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Groundwater Monitoring Plan <br />Piezometers were installed around the site to monitor water level in the alluvium bedrock, refuse <br />fill material and the Roadside South Portals mine. Monitoring sites have included the Rapid and <br />Cottonwood Creeks, the Cameo Refuse Disposal Areas No 1 and 2, the Unit Train Loadout, the <br />Rollins Sandstone wells, and the North Decline. Monitoring data and analysis of ground water <br />will be submitted annually as part of the Annual Hydrologic Report. Ground water monitoring <br />points are shown on Exhibit 56. <br />The Rapid Creek and Cottonwood Creek piezometers (GWMS-01A, 01 B, 02A, 02B, 03A, and <br />03B) were installed, according to stipulation response SR06, to determine if the alluvium along <br />the creeks is being dewatered by mining activities. Baseline monitoring of water levels in these <br />piezometers was generally done monthly from September 1984 through September 1987 when <br />accessible. Monitoring continued on a biannual basis in May and September corresponding to <br />the months of high and low flow in the adjacent creeks until, with the approval of SL -8 and TR - <br />67 in 2015, monitoring was discontinued. These piezometers will be abandoned and plugged in <br />early 2016. <br />Piezometers were installed in the Cameo Refuse Disposal Areas No. 1 and No. 2 (CRDA-1 and <br />CRDA-2) to monitor the actual piezometric water level in the piles compared with the stability <br />design assumptions. Three piezometers (CRDA-01 through 03) were installed on CRDA-1 in <br />1984 and a fourth (CRDA-01 a) was installed in 1991. In 1991, 3 piezometers (CRDA-04 <br />through 06) were installed on CRDA-2. These piezometers were developed by installing a 2" <br />perforated PVC pipe in an approximate 4" diameter auger hole. The hole was left open the full <br />length and sealed near the surface. Piezometer CRDA-01 on CRDA-1 consistently showed <br />higher water levels than assumed in the stability design calculations. To reevaluate stability of <br />the pile, an additional 16 temporary piezometers were installed in the same manner as the <br />original ones to define the extent of the high piezometric water level. In December, 1993, <br />Western Engineers of Grand Junction, Colorado was retained to evaluate stability as a result of <br />higher than expected water levels in the pile. Their evaluation was inconclusive due to the <br />piezometers being open the full length of the hole. <br />TR -67 18-4 Rev 11/15 <br />