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. Pond 9A-P4 <br />The embankments were in good condition. No signs of distress or movement in the downstream or upstream faces <br />of the embankments. Pond was dry. Crest width is 10 ;embankment height is approximately 10 ;downstream face <br />a[ 2:1 (H:V) and upstream face at 3:1 (H:V) configurations. <br />Pond SH-PI <br />The embankments were in good condition. No signs of distress or movement in the downstream or upstream faces <br />of the embankments. Pond was dry. Crest width is 10 to 12 ;embankment height is approximate]y 7 ;downstream <br />face at 2.5:1 (H:V) and upstream face at 2.5:1 (H:V) configurations. <br />Pond SH-P2 <br />The embankments were in good condition. No signs of distress or movement in the downstream or upstream faces <br />of the embankments. Pond was dry. Crest width is 8 to 9; embankment height is approximately 2 to 3'; <br />downstream face at 4:1 (H:V) and upstream face at 2.5:] (H:V) configurations. <br />STABILITY ANALYSES <br />Individual stability analyses were completed on five (5) of the seventeen (17) embankments. The stability analyses <br />were conducted on the larger of the embankments, as well as on one of the smaller embankments. The stability <br />analyses were completed for all of the embankments with Drainage Areas greater than 20 acres and with Total <br />Storage Volumes greater than 2.0 acre-feet. <br />To determine the stability of the slopes in the subject embankments, the computer program called SB-SLOPE was <br />employed. This program is a comprehensive slope stability program, which uses the "Simplified Bishop Method of <br />Slices". The stability analyses were conducted assuming that the ponds were full and the water level in the ponds <br />were a[ the emergency spillway elevations. We also assumed that a phreatic swface (steady state seepage) was <br />resent in each of the embankments. The analyses were conducted assuming static loadings and no seismic <br />coefficients were used. The stability analyses data is shown in the attached Appendix A. <br />Since subswface investigations were not completed at the subject sites and no information indicating the soil types <br />were shown on the as-built/design plans, we have assumed [hat the embankment materials and underlying natural <br />soils consist of clays. We assumed various strength parameters for the clays and ran separate analyses using the <br />different strength parameters. The first set of strength parameters were obtained from the Bweau of Reclamation, <br />DESIGN OF SMALL DAMS, Third Addition. Per table 5-1 on page 96 of this design manual, they indicated that <br />the average strength parameters for thirty one (31) samples of compacted clays (CL) was a unit weight of 100.0 pcf, <br />an effective cohesion value (c') of 1,400 psf and an effective angle of internal friction (jl') of 25°. Using these <br />strength parameters, we calculated that the factors of safety ranged from 5.6 to 10.5 for the embankments ]0 to 11 <br />feet in height and a factor of safety of 18.1 was calculated for the five-foot high embankment. <br />We then conducted the stability analyses using very conservative strength parameters, which we have obtained on <br />• samples from other projects in this area on very soft clays. These values were a unit weight of 100 pcf, a c' of 500 <br />psf and a ~ of 0. Using these strength parameters, we have calculated that the factors of safety ranged from 1.7 to <br />Job Number: 01-0857 NWCC, Inc. Page 4 <br />