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3.2 Secondary Drinking Water Standards <br />Secondary drinking water parameters tested for include (iron, sulfate, total dissolved solids, pH, and chloride). Out of these <br />five parameters, iron, sulfate, chloride, and total dissolved solids exceeded Colorado's Secondary Drinking Water Standards <br />• (SDWS) at least one time during the sampling period. <br />3.2.1 Iron <br />During the November and December 2005 sampling events dissolved iron was determined and during the October 2005, <br />April, July, and October, 2006 sampling events total iron was determined. Dissolved iron was determined from December <br />2006 through October 2007. The baseline levels proposed below were determined using only the dissolved iron results. The <br />baseline levels were determined by calculating the average of the dissolved iron results and adding one standard deviation. <br />The same method was applied in the WOBR. No spatial or temporal trends are apparent in the iron concentrations besides <br />the relatively higher April 2006 concentrations. Even though active mining was taking place in some areas of the site, the <br />dissolved iron concentrations have decreased from the dissolved iron concentration in the November and December 2005 <br />samples. There appears to be no direct influence on the dissolved iron concentrations at this time and the dissolved iron <br />concentrations from November and December 2005 along with December 2006 through October 2007 were used in <br />determining the new baseline level. An unusually high concentration was reported in CRMW16 from the sample collected in <br />December 2006. This high concentration was thrown out and not used in the baseline calculations. <br />There was only one dissolved iron result reported at the time of the WOBR in CRMW09 and CRMW16. Since that time four <br />additional tests have been completed on each of these wells. Both of these wells are located at a fair distance from the active <br />mine area and the groundwater from these two wells are not likely to have been influenced from the mining over the past year. <br />Because of the above mentioned reasons new baseline levels are proposed for these two wells below. <br />Iron <br /> Wells (CRMW) Site/Group <br /> <br /> 01 02 04 05 O6 07 09 16 40 41 42 A VG <br />C)ct !)5 10.33 24.56 32.08 1.721 7.427 4.566 --•- •--- 0.871 7.379 ---- 11.12 <br />Nov-05 0.66 0.79 0.66 0.87 0.63 0.57 0.85 0.72 0.51 0.65 0.70 U.69 <br />Dec-OS 0.72 0.68 0.68 ---• 0.63 0.63 ---- ---- 0.51 0.74 -••• 0.66 <br />Apr-O6 65 76 420 •--- 58 110 ---- ---- 280 43 ---- 150.29 <br />Jul-O6 28 55 13 ---- 33 75 ---- ---- 48 19 ---• 38.71 <br />Oct-06 32 23 16 69 37 73 5.5 55.0 130 8.2 8.9 41.60 <br />Dec-06 0.022 0.012 0.013 ---- ---- ---- 0.009 3.197 ---- ---- ---- 0.851 <br />Apr-07 0.028 0.052 0.042 ---• 0.068 ---- 0.068 0.047 ---- 0.030 ---- 0.048 <br />Jul-07 0.211 0.204 0.006 ---- 0.010 -•-- 0.026 0.208 ---- 0.222 0.016 0.113 <br />Oct-07 0.305 0.041 0.224 0.194 0.470 -•-- 0.061 0.040 0.048 0.266 0.281 0.193 <br />Average 0.32 0.30 0.27 0.53 0.36 0.60 0.20 0.25 0.36 0.38 0.33 0.33 <br />Stnd Dev. 0.30 0.35 0.32 0.46 0.30 0.04 0.36 0.32 0.27 0.30 0.34 0.30 <br />2006 <br />Baseline 0.77 0.77 0.77 ---- 0.77 ---- ---• ---- --•- 0.77 ---- 0.77 <br />2007 <br />Baseline 0.63 0.64 0.63 •••- 0.66 ---- 0.63 0.63 ---- 0.68 ---- 0.63 <br /> <br />The average site-wide result for dissolved iron is 0.33 mg/L with a standard deviation of 0.30 mg/L. Based on the groundwater <br />sampling plan approved by the DBMS, a site wide average may be used plus one standard deviation to establish background <br />levels. This will establish a site wide baseline dissolved iron concentration of 0.63 mg/L. <br />• <br />Annual 2007 Sampling Report -Lupton Lakes -8- January 2008 <br />