2025 06 18 WEH Slope Stability Analysis Letter Report

Color Proposed Building D.1 690 Name Slope Stability Material Model Bedrock Hoek-Brown 180 Decomposed Rock/Very Dense Granular Soil Mohr-Coulomb 135 0 38 Dense to Very Dense Mohr-Coulomb Sand 125 0 34 Medium Dense Sand Mohr-Coulomb 120 0 32 Top Soil 115 0 30 Mohr-Coulomb Unit Weight (pcf) Effective Effective UCS Cohesion Friction Intact (psf) Angle (psf) (°) Intact Geological Disturbance Piezometric Rock Strength Factor D Surface Parameter Index GSI mi 323,263 17 65 1 1 1 2.229 640 Criticalsurface Failure Failure Surface (CFS) TP-8 LB-1 8.2753 ft TP-1 TP-2 590 Factor of Safety: 2.229 Current Slip Surface Number: 221 Horz Seismic Coef.: 0.0875 TP-3 540 LB-2 Approximate location of Existing Building Elevation 490 440 390 340 290 240 190 0 100 200 300 400 500 600 700 Distance Cross Section A_Proposed Condition 800 900 1,000 1,100 1,200

Cross Section B (Seismic Condition)

Color 690 Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Bedrock 180 Decomposed Rock/Very Dense Granular Soil 135 0 38 Dense to Very Dens Sand 125 0 34 Medium sand 120 0 32 Top soil 115 0 30 UCS Intact (psf) Intact Rock Geological Parameter Strength mi Index GSI Disturbance Factor D Piezometric Surface 323,263 17 1 1 65 1 1.293 640 Factor of Safety: 1.293 Current Slip Surface Number: 271 Horz Seismic Coef.: 0.0875 TP-7 TP-4 LB-3 B-13 TP-14 590 TP-5 Approximate Projected Location of Existing Building LB-4 540 TP-6 Elevation 490 Critical Failure Failure surface Surface (CFS) 440 390 340 290 240 190 0 100 200 300 400 500 600 700 Distance Cross Section B_Existing Condition 800 900 1,000 1,100 1,200

Color Proposed Building D.2 Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Bedrock 180 Decomposed Rock/Very Dense Granular Soil 135 0 38 Dense to Very Dens Sand 125 0 34 Medium sand 120 0 32 Top soil 115 0 30 UCS Intact (psf) Intact Rock Parameter mi Geological Strength Index GSI Disturbance Factor D Piezometric Surface 323,263 17 65 1 1 1 690 1.297 640 TP-4 TP-14 Factor of Safety: 1.297 Current Slip Surface Number: 271 Horz Seismic Coef.: 0.0875 TP-7 LB-3 12 ft LB-13 590 TP-5 Approximate Projected Location of Existing Building LB-4 540 TP-6 Elevation 490 Criticalsurface Failure Failure Surface (CFS) 440 390 340 290 240 190 0 100 200 300 400 500 600 700 Distance Cross Section B_Proposed Condition 800 900 1,000 1,100 1,200

Color 690 Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Bedrock 180 Decomposed Rock/Very Dense Granular Soil 135 0 38 Dense to Very Dens Sand 125 0 34 Medium sand 120 0 32 Top soil 115 0 30 UCS Intact (psf) Intact Rock Geological Parameter Strength mi Index GSI Disturbance Factor D Piezometric Surface 323,263 17 1 1 65 1 4.594 Criticalsurface Failure Failure Surface (CFS) 640 Factor of Safety: 4.594 Current Slip Surface Number: 217 Horz Seismic Coef.: 0.0875 TP-7 TP-4 LB-3 B-13 TP-14 590 TP-5 Approximate Projected Location of Existing Building LB-4 540 TP-6 Elevation 490 440 390 340 290 240 190 0 100 200 300 400 500 600 700 Distance Cross Section B_Existing Condition 800 900 1,000 1,100 1,200

Color Proposed Building D.2 Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Bedrock 180 Decomposed Rock/Very Dense Granular Soil 135 0 38 Dense to Very Dens Sand 125 0 34 Medium sand 120 0 32 Top soil 115 0 30 UCS Intact (psf) Intact Rock Parameter mi Geological Strength Index GSI Disturbance Factor D Piezometric Surface 323,263 17 65 1 1 1 690 4.585 640 TP-4 TP-14 Criticalsurface Failure Failure Surface (CFS) TP-7 LB-3 12 ft LB-13 590 Factor of Safety: 4.585 Current Slip Surface Number: 217 Horz Seismic Coef.: 0.0875 TP-5 Approximate Projected Location of Existing Building LB-4 540 TP-6 Elevation 490 440 390 340 290 240 190 0 100 200 300 400 500 600 700 Distance Cross Section B_Proposed Condition 800 900 1,000 1,100 1,200

Cross Section C (Seismic Condition)

Color Name Color 660 Unit Weight (pcf) Name Unit Weight (pcf) Bedrock 180 Bedrock Decomposed Rock/Very Dense Decomposed Granular Soil Rock/Very Dense 180 135 135 Effective Cohesion (psf) Effective Cohesion (psf) 0 0 Effective Friction Angle (°) Effective Friction Angle (°) 38 UCS Intact (psf) UCS Intact (psf) 323,263 Intact Rock Parameter mi Intact Rock Parameter mi Geological Strength Index GSI 17 65 323,263 17 Geological Strength Index GSI Disturbance Factor D Disturbance Factor D Piezometric Surface Piezometric Surface 65 1 1 1 1 1 38 1 Granular Soil Medium sand 120 Medium sand 120 Retaining Wall Retaining Wall 150 150 Topsoil Topsoil 115 115 0 0 32 1 32 1 1 1 00 30 640 30 1 1 1.259 Factor of Safety: 1.259 Current SlipSurface SurfaceNumbe Number: 401 Current Slip 620 NLB-2 Horz Seismic Coef.: 0.0875 NTP-1 Critical Failure Surface (CFS) 600 NTP-2 NLB-1 Property Line Elevation 580 560 540 520 500 480 460 440 0 100 200 Distance Cr Cross Section D_Existing Condition 300 400

Color Name Unit Weight (pcf) Color Name Unit Weight Effective Cohesion (psf) 180 (pcf) Bedrock 660 Effective Cohesion (psf) Decomposed 135 180 Bedrock Rock/Very Dense Decomposed 135 Granular Soil 0 Medium sand 0 Rock/Very Dense Granular Soil 120 Medium sand 120 Effective Friction Angle (°) UCS Intact (psf) Intact Rock Parameter mi Geological Strength Index GSI Topsoil 115 115 UCS Intact Rock Intact Parameter (psf)323,263 mi 17 Geological Disturbance Strength Factor D Index GSI 65 1 1 38 323,263 65 1 1 0 38 0 32 17 1 Piezometric Surface 1 32 1 1 1 1 0 0 Piezometric Surface Effective Friction Angle (°) Retaining Retaining Wall Wall 150 150 Topsoil Disturbance Factor D 30 30 640 1 1 1.259 620 NLB-2 NTP-1 Critical Failure Surface (CFS) 600 NTP-2 NLB-1 Factor of Safety: 1.259 Current Slip Surface SurfaceNumbe Number: 401 Current Slip Horz Seismic Coef.: 0.0875 Property Line Elevation 580 560 540 520 500 480 460 440 0 100 200 Distance Cross Section D_Proposed Condition Cr 300 400

Cross Section D (Seismic Condition)