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Exhibit 71 Hydrologic Characterization South of [he Divide Area and Monitoring Plan 1 <br />• 1.0 SUMMARY <br />Mountain Coal Company, LLC (MCC) is planning to develop a new coal lease tract south of the existing <br />West Elk Mine (WEM), the South of the Divide Permit Revision Area (SOD). The boundaries and <br />location of the SOD tract are illustrated on Map 1. This document, Exhibit 71, includes a detailed <br />hydrologic chazacterization of the SOD tract and asite-wide hydrologic monitoring plan to support the <br />Permit Revision (PR) for the SOD tract (PR-10) at the request of the Colorado Division of Mining and <br />Geology (CDMG, 2006a). MCC retained HydroGeo, Inc. (I-IydroGeo) to complete Exhibit 71 and to <br />provide additional hydrologic consulting services, as necessary, in pwsuit of the PR-10 approval. <br />HydroGeo is very familiar with the hydrology of the WEM area, as a result of expertise gained while <br />conducting the annual hydrologic monitoring and prepazing Annual Hydrologic Reports for the WEM, as <br />required by the CDMG, for the past four consecutive years. In addition, HydroGeo has over 25 years of <br />professional consulting experience covering a vast array of mining-related hydrology issues for projects <br />in the U.S. and abroad. <br />This document characterizes the swface and ground water hydrology in the SOD area including the Deep <br />Creek, Dry Fork, Lick Creek, and South Prong Creek drainages. This document also presents a <br />hydrologic monitoring plan for the WEM that is designed to provide information on the PR-10 azea. The <br />• hydrologic monitoring plan incorporates a separate baseline monitoring schedule for approximately one <br />yeaz prior to expanding mine development in new areas for newly added monitoring sites (CDMG, <br />2005b). <br />The information presented in this report is derived, in part, from the following resowces: <br />o Annual Hydrology Reports, West Elk Mine (HydroGeo, 2001 - 2005) <br />o Baseline water quality statistics, Pre-2000 data (Wright Water Engineers (WWE), 2001) <br />o Seep, Spring, and Stock Pond Inventory of the South of Divide Study Area (W WE, 1997b) <br />o Updated Natwal Resowces Inventory for South of Divide Study Area (W WE, 2005) <br />0 2004 aerial photographs of the WEM azea (MCC, 2005) <br />o U.S.G.S. quadrangle maps of the area. <br />It is important to note that the raw data used to derive baseline water quality statistics presented in this <br />report for the older monitoring sites were collected prior to year 2000 and were not available for this <br />document. However, all water quality data collected from years 2000 through 2005 are presented in the <br />appendices along with the original (pre-2000) baseline statistics. Flow data for surface water stations <br />(WY 2005} and water level data for wells (period of record) are presented graphically in the appendices. <br />CDMG and MCC agreed with the arrangement of the hydrologic data presented in this document in April <br />2006 (CDMG, 2006b). <br />Apri12006 HydroGeo, Inc <br />