Langan Rebuttal Report 9 15 2025

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 50 1 1.669 640 TP-7 TP-4 LB-3 B-13 Utility Trench (8 ft wide) TP-14 590 Factor of Safety: 1.669 Current Slip Surface Number: 271 TP-5 LB-4 540 TP-6 Elevation 490 Critical Failure Surface (CFS) 440 390 340 290 240 190 0 100 200 300 400 500 600 700 Distance Cross Section B_Existing Condition (GSI = 50) 800 900 1,000 1,100 1,200