2025 06 18 WEH Slope Stability Analysis Letter Report

SLAY HOWELL DRIVE HOWELL DRIVE RG EME ENC Y AC S CES ROAD 'D' ROSEMONT TERRACE FF:618.0 GF:607.0 ING ILD BU D.1 FF:618.0 GF:597.0 w A w w B C FF:600.1 BF:587.1 POOL 586.2 CLUBHOUSE LGF:582.0 DRI R I VE A F Y MA RO Langan Engineering and Environmental Services, Inc. 300 Kimball Drive Parsippany, NJ 07054 T: 973.560.4900 F: 973.560.4901 © 2023 Langan AD 'D' BUILDING D.2 FF:618.0 GF:594.0 www.langan.com NJ CERTIFICATE OF AUTHORIZATION NO. 24GA27996400 Date: 6/18/2025 Time: 12:20 User: rblocker Style Table: Langan.stb Layout: Layout1 Document Code: 101049801-0201-BL101-0101

N APPROXIMATE DEVELOPMENT BOUNDARY APPROXIMATE BUILDING D LOCATION 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 1010498014 N.T.S. 6/18/2025 2 \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Geotechnical\Reports\Slope Stability\Figures, Tables, Plans\Figure 2 - Geologic Map.docx

ATTACHMENT A SUPPORTING GLOBAL STABILITY STUDY MEMORANDUM BY LANGAN = = =

Memorandum 300 Kimball Drive To: Parsippany, NJ 07054 T: 973.560.4900 F: 973.560.4901 Mark Hoffman / Garden Homes From: Mark K. Seel / Langan Ronald D. Boyer / Langan Info: _____________________ Mark K. Seel, P.E. Professional Enineer NJ Lic. No. 24GE04229500 Adam Yoda / Langan John Cote / Langan Michael Vitello / Langan Ronald D. Boyer, P.E. Date: 14 January 2025 Revised 18 June 2025 Re: Global Slope Stability Study for Building D West Essex Highlands Project West Orange, New Jersey Langan Project No.: 101049801 Professional Engineer NJ Lic. No. 24GE04200300 This memorandum summarizes the subsurface investigations and global slope stability evaluations performed by Langan Engineering and Environmental Services, LLC (Langan) for the eastern portion of the proposed West Essex Highlands development site located in West Orange, New Jersey. The following sections provide a description of existing site conditions, proposed development, subsurface investigations performed, and conditions encountered, our global slope stability analysis and our evaluation regarding slope stability with respect to the associated building construction. EXISTING CONDITIONS AND PROPOSED CONSTRUCTION The subject project site is located on Lot 32, Block 179, and is bounded by Avon Drive and Howell Drive and residential properties to the north, and residential developments to the south, east and west. The focus of the investigations (the “Study Area”) and subsequent global slope stability analysis is the easternmost portion of the site bounded by Howell Drive, Rosemont Terrace and Mayfair Drive to the east. The Study Area is heavily wooded and surface grades slope downward from west to east. There is a 25-foot-wide utility easement that bisects the subject area running in the north-south direction. Site surface grades generally range from approximately elevation (el) 616 to el 450. Typically, the slope in the Study Area ranges from about 2 Horizontal (H): 1 Vertical (V) or approximately 26 degrees from horizontal at its steepest to approximately 6H:1V or approximately 10 degrees from horizontal east of the utility easement. Hard basalt rock outcrops locally, typically 2 feet (ft) to 15 ft tall, have nearly vertical faces. The proposed residential development will consist of the construction of new 4-story structures over structured parking. Based on available site drawings

ft) to 15 ft tall, have nearly vertical faces. The proposed residential development will consist of the construction of new 4-story structures over structured parking. Based on available site drawings prepared by Anderson Consulting

MEMO Global Slope Stability Study for Building D West Essex Highlands Project Langan Project No.: 101049801 Revised 18 June 2025 Revised 18 June 2025 - Page 2 of 13 Services, LLC. (ACS), the closest building to the subject slope is proposed Building D, which is to be located at the top of the slope within the study area approximately 700 ft west of the eastern property line and approximately 150 ft southwest of the northernmost residence on Howell Drive. We understand that no site improvements are proposed in the wooded subject area located approximately 20 ft east of the proposed eastern building line of Building D. An emergency access road connected to the existing Howell Drive cul-de-sac is also proposed as part of the construction. Based on the proposed grading plans, we understand the proposed construction of Building D and the associated access road will not include any grade changes from the existing conditions immediately east. The lowest proposed level will range from elevation (el) 607 to el 582 which will require cuts up to about 25 ft from existing surface grade in some isolated areas. The lower structured parking level for Building D will be nested into the eastern slope with adjacent grades east of the proposed building remaining unchanged. The building will be supported on shallow foundations bearing on natural soils or rock. A site location map showing the approximate limits of the study area and proposed Building D is provided below and as Figure 1. PROPOSED EMERGENCY ACCESS ROAD HOWELL DRIVE PROPOSED BUILDING D LOCATION APPROXIMATE SUBJECT SLOPE AREA (WOODED) N ROSEMONT TERRACE 700 FT +/EXISTING SEWER EASEMENT APPROXIMATE TOP OF SLOPE MAYFAIR DR APPROXIMATE BOTTOM OF SLOPE Proposed Study Area Site Map REGIONAL GEOLOGY According to the available geological maps we reviewed, the upper portion of the subject slope is underlain by the Preakness Basalt, which is a hard fine-grained igneous rock. The lower portion

MEMO Global Slope Stability Study for Building D West Essex Highlands Project Langan Project No.: 101049801 Revised 18 June 2025 Revised 18 June 2025 - Page 3 of 13 of the slope is mapped as the Feltville Formation, which consists of sandstone, siltstone or mudstone. A high-angle fault with no history of activity is mapped about 2,000 ft to the east of the site. An abandoned sandstone rock quarry is also identified about 1,000 ft southeast of the site. A copy of the geologic map is provided as Figure 2. SUBSURFACE INVESTIGATION A targeted subsurface investigation for the global slope stability study consisting of borings and test pits was completed between November and December 2024. A supplemental subsurface investigation for the global slope stability study located at the northern portion of the subject area consisting of borings, test pits and a rock outcrop and boulder evaluation was completed between April and June 2025. Both investigations were performed under full-time supervision by Langan. The borings and test pits were performed at accessible areas along four cross-sections running in the east-west direction through the subject area. The locations of the borings, test pits and cross-sections are shown on Figure 1. Logs of the borings and test pits are provided in Appendix A and Appendix B, respectively. Borings Eight (8) borings, identified as LB-1 through LB-4 and NLB-1 through NLB-4, were drilled within the subject area by Craig Geotechnical Drilling Co. Inc. (Craig). The borings were performed using a track-mounted drill rig and mud-rotary drilling techniques. Borings extended approximately 19 ft to 50 ft below existing surface grades. Borings NLB-2, NLB-4, LB-1 and LB-3 were performed at the higher portion of the slope near the proposed Building D footprint. Borings NLB-1 and NLB-3 were performed at the lower portion of the slope near the northeastern property line. Borings LB-2 and LB-4 were performed east of the existing sewer easement located at the lower portion of the slope. Soil samples were collected, and Standard Penetration Tests (SPT) were performed using a standard 2-inch outside-diameter split-spoon sampler driven by a 140-pound automatic hammer in accordance with ASTM D1586. Soil sampling and SPTs were typically performed continuously in the upper 12 ft and at 5 ft intervals thereafter. Recovered soil samples were visually

d automatic hammer in accordance with ASTM D1586. Soil sampling and SPTs were typically performed continuously in the upper 12 ft and at 5 ft intervals thereafter. Recovered soil samples were visually examined and classified in the field in accordance with the Unified Soil Classification System (USCS). Where encountered, rock was cored for a minimum of 10 ft using an NQ-sized core barrel. Test Pits Eight (8) test pits, identified as TP-1 through TP-8, were excavated by Frank Semeraro Construction Co., Inc. (Semeraro) using a John Deere 75G excavator during the initial subsurface investigation. Five (5) test pits, identified as NTP-1 through NTP-5, were excavated at the northeastern portion of the subject slope area by Semeraro using a CAT 308 Excavator or Hitachi 7X85 excavator during the supplemental subsurface investigation. The test pits extended approximately 3.5 ft to 13 ft below existing surface grades. Upon completion, the test pits were backfilled with excavated materials and the backfill was compacted with the excavator bucket.

MEMO Global Slope Stability Study for Building D West Essex Highlands Project Langan Project No.: 101049801 Revised 18 June 2025 Revised 18 June 2025 - Page 4 of 13 Rock Outcrop and Boulder Mapping As part of the supplemental investigation, exposed rock outcrops and boulders along the subject slope were located using handheld survey equipment and evaluated from a slope stability perspective. Six (6) shallow test pits, identified as R-series test pits, were performed at exposed rock outcrop areas or boulders observed on the slope to gather further information for our evaluation. The approximate location of the rock outcrops and boulder and select photographs are provided on Figure 3. Logs of the R-series test pits are provided in Appendix C. A discussion of observations is presented in the following section and findings are presented in the “Geological Hazard Review” section of this memorandum. Geotechnical Laboratory Testing Soil and rock samples collected during the subsurface investigation were classified and examined in the field by a Langan geotechnical engineer. Representative rock samples were tested by a geotechnical laboratory to determine the unconfined compressive strength of the rock. The results of the laboratory tests are included in Appendix D. SUBSURFACE CONDITIONS The generalized subsurface conditions consisted of surficial materials (topsoil) underlain by natural sand and silt overlying a decomposed rock and rock strata. Detailed descriptions of the subsurface conditions are given below. Surficial Materials Surficial materials at the test locations generally consisted of topsoil. The thickness of the topsoil was observed to vary from 6 inches to 24 inches. Boulders and cobbles as well as rock outcrops were also visible at the surface throughout the subject area. It should be noted it was difficult to differentiate between deeply buried boulders and a rock outcrop during our evaluation. Rock Outcrops: Rock outcrops and boulders were identified on or near the subject eastern slope. Generally, the rock outcrops had exposed faces less than 15 ft high with the majority of the outcrops having exposed faces less than 2 ft high. In general, the larger exposed rock outcrops (Outcrop #1 and #4 identified in Figure 3) with two principal joint sets, one near vertical that is oriented perpendicular to the rock face and one dipping 10 degrees to 20

arger exposed rock outcrops (Outcrop #1 and #4 identified in Figure 3) with two principal joint sets, one near vertical that is oriented perpendicular to the rock face and one dipping 10 degrees to 20 degrees out of the face. The near vertical jointing pattern for these outcrops was generally observed to be spaced 1 inch to 12 inches apart with the horizontal jointing pattern typically spaced 2 ft to 4 ft apart. The exposed outcrop faces typically dip eastward (downslope) between 60 degrees and 85 degrees from horizontal. Separated rock pieces that originated from the parent rock outcrop were observed to be generally less than 6-inch-thick sheets and located immediately in front of the exposed face at Outcrop #4. The joint surfaces are typically rough and slightly irregular. Exposed Boulders: Boulders with varying sizes were observed along the subject slope. Larger boulders were observed on top of or in close proximity to Outcrop #1. The dimensions of a large