Laserfiche WebLink
described will be several years before the TDS levels begin attenuating. Based on <br />analyses of alluvial aquifer data below the 004 pond at Seneca 11, the alluvial TDS levels <br />have peaked and begun declining even though the spoil discharge TDS levels are still <br />increasing. <br />The AVF study conducted by Peabody Coal Company determined That there are two subirrigated <br />grass hay fields (Section 9, TSN, R88 W, Exhibit 16-3) that could potentially be effected <br />by higher TDS levels within Dry Creek due to mining activities. The following equation, <br />provided in the CMLRD guidance document " A Description of the Material Damage Assessment <br />Process Pertaining to Alluvial Valley Floors, Surface Voter, Ground Voter and Subsidence <br />at Coal Nines", can be used to estimate the effects of increased dissolved solids levels <br />an crop species: <br />Y = 100-B(ECV-AV), where: <br />Y = Relative Yield, <br />B = Percent yield decrease per unit salinity increase, <br />ECV = Predicted conductivity of irrigation water (mmhos/cm), and <br />AV = Salinity threshold of irrigation water Cmmhos/cm). <br />• bi <br />fi <br />d <br />h <br />h <br />i <br />d h <br />l <br />f <br />lf <br />lf <br />20 <br />d <br />30 <br />h <br /> rr <br />ds are compose <br />ar <br />grass ( <br />T <br />e su <br />gate <br />ay <br />e <br />o <br />a <br />a <br />a ( <br />X), orc <br />X), and smoot <br /> brume (SOY,). As calculated above, post-mining TDS concentrations in Dry Creek are <br /> expected to reach 1154 mg/l, which equates to 1614 mmhos/cm (using a conversion factor of <br /> 1.399). Values for "Aw" and "B" are given in Table 1 of the CMLRD guidance document for <br /> alfalfa and orchardgrass; however, no values ere given for smooth brome, which is only <br /> classified as moderately tolerant in Table 1. Based on information obtained from the U.S. <br /> Salinity laboratory (Leland Francois, personal communication, 1991) and the text of the <br /> CMLRD guidance document, en Aw value of 1.5 mmhos/cm end e B value of 7.0X are used as <br /> conservative estimates for smooth brome in the calculations below. Relative yields for <br /> each species are: <br /> Alfalfa: Y = 100-7.3 (1.6-1.3) <br /> Y 97.8X (i.e., a 2.2X reduction) <br /> Drchardgrass: T = 100-6.2 (1.6-1.0) <br /> Y = 46.3X (i.e., a 3.7X reduction) <br /> Smooth Brome: Y 100-7.0 (1.6-1.5) <br /> Y = 99.3X (i.e., a 0.7X reduction). <br />• Using the relative percent composition for each species, the projected total reduction <br /> (TR) in production is: <br />47 Revised 04/24/91 <br />