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Groundwater Monitoring Plan <br />Piezometers have been installed around the site to monitor water level in the <br />alluvium bedrock, refuse fill material and the Roadside South Portals mine. Monitoring <br />sites have included the Rapid and Cottonwood Creeks, the Cameo Refuse Disposal <br />Areas No 1 and 2, the Unit Train Loadout, the Rollins Sandstone wells, and the North <br />Decline. Monitoring data and analysis of ground water will be submitted annually as <br />part of the Annual Hydrologic Report and quarterly with the other results. Ground <br />water monitoring points are shown on Exhibit 56. <br />The Rapid Creek and Cottonwood Creek piezometers (GW MS -01 A, 01 B, 02A, <br />02B, 03A, and 03B) were installed, according to stipulation response SR06, to <br />determine if the alluvium along the creeks is being dewatered by mining activities. <br />Baseline monitoring of water levels in these piezometers was generally done monthly <br />from September 1984 through September 1987 when accessible. Monitoring will be <br />continued on a biannual basis in May and September corresponding to the months of <br />high and low flow in the adjacent creeks. <br />Piezometers have been installed in the Cameo Refuse Disposal Areas No. 1 <br />and No. 2 (CRDA -1 and CRDA -2) to monitor the actual piezometric water level in the <br />piles compared with the stability design assumptions. Three piezometers (CRDA -01 <br />through 03) were installed on CRDA -1 in 1984 and a fourth (CRDA -01 a) was <br />installed in 1991. In 1991, 3 piezometers (CRDA -04 through 06) were installed on <br />CRDA -2. These piezometers were developed by installing a 2" perforated PVC pipe <br />in an approximate 4" diameter auger hole. The hole was left open the full length and <br />sealed near the surface. These piezometers have been monitored at least quarterly <br />since installation. Piezometer CRDA -01 on CRDA -1 consistently showed higher <br />water levels than assumed in the stability design calculations. To reevaluate stability <br />of the pile, an additional 16 temporary piezometers were installed in the same <br />manner as the original ones to define the extent of the high piezometric water level. <br />In December, 1993, Western Engineers of Grand Junction, Colorado was retained to <br />TR -62 18 -4 Rev 07/11 <br />