Laserfiche WebLink
4 1 <br /> 3.0 HYDROLOGY AND MINE DEVELOPMENT <br /> This monitoring period from October 1, 2019 to September 30, 2020 provided the hydrologic <br /> information necessary to assess the adequacy of monitoring program, the adequacy of the <br /> mitigating measures designed to protect the hydrology, and identify and quantify impacts <br /> that may have occurred during this period. <br /> 3.1 Mining Related Hydrologic Impacts <br /> The only impacts identified to date include: <br /> ■ Withdrawal of water for the mine from the lagoon adjacent to the White River thus <br /> slightly reducing the flow in the White River. BME has legal right to this water. <br /> ■ Discharge of storm water from pond DP-1 into Scullion Gulch, a White River tributary. <br /> Discharges contained lower TSS than typical receiving stream flows during storm <br /> events. <br /> ■ Decline in piezometric level in wells in close proximity to mine workings. Holes that <br /> were mined through have turned dry. <br /> ■ Subsidence in Red Wash resulting in ponding of surface water. The ponds quickly fill <br /> with clay and silt with Red Wash maintaining its original channel. <br /> ■ Subsidence in Scullion Gulch resulted in no surface hydrologic consequences observed <br /> to date. Not enough precipitation has occurred to truly test the system. Runoff was <br /> rarely observed in the impacted sections of Scullion Gulch prior to mining. <br /> 3.2 Comparison of Projected Impacts with Observed Impacts <br /> The comparisons of the projected impacts (probable hydrologic consequences) with the <br /> observed impacts are discussed in the following. <br /> The water withdrawal rate from the lagoon at the White River this reporting year was <br /> estimated at 133,829,601 gallons or 410.74 acre-feet. This compares with a projected <br /> withdrawal rate of 552 acre-feet per year at full production. <br /> The decline in piezometric levels in bedrock zones "upper sandstone facies", "siltstone/coal <br /> facies", and 'lower sandstone facies" was anticipated as probable impacts as the result of <br /> 13 <br />