2010-01-28_PERMIT FILE - M2009082

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Memo to Jared Ebert 2 January 8, 2010 Slope Stabilit Review File No. M-2009-082 Phase 1C 3. The depth to bedrock used for the Boring No. 5 analysis (20 feet) does not match the depth to bedrock indicated on Table 1: Parsons Mine Borings and boring log (15 feet). Please explain the discrepancy. 4. Please provide the source of the ground water data for Boring No. 5. The applicant's analysis was duplicated for verification; a failure surface with lower safety factor than the applicant's identified critical slip circle was located, however the safety factor was above 1.00 and therefore acceptable to the Division. The accuracy of the applicant's analysis is confirmed (see attached). Phase 2 Eastside The applicant's analysis was duplicated for verification for the critical cross section (No. 3); no potential failure surfaces with lower safety factors than the applicant's identified critical slip circle were located. The safety factor produced by Galena is higher than that produced by Slope/W; this is due to slight programming differences in the software packages and is not significant. Therefore, the accuracy of the applicant's analysis is confirmed (see attached). Phase 2 Westside 5. The cross section profile analyzed for Boring L103-BH02 does not match the profile indicated on Table 1: Parsons Mine Borings and L103-BH02 Borehole Log. The stability analysis does not include the Silt and Clay layer from 24 to 29 feet. Please explain the discrepancy. 6. The stability analysis performed by the Division indicates a slope failure when the profile is analyzed with the second silt and clay layer at the proposed 37 foot offset. The profile was analyzed with the proposed 82 foot offset from the adjacent fence line and indicated safety factor was above 1.00 and therefore acceptable to the Division (see attached). Phase 3 The applicant's analysis was duplicated for verification; a failure surface with lower safety factor than the applicant's identified critical slip circle was located, however the safety factor was above 1.00 and therefore acceptable to the Division. The accuracy of the applicant's analysis is confirmed (see attached). Phase 4A 7. Please indicate the location of PA04-BH08 on Figure No. 1- Parsons Mine - Borings Used for Stability Analysis. 8. Please provide the source of the ground water data for Borings PA04-BH08 and PA04-BH11. The applicant's analysis was duplicated for verification; no potential failure surfaces with lower safety factors than the applicant's identified critical slip circle were located. The safety factor produced by Galena is higher than that produced by Slopeft this is due to slight programming differences in the software packages and is not significant. Therefore, the accuracy of the applicant's analysis is confirmed (see attached).