2010-09-15_ENFORCEMENT - C1981008

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C -1981 -008 Soil Suitability 16- Sep -2010 Page 2 of 2 For Abatement Step 1, addressing mixed topsoil placed on the Lloyd property, there were no exceedances under either the current or the proposed criteria. Following approval of PR -06, the list of parameters requiring analysis will be somewhat reduced, as shown on the spreadsheet. Abatement Step 2 addressed the suitability of subsoil placed on the Lloyd property. All criteria, both current and proposed, were successfully met, with the exception of the percentage of Rock Fragments. Under the current permit, results for sample locations SS -240A, SS -241A and SS- 241B exceeded 35 %, the maximum allowable proportion. In addition, the allowable average of 25% was exceeded (30% was computed). Evaluation of the same data using the system proposed with PR -06 results in two, rather than four exceedances. In this case, SS 240A and SS 241A (38% and 37 %, respectively) exceed the 35% allowable Rock Fragments. Abatement Step 3 addressed Bench 1 material placed on the Morgan property. The single exceedance was for Electrical Conductivity (EC), reported at sample site SS -32 in the Lambert study. This value exceeds the 6.0 mmho /cm threshold in place for both current and proposed criteria. Mitigative sampling and analysis for the high EC at sample site SS -32 has been previously undertaken. With the current permit, as modified by TR -57, it was presumed that mixed topsoil would be placed directly on top of the regraded Bench 1, in which case the Bench 1 material was required to function as a substitute for subsoil. Under PR -06, the specific areas in question will fall within reclamation "Zone 3 ", which means that 33 inches of Lift B topsoil will be distributed on top of the regraded Bench 1 material prior to the placement of mixed topsoil. Suitability parameters analyzed for Bench 1 "Surface Spoil" placed in Zone 3 will be substantially fewer than those which are currently required. Mitigation of Unsuitable Spoil The Rock Fragment results reported for sites SS -240A and SS -241A exceed the allowable threshold by a small margin. Sample site locations are depicted on Exhibit (map) 2009 -7 in the 2009 ARR. From this map, SS -240 and SS -241 appear to be located in the northern portion of the Lloyd property. The Division understands that topsoil may have been already distributed across this area, which would make investigation of the lateral extent of the rocky area unfeasible and potentially damaging, particularly given the small magnitude of the exceedance. For all future topsoil redistribution campaigns at the New Horizon Mine, please be reminded that suitability of the underlying layer, whether Bench I Surface Spoil or Lift B Topsoil, must be evaluated, confirmed, and mitigated if necessary, in accordance with the approved permit, prior to any placement of the subsequent Lift B, Lift A or Mixed topsoil. Sincerely, Marcia L. Talvitie, P.E. Environmental Protection Specialist Enclosures — (2) cc: Sandy Brown, DBMS