2019-11-27_PERMIT FILE - M2019058 (20)

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Appendix-5 Keenesburg Project RETTEW Project No.114782000 Colorado Sand Company LLC April26,2019 Supplement to the Corps of Engineers Wetland Delineation Manual: Great Plains Region, Version 2.0. This approach recognizes the three parameters of hydrology, vegetation, and soils to identify wetlands. Palustrine emergent (PEM) wetlands were documented within Ennis Draw at Sample Point W-1 in the northeast quarter of Section 12,T2N-R64W, at Sample Point W-2 in the southwest quarter of Section 7, T2N-R63W,at Sample Point W-3 in the southwest quarter of Section 12,T2N-R64W. Upland Sample Points U-1 and U-2 were collected to document conditions in upland habitat adjacent to Sample Points W-2 and W-3. Sample Points W-1,W-2,W-3, U-1 and U-2 are depicted on Appendix A, Figure 2. Hydric soils were observed in multiple soil test pits that were dug throughout the drainage. Wetland Determination Data Forms were completed to document conditions and are provided in Appendix C. Photographs of the wetlands within Ennis Draw are provided in Photographs 45—50,63—65,and 68 in Appendix B.Wetlands were identified but not delineated during the field investigation;areas not investigated as part of the field investigation may contain additional wetlands.Wetlands and streams are regulated by the United States Army Corps of Engineers(USACE). 2.2 Ground Water The project area falls within the South Platte River Valley. Surficial aquifers here generally contain the shallowest ground water and consist of Quaternary deposits of alluvial gravel, sand, silt, and clay or Quaternary deposits of eolian sand and silt (USGS, 1995). The stream valley of the South Platte River is eroded into the surface of the underlying bedrock formations. The sedimentary rocks that underlie the alluvium of the South Platte River Valley on the plains generally consist of shale and sandstone of Cretaceous age that are easily eroded to form broad,gently sloping valleys with meandering streams and moderately thick alluvium (USGS, 1995).The surficial aquifer of the South Platte River ranges in thickness from about 20 to 200 feet and ranges in width from about 1 to 15 miles (USGS, 1995). The project area is within the Denver Basin aquifer system,which underlies an area of about 7,000 square miles that extends south from Greeley to near Colorado Springs (USGS, 1995). The Denver Basin aquifer system is not well connected to other major aquifers in the area,and the surficial aquifer along the South Platte River Valley is the only other major aquifer near the Denver Basin (USGS, 1995). Shallow, discontinuous surficial aquifers overlie parts of the Denver Basin aquifer system, primarily along small streams that extend south from the South Platte River. The system consists of four aquifers that are present in five geologic formations (Illustration 1). The project area is located along the borders of the Arapahoe and Laramie-Fox Hills aquifers. Unconfined and confined conditions are present in the bedrock aquifers of the Denver Basin.The aquifers are unconfined primarily near outcrops where the water table may be at relatively shallow depths. The aquifers are confined in deeper parts of the basin where confining units restrict vertical movement of water and cause water levels in wells to rise above the top of the aquifer(USGS, 1995). Depth to water in wells completed in the north half of the Denver Basin aquifer ranges from 0 to 250 feet. Water in the aquifer system generally has a low dissolved-solids concentration and, in most areas, meets drinking- water regulations established by the U.S. Environmental Protection Agency for public water supplies (USGS, 1995). The Division of Water Resources (DWR) online web viewer was used to identify water wells within and adjacent to the project area. Four DWR permitted water wells are depicted on Appendix A, Figure 2. The DWR water well (permit No. 75237) in Section 1 is currently permitted for watering livestock. Per DWR, there is a high probability that this well can be re-permitted for drinking water and sanitation uses with limits of 15 gallons per minute(gpm)and 1/3 acre feet per year.The water well in Section 12(permit No. 159505) and the water well in Section 7(permit No. 75234)are both used for watering livestock. 2