2022-04-04_PERMIT FILE - M2022013 (28)

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Page 15 6.4.5 EXHIBIT I/J — Soils and Vegetation Information Reclamation Costs, the initial exposure of lands requiring revegetation will be approximately 6.15f acres, requiring 4,961± cu.yds of soil. Total replacement volume required for Central and North- West Fields combined is 16.52± cu.yds of soil. Once removed from its native location, soil retained for reclamation will be stockpiled over the North-East portion of Central Field, in an area already improved above the prior floodplain; or otherwise windrowed along the perimeter of the basin area of extraction or area to be resoiled and seeded with the reclamation seed mixture specified under Exhibit L - Table L-1: Primary/Preferred Revegetation Seed Mixture, or as otherwise determined under an approved revision. Stabilization of inactive soil stockpiles will provide an opportunity to gauge the performance of the seed mixture while attempting to provide a stabilizing cover of vegetation over the stockpiled soil until it is ready for replacement on finished slopes and affected lands remaining above the anticipated static water level of the completed reservoir basins. Direct precipitation from short duration high intensity rainstorm events, and wind, are the common erosion forces opposed to soil stability over in situ or established perimeter basin slopes at this location. The more uncommon flood event is considered under Exhibit G: Water Information, in the included Flow Technologies, Flood Control Mitigation Plan of 22 January 2020. Never the less, with few exceptions, the natural forces are commonly slight since the location geology and agricultural uses form a nearly flat table beyond the slopes of the extracted basins. Further, extraction will result in basin slopes that cause water from direct precipitation to drain internally, minimizing concentrated flows to existing area drainageways outside of the basin areas; while acting as detention and temporarily lowering any intersecting flood velocity and peak flows during a flood event. Additional conservation measures will be taken for common storm events to assure site stability and protection of off-site areas. An example would be directing overland flows, beyond the influence of the extracted basins, to existing or established grassed water ways. The operator's stormwater management plan may address additional detailed information about maintaining on-site stability consistent with its pending Colorado Department of Health stormwater permit. The measures taken to stabilize soil stockpiles described above, should be adequate for controlling erosion from wind and direct precipitation at those locations. Wind born effects are reduced by surface roughing during continued development of agricultural row crops, or from the natural consequence of extraction activity, itself. Due to the flat topography of the parcel, the interception of upland overland flows by local irrigation ditches and surrounding roads, there is little upland watershed that would impact these locations as a result of nominal storm related events. The greater threat of erosion will be to resoiled slopes pending establishment of vegetation during reclamation. While some sheet and rill erosion can be anticipated on unprotected areas following seed bed preparation and seeding, planned conservation measures should help to limit erosion potential that would threaten the revegetation efforts. Prior to resoiling, the foundation material that will underlie the soil will be sculpted to establish initial soil stabilization features, and left rough to aid in resoil adherence. Soil will be placed over a 12-18± inch minimum friable, or otherwise unconsolidated, subsoil. A 12-18± inch Swale with VARRA COMPANIES, INC. TWO RIVERS SAND GRAVEL AND RESERVOIR PROJECT MARCH 2O22 A REGULAR IMPACT[1121 CONSTRUCTION PERMIT APPLICATION-COLORADO DIVISION OF RECLAMATION MIING&SAFETY OFFICE OF MINED LAND RECLAMATION