Laserfiche WebLink
drained in 1993. The resultant transmissivity was 80 gpd/ft and the storativiry was 0.00005. These values are very <br />close to the value of 53 gpd/ft measured in well tests (Table 63A, Bedrock Hydraulic Characteristics) and <br />.0.000075 estimated by HydroSearch (1996). The resultant calibration is presented in Figure 28. <br />Many fault zones have been encountered in the mine. None of them produced significant quantities of water. <br />However, beginning in July 1997 in the southeast Submain stub area, particulazly near No. 6 Entry Cross-Cut 1, <br />reportedly produced over 30 gpm. Measurements on December 2 indicated that inflow to this area was less than l0 <br />gpm. The water had a conductivity of approximately 4000 umhos/cm. In late November 1997 significant inflows <br />were encountered in the 6-Right Gateroad, primarily through the roof beginning after Cross-Cut 25 and continuing <br />to approximately Cross-Cut 27. These inflows also had a conductivity of approximately 4000 umhos/cm. The high <br />conductivity of this water indicates that it is derived from the Wadge Overburden in the vicinity of the spoils. All <br />other underlying aquifers have a much lower conductivity. <br />The areas of the inflow are on the limb of an anticline with dips to the North to Northeast. No indication of faulting <br />was observed in either area. The areas of highest inflow are also coincident with the location of the Foidel Creek <br />liniment. There is also relatively thin overburden (<400 to <600 feet). The Southeast Submain stub area has a <br />relatively shallow dip. The 6-Right Gateroad is being driven in a direction of increasing dip. The azea of highest <br />inflow (near Cross-Cut 26) is at the intersection of Foidel Creek lineament and an area of increasing dip. Both of <br />these geologic features can increase the fracturing of the rock, producing increased permeabilities. When the <br />liniment was penetrated farther downdip in Panel 7-Right, no significant inflows were encountered. Since the <br />remaining panels in the Eastern Mining District are in areas of shallow dip, moderate to high overburden and do not <br />cross the Fish Creek liniment, similar fracture flow conditions are not expected to be encountered. <br />The model of the fracture flow portion of the inflow to the mine assumes a fracture zone of high permeability <br />relative to the Wadge Overburden. The size of the zone was assumed to be large relative to the size of the well. <br />The well is modeled as the area of the mine around Cross Cuts 26 and 27 where the largest flows were encountered. <br />Based upon an estimated 400 feet of drawdown, a 150 foot radius well, inflow of 270 gpm seven days after the <br />• fracture zone was penetrated and 210 ~pm 30 days after the fracture was penetrated the Transmissivity and <br />Storativiry were estimated to be 54 ft /day (400 gpd/ft) and 0.0002 respectively. They were estimated by <br />substituting the above values in the following equation. <br />~. = O"(2.30*logio(2.25*T*d(S*rzwll/(4*rz*T) (see equation below) <br />sw = drawdown, feet <br />Q =discharge, ft'/day <br />T = transmissiviry, ft2/day <br />rw =radius of pumping well, ft <br />S = stomtivity <br />t =time since pumping began, days <br />Once the values of T and S were estimated the above formula was solved for Q and the future flows estimated using <br />the following equation. <br />0 = (4*a*T*sw / 2.30*l0 ,°(2.25*T*1/(S*r'wy (Jacob and Lohman. 19521 <br />The discharge form the main mine area was added to the discharge from the fracture zone. <br />The predicted inflows are presented in Figure 29 and Table 70. They indicated that as the mine increases in size, <br />the inflows would only increase by small increments. Future predicted inflows range from 153 gpm in 1997 to 199 <br />gpm in 2003. Based upon the fit to the measured data, these estimates should be within f 30%. This is because the <br />mine has been pumped for a very long time, reducing the head around the mine so that its adjacent areas are already <br />partially dewatered. Also, because the mine is already very large, each new panel represents only a small <br />. percentage increase in size. <br />- .. , ~rr^~~^r.{~ J'J~@ 2 8 2000 <br />L <br />PR 99-OS 2.05-171.12 8/27/99 <br />