Laserfiche WebLink
The model projection of mine inflow over time, shown in Figure E-5, indicate that mine inflow <br /> will range from less than 20 gallons a minute (gpm)to about 50 gpm over most of the mine life, <br /> with a maximum of about 100 gpm during Phase 4 of mining operations when the mining <br /> intercepts the thickest sequence of saturated rock. Projected mine inflow into the reclaimed <br /> quarry, after mining ceases,will decline over time and steady out at around 20 gpm. <br /> Low mine inflows are projected largely due to the low bulk hydraulic conductivity of the <br /> fractured granodiorite in the south ridge area south of the Little Turkey Creek valley that will be <br /> mined out by the HRR quarrying operation. The fact that two separate analyses demonstrating <br /> that the bulk transmissivity (and associated bulk hydraulic conductivity) within the fractured <br /> granodiorite rocks of the south ridge is very low, substantiates the projection of low mine inflows. <br /> It should be noted that the projections of a post-mining, long-term seepage rate of about 20 gpm <br /> matches the calculated current (pre-mining) groundwater flow rate from the south ridge towards <br /> Little Turkey Creek. This indicates that, in the post-mining equilibrium situation, the 20 gpm of <br /> groundwater in the south ridge that currently discharges to Little Turkey Creek will be diverted <br /> into the mine and then passively flow directly to the creek via the reclaimed mine drainage <br /> system. The projections confirm that mine impacts to the groundwater system are limited and <br /> localized,and that there is no net loss of flow to Little Turkey Creek. <br /> The model projections of potentiometric drawdown, over the course of the 40-yr mining <br /> operation, are shown at the end of each phase of mining in Figures E-6 to E-10, and in cross- <br /> section in Figure E-11 for the maximum drawdown case during Phase 4. The very low bulk <br /> hydraulic conductivity of the fractured rocks, as determined by model calibration, and water <br /> balance considerations described in Section 3.5.2 of the main report text, limits the extent of the <br /> drawdown to the quarry area and a small area west of the Hitch Rack Ranch property. <br /> TRANSIT MIX-HITCH RACK RANCH <br /> HYDROGEOLOGY AND IMPACT ANALYSIS <br /> E-11 <br />