2009-05-14_REPORT - M2007044 - Laserfiche WebLink

Home Browse Search

Page 7 May 5, 2009 The analytical water quality results for the December 2008 samples and historical data are presented in Table 2, which is an updated version of a table prepared by EFR. The laboratory reported analytical results are presented in Attachment C. Monitoring Well NM-WI Monitoring well MW-W1 was installed from October 9-12, 2008. The well is located approximately 20 ft north of County Road 5/10 and 350 ft east-northeast of the Whirlwind Mine portal (see Figure 2). The well was completed at a depth of 120 ft in the Brushy Basin Member, in the first strata that yielded significant groundwater. The final surveyed coordinates for the completed well as provided by EFR are N1314621.40, E 1987519.84; ground elevation 7042.53 ft. These coordinates are based on NAD27 and NAVD29. The elevation of the top of the PVC well casing is 7045.20 ft. Drilling was conducted using air and air-mist rotary methods with a 5 5/8-inch bit from 3 ft to 120 ft below ground surface (bgs) and an 8 5/8-inch bit for the surface casing from 0 to 3 ft bgs. Air rotary drilling of MW-W1 was used to a depth of 110 ft. Air-mist was used from 102 to 120 ft. Surface casing consisted of 6 5/8-inch OD'/4-inch steel from 3.0 ft (bgs) to + 3.0 ft above ground surface. Well casing consisted of Johnson 2-inch ID (2 3/8-inch OD) schedule 40 flush joint PVC with 0.020-inch slot size. The well construction specifications are shown in the Table 3. Table 3. MW-W1 Well Construction Summarv Depth Depth ft b s Well Casing ft b s Annulus Materials +2.7-60.3 Johnson 2-inch ID (2 3/8-inch +1.5-1.0 No. 8-12 Colorado Silica Sand OD) schedule 40 flush joint PVC +1.0-40.5 Bentonite grout 60.3-110.3 2-inch ID (2 3/8-inch OD) 40.5--44.0 Bentonite pellet seal (hydrated) schedule 40 flush joint PVC with -44.0-59.3 Potential void or borehole slough 0.0204nch slot 110.3 -115.3 2-inch ID (2 3/8-inch OD) -59.3 -115.3 No. 8-12 Colorado Silica Sand schedule 40 flush joint PVC sum with end ca 115.3-120 115.3-120 Washed 3/4-inch gravel INTERPRETATION The December 2008 field reconnaissance did not result in significantly different interpretations than those presented in the September 2008 report with regard to underground and Packrat Mine area findings. However, for convenience some of the June 2008 findings are presented here with the results and interpretation of the Lumsden Canyon reconnaissance. Whirlwind Mine As discussed in the September 2008 report and also observed in the December 4, 2008 mine inspection, groundwater in the mine occurred at three general locations: 1) in the Brushy Basin/colluvium area of the shallow portion of the decline (approximately 280 ft inside the portal); 2) the lower sandstone unit of the Brushy Basin Member; and 3) the upper portion of the Salt Wash Member sandstone as noted in the far end of the drifts. Weans=709.doc