2010-05-19_REPORT - C1981008 (2)

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Table 2.05.4(2)(d)-1 Criteria for Evaluating Soil Suitability (Reproduced Table 2.04.9-2; Revised with NRCS 2008) PARAMETER - UNITS PH Conductivity (mmhos/cm) Saturation percentage (%) Sodium adsorption ratio3 Exchangeable Sodium % Calcium carbonate percentage Selenium (ppm) Particle size" Coarse fragments (%)5 THRESHOLD SUITABILITY LEVELS' Prime Farmland Prime Farmland Lift B Lift A and Single-Lift Soils <6.1->8.4 <6.1->8.4 4.02 6.02 >80% >80% <25% <25% >4 >4 >15 15% >40% >.2 ppme >1 ppms All soil textures except: s, Is, sc, sic, c >15% >35% one location; >10% 3" diam + (>25% average) i The threshold levels are to be used as a guide in evaluating the suitability of a soil material for reclamation. An evaluation should take into account the "total system". Interactive parameters may either nullify or verify the significance of a potential problem. ' The actual maximum acceptable salt level will depend on the plant species proposed in the revegetation plan and the potential for upward salt movement. As pointed out in the Baltzer report in Attachment 2.05.4(2)(d)-1-4, Dave Dearstyne of the NRCS said that 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 conductivity of 4-8 mmhos/cm. The specific species cited is Medicago Sativa, which is exactly the same as that prescribed in the revegetation plan for irrigated cropland. Also, this reference does not differentiate between topsoil and subsoil. Since WFC is maintaining a limit of 4.0 in the topsoil (Lift A), the revised limit of 6.0 mmhos/cm in the subsoil (Lift B) should be conservative. (Revised Nov 2008) 2.05.4(2)(d)-15