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These conditions make recharge projects viable for purposes of supplying additional <br /> water to the South Platte River. <br /> Maps produced by Hurr et al. (1972) describe the hydrogeological characteristics of the <br /> aquifer in several reaches of the South Platte River Valley. According to these maps, the <br /> aquifer underlying the proposed recharge structures is very amenable to ground water <br /> recharge. Aquifer material is primarily gravel and is highly permeable. Highly permeable <br /> soil conditions have been verified by observations of longtime agriculturalists. In the <br /> vicinity of the Union Ditch, the aquifer saturated thickness ranges from 30 to 80 feet and <br /> transmissivities range from 100,000 to 200,000 gallons per day per foot (Hurr et al., <br /> 1972). <br /> A percolation test was conducted in 2003 on a property owned by Mike and Janet Ream, <br /> which is near the river within the Union Ditch service area. The results of this test <br /> indicate highly permeable soils, which is expected near the river where subsoil is course <br /> and gravelly. Although this test was conducted within the Union Ditch service area, <br /> results may not be indicative of all proposed recharge sites in this study. <br /> Several percolation tests for potential recharge ponds have been conducted for the New <br /> Cache La Poudre Irrigation Company by Peel (2003). One of the percolation tests was <br /> performed on a Vona loamy sand soil texture, which is also present at some of the <br /> proposed recharge sites for the Union Ditch. Although the results of the New Cache <br /> study show only a 0.19 feet per day infiltration rate for this soil texture, under normal <br /> conditions the rates are expected to be significantly higher because the test was <br /> performed on highly compacted soil conditions. Compacted soil conditions tend to slow <br /> the rate of infiltration. <br /> According to the Soil Survey of Weld County, soil textures in the vicinity of the recharge <br /> sites for Union Ditch are primarily sandy loams or clay loams. The soil textures vary <br /> significantly from site to site and within the vertical soil profile. These soils have <br /> permeability rates that range between 0.2 to 20 inches per hour (0.4 to 40 feet per day). <br /> The Soil Survey only provides an assessment of the soil types in the upper soil profile <br /> (top 3 to 5 feet) and may not represent the soil texture directly above and within the <br /> aquifer. For this reason, it is recommended that more specific tests be conducted at a <br /> site prior to developing a recharge pond to determine the characteristics of the entire soil <br /> profile and its ability to transport water to the aquifer. <br /> Due to the relatively permeable nature of the soil underlying the proposed recharge <br /> structures, it is expected that water diverted into recharge structures will percolate into <br /> the aquifer, where ground water will move towards the river. <br /> Selection of Recharge Sites <br /> Through the work reported here, and the complementing work completed as a part of the <br /> Union Ditch Augmentation Plan, it is possible to conceptually identify what appear to be <br /> suitable recharge structures. This report identifies structures based on field surface <br /> observations, perceived land values, observable land use, and proximity to the Union <br /> Ditch and the river. <br /> The proposed recharge ponds were located by balancing a number of issues and <br /> factors. Some examples of sites that would be of interest include: (1) a low lying, weedy <br /> Aqua Engineering, Inc. Recharge Project Potential <br /> February 17, 2004 -4 - <br />