2025 01 14 West Essex Highlands Development Building D Slope Stability Study

Global Slope Stability Study for Building D West Essex Highlands Project Langan Project No.: 101049801 14 January 2025- Page 6 of 11 MEMO 4. We estimated strength parameters for the rock based on laboratory testing results and rock recovery and rock quality designation values obtained in the rock cores. 5. We analyzed the global slope stability using LEM for the estimated proposed Building D load and we calculated factors of safety with respect to global stability for the static condition. 6. We analyzed the slope stability using the LEM for the combined service and seismic loads and we calculated factors of safety with respect to global stability for the maximum considered earthquake. We used the computer software SLOPE/W for the LEM analyses. An overview of our analyses and a summary of our results are presented below. Model Parameters Model Geometry For our two-dimensional global stability analyses, we selected two representative cross-sections (section A and section B) across the proposed Building D footprint extending to the eastern property line in the subject area. The eastern property line is approximately 900 ft east of the proposed Building D footprint. The soil and rock elevations used in the model are based upon the results of available subsurface investigation information, which was collected from the accessible explored areas of the site. Material Properties The generalized subsurface conditions consisted of surficial materials (topsoil) underlain by natural sand and silt over decomposed rock and rock strata. Due to steep slope geometry, no subsurface investigation was performed at the lower slope located northeast of proposed Building D. We estimated the material parameters including friction angle (ϕ’), of the surficial fill, natural soil and decomposed rock layers based on in-situ test data. The soil parameters utilized in our analyses are presented in Table 1 provided on the following page. Table 1: Soil Strength Properties Soil/Rock Unit Weight (pcf) ϕ' (deg.) c (psf) Topsoil 115 30 0 Medium Dense Sand 120 32 0 Dense Sand 125 34 0 Decomposed Rock/Very Dense Granular Soil 135 38 0 = = =