PERMFILE63761 - Laserfiche WebLink

Home Browse Search

exposed, natural slaking and weathering occurs very rapidly (within one 4reek) which results in a loose layer to a depth of 1 to 2 feet. Consequently, no additional ripping is needed. As noted in the permit application the overburden material is very gravelly and well drained. The natural distribution of rock fragment sizes is characterized as well graded, that is, the sizes vary fairly uniformly from 24" cobbles to loamy sand. Provision for a one-foot thick layer of gravel between the overburden and impermeable shale is like putting gravel under gravel. Further, we strongly disagree with the assertion that placing a one foot layer of gravel beneath the overburden on the slopes would improve slope stability. The fact is that a poorly graded (uniform sized) gravel layer would substantially increase the probability of slope failure. Finally, with time fines would wash down into the gravel layer and in effect, create a medium very similar to the existing overburden such that the net result will be a higher probability of slope failure during the first year, gradually diminishing as fines wash into the gravel layer to eventually achieve a condition which would exist if the overburden were placed directly over the weathered shale pit slopes. 13. In addition to water bar and terrace construction, please consider slope m~jnipulation such that smooth, uniform slopes are avoided, thereby creating microclimates for enhancing vegetation and wildlife diversity and minimizing erosion. Response - WAI will consider slope manipulation in its final reclamation which will include small mounds, slope variation, etc. to the extent tFiat such provision does not severely impact the mining plan. 14. Please consider diverting surface water around the waste stowage sites by utilization of upland berms, mounded profiles, etc., thereby minimizing the percolation/infiltration potential of the waste materials. Response - The initial waste stowage area by review of the quarry topographic map is bounded on the east side by a berm, on the south side by a diversion ditch, and on the north and west sides by the quarry as it presently exists. Post reclamation the waste stowage area will be part of the final reclaimed pit slope as shown in Exhibit F of the permit application a portion of the existing berm will remain up-slope from the stowage area to divert runoff away from the stowage site. Other sites established as mining proceeds will be constructed similarly. 15. Please provide the catchment area reporting to the southern and western upland ditch, the diversion ditch sizing and channel-lining erosion control and energy dissipation measures proposed. Re:>ponse - Attached please find a revised Exhibit F which shows no ditch on the south and west sides of the quarry. After the question was ra__sed by MLRD staff~an on-site inspection of the southern edge of the qu~irry property indicates the presence of an adequate drainage ditch immediately adjacent to the southern property line (permit boundary)