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maximum 12 inches, compacted to approximately 8-9 inches) before placement of soil.Where tires/tirebales are used, bales will be placed before doing cut or fill of the slope behind and above them. Rock walls will be placed after cut or fill is done. As described above, on-site material is a well-graded mixture including cobbles/boulders of up to 2 foot in size (although larger boulders up to 6 feet in size are also found), relatively high clay content(no swelling clay observed), and well-suited for engineered fill, with larger rocks removed and used for facing material. Analysis and FACTOR OF SAFETY Primary concern is stability of backfilled slope areas. Cut slopes do not have significant concerns for slumping or other failure, based on lack of surcharge and existing stable in-place and undisturbed materials at a 2:1 or flatter slope.This is the case for the new road cut and the north and south edges of the pit floor open areas. Primary concern for filled slopes is material placed in front of cut faces. The major portion of the large cut face on the east edge of the site (below the fence on the property/permit boundary) is actually not a significant area of concern because the northern portion of the backfill is to be placed into the existing roadcut and therefore is supported by existing undisturbed cut slopes to both the east and west. To the north (facing the street)the slope will in essence reestablish the original natural face of the hillside.To the south,this fill will be supported by the longer, higher backfill slope. This slope requires the greater analysis and care in design and placement. Standard engineered fill (see above)with well-graded on-site material, including possible use of geomesh to reinforce backfilled slope,will provide long-term stable slopes. No Flow Slope Stability Analysis: FS=tan (internal friction angle)/tan (slope angle) Undisturbed material (cut slopes)tan (50°)/tan (26.57 ') = 1.192/.5001= 2.4 Placed material (fill slopes)tan (40°)/tan (26.57 °)= .8391/.5001= 1.7 Flow Parallel to Slope Analysis: Not applicable: unsaturated conditions(water table below toe of slope) Horizontal Slope Analysis: Not applicable: unsaturated conditions (water table below toe of slope) Sliding Analysis (worst case 20 FT slope height 2:1 non-cohesive, µ=0.8: Drylaid rock wall (facing):8 ft FS= 1.60 not okay for 20-ft height. Limit to: Drylaid rock wall (facing): 6 ft FS= 2.13 Tire bales: 5 ft FS= 2.25 Filled tires: 5 ft FS= 2.11 Summary:Adequate factor of safety for 5-6 ft height for 20-ft high slope at 2:1 Tipping Analysis: (point of rotation,face of toe of retaining wall)—not applicable: slope, rock, and tire walls are not rigid structures. sla Prepared by Nathan A. Barton 17JUL2019 P V.- RM%. ..«....• Red; drylaid rock • '� n z M®gento f iUEd z L tires -01 Blue0 fire boles ��, 24 slope .��•,�, �.• � M*x 20 fee �ss�ONAL ti�G NNE Stability Analysis M2011-014 Schmidt Site Page 3 of 3