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Ground Water Summary <br />TDS trends are decreasing at four wells and increasing at five wells. <br />CDPHE agricultural ground water standards for pH were exceeded at one <br />monitoring well. In the area surrounding Yoast, ground water is not <br />being pumped for irrigation or livestock watering purposes, nor has the <br />CDPHE classified any aquifer in this region for any use. The above <br />discussion is provided only to serve as a comparative basis to judge <br />ground water quality. <br />In the Probable Hydrological Consequences (PHC, Tab 17, Attachment 17 -5) <br />section of the Yoast Mine PAP, predictions were made as to the expected <br />TDS increases to be observed at various monitoring wells. The following <br />table outlines these predictions along with this year's observed average <br />values (annual average for bedrock wells, May- September average for <br />alluvial wells). <br />Well Predicted TDS values (m /1) <br />YOV30 3201 <br />YW30 2570 <br />YWC33 2721 <br />YAAL14 2036 <br />YGAL16 1296 <br />YSALl 798 <br />YSAL3 798 <br />* indicates value above prediction <br />This years average TDS (mom) <br />2740 <br />7270* <br />790 <br />5030* <br />1590* <br />920* <br />1440* <br />At Annand Draw alluvial well YAAL14, the TDS value observed this year <br />was 5030 mg /l. This value exceeds the predicted value of 2036 mg /1. The <br />GWPOC well for the Grassy Creek Alluvium (downstream of Annand Draw), <br />SGAL70, did not exceed the TDS GWPOC standard, 5036 mg /l. <br />At Grassy Creek alluvial well YGAL16, the TDS value observed this year <br />was 1590 mg /l. This value exceeds the predicted value of 1296 mg /l. The <br />GWPOC well for the Grassy Creek Alluvium, SGAL70, did not exceed the TDS <br />GWPOC standard, 5038 mg /l. <br />9 <br />