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Technical Revision 69 12010) Monitoring Reductions 0 <br />Additional reductions of the monitoring plans were requested. Table 1, Current Hydrologic Monitoring <br />Program, has been revised to reflect these changes. In addition, the Surface and Ground Water <br />Parameter Lists (Table 2 and 3) have also been changed. The details of the changes are provided <br />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 4). 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 monitoring wells <br />(see Table 5). On Table 2 and 3, those parameters are indicated with a single strikethrough. One year <br />prior to final bond release, those parameters will be added back onto the parameter lists. Likewise, lab <br />pH and lab conductivity will also be temporarily suspended. Finally, the 'Potentially Dissolved' <br />analytical technique (on the Surface Water Long Parameter List) will be changed to 'Dissolved' as <br />recommended by the CDPHE. <br />Short Surface and Ground Water Parameter Lists (Tables 2a and 3a) have been added to the monitoring <br />plan. These lists were derived from Section 2.05.6(3) of the Colorado coal mining regulations, 2 CCR <br />407 -2. They consist of pH, TDS, iron, manganese (for both ground water and surface water sites) and <br />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 the <br />1980's, a stabilizing trend in the 1990's, and a decreasing trend in the 2000's. Most traditional <br />regression models would fit a straight line to this data set. LOWESS, on the other hand, would plot a <br />smooth curve through the set of data points, indicating a decreasing trend towards the end of data <br />points. A good description of LOWESS may be found on the website: <br />http / /en. wikipedia .org /wiki // olL, _regression <br />Monitoring frequencies for stream sites have been changed from triannual to biannual. Monitoring <br />frequencies for alluvial wells have been changed from biannual (or triannual) to annual. Monitoring <br />frequencies for bedrock wells will remain annual. These monitoring frequencies will be increased to their <br />previous frequencies (as defined above in this paragraph) one year prior to final bond release. <br />TR -69 15 -3a -14 Revised 4/10 <br />