2013-02-04_REVISION - C1981008 (3)

Home Browse Search

JoEllen Turner 970 - 864 -7682 p.17 Borch Environmental Pollution Consulting, LLC October 2, 2032 The petrogypsic horizon is a horizon in which visible secondary gypsum has accumulated or has been transformed. The horizon is cemented (i.e., extremely weakly through indurated cementation classes), and the cementation is both laterally continuous and root limiting, even when the soil is moist. The horizon typically occurs as a subsurface horizon, but it may occur at the surface in some soils. A perogypsic horizon meets all of the following requirements: 1. Is cemented or indurated by gypsum, with or without other cementing agents; 2. Because of lateral continuity can be penetrated by roots only along vertical fractures with a horizontal spacing of 10 cm or more; 3. Is 5 mm or more thick; and 4. Is 40 percent or more (by weight) gypsum. It is my opinon that the Morgan Property does not contain Gypsiferous Soil_ This conclusion was reached after consulations with Dr. Eugene Kelly and Dr. Suellen Melzer at Colorado State University based upon review of the soil maps and surveys for the Morgan property. Thus, it is not appropriate to subtract 2 dSlm from the measure of the EC values in the soil substitutes proposed for the Morgan property when determining the potential impact on crop yield. If it was an acceptable method to subtract 2 dS /m then that should also be done for measurements of the native soils, which would mean that in several cases you would end up with negative salinity values (measured EC values were often below 2 dS /m), which is not possible. Also several other ions were detected in the water such as Na, Cl, Mg, HCO3, K etc. and they all contribute to the measured EC value indicating, again, that gypsum can not account for 2 dS/m for soils on the Morgan property. I also note that soil can be saline and non - toxic, but salinity will always require a higher water demand by the crops due to osmotic stress. The higher salinity levels present in the Bench One material are problematic in this sense. But since Mr. Dejoia brings up the presence of gypsum (CaSO4 * 2H20) on the Morgan property I am wondering what the source of gypsum is. Since there is no noteworthy amount of gypsum in the parent material or bedrock the sulfate in the soil must come from sources such as irrigation water (CCC ditch), atmospheric deposition (unlikely), dust from the coal mining operation, oxidation of pyrite (pyrite is oxidized to sulfate when reacted with water and oxygen) or due to dust control using (pit) water high in sulfate (SO4 "). Based on the average values given for the gypsum concentration in the soils (see table below) it appears to me that its likely that the stockpiled soils were contaminated with sulfate or that sulfate was produced (pyrite oxidation; similar to the reactions that results in acid mine drainage) during storage since the A lift, 13 lift, mixed soil and the substitute soils contains more than double the amount of gypsum than the undisturbed soil. The pit water that was used for dust control is a likely source of contamination and if pyrite was oxidized in the stockpiled soil that could also help explain the elevated — 16 IPage PLTF 002490