25 10 28 Slope Stability Review

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