2025 06 18 WEH Slope Stability Analysis Letter Report

14 January 2025 Revised 18 June 2025 Mark Hoffman Garden Homes Management 820 Morris Turnpike, Suite 301 Short Hills, New Jersey 07078 Re: Executive Summary of Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 Dear Mr. Hoffman: This letter serves as an executive summary of the enclosed report that documents the findings of subsurface investigations and global slope stability evaluations performed by Langan Engineering and Environmental Services, LLC (Langan) for the eastern portion (the “Study Area”) of the proposed West Essex Highlands development site located in West Orange, New Jersey. EXECUTIVE SUMMARY Langan was requested by West Essex Highlands, Inc. (“WEHI”) to perform a global slope stability evaluation in response to the comments made by the public during Planning Board hearings regarding the proposed location of Building D. As depicted on the “Overall Grading Plan” (Sheet SP-11) prepared by Anderson Consulting Services, LLC, Building D is proposed to be constructed near the eastern portion of the subject property, but west of the slope which descends towards the Rosemont Terrace and Mayfair Drive developments and a portion of Howell Drive to the east (the “Subject Slope”). Langan’s investigations summarized in the enclosed letter report evaluate the proposed construction of Building D from a geotechnical standpoint as it relates to the stability of the adjacent Subject Slope. As set forth therein, the subsurface investigations performed as part of this study consisted of soil borings and test pits and rock outcrop mapping that were performed in November and December 2024 and April through June 2025. Based on our study, it is the professional opinion of the undersigned that the Subject Slope is stable under current conditions, would remain stable during the rock excavation to construct Building D foundations provided appropriate excavation and blasting

Executive Summary of Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Revised 18 June 2025 Page 2 of 2 methods are utilized, and would be stable following the construction of Building D based on its anticipated structural loads and distance of Building D from the top of the slope. It should be noted that Langan’s study is based on the geotechnical subsurface data collected at accessible locations within the Study Area, the topographic survey data, currently existing site conditions and proposed building information made available to us. Any proposed changes in proposed structures (location, layout, loading, elevation) or existing slope conditions should be brought to our attention so that we can determine whether such changes affect our conclusions. Sincerely, Langan Engineering and Environmental Services, LLC Mark K. Seel, P.E. Vice President Ronald D. Boyer, P.E. Senior Principal / Senior Vice President Enclosure(s): Letter Report cc: John Cote, Michael Vitello, Adam Yoda / Langan NJ Certificate of Authorization No. 24GA27996400 \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Geotechnical\Reports\2024 - Slope Stability Memorandum\2025-01-14 - Slope Stability Analysis Executive Summary.docx

14 January 2025 Revised 18 June 2025 Mark Hoffman Garden Homes Management 820 Morris Turnpike, Suite 301 Short Hills, New Jersey 07078 Re: Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 Dear Mr. Hoffman: This letter report documents the findings of subsurface investigations and global slope stability analysis performed by Langan Engineering and Environmental Services, LLC (Langan) for the eastern portion (the “Study Area”) of the proposed West Essex Highlands development site located in West Orange, New Jersey. The purpose of the study is to address perceived slope stability concerns (the “Subject Slope”) raised by the public during previous Site Plan review meetings, related to the proposed construction of Building D on the West Essex Highlands Development. This report provides an overview of the study and statements of our opinions in that regard. Details concerning our subsurface investigation, analysis, and evaluation are provided as Attachment A in support of the statements and opinions herein. OVERVIEW DISCUSSION Langan initially investigated the subsurface conditions within the Subject Slope/Study Area along two transects roughly 385 feet apart using a combination of drilled borings and test pit excavations. These findings were presented in a report dated 14 January 2025, and the undersigned provided testimony during a public hearing on 29 January 2025. Based on comments received from the public during that hearing, Langan performed additional investigation and analysis immediately north of the original study area. Those findings are presented in this report, and include two additional transects along which slope stability was evaluated. The locations of all transect lines and boring/test pit locations are shown on attached Figure 1. Soil and rock samples were collected and laboratory testing was performed to determine physical and strength parameters, which along with data from our logs of borings and test pits were utilized in our 2dimensional slope stability analysis.

Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Revised 18 June 2025 Page 2 of 5 The Subject Slope descends about 150 feet in elevation to the east from the east side of proposed Building D at an overall slope of roughly 10 degrees (or roughly 17%) to the neighboring properties located on Rosemont Terrace and Mayfair Drive. The distance to the adjacent Rosemont Terrace and Mayfair Drive developments at the bottom of the slope is roughly 700 feet east of the proposed Building D. Immediately to the north of proposed Building D, the ground descends about 50 feet in elevation to the top of a 2 tiered timber and modular block retaining walls located on the property at 15 Howell Drive at a slope of roughly 19 degrees (roughly 35%). A site location map showing the approximate limits of the Study Area is provided below. As part of our supplemental investigation performed between April and June 2025, we mapped rock outcrops and boulders with the Study Area to account for variations in the slope. In general, the subsurface profile in the northernmost part of the study area (upslope from 15 Howell Drive) consists of a relatively thinner relatively dense soil overly hard basalt bedrock the upper 0.5 feet to 4 feet of which was found to be fractured and barely rippable using an excavator. The overburden soils thicken south of the 2-tiered retaining wall. Generalized subsurface conditions encountered in the borings and test pits, and from our mapping revealed the balance of the Study Area to consist of relatively shallow (outcrop to 15 feet deep) hard rock in and near the top of the slope where proposed Building D is to be located. Soils consisted of up to 2 feet of silty, sandy topsoil over relatively dense gravelly sandy soils overlying basalt bedrock at the top of the slope with similar dense sands over basalt and sedimentary bedrock at greater depths lower on the slope further to the east.

Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Revised 18 June 2025 Page 3 of 5 During our subsurface investigation, groundwater was observed in only one test pit (TP-1), at a depth of roughly 11 feet below existing grade, which is below the top of decomposed basalt. There was no indication of mottling of soils in the test pits that would suggest a seasonal water table. All test pits, excluding R-1B, excavated during the wet season in April, similarly did not encounter water nor did the soil exhibit mottling. Minimal water seepage was observed on top of the rock surface that was encountered approximately 2 feet below existing surface grade. Geologic Hazard Review and Rock Outcrop Stability The Subject Slope has a few scattered rock outcrops along the top and upper portions of the slope. No adverse / problematic jointing was observed. The potential for rock fall hazard is low and would be expected to ravel directly to the ground beneath the outcrops. A high-angle fault with no history of activity is mapped about 2,000 feet to the east of the site. A copy of the geologic mapping is provided as Figure 2. The seismic risk at the site is considered low based on our review of available New Jersey earthquake history in the area. Nonetheless, we included a seismic case in our slope stability analysis. The state of New Jersey published a Landslide Susceptibility Map for Essex County dated 2001, which uses landslide classes from the HAZUS User Guide (FEMA) Table 9.5. One area, identified as Landside Class B III, appears on the map which closely correlates to areas of outcropping shown in Figure 1. We evaluated global slope stability separately from rock stability, which is governed by rock jointing. Due to the typically favorable joint orientation in the outcrops, the rock is stable. Global Stability of Slope Our analysis included an evaluation of slope stability under both static and seismic (dynamic) design conditions. Building D is far enough from the top of the slope that there is no surcharge load that would impact the slope stability, nor will transient automobile loading on the emergency access road connecting the Howell Drive cul-de-sac to the development impact slope stability. Although no indication of a continuous groundwater table was

transient automobile loading on the emergency access road connecting the Howell Drive cul-de-sac to the development impact slope stability. Although no indication of a continuous groundwater table was observed in the test pits, we performed a sensitivity analysis to determine if changes in groundwater level would impact the stability of the subject slope. Analysis Sections A-A’ and B-B’ Our base case static and seismic analyses used the base groundwater level encountered in our one test pit. The results of the static case indicate the lowest factors of safety exceed 1.5, indicating stable slopes. The potential slip plane surface that resulted in the lowest factor of safety was limited in length to roughly 100 feet and occurred near the middle of the Subject Slope as a shallow surficial slip surface (i.e., within the upper 2 feet of soil). Similarly, the results of the dynamic (seismic) case indicate the lowest factors of safety to be greater than 1.2, indicating stable slopes during a potential earthquake. Factors of safety greater than 3.29 and 2.23 were computed where software-generated potential slip planes extend from the top of the Subject Slope to the downslope neighboring properties for the static and seismic cases,

Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Revised 18 June 2025 Page 4 of 5 respectively. In addition to the base cases described above, we analyzed groundwater at the the top of decomposed rock. Factors of safety greater than 1.5 resulted, indicating stability. Analysis Sections C-C’ and D-D’ Our base case static and seismic analyses used the base groundwater level encountered in our one test pit. The results of the static case indicate the lowest factors of safety exceed 1.5, indicating stable slopes. The potential slip plane surface that resulted in the lowest factor of safety was limited in length to roughly 100 feet to 125 feet and occurred east of the rock outcrop as a slip surface within the upper 6 feet of soil. Similarly, the results of the dynamic (seismic) case indicate the lowest factors of safety to be greater than 1.2, indicating stable slopes during a potential earthquake. In addition to the base cases described above, we analyzed groundwater at the the top of decomposed rock. Factors of safety greater than 1.5 resulted, indicating stability. Construction Related Blasting Impacts We understand up to 25 feet of rock is expected to be excavated from one localized area at the top of the Subject Slope in order to reach design grades for Building D. If blasting is to be performed for construction, we recommend using controlled blasting techniques, which include but are not limited to line and/or channel drilling, limiting charge per delay, use of blasting mats, and performing vibration monitoring to assess the effects of blasting. Controlled blasting techniques thereby limit the amount of energy transmitted to the surrounding rock, generally limit the nuisance impacts of construction compared to conventional earth excavating methods (i.e., less time to excavate and haul off material), and limit the potential for impacts to neighboring properties. OPINIONS Based on our investigation and analysis, the Subject Slope is not at risk of failure under current conditions or from proper construction of Building D. Our analyses further indicate that there would be negligible impact on the global stability of the Subject Slope even if groundwater levels were to rise. However, direct precipitation and runoff can be expected to flow over the

te that there would be negligible impact on the global stability of the Subject Slope even if groundwater levels were to rise. However, direct precipitation and runoff can be expected to flow over the sloping ground surface with some lesser amount of infiltration, and the development is not expected to increase stormwater run off toward the Subject Slope. As part of the proposed development, we understand that appropriate drainage and conveyances will be provided to prevent site development stormwater from entering the Subject Slope. LIMITATIONS Our study is based on the geotechnical subsurface data collected at accessible locations within the Study Area, the topographic survey data, currently existing site conditions and proposed building information made available to us. Any proposed changes in proposed structures

Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Revised 18 June 2025 Page 5 of 5 (location, layout, loading, elevation) or existing slope conditions should be brought to our attention so that we can determine whether such changes affect our conclusions. Sincerely, Langan Engineering and Environmental Services, LLC Mark K. Seel, P.E. Vice President Ronald D. Boyer, P.E. Senior Principal / Senior Vice President Enclosure(s): Figure 1, Figure 2, Attachment A cc: John Cote, Michael Vitello, Adam Yoda / Langan NJ Certificate of Authorization No. 24GA27996400 \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Geotechnical\Reports\2024 - Slope Stability Memorandum\2025-01-14 - Slope Stability Analysis LetterRpt.docx

FIGURES Figure 1 Figure 2 Boring and Test Pit Location Plan with Building Sections Geological Map = = =