2025-03-14_PERMIT FILE - M2025016 (12)

Home Browse Search

// PAGE 4 EXHIBIT D Raptor Materials, LLC Cogburn Sand, Gravel, and Reservoir Project February 2025 A Regular Impact (112) Construction Permit Application – Colorado Division of Reclamation Mining and Safety, Office of Mined Land Reclamation To determine the influence of past activities on groundwater, six (6) piezometer wells were advanced and developed along and within the entire Cogburn site boundary. Groundwater level information is based on three quarters of continuous monthly measurements at these piezometers, whose locations are identified on map Exhibit G: Water Information Map. Recorded groundwater depths vary in elevation below the surface, ranging from an average of approximately 23.5± feet bgs in the southeastern portion of the property to 8.5± feet bgs in the northwestern portion. Groundwater elevations are influenced by crop irrigation practices that run generally from April through September and may occasionally lag into the middle of October. During this time groundwater depths may be skewed higher in elevation in Pits P125_S1, P125A, and the eastern portion of P125B; however, throughout the 2024 monitoring period, groundwater elevations over the entire site have remained deeper than 7.0± feet from the surface. Using the approximate surface elevations at the eastern boundaries of Pits P125A (4,800’) and P125B (4,790’), and noting that groundwater monitoring results have reported depths between 14-16 feet bgs in the northern corner of P125A and vary between 7-9 feet bgs along the eastern boundary of P125B, we have estimated static water levels of 4,785’ in Pit P125A and 4,782’ in Pit P125B. The cyan colored contours shown in the map Exhibit G: Water Information represent the static groundwater elevation in each reclaimed pit. Since completed reservoirs will be lined to meet State of Colorado Water Resources specifications and requirements, and since lined basins will ultimately equalize with the surrounding groundwater elevations, the static water levels shown should reasonably reflect those of both the lined or unlined state, and represent a proper reflection of the optimal surface area of the water over the finished basins. Raptor Materials, LLC has sufficient water to meet the circumstances and obligations of both the lined and unlined states and, as reflected in Exhibit G: Water Resources Information, until and unless the reservoirs have an approved liner, the Operator will dedicate sufficient waters to secure the reclamation of the resulting basins in the unlined state. As extraction activity progresses into the aggregate profile, groundwater must generally be removed in advance through the use of pumps and subsequent discharge into area tributaries. A complete dewatering evaluation was performed by AWES in their report dated October 2024, and is included as an addendum to this permit application. The report concludes that ‘the results of analytical and numerical solutions indicate that the proposed mine dewatering activities will not adversely affect the regional groundwater hydrology’. All discharge of waters will be conducted under an approved CDPHE discharge permit. Initial dewatering of the property in preparation for extraction and resource recovery will occur by establishment of a dewatering pump and/or well in the northwestern corner (low point) of Pit P125_S1 and discharged to an adjacent settling pond prior to eventual release into the Last Chance Ditch. The point of discharge and settling pond location are on Exhibit C2: Extraction Plan Map. Preliminary discharge locations from Pits P125A and P125B are also identified on this map; these locations may change and additional locations may need to be added or field fit as operations advance. All discharge will conform to the applicable CDPHE discharge permit requirements, and locations will be updated in the following DRMS Annual Report. Cut slopes will cause direct precipitation to drain internally into the resulting basins and are not anticipated to result in any off-site impacts due to erosion or stormwater runoff. The gentle to near flat topography of the area landscape tends to aid in overall stability above the planned areas of extraction. While some erosion of resulting basin perimeter slopes will be evident subsequent to extraction, the advance of reclamation activity over affected lands will provide cover for both near and long-term stability of those lands remaining above water level of the finished basins. All completed slopes above the anticipated static groundwater elevation will be soiled, seeded and stabilized as provided for under Exhibit E - Reclamation Plan.