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silts form "tack-welds"that support the larger grained materials. The "tack-welds"that the soils <br /> are supported by can be easily dissolved into solution with the introduction of water. The voids <br /> left behind after the "tack-welds" are dissolved result in settling of the surface. Water entering <br /> hydrocompactive soils will follow the path of least resistance either by following void spaces or <br /> the dip of the deposit. The Roadside Mine is located in western Colorado, known to be a semi- <br /> arid and climate. Palisade, CO receives approximately 10 inches of rainfall precipitation <br /> annually. The soils deposited on the site are derived from colluvium originating from the Grand <br /> Mesa and Alluvial material from the ancestral Rapid Creek. These soils ae fine grained, loamy <br /> silts and clay soils mixed with basaltic gravels, cobbles, and boulders. The Colorado Geologic <br /> Survey has mapped the permit area containing hydrocompactive soils. Please see the Division's <br /> Exhibit 1, attached to the end of this Findings, for a map showing the CGS mapped collapsible <br /> soils and the Roadside Mine permit area. <br /> The water introduced to the Tract 70 Mesa from the landowner's water system has provided the <br /> necessary dissolution of the "tack-welds", resulting in the rapid settlement of the soils. The <br /> magnitude of the features observed during field inspections were isolated to the areas of the <br /> Tract 70 Mesa impacted by the landowner's water system. Water was observed to be flowing <br /> directly into the settled features and desiccation cracks (DRMS Coal July 2019 Partial Inspection <br /> Report). These pathways allow lateral "piping"to occur, resulting in the enlargement of the <br /> settled features. The Division also noted on the July 9t' inspection that Mr. Fontanari's water <br /> system was applying water in ditches adjacent to SCC's maintenance repair work for this SL-11 <br /> bond release. The water from the ditches was flowing over the surface and onto SCC's <br /> maintenance repairs. Another set of ditches were observed to be dry during the inspection but <br /> had cut through a portion of the Line Object 9 maintenance repairs. The Division's Exhibit 2, <br /> attached to the end of this Findings, is an aerial photo showing the location of Mr. Fontanari's <br /> ditches to the maintenance repairs completed by SCC. Mining subsidence does not manifest <br /> itself at the surface this way. <br /> In contrast, subsidence from room and pillar mining creates "troughs" on the surface. "Troughs" <br /> or surface depressions overlie areas of extracted coal and the highpoints in between "troughs" are <br /> located above the pillars that remain in place. Subsidence cracks occur at the surface at the <br /> boundary of the land over the collapsed workings and the land overlying the pillars due to <br /> tensional strain. Surface cracks from subsidence will outline the boundaries of subsidence <br /> troughs. Cracks observed on the surface of Tract 70 were not observed to be oriented in a <br /> manner outlining a surface depression. The Roadside Mine Permit includes a prediction of the <br /> maximum possible predicted subsidence and a subsidence monitoring program. The mine plan <br /> was designed to incorporate the subsidence predictions to minimize the impact to pre-existing <br /> structures and man-made features. Pre-existing man-made features on the Tract 70 Mesa <br /> included powerlines and a Ute Water line. The post-mining land use for Tract 70 is wildlife <br /> habitat and rangeland. <br /> Table 2. SL-11 Application,Areas Requested For Final Bond Release <br /> 9 <br />