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,. In order to assess potential mining related impacts to the local hydrologic system, the Division has determined that the installation of two monitoring wells within the Hay Gulch alluvial valley is required. One well is to be completed within the Hay Gulch alluvium immediately down gradient of the sediment pond. This well will provide alluvial water quality and depth-to-water information: The quarterly depth-to-water measurements and semi-annual water quality samples for the parameters tabulated in Table "I" will be sufficient to verify that the sediment pond will not adversely impact the alluvial valley floor. The Division incorporates the following stipulation. STIPULATION N0. 2 LA PLATA COAL CORPORATION WILL COMPLETE A WELL WITHIN THE HAY GULCH ALLUVIUM WITHIN TEN (10) FEET, MEASURED HORIZONTALLY, DOWNGRADIENT FROM THE OUTSLOPE OF THE SEDIMENT POND WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE. THIS WELL WILL BE OF ADEQUATE DIAMETER AND DEPTH TO PROVIDE WATER QUALITY AND DEPTH-TO-WATER INFORMATION. DEPTH-TO-WATER INFORMATION WILL BE OBTAINED, AT A MINIMUM, ON A QUARTERLY BASIS. WATER WILL BE SAMPLED SEMI-ANNUALLY AND ANALYZED FOR THE PARAMETERS LISTED IN TABLE I. REPORTS WILL BE SUBMITTED TO THE DIVISION ON AN ANNUAL BASIS. A second well is to be completed in the Hay Gulch alluvium immediately down gradient of the proposed leach field. This well will provide alluvial depth-to-water information which will be used to verify that the water table does not encroach upon the leach field. The semi-annual water level measurements will be adequate to provide information to ensure that off-site damage does not occur. The Division incorporates the following stipulation. STIPULATION N0. 3 LA PLATA COAL CORPORATION WILL COMPLETE A WELL (SEPARATE OF THE WELL ADDRESSED IN STIPULATION NO. 2) WITHIN THE HAY GULCH ALLUVIUM WITHIN TEN (10) FEET, MEASURED HORIZONTALLY, DOWNGRADIENT FROM THE EDGE OF THE PROPOSED LEACH FIELD WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE. THIS WELL WILL BE OF ADEQUATE DIAMETER AND DEPTH TO PROVIDE DEPTH-TO-WATER INFORMATION. DEPTH-TO-WATER INFORMATION WILL 8E OBTAINED, AT A MINIMUM, ON A SEMI-ANNUAL BASIS. MONITORING WILL BE CONDUCTED DURING SPRINGTIME SNOWMELT RUNOFF AND THE WET PERIOD OF SEPTEMBER OR OCTOBER. MONITORING REPORTS WILL BE SUBMITTED TO THE DIVISION WITHIN THIRTY (30) DAYS OF THE DATE OF MONITORING. The Hay Gulch alluvial aquifer, which is adjacent to the proposed operation, has an estimated average depth of 20 feet and an estimated cross-sectional area of 25,200 square feet. The transmissivity of this aquifer has been estimated to be 70,400 gallons per day per foot. The water table surface varies from above ground surface to an estimated eight feet below surface. The water level is seasonally dependent and varies between locations. The direction of flow in this unconfined system is postulated to be parallel with the strike of Hay Gulch. Recharge to the alluvium is principally from snowmelt runoff and precipitation infiltration. Some contribution may be made from the lower Menefee Formation as well as from other tributary alluvial bodies. -12-