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2019 Plan of Operations Modification American Gypsum Company, LLC <br /> density and size of vegetation is inversely proportional to the steepness of the slopes and the <br /> presence of solid gypsum rock outcroppings. <br /> NRCS soil group boundaries correlate well with vegetation (Drawing 05, Section 3.6.1); Soil <br /> Group D (high runoff and low infiltration) areas are typically devoid of vegetation while Soil <br /> Group B (fairly low runoff and higher infiltration)areas are more highly vegetated. Steeper slopes <br /> typically have little to no vegetation, as they typically consist of gypsum outcrops or are crusted <br /> with gypsite. Based on aerial photography and site reconnaissance, the southern extent of the <br /> proposed Upper Pit expansion consists mostly of gypsum outcrops or gypsite and little to no <br /> vegetation is present. Similarly, the southern portion of the East Pit area is comprised of gypsum <br /> outcrops or gypsite,while the northern portion shows signs of vegetation.There are also biological <br /> soil crusts (consisting of algae, fungi, and lichens) throughout the proposed disturbance area <br /> (Section 6.8). <br /> Juniper and pinion trees cleared ahead of the active mining area would be utilized in the <br /> reclamation process. Pinion and juniper slash cleared at the existing Mine have added success <br /> to revegetation plots.The technique has consisted of placing slash over plots graded with volcanic <br /> ash growth medium and then seeding the plot. The slash has shown to aid revegetation by <br /> providing shade for the early seedlings, helping to stabilize and control erosion of the plots, and <br /> eventually adding organic nutrients back into the soil. <br /> 3.6.1 Relationship of Vegetation to Soil Types <br /> The steep slopes encrusted with gypsite support virtually no vegetation. However, flatter areas <br /> tend to be layered by a thin crust of volcanic ash that varies from depths of 3 inches to several <br /> feet in some areas. This volcanic ash was apparently deposited over the area during the last <br /> active period of the Dotsero volcano.The volcanic ash essentially serves as the indigenous topsoil <br /> for the area and supports the growth of the pinion and juniper stands in the flatter area. Deposits <br /> of the volcanic ash tend to occur in basins that intermingle with hummocks of gypsum <br /> outcroppings. Hummock units vary from 4 to 20 feet in maximum dimension. <br /> Successful reclamation efforts at the existing operation have shown that the indigenous volcanic <br /> ash can be utilized as a growth medium. The procedure in that area has consisted of removing <br /> volcanic ash basins ahead of the active mining area and stockpiling this material for later use in <br /> reclamation. There is enough organic content in the ash to support the growth of dry land <br /> vegetation. Successful reclamation plots (located on the east side of the Lower Pit and northeast <br /> corner of the Upper Pit based on field observations) were previously realized at the existing <br /> operation with a seed mixture consisting of Indian Rice Grass (Nezpar), Critana Thickspike <br /> Wheatgrass, Sodar Stream Bank Wheatgrass, and Salina Wild Rye (Centex, 2001). This seed <br /> mixture was used historically but is not proposed as part of this Modification. <br /> 3.7 Fish and Wildlife <br /> There are no perennial streams or water bodies near the Mine, so there is no habitat for fish. The <br /> nearest perennial stream is Eagle River, south of 1-70, about a mile downslope from the Mine. <br /> Short-term runoff does occur during rare major storms and would be captured by stormwater <br /> management systems. Best management practices are in place at the Mine for the protection of <br /> surface water resources. <br /> Am Gypsum Poo Mod ISSD 20190909 September 2019 [15] <br />