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ion logs and laboratory test result reports contained in the CME files for the Planning Board Application review. Langan performed explorations on the slope for the slope stability investigation being evaluated herein. Sor Engineering (“Sor”) performed a geotechnical evaluation for the site buildings including Building D near the ridge. In addition, they performed 3 additional investigations for analysis and design of stormwater management systems including Basins 10 and 11 on the western side of Building D. The layout of explorations is shown on the Langan Investigation Plan. A copy of this plan marked with our notes is contained in this report to assist the Board in understanding our descriptions.

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 12 of 21 Field and Laboratory Investigation Performed by Langan for the Applicant The report indicates that the investigation included field examination of rock outcrops on the slope, and two series of test borings and 3 series of test pit explorations on the slope. The first phase included 4 test borings (LB-1 – LB-4) and 8 test pits located on the slope to the east of Proposed Building D and are arrayed primarily along analysis Sections A and B on their Investigation Plan. The first series of borings were performed in December of 2024. The first series included 8 test pits TP-1 to TP-8 which were performed in November of 2024. The report indicates that a series of 6 shallow test pits were performed in April of 2025 around the outcrops and included Test Pits R1A, R1B, R-2, R3, R-4A and R-4B. This series of test pits was performed in April of 2025. The third series of explorations included 4 test boring (NLB1-NLB4) and 5 test pits (NTP-1 to NTP-5). The Borings were arrayed along Analysis Sections C and D. Test Pit NTP 3 was performed between Sections C & D and Test Pit NTP-5 was performed approximately 110 feet south of the analysis Section D. The test borings in this series were performed in early May of 2025. The Langan Reports indicate that the borings were performed using all terrain drilling equipment and were drilled using mud-rotary drilling techniques. The logs indicate that casing was advanced which would be necessary to core bedrock. The borings were advanced to depths ranging between 19 and 50 feet below the grade at the ground surface at the boring location. The logs indicate that Standard Penetration Test sampling procedures were used to obtain samples of soil encountered in the borings. Core samples were taken in the rock using N size double tube core samplers. The overburden soils were reported to have been classified visually. There were no index testing results, such as moisture content and grain size tests, included in the report. Two unconfined compression tests were performed on samples of the basalt bedrock. Field and

There were no index testing results, such as moisture content and grain size tests, included in the report. Two unconfined compression tests were performed on samples of the basalt bedrock. Field and Laboratory Testing Performed for Stormwater Management System Design A geotechnical report and 3 reports related to investigations to provide criteria for design of stormwater management systems were performed for the Applicant by Sor. The reports are included in the list of references presented previously. We reviewed the results of boring logs and test pits that were performed along the west side of proposed Building D including those in the area of proposed infiltration Basins Nos. 10 and 11. These were contained in the report dated May 23, 2023. This report, which contained the Logs of Sor Engineering Boring B-12 and Test Pits E1, E-2, D1 and D2, was reviewed for this letter. The Boring B-12 was drilled to refusal on

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 13 of 21 rock. The test pits extended to depths of 12, 14, 16 and 9 feet below the existing grade respectively. Bedrock was reported encountered only in Test Pit D2. The report included the results of grain size tests, moisture content and falling head permeability test results for bulk samples taken from the test pits. INFERRED SUBSURFACE CONDITIONS General Our review indicates that Langan has prepared a generalized stratigraphy for their stability analysis that conforms generally to the anticipated geology contained on the reference geologic mapping of bedrock and surficial geology of the Caldwell Quadrangle. The stratigraphy is shown on the attached markup of the Langan Analysis Sections A through D. Our review is summarized below. In addition, we have reviewed comments on the inferred stratigraphy provided by Princeton Hydro for the Objector in this section of the letter. Generalized Stratigraphy for Stability Evaluation The soil overburden varied from 7 to 20 feet thick in the borings that encountered the underlying Basalt. Borings LB-2 and LB-4 were advanced to depths of 50 and 45 feet and did not encounter Basalt. The soil overburden conformed to the following generalized stratum as established by Langan for their evaluation of the stability of the slope: Topsoil: The boring’s sample descriptions indicate a “topsoil” layer approximately two feet thick with field standard penetration test values indicating that the layer is generally in a loose state of compaction. Langan has assigned a strength envelope with cohesion of 0 psf and a friction angle of 30 degrees. Medium Dense Sands: Medium dense sands with field standard penetration test values indicating that they are in a medium dense state were indicated on the Analysis Sections below the topsoil in the NLB borings on Cross Sections C and D. On Analysis Sections A and B, the medium dense sands are shown as an inclusion within the dense to very dense glacial tills. Langan has assigned a strength envelope equivalent to a cohesion intercept of 0 psf and an angle of internal friction of 32

ands are shown as an inclusion within the dense to very dense glacial tills. Langan has assigned a strength envelope equivalent to a cohesion intercept of 0 psf and an angle of internal friction of 32 degrees. Dense to Very Dense Sands with varying percentages of Silt and Gravel: Most of the borings encountered dense sands with field blow counts indicating that the materials are dense to very dense. Boulders were encountered within this layer. These sands conform generally with the materials described as yellow Rahway till on the Surficial Geology

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 14 of 21 Mapping. The apparent density indicates that the materials were likely to have been deposited by the glacier and subject to heavy pressures from the overlying glacier. These soils extended to the decomposed rock layer in most of the borings directly underlain by the Basalt formation. Langan has assigned a strength envelope based on a cohesion of 0 psf and an angle of internal friction of 34 degrees. The bedrock formation, as described by Langan based on observations of the outcrops and descriptions and photographs of rock cores in their report, conformed, based on our understanding, to the following description: Decomposed Rock: This description, in our experience, describes the zone of deterioration of the parent bedrock material and, in at least one classification system, may be represented as rock with a standard penetration resistance less than 50 blows per inch. The area was glaciated, and it is apparent that the igneous rock had been worked by the action of the glacier. The decomposed layer appears to be a few feet thick. Langan has assigned a strength envelope based on a cohesion of 0 psf and an angle of internal friction of 38 degrees. Basalt Bedrock: The outcrops of basalt as mapped on the drawings are of low height. Langan reported a joint set dipping downward to the east on a slope of 17 degrees. A downward dip to the east is not, in our experience, a favorable inclination, which would be downward towards the west. Langan indicated a contact rock on rock friction angle of 35 degrees. Unconfined compressive strength test results were examined for 2 rock samples obtained from Boring LB-3, reportedly from 8.5 to 10.5 feet. We anticipate that the core samples were taken from the same segment of core since the depth of the sample is listed as the same range. We reviewed the core box photo (Exhibit C – Select Rock Core Photographs) in the Langan Rebuttal Report (Reference 1C) but were unable to identify the section of core from which the samples were taken. The laboratory report prepared by RSA Geolab of Union, New Jersey,

aphs) in the Langan Rebuttal Report (Reference 1C) but were unable to identify the section of core from which the samples were taken. The laboratory report prepared by RSA Geolab of Union, New Jersey, indicated an unconfined compressive strength of 515,719 pounds per square foot (psf) which is equivalent to 3,580 pounds per square inch (psi) for C1-A. The result for C1-B was 323,260 psf (2,200 psi). The results are a small fraction of the anticipated strength range for Basalt and roughly equivalent to that of a low to medium strength concrete. The wet density of the core was recorded to be 182.3 pounds per cubic foot (pcf) which we understand to be in the normal range. Langan, in their Rebuttal Report, attributed the unusually low strength to porosity, and crystalline grain size characteristics in the rock which would likely have been subjected to external cooling at the edge of the sill. Langan has used the Slope/W computer software which utilizes the Rock Mass Rating (RMR) and Geologic Strength Index (GSI) to model a representative strength for failure

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 15 of 21 surfaces passing through the rock. Langan employed a GSI of 65 in their initial analysis and considered a GSI of 50 in their supplementary analysis for their Rebuttal Memorandum. Princeton Hydro recommended a low value of the index of 20. Sandstone Bedrock (Feltsville Formation): The geologic mapping indicates that the sandstone contact with the Basalt Sill is likely located near the elevation 500 contour and that the sandstone dips below the basalt on a westerly inclination on the order of 10 degrees from the horizontal. Langan recognized in their Rebuttal Report (Ref.1C) that Borings LB-2 and LB-3 were likely to have been drilled into decomposed Sandstone bedrock and terminated at elevations 472 and 503 feet, respectively, which is below and slightly above elevation 500, which is the approximate contact indicated on the Geologic Maps. The analysis sections do not include the decomposed Sandstone bedrock in the failure surface penetrating the rock. We anticipate that strength indicated for the Decomposed Rock would be appropriate for the decomposed sandstone (cohesion = 0) since the failure surfaces in the overlying soil are likely to be the determinant factor for assessing the stability of the slope. Groundwater Conditions In our experience, establishment of a consistent groundwater surface in jointed bedrock in the area of a slope with relatively high topographic relief is very difficult to achieve. In addition, the intact rock has a very low permeability. The rock formation, however, has a variable secondary permeability which is created by the complex network of intersecting fractures. Depending on the width of the fractures, the filling and surface roughness of cracks surcharged by water levels high up on the slope can develop localized high hydrostatic pressures which could affect the local stability of the soil overburden. The persistent wetland delineated on the site plan in the stream valley about 350 feet west of the ridge is an indication of a possible groundwater level. The plan indicates a persistent stream that may give

sistent wetland delineated on the site plan in the stream valley about 350 feet west of the ridge is an indication of a possible groundwater level. The plan indicates a persistent stream that may give an indication of the groundwater levels behind the ridge. The nearest stream to the west of the ridge is shown to emerge near elevation 592. The wetlands markers to the west of the building indicate potential water levels as high as elevation 606 feet to the north of the ridge. The Langan explorations encountered seepage in Test Pit TP-1 at eleven feet below the ground surface at approximate elevation 595 at a point that is about 45 feet west of the crest of the ridge. Sor reported water seepage elevations ranging from elevation 584 at TP-E1 to elevation 581 at TP-E2, located in proposed infiltration Basin 11. They reported seepage at 10 feet below grade in Test Pit TP-D1 at elevation 571 feet which is 10 feet below that observed at TP-E2, which is only 45 feet away. The seepage level noted at Test Pit TP-D2 at elevation 572 is consistent with the level observed at TP-D1 which is 205 feet away.

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 16 of 21 Langan considered a seepage case in their analysis with the phreatic surface approximately following the top of the decomposed Rock. This approach is, in our opinion, reasonable provided there is no indication of spring activity or emerging seepage on the slope below the ridge under present conditions. STABILITY ANALYSES General Both the Applicant’s and the Objector’s Engineers (the “Engineers”) have utilized the Slope/W computer software program to perform the comparative analyses of the slope stability. This program is recognized as an effective analysis tool for complex slopes and is capable of performing searches to determine the critical failure surface that determines the stability of the slope. The Engineers disagree, as indicated in the Objector Report and the Langan Rebuttal, on the strength properties used for the strata and, in particular, for the bedrock, as determined by the Geological Strength Index. The presentation of the results in the report provides the geometry of the slope and sub-surface stratification model prepared by the user and the strength properties derived by the user and entered in the input file. The analyses have been performed using the Limiting Equilibrium Method which derives the safety factor as the limiting shearing resistance available on the assumed failure surface divided on the shearing resistance required on the surface to maintain equilibrium. The method of computation selected by Langan is the Morgenstern Price method which is considered the most rigorous method of analysis. In our opinion, the method of analyses selected by the Engineers are appropriate for evaluation of the stability of the slope. A detailed summary of the computation results is summarized in the individual Engineer’s reports and are not repeated in detail herein. Required Minimum Factors of Safety The Langan report references 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