Laserfiche WebLink
dischazged seasonally at a rate of 4 to 5 gallons per minute and a pH of 3. <br />The seep has not flowed in recent years and, due to its small size, is not <br />considered to have a significant impact on the hydrologic balance. <br />Surface Water Impacts: <br />The only surface water feature that would receive surface runoff from the La Plata <br />surface disturbance is Hay Gulch. The Gulch does not have a stream channel An <br />irrigation ditch flows through the bottom ofthe Gulch. The King Coal Mine monitors <br />the quality of Hay Gulch alluvial water in the Wiltze well, approximately one mile <br />downstream from the La Plata Mine. This monitoring indicates no adverse impacts <br />to the alluvial water from the La Plata Mine. The only surface water from the La <br />Plata surface disturbance that would reach Hay Gulch is surface runoff from rain or <br />snowmelt. (As previously discussed, a dischazge from the portal azea has not <br />occurred.) Surface runoff from the disturbed area can be expected to be alkaline and <br />free of contaminants as there are no leachate-forming materials on the land surface. <br />The quality of this runoff should be closely similar to runoff from surrounding <br />undisturbed lands, and therefore, does not have the potential to degrade surface <br />waters or alluvial water in Hay Gulch. <br />Impacts to Alluvial Valley Floors (AVFs): <br />Hay Gulch meets the regulatory definition of an alluvial valley floor. The essential <br />hydrologic functions of the Hay Gulch AVF aze flood imgation and subirrigation. <br />The only surface disturbance to this alluvial valley floor from the mining operations <br />at the La Plata Mine was the construction of a sediment pond in the alluvium across <br />County Road 120 from the mine. The pond was reclaimed in 1990, and this land has <br />been successfully used as pastureland since then. The previously described absence <br />of adverse hydrologic impacts to Hay Gulch surface water and alluvium indicate the <br />essential hydrologic functions have been preserved by maintaining the geologic, <br />hydrologic, and biologic chazacteristics that support those functions. <br />Findines on Protection of Hvdroloeic Balance <br />All hydrologic structures have been reclaimed and there is no water pollution occumng. All <br />of the observed hydrologic impacts aze consistent with those predicted in the Division's La <br />Plata River Cumulative Hydrologic Impact Assessment. Based on the foregoing <br />observations, the Division finds that the La Plata Mine has minimized disturbance of the <br />hydrologic balance in the mine plan and adjacent areas, and prevented material damage <br />outside the permit area. The Division also finds that the La Plata Mine has not caused <br />hydrologic changes that adversely affect the approved postmining land use in the permit area. <br />11 <br />