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Table 1 - Soil Properties <br /> Description Max dry Saturated Cohesion Internal <br /> density Density (psf) Friction <br /> c c Angle <br /> Overburden 110 131 150 22 <br /> Sand and Gravel 110 131 0 35 <br /> Weathered 125 141 100 18 <br /> Bedrock <br /> Stable Bedrock 125 141 2000 20 <br /> Slurry Wall 100 110 0 45 <br /> IV - DESIGN ANALYSIS AND CRITERIA <br /> The proposed mining slopes were analyzed using Clover Technologies Galena Slope <br /> Stability Analysis System, version 7.2. Galena was designed to analyze the slope <br /> stability of earth embankments subjected to several critical situations that may occur <br /> during the life of the embankment. For this project, fifteen cases were identified as <br /> critical during the mining operation. Static and pseudo-static conditions were analyzed <br /> in each case. <br /> Pseudo-static peak acceleration factors (peak horizontal acceleration, or PHA) were <br /> taken from USGS information for the western United States. The 2% probability of <br /> exceedance in 50 years (the most conservative) was used. A peak acceleration factor of <br /> 0.06 x gravity was taken from this data. A conservative earthquake loading coefficient of <br /> 0.50 x PHA is often used for slope stability analyses (50% of PHA). We used an even <br /> more conservative approach and used 70% of the PHA for this area for our earthquake <br /> loading coefficient. Hence, 0.70 x 0.06 = 0.042 which was used in the models. <br /> All mining side slopes will be 3H:1V. <br /> Case 3-1 —Ditch Bank to the West of Phase 3. <br /> The proposed setback for mining is 85 feet from the edge of the ditch bank. The <br /> mining depth was assumed to be 60 feet in this area based on the bore log <br /> information in the geotechnical investigations. <br /> Case 3-2 — Edge of Highway Realignment Parcel to the East of Phase 3. <br /> The proposed setback for mining is 75 feet from the edge of the parcel. The <br /> mining depth was assumed to be 65 feet in this area based on bore log <br /> information in the geotechnical investigations. <br /> Case 3-3 — Edge of Highway Realignment Parcel to the North of Phase 3. <br /> The proposed setback for mining is 65 feet from the edge of the parcel. The <br /> mining depth was assumed to be 56 feet in this area based on bore log <br /> information in the geotechnical investigations. <br /> West Farm Gravel Pit Expansion <br /> Slope Stability Analysis <br /> Page 2 <br />