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Evaluation of Potential impacts <br />From The Proposed Nix Property Sand and Gravel Operation <br />On Shallow Groundwater Levels, Water Wells and Wetlands <br />The Nix property is relatively flat and located in the historic floodplain of the St. Vrain River, <br />approximately eight miles south of its confluence with the South Platte River. According to the <br />"Geologic Map of the Boulder, Fort Collins, Greeley Area" (USGS 1978), the Nix property is <br />underlain by Piney Creek alluvium, Broadway alluvium and aeolian deposits. The Piney Creek <br />and Broadway alluviums are described as sandy and gravelly deposits azound 20 to 35 feet thick, <br />respectively. <br />The 1972 U.S. Geological Survey (USGS) open file report entitled "Hydrogeologic <br />Characteristics of the Valley-Fill Aquifer in the Brighton Reach of the South Platte River, <br />Colorado (Hun, et al.)" identifies the depth of alluvium in this area as approximately 40 to 50 <br />feet with a saturated thickness of 35 to 45 feet. Based on this report, groundwater across the Nix <br />property flows in a northwesterly direction towards St. Vrain Creek with a gradient of between <br />0.5 and l percent. The transmissivity of the aquifer in this area is described in this same report as <br />approximately 200,000 gallons per day per foot (gpd/ft). The water table is reported as being <br />from 5 to 20 feet below the surface in the southern and central portions of the site, and less than 5 <br />feet below the surface in the northern portion of the site, on the "Depth to Groundwater Table <br />Map..." (USGS 1979). - <br />According to the soil survey, a variety of soils exist on the Nix property, including Valant sand, <br />Bankhard sandy loam, Lund clay loam, Vona loamy sand and aqualls and aquents. This latter <br />mapping unit occurs in the northern portion of the Nix property where shallow groundwater (less <br />than 5 feet) is reported on the 1979 USGS water level map. Vona sandy loam is shown as <br />occurring in the subject wetland. <br />2.1 Wetland on Sage Hill Farm <br />An approximately 11-acre wetland exists in a relative low spot immediately south of Weld <br />County Road 28 on the Sage Hill Farm. The approximate limits and features of this wetland are <br />shown on Figure 2. Photogaphs of the wetland are included in Appendix A. The wettest <br />portion of the wetland occurs in the north and east portions of the wetland along a barrow ditch <br />Ot 1-074.000 Wright Water Engineers, Inc. Page 2 <br />April 2002 <br />