2019-05-24_PERMIT FILE - M2019027

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B-28 Keenesburg Project RETTEW Project No.114782000 Colorado Sand Company LLC April2019 three parameters of hydrology, vegetation, and soils to identify wetlands. A linear palustrine emergent (PEM)wetland (Wetland 1)was documented within the drainage at Sample Point W-1,and is depicted on Appendix A, Figure 2. Hydric soils were observed in several soil test pits that were dug within Wetland 1 and throughout other portions of the drainage. A Wetland Determination Data Form was completed to document the conditions at Sample Point W-1 and is provided in Appendix C. Photographs of the wetland are provided in Photographs 17 and 18 in Appendix B. Additional NWI mapped wetlands are located in the southeast quarter of Section 12 (Appendix A, Figure 2). This area was not visited during the field investigation. Wetlands were not delineated during the field investigation. 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 that contain 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 Denver Basin aquifer 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 Denver Basin aquifer system generally has a small 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. Three DWR permitted water wells are depicted on Appendix A, Figure 2. The DWR water well (permit No. 75237), located in Section 1 outside the AOI to the north, 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), outside the AOI to the east, were both identified as being used for watering livestock. 2 Keenesburg Project—Limited Impact 110 Application_May 24,2019