varies over time. Take, for example, a site that had increasing TDS values in <br />the 1980's, a stabilizing trend in the 1990's, and a decreasing trend in the 2000's. Most traditional <br />TR -47 31 Revised 4/10 <br />