Langan Rebuttal Report 9 15 2025

Color 660 Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) UCS Intact (psf) Intact Rock Parameter mi Geological Strength Index GSI Disturbance Factor D Piezometric Surface 323,263 17 37 1 1 Bedrock 180 Decomposed Rock/Very Dense Granular Soil 135 0 38 1 Medium sand 120 0 32 1 Retaining Wall 150 Topsoil 115 0 30 1 640 1 1.589 620 Factor of Safety: 1.589 Current Slip Surface Number: 401 NLB-2 NTP-1 600 NTP-2 NLB-1 Property Line Elevation 580 560 540 520 500 480 460 440 0 100 200 Distance Cross Section C_Existing Condition (GSI = 37) 300 400