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The stratum immediately below the lowest mineable coal seam consists of a <br />soft, gray to blue shale with sparse shaley siltstone lenses. This strata is <br />generally 26 feet thick throughout the permit area. Below this strata there <br />are four coal seams that are not considered mineable within the permit area. <br />These coal seams are referred to as Naturita Seams 1 through 4, in descending <br />order. <br />Hydrologic Balance - Ground Water <br />Information on the occurrence and quality of ground water in the permit and <br />surrounding area is provided in Sections 2.04.7(1) and in Exhibit 3 of the <br />Hamilton Mine permit application. The hydrologic monitoring plan is presented <br />on page 2.05-35, and is approved as proposed. <br />The only significant ground water in the permit area occurs in sandstones of <br />the lower Burro Canyon Formation. The applicant has installed 3 monitoring <br />wells, designated BW-1, BW-2, and BW-3, in this aquifer. Alluvial ground <br />water along Naturita Creek will be monitored in four wells installed by the <br />applicant. A well has also been installed in order to monitor alluvial ground <br />water quality in Section 33 Creek. The applicant has collected baseline water <br />level and quality data, and upon commencement of mining all wells will be <br />sampled quarterly for field parameters and full-suite samples will be <br />collected twice per year. <br />The applicant has committed to a spoil spring survey following <br />snowmeit each year. The applicant will sample for water quality any spoil <br />acquifer spring which discharges at least 10 GPM. A report submitted to the <br />Division by June 15 each year will document the survey and report any <br />analytical results. <br />The application is in compliance with the requirements of this section. <br />Hydrologic Balance: <br />Surface Water <br />The Hamilton Mine is located in the San Miguel River drainage basin <br />approximately three quarters of the distance between its source in the San <br />Juan Mountains and its confluence with the Dolores River. The San Miguel <br />River drains an area of 1,080 square miles. The .proposed permit area <br />constitutes 0.1 percent of the San Miguel River drainage. The area disturbed <br />by mining activities will be 0.04 percent of the same drainage basin. It <br />traverses the interior portions of a basin within the Uncompahgre Plateau. <br />This basin trends southeast to northwest and is chiefly underlain by Dakota <br />and Burro Canyon Sandstones, the Morrison Formation and Mancos Shale. The <br />source area is primarily composed of teritary volcanic intrusives. The <br />Morrison Formation and Mancos Shale have the greatest potential for <br />influencing San Miguel river water chemistry. Iorns, et al. (1965) indicate <br />that the waters draining from this area are of a calcium bicarbonate - sulfate <br />type during high flow periods. These waters contain less bicarbonate during <br />low flows while the calcium and sulfate concentrations increase. This <br />concentration increase is caused by less dilution from snowmeit runoff. In <br />addition, approximately 15,500 acres of irrigated land lies between <br />-3- <br />