2021-06-17_PERMIT FILE - M2001046 (4)

Home Browse Search

Page 2 Mr. Eric Scott June 4th, 2021 full removal of the batch plant at the end of mining. The site will include a portable concrete and/or asphalt batch plant.The portable concrete batch plant will sit on a 30'by 50' concrete pad and the portable asphalt batch plant will sit on concrete footings.Since the plants will be portable,the cost of reclamation will be limited to removing the concrete pad and footings.The portable concrete batch plant and asphalt batch plant have been included on the Mining Plan Map(See Attached). • The unlined slopes of the freshwater and siltation pond are shown on the modified mining plan map as 1:1, however, the geotechnical stability exhibit provides analysis of 2:1 slopes for all excavations and only in three locations for the entire site. Please either re-run the stability model to demonstrate adequate setbacks for the freshwater and siltation pond at a 1:1 slope and at the maximum projected depths, or modify the mining plan map to reflect 2:1 slopes for these excavations as described in the current stability exhibit. Please also describe more fully how it was determined that only 3 sections would be needed to provide adequate stability setback data for all structures within and within 200'of the permit area. Additional analysis may be required for structures currently shown to be within mining cells as shown.The siltation and freshwater ponds will be mined at a 3:1 instead of the 1:1.The mine plan has been updated to reflect this and a new stability model has been rerun at a 2.5:1 slope(See attached Mine Plan Map and Stability Analysis). For the siltation and freshwater ponds,the closest structure is a gas line that runs along the western edge of the property.The deepest section of the siltation pond was chosen for the model as this represents the worst case scenario for each of these ponds. The closest structure in the slung wall lined cells is the slurry wall itself.The deepest section along each slurry wall was chosen to represent the worst case scenario for the closest structure.Since all other structures within 200' of the permit boundary are either further away from the mine limit, have a shallower depth to bedrock, or both,the mine highwall would be more stable than the worst case scenarios modeled. •None of the monitoring wells are shown on the mining plan map, however, at least one appears to be within an area to be mined? Please addresedescribe. Monitoring wells MW-9, MW-10, MW-11 and MW- 12 were drilled interior to the proposed slurry wall and will be isolated from the groundwater table after slurry wall construction.These wells will be utilized during the leak test and will be abandoned after the leak test is completed.All other wells are external of the mine limit. •Please show the locations of the eight permitted wells within 600'of the permit boundary on the provided structures map ifpossible, or on a separate map if needed. The eight permitted wells within 600'of the permit boundary have been added to the structures map. EXHIBIT D-Mining Plan(Rule 6.4.4): •Please address/fully describe the batch plant shown on the mining plan map within the mining plan as described above. RMCC anticipates installing a portable concrete and/or asphalt batch plant(See description above). •DRMS acknowledges the statement provided that all mining will take place at 3:1 slopes and that the operator will provide a technical revision, including bond revision, if steeper slopes will be utilized during mining. • What will be done with the excess overburden from the site that will not be utilized to backfill the freshwater and siltation ponds?Excess overburden will be sold as fill or utilized offsite. EXHIBIT E-Reclamation Plan(Rule 6.4.5): •DRMS acknowledges the provided statements stating that the freshwater and siltation ponds will be fully