2008-01-15_HYDROLOGY - M2004078 - Laserfiche WebLink

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3.2.2 Sulfate Sulfate concentrations exceeded SDWS five times from the December 2006 through October 2007 sampling events. A sulfate • concentration in a sample collected from CRMW01 of 272 mg/L exceeded the SDWS of 250 mg/L in December of 2006. The sulfate concentration in a sample collected from CRMW02 in April 2007 was 257 mg/L and in July 2007 was 255 mg/L. The sulfate concentration in a sample collected from CRMW09 in April and October 2007 were 255 mg/L. The highest overall sulfate concentrations are found in the northern portion of the site downgradient of cultivated farm fields. The highest concentration of sulfates can generally be found in wells CRMW01, CRMW02, CRMW09, and CRMW16. Wells located near the active mine area have shown a slight decrease in sulfate concentrations. The sulfate concentration in CRMW01 exceed the baseline level of 243 mg/L in December 2006 and also in the baseline level in CRMW02 of 240 mg/L in December 2006, April 2007 and July 2007. Both of these wells are located in the northwest corner of the site about a mile from the active mine area. Since the groundwater in these two wells have likely had very little influence from the mining activities a new baseline level is proposed below that incorporates sulfate test results from October 2005 through October 2007. There were only two sulfate results reported at the time of the WOBR in CRMW09 and CRMW16. Since that time four additional tests have been completed on each of these wells. Both of these wells are located at a fair distance from the active mine area and the groundwater from these two wells are not likely to have been influenced from the mining over the past year and therefore new baseline levels are proposed for these two wells below. Sulfate Wells (CRMW) Site/Group 01 02 04 05 O6 07 09 16 40 41 42 A VG Oct-05 194 204 151 ---- 220 190 ---- ---- 174 176 ---- 187.1 Nov-05 216 238 223 265 240 209 135 249 192 216 227 219.1 Dec-05 208 222 223 ---- 220 199 ---- ---- 186 213 -•-• 2i0. i Apr•O6 206 211 246 ---- 215 192 ---- ---- 171 213 ---• 207.7 Jul•06 227 217 139 •--• 224 181 --•- ---- 149 215 -•-- 193.1 Oct-06 263 249 201 151 171 228 181 234 208 222 230 212.5 Dec-06 272 248 214 ---- ---- ---- 201 244 ---- ---- ---- 235.9 Apr-07 225 257 143 ---- 199 ---- 255 243 ---- 223 ---- 220.8 Jul-07 221 255 95 ---- 190 ---- 232 253 --•- 213 196 206.9 Oct•07 230 233 131 205 185 ---- 255 222 138 161 170 193.0 Average 226.3 233.4 176.7 207.0 207.1 199.6 209.8 240.9 174.0 205.8 205.6 208.06 Sind Dev. 24.4 19.2 50.5 57.0 22.2 16.7 47.1 11.1 24.2 21.8 28.5 35.51 2006 Baseline 243 240 240 ---- 238 237 ---- ---- 237 237 --•- 237 2007 Baseline 251 253 240 ---- 238 237 25? 252 237 237 ---- 237 The average site-wide result for sulfate has increased 1.37 mg/L from the WOBR to 208 mg/L with a standard deviation of 35.51 mg/L. • Annual 2007 Sampling Report -Lupton Lakes -9- January 2008