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SUMMIT BRICK AND TILE COMPANY Permit# M-1977-219 Fox No 1 Clay Pit November 13, 2017 GEOTECHNICAL STABILITY EXHIBIT This information is presented to address the plan to mine within 200 feet of the structures listed in Exhibit S . The mine depth closest to any structure, where no waiver agreement has been obtained, is 45 feet . This is a dry mining operation and mined dry. The closest structure for which there is no damage agreement is the fence line on the north side where mining will be within 50 feet . Ownership is shared by the lessees and the neighboring landowners . In this area, the setback from the permit/affected lands lines to the dig line will be 50 feet . There are 3 types of material to be mined on the site, the dirt overburden, 0 to 9 ft deep; the Sandstone, 25 to 30 feet thick and the clay up to 10 feet deep. The following information is presented using these distances to determine the safety factors that show there would be no potential impacts to structures within 50 feet of the near vertical mine face during mining. Note that when the mine area is partially reclaimed and/or when the final slopes are done, then the factors of safety are greater, therefore the following calculations are based pre-reclamation or backfilling, when the mining face is at its maximum height . Included are sketch plats for each layer showing the friction angles for each type of material and the angle from the tow of the near vertical mining face to the property line . As mining approaches the perimeter of the mine a 50 foot mining setback will be staked from the property line to establish the mining limit. The 3 cross-sections show that the safety factors for staying 50 feet from the permit line vary from 1 . 31 to 6 . 11 . In the past, Mr. Alan Sorenson reviewed Slope Stability Reports prepared for the mines in Colorado. He suggested that an appropriate friction angle for any given material could be found in the Publication Rock Slopes: Design, Excavation and Stabilization, Publication No. FHWA-TS-89-045, Table 1 - Typical Soil and Rock Properties when non-site-specific information was available for the mate- rial . So for this analysis the 35' angle (the natural friction angle (V is used to calculate the safety factor for the dirt overburden and the clay. The 450 Friction Angle was used for the sandstone even though it appears to be higher on this site . This is consistent with observations made along the north side of the current permit area where the old mined slopes fall into the pre law mined area. Using this information from the sections, the safety factors for each material slope was calculated using the