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the Naval Facilities Command Manual DM7 standards for a recommended minimum factor of safety of 1.50 for static load cases and 1.15 for seismic load cases. This standard is, in our opinion, applicable as a standard for the slope in this case. The Army Corps of Engineers Engineering Manual EM1110-2-1902 is consistent with the recommendation of DM-7. Princeton Hydro has referenced Corps of Engineers Manual EM-1110-2-2908 Rock Foundations as requiring a minimum factor of safety of 2.00. This standard is not, in our opinion, applicable as a standard for the slope in this case.

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.

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 18 of 21 Princeton Hydro Analysis Cases Static Case with Groundwater Phreatic Surface at Top of Decomposed Rock Failure Surfaces in Soil Overburden: 1. The critical factor of safety on Section C was computed to be 1.589 for the proposed condition. 2. The critical factor of safety on Section D was computed to be 1.938 for the proposed condition. Static Case with Groundwater Phreatic Surface at Top of Decomposed Rock Failure Surfaces in Weak Zone of Rock with GSI = 20: 1. The critical factor of safety on Section C was computed to be 1.76 for the proposed condition. 2. The critical factor of safety on Section D was computed to be 1.65 for the proposed condition. The computed minimum factors of safety exceed 1.50 in the analysis cases presented by Princeton Hydro. There is a surface shown for analysis Section C with critical failure surface passing through the medium dense sands with factor of safety of 1.48 which is only slightly less than 1.50. Langan has questioned the assumed stratification on that section stating that it does not consider dense sands on that section, which were indicated by the borings. Langan Rebuttal Analysis Cases In Exhibit A of their rebuttal, Langan derives a lower-bound Rock Mass Rating and Geologic Strength Index of 50, which exceeds the value of 20 used by Princeton Hydro. They also performed analyses which indicate that the existing sanitary sewer trench would not significantly reduce the stability of the slope. The factors of safety exceed the values computed by Princeton Hydro, but the factors of safety using the GSI of 20 were, in our evaluation, satisfactory and do not indicate instability. The detailed results are contained in the Langan Rebuttal Case. CONCLUSION AND RECOMMENDATIONS TO THE BOARD General We have described our review of the project based on the submittals to the Planning Board. Our evaluation of the Memoranda from the Applicant’s and Objector’s Engineers is as follows: 1. The description of subsurface conditions conforms to the reported bedrock and surficial geology with the exception that Langan

Memoranda from the Applicant’s and Objector’s Engineers is as follows: 1. The description of subsurface conditions conforms to the reported bedrock and surficial geology with the exception that Langan did not consider the transition to the Feltsville

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 19 of 21 2. 3. 4. 5. 6. 7. bedrock formation which appears to begin near Borings LB-2 and LB-4. Nevertheless, we do not anticipate that this will significantly modify the range of critical safety factors. The results of the Langan analyses that included a presumed groundwater level at the surface of the decomposed rock were reported, but the computer output plots were not included. These output plots should be submitted for the record. The results of the stability analyses by both the Objector’s and the Applicant’s Engineers exceed a safety factor of 1.50. On this basis, we may conclude that conventional analysis does not indicate instability for static and seismic stability. The results of the analyses do not discount the concerns for the risk of landslide indicated by the Hazus mapping which underestimated the effective angle of the slope. In our experience, landslides frequently occur in tandem with heavy rainfall. Neither of the Engineers has adequately considered the response of the slopes to heavy rainfall, and groundwater interflow. In addition, the Stormwater Management Plans propose introduction of substantial infiltration basins close to the top of the slope. The Applicant’s Engineers should propose and perform a stability evaluation using a conservative piezometric surface that would reflect the response of groundwater to heavy storm-induced rainfall. The Applicant’s Engineers should, in our opinion, review the mounding influence of the proposed infiltration Basins Nos. 10 and 11 and consider mitigation by either providing a cutoff (possibly using the building foundation walls) preventing infiltration flow to the east, or relocation of the basins further down the backslope. Recommended Requirements to be Considered by the Board The stability of the slope should not be considered a fixed or permanent condition. We recommend that the Planning Board and Municipal Agencies having jurisdiction establish and enforce the following requirements. 1. Clearing Site: The limits of earthwork and disturbance should be strictly adhered

hat the Planning Board and Municipal Agencies having jurisdiction establish and enforce the following requirements. 1. Clearing Site: The limits of earthwork and disturbance should be strictly adhered to maintain the stability of the slope. 2. Long-term measures should be required to maintain the health of the forestry on the slope. The health of the root systems provides reinforcement to the shallow topsoil layer on the slope. 3. The provisions of the Soil Erosion Plan should provide details for protection of the ridge and slope. Discharge of water from dewatering during construction should not be permitted. 4. Surcharges resulting from the stockpiling of materials and heavy equipment should not be permitted on the ridge immediately above the slope to avoid a reduction of the stability of the slope. 5. The requirements for construction should include an excavation and dewatering work plan addressing the stability of the slope during the construction. This work plan should be

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 20 of 21 prepared by a licensed Professional Engineer currently registered in the State of New Jersey. 6. Support of excavation should be required along the ridge. Cutting back the slope beyond the limits of the earthwork should not be permitted. 7. Rock excavation should be controlled to minimize vibrations and disturbance to the ridge. The design of blasting charges, if required, should consider the controlling distance to be the distance to the top of slope, which is in the maximum range of 40 to 100 feet. 8. Dewatering and control of runoff should be required. Ponding of water in the excavation could surcharge the joints in the rock and should not be permitted. 9. Slope indicators should be installed on the slope to monitor for movement during construction. 10. Installation of groundwater monitoring wells should be considered at infiltration basins located along the ridge. 11. Final grading and landscaping should be strictly performed to ensure that runoff is intercepted and prevented from runoff over the slope. Closure We appreciate the opportunity to assist the West Orange Planning Board in the review of slope stability issues related to the proposed construction in the area of the proposed Building D for the West Essex Highlands Development. Our review is based on our best professional judgement and on our experience in evaluating the stability of slopes. The construction should be monitored by qualified Geotechnical Engineers familiar with the anticipated conditions and requirements for maintenance of stability. Any variation in conditions encountered should be brought to our attention to determine if modifications of the conclusions and recommendations contained herein is necessary.

d Consulting & Municipal Se ENGINEERS 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 21 of 21 If you have any questions or concerns regarding any portion of this report, please do not hesitate to contact our office. Very Truly Yor fos imuel N. LAL PE Principal Engineer ce: Geniece Gary-Adams — Director of Planning & Development & Zoning Official Zayibeth Carballo, PE, PLS, PP, CME, CFM, CFS — Township Engineer Diana McGovern, Esq. — Planning Board Attorney George Wheatle Williams, PP — Planning Board Planner West Essex Highlands, LLC — Applicant Bryan D. Placker, Esq. — Applicant's Attorney Paul W. Anderson, PE — Applicant's Engineer