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

14 January 2025 Mark Hoffman Garden Homes Management 820 Morris Turnpike Suite 301 Short Hills, NJ 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 a subsurface investigation and global slope stability evaluation 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 to the east (the “Subject Slope”). Langan’s investigation summarized in the enclosed letter report evaluates 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 investigation performed as part of this study consisted of soil borings and test pits that were performed in November and December 2024. 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 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 Mark Hoffman Garden Homes Management 820 Morris Turnpike Suite 301 Short Hills, NJ 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 a subsurface investigation and global slope stability evaluation 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 issue being investigated 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 The Subject Slope descends about 150 feet in elevation to the east from the east side of proposed Building D at roughly 10 degrees (or roughly 17%). 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. A site location map showing the approximate limits of the Study Area is provided below. Langan investigated the subsurface conditions within Subject Slope/Study Area along two transects roughly 385 feet apart using a combination of drilled borings and test pit excavations. The locations of the 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 2-dimensional 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 Page 2 of 4 The generalized subsurface conditions encountered in the borings and test pits 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 sedimentary bedrock at greater depths lower on the slope further to the east. 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. Geologic Hazard Review The Subject Slope has a few scattered rock outcrops along the top and upper portions of the slope. No adverse / problematic jointing was observed. 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 on 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.

Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Page 3 of 4 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. Although no indication of a seasonal variability in groundwater elevation 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. 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, respectively. In addition to the base cases described above, we analyzed groundwater midway in the soil profile and at a depth of 2 feet below grade. Only when groundwater was modeled at a depth of 2 feet below grade did the factor of safety decrease to 1.36 under the static case. This potential slip surface is within 2 feet of ground and does not pose a hazard to the site of neighboring properties. Factors of safety greater than 3.0 were computed where software-generated potential slip planes extend from the top of the Subject Slope to the downslope neighboring properties and include unrealistically high-water levels in the soil. 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. It is common for

lasting 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. It is common for rock excavation to be achieved 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. Such methods 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 sloping

Global Stability Study for Eastern Slope near Building D West Essex – Highlands Development West Orange, New Jersey Langan Project No.: 101049801 14 January 2025 Page 4 of 4 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 (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 A and B Geological Map = = =

TP-F2 TP-F1 B-11 FF: 618.0 GF: 607.0 BUIL D ING 101147901 D.1 TP-12 B-12 TP-1 AA el 606 > 9 ft belowLB-1 elel597 597 TP-8 beyond TP-2 TP-3 LB-2 A A 3 LB-1 el 606 11 13 ft el 595 593 el el 582 582 > 5.5 4 ft ft below 576.5 el el 578 el 604 14 ft el 590 el 522 >> 50 50 ftft below elel472 beyond 472 el 550 >> 12 12 ftft below elel538 beyond 538 TP-13 FF:618.0 GF: 597.0 TP-E2 B-13 TP-D1 FF: 618.0 GF: 594.0 TP-14 BB LB-3 TP-4 TP-4 T LB-3 TP-7 el el616 616 3.75 > 5 ft el 612.2 below el 611 TP-5 TP-5 LB-4 TP-6 TP-6 B el 584 >4.5 4.8ftft below elel579.2 beyond 579.2 el 579.5 el 528 > 12 ft below elel516 beyond 516 LB-4 B el 548 584 el > 45ftft >45 below el beyond el 503 503 DING D.2 el el 614 614 > 3.5 3.7 ftft below el 610.3 el 610.5 el 614 9 ft el 605 TP-D2 B-14 BUIL TP-15 LGF: 582.0 TP-C2 1. BASE PLAN OBTAINED FROM PLAN TITLED "OVERALL GRADING PLAN SP-11" DATED 1 OCTOBER 2024 PREPARED BY ANDERSON CONSULTING SERVICES LLC (ACS).AND IS 1. AERIAL PHOTOGRAPH TAKEN FROM NEARMAP LB-1 ED 30 OCTOBER 2024. el 606 13 ft el 593 SCALE: 1" = 50' LEGEND: APPROXIMATE LOCATION OF LANGAN BORING Langan Engineering and Environmental Services, LLC. TP-1 APPROXIMATE SURFACE ELEVATION APPROXIMATE LOCATION OF LANGAN TEST PIT APPROXIMATE OVERBURDEN SOIL AND DECOMPOSED ROCK THICKNESS APPROXIMATE TOP OF ROCK Figure 101049801 101147901 A A APPROXIMATE LOCATION GLOBAL SLOPE STABILITY ANALYSIS SECTION 300 Kimball Drive Parsippany, NJ 07054 T: 973.560.4900 F: 973.560.4901 www.langan.com NJ CERTIFICATE OF AUTHORIZATION No. 24GA27996400 WEST ESSEX HIGHLANDS WEST ORANGE NEW JERSEY PROPOSED INVESTIGATION INVESTIGATION PLAN PLAN 1/14/2025 11/4/2024 1 RLB AY © 2021 Langan NOTES:

N APPROXIMATE SUBJECT SLOPE AREA LEGEND Preakness Basalt – Dark-greenish-gray to black, fine-grained, dense, hard basalt Feltville Formation – Reddish-brown or light-grayish-red, fine-to-coarse-grained sandstone, siltstone, shaly siltstone and silty mudstone. Source: Bedrock Geologic Map of The Caldwell Quadrangle, Essex and Morris Counties, New Jersey by Richard A. Volkert (2006) WEST ESSEX - HIGHLANDS GEOLOGIC MAP WEST ORANGE NEW JERSEY PROJECT NO. SCALE DATE FIGURE 101049801 N.T.S. 1/14/2025 1/13/2025 11/4/2024 2 \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Geotechnical\Reports\2024 - Slope Stability Memorandum\Figure 2 - Geologic Map.docx