25 10 28 Slope Stability Review

Chairman and Members of the West Orange Planning Board Application No. PB24-01, West Essex Highlands, LLC, Warner Road, Block 179, Lot 32 Review of Applicant’s Engineer’s Slope Stability Analysis Reports, the Objector’s Engineer’s Response Reports; and the Applicant’s Engineer’s Rebuttal Report October 28, 2025 Page 17 of 21 Langan Analysis Cases Our review of the cases contained in the Memorandum submitted on June 18, 2005, indicates the following interpretation of results: Static Load Cases with No Groundwater – Analysis Plots in Report Appendix E: 1. Cases on all the analysis sections that involve circular surfaces penetrating into the bedrock yielded high factors of safety and are not, in our opinion, critical. 2. The critical factor of safety with minimum factor of safety on Analysis Section A was computed to be 2.201 under the proposed condition and only slightly less than 2.204 computed for the existing condition. 3. The critical factor of safety on Section B was computed to be 1.676. 4. The critical factor of safety on Section C under proposed conditions was 1.589 for a shallow surface passing through medium dense sands. 5. The critical factor of safety on Section D under proposed conditions was 1.936. Seismic Static Case with No Groundwater – Analysis Plotted in Appendix F: 1. The critical factor of safety with minimum factor of safety on Analysis Section A was computed to be 1.65 under the proposed condition. 2. The critical factor of safety on Section B was computed to be 1.297. 3. The critical factor of safety on Section C under proposed condition was 1.259. 4. The critical factor of safety on Section D under proposed conditions was 1.473. Static Case with Groundwater Phreatic Surface at Top of Decomposed Rock – Analyses Reported on Page 11 (but not plotted): 1. The critical factor of safety with minimum factor of safety on Analysis Section A was computed to be 2.20 under the proposed condition. 2. The critical factor of safety on Section B was computed to be 1.67. 3. The critical factor of safety on Section C under proposed condition was 1.59. 4. The critical factor of safety on Section D under proposed conditions was 1.94. The computed minimum factors of safety exceed the requirements in the referenced standards listed above. The analysis plots for the groundwater case should be submitted.