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~ L <br />Historical observations from mines in the Hay Gulch area indicate that the <br />coal bearing strata are essentially dry. There have not been any documented <br />discharges from the La Plata No. 1 Mine or from adjacent, abandoned mines. <br />Although it is expected that the workings will not encounter significant <br />quantities of water, overlying perched aquifers may dewater into the mine due <br />to mining activities. The inflow from these units should be small. This <br />water will be used within the mine during the course of operations. <br />The Point Lookout Sandstone aquifer is located about 275 feet below the mined <br />unit and will not contribute water to, or be affected by, mining operations. <br />With the acceptance of the above stipulations, the applicant is in compliance <br />with requirements of this section. <br />VI. Surface Water Hydrology - Rules 2.04.5, 2.04.7(2}, 2.05.3(4), 2.05.6(3) <br />and <br />Information on surface water hydrology can be found in Sections 2.04 (pages <br />2.04-12, -19 to -21), 2.05 (pages 2.05-18, -20 to -23, -48 to -49), 4.05 <br />(pages 4.05-1 to -12) and Exhibits 3, 7, and 13 of the permit application. <br />The facilities of the proposed La Plata No. 1 Mine are located in a small <br />ephemeral drainage basin which is tributary to Hay Gulch. There is no flowing <br />stream within the valley of Hay Gulch at the location of the mine. Instead, <br />an irrigation ditch has been constructed on the north side of the valley to <br />transport streamflow. Prior to diversion, the stream flowed in a westerly <br />direction on the south side of Hay Gulch. Runoff from upland areas enters the <br />alluvium in the valley bottom and is eventually discharged into the La Plata <br />River at a location about 7.5 miles downstream (southwest) of the mine. <br />A sediment pond will be located below the facilities area to control runoff <br />and sediment generated within the drainage basin. The basin encompasses an <br />area of 11.2 acres. Basin boundaries are delineated on Map 7 in the permit <br />application. The basin presents a south-facing aspect and has fairly steep <br />slopes. Runoff above the portals will be routed to the sides of the bench <br />with a berm. Runoff from the bench area will be routed to a downdrain and <br />directed into the lower bench drainage system. Ditches along the sides of the <br />bench empty into grated concrete drop inlets. Runoff is routed to the <br />sediment pond under County Road 120 via culverts and ditches as described in <br />Exhibit 13 and shown on Map 7. <br />The sediment pond has been designed to treat the runoff from the 10-year, <br />24-hour rainfall event. The pond was constructed by Sunbelt Mining, Inc., and <br />will be modified to meet the design requirements of Rule 4.05.6. Calculations <br />used in the pond design are provided in Exhibit 7 and are shown on Figure 8. <br />A review of these materials indicates the pond design meets the requirements <br />of Rule 4.05.6. <br />A sewage treatment system will be constructed at the mine. The septic tank <br />and leach field system have been approved by the San Juan Basin Health Unit. <br />This permit is located in the application under Exhibit 3. As the potential <br />exists for a seasonal high water table to reach the bottom of the leach field, <br />an observation well will be installed and monitored. <br />-14- <br />