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Appendix C <br />Refuse Pile Expansion East <br />Sampling, Testing, and Monitoring Plan <br />Mountain Coal Company, LLC <br />January 2010 <br />The monitoring plan for the RPE East includes installation of instrumentation to monitor and analyze <br />the following aspects: seepage /groundwater, deformation /stability, and geotechnical properties of <br />refuse material. These are relevant aspects associated with the design assumptions used in the <br />geotechnical design and analysis that need to be verified during construction in accordance with the <br />Observational Approach (R.B. Peck, 1969), which is recommended for monitoring the RPE East. <br />The results of the monitoring program will be compared to design parameters established in the <br />permit application and analyses performed as required. The following describes in detail the <br />anticipated monitoring plan of these aspects for the site. <br />Seepage /Groundwater <br />Piezometers will be installed in the RPE East and a weir will be installed near the toe of the buttress <br />to monitor groundwater and seepage. <br />The piezometers will be installed along the centerline of the pile alignment in the intermediate <br />benches in the approximate locations shown on Figure C -1. The piezometer tips will be located <br />within the refuse pile material and in bedrock as shown in the cross section (Figure C -2). It is <br />anticipated that a total of 12 piezometers will be installed. Two piezometer tips will be installed in a <br />single borehole at locations PZ -3, PZ -5, and PZ8. It is anticipated that the piezometers will be <br />installed using the fully - grouted method. The piezometers will be installed as construction of the <br />pile proceeds. Pore - pressure readings will be collected using data loggers and the data will be <br />downloaded quarterly. <br />The weir will be installed near the toe of the buttress as shown on Figure C -1. Flow measurement <br />will be collected at the weir once a month (when not frozen or snow- covered) for the first two years <br />and once quarterly thereafter. <br />Deformation/Stability <br />Deformation and stability will be monitored through the installation of inclinometers and mirrors. <br />The inclinometers will be installed along the centerline of the pile alignment in the intermediate <br />benches at the approximate locations shown on Figure C -1 (INC - -1, INC -2, and INC -3). The <br />P:\Mpls \06 CO\26 \06261003 MCC Refuse Pile Site Review & Permit\WorkFilesTermit Application\Appendix C Monitoring Plan\Monitoring <br />Plan.doc <br />