2010-12-08_PERMIT FILE - C1981008A (11)

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'The actual maximum acceptable salt level, measured by Electrical Conductivity, will depend on the plant species proposed in the revegetation plan and the potential for upward salt movement. As pointed out in the report in Attachment 2.05.4(2)(d) -1, NRCS stated a level of 6.0 in the subsoil would not be detrimental to grasses or alfalfa. A study done by Curtis Swift, PhD. of Colorado State University (Attachment 2.05.4(2)(d) -2), titled Salt Tolerance of Various Temperate Zone Ornamental Plants, shows that alfalfa handles a soil conductivitiy of 4- 8mmho /cm. The specific species cited is Medicago Sativa, which is the same as that prescribed in the revegetation plan for Irrigated Cropland. Also this reference does not differentitate between topsoil and subsoil. Based on this data, and NRCS recommendations, the limits for Electrical Conductivity are shown in Table 2.05.4(2)(d) -1A and 1B for the various topsoil and subsoil types. The averages will be reported for each landowner in the Soil Sampling Report. 2 USDA Soil Textures - unsuitable textures area: S -sand, LS -loamy sand, SC -Sandy clay: SIC -Silty clay, C- Clay 3 The 3- inch -plus % is estimated visually (by volume) by sweeping the face of the area being inspected, measuring out the area's depth, and then estimating boulders, cobbles, and stones using USDA criteria. The 3- inch -minus rock fragment volume is estimated using sieve and collection pans. This is done by taking the thickness sample of the material, placing it in a graduated sieve with a 2 mm final sieve size, and sieving the soil to the bottom of the sieve pan. The volume of soil remaining in the 2 mm and larger sieves is then estimated for the 3- inch -minus rock fragment. These two component measurements are then summed to give the Rock Fragments value- 4 pH values in the table represent the acceptable range that sample pH must fall between. Revised September 2010 (PR 06) 2.05.4(2)(d) -8