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 9 of 21 the formation. Our Geotechnical Engineers observed the outcrop of the rock referenced as Outcrop No. 4. The height of the exposure was only 4 to 6 feet. The appearance of the rock indicated that it has been weathered and somewhat softer than fresh cuts exposed in outcrops or as was exposed in the highway cut for Route 280 to the southwest of the site. The principal jointing pattern indicated jointing with dip favorably downward into the slope and steep, nearly vertical joints. Some of the exposed rock showed a series of tight vertical cracks spaced as close as 1 or 2 inches. We anticipate that the outcrops represent the materials that were near the edge of the volcanic flow, and that the outcrops have been exposed and undergone substantial deterioration. 2. The reference map indicates that jointing in the igneous rocks (i.e., the basalt) consists of columnular joints that are rated due to cooling and joints due to faulting. A prominent fault is mapped approximately 2,000 feet from the site, as shown on the copy of Langan Figure No. 2. Tectonic jointing is reported to range from a few feet to many feet far from the mapped faults but become closely spaced near the faults. We note that several closely spaced faults were identified in the Route 280 cut into the Second Watchung Mountain. 3. The closest well to the site shown on the reference map is Well No. 53 and appears to have been drilled with a ground surface elevation near elevation 560 feet. The following results were indicated on the map for Well No. 53, assuming the surface elevation was near elevation 560 feet: Depth 0 to 35 feet 35 – 165 165 – 300 Driller Description Sand and Clay Trap Rock Red Sandstone Inferred Elevation Top of basalt near Elev. 525 feet Base of basalt near Elev. 395 feet Bottom of well near Elev. 260 feet 4. The surface contact between the Preakness Basalts and the Feltville formation red sandstones in the area near the site is mapped along the elevation 500 contour on the reference map. The mapping indicates that the bedding of the sandstones dip towards the

he Feltville formation red sandstones in the area near the site is mapped along the elevation 500 contour on the reference map. The mapping indicates that the bedding of the sandstones dip towards the west (into beneath the basalt sill on a slope of approximately 9 degrees from the horizontal. The surficial soils reported in the borings and in the test pits performed by the Applicant’s Engineers conformed to the description of Rahway Till Yellow Phase included on the surficial Geology Map. The description in the mapping indicates that the formation on the slopes contain concentrations of basalt cobbles and “flagstones” formed by both post-glacial mechanical weathering and glacial deformation of finely jointed basalt. This description agrees with the weathered appearance of the outcrops on the site. The confirmation that the site had been