J_2024 05 09_West Orange Stormwater Management Plan

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 3 Proactive by Design encountered. Approximately 10 feet of rock core was then obtained from each of the borings. The test pits were excavated using a Komatsu PC 45MR track excavator provided by a PSE&G subcontractor (Furino & Sons) and extended to depths of approximately 5 to 9.5 feet bgs. The approximate locations of the explorations performed for this study and two nearby test pits from a prior study performed at the station are shown on the Plot Plan, Plate 2. All field work was performed under the direct technical observation of representatives from GZA. Our representatives located the explorations in the field relative to existing surface features, maintained continuous logs of the explorations as the work proceeded and supervised the soil and rock sampling operations. After hand excavating to 3 feet for the borings, soil samples suitable for identification purposes were extracted from the borings at closely spaced intervals in general accordance with the procedures of the Standard Penetration Test (ASTM D-1586). Ten feet of rock was cored at each boring location using an NX-size core barrel which extracts a core approximately 2 inches in diameter. Upon completion, the borings were grouted. Photographs of the rock cores are presented in Appendix I. In addition, our representative collected representative bulk and relatively undisturbed tube samples from the various strata encountered in the test pits. Single ring infiltration tests were initiated within the upper 3 to 3.3 feet in the test pits to obtain information for stormwater design purposes. Three-inch diameter tubes were collected from each test pit at approximate depths of 3 and 8 feet for geothermal testing. After the test pits were completed, they were backfilled using the excavated materials. Detailed descriptions of the encountered subsurface conditions are presented on the Test Boring Logs, Plates 3A through 3E and Test Pit Logs, Plates 4A through 4C. The soil samples obtained from the test An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 4 Proactive by Design borings were visually described in general accordance with the Unified Soil Classification System shown on Plate 5, while the soils encountered in the test pit excavations were described using the USDA Soil Classification Chart (typically used for stormwater purposes) shown on Plate 6. The rock type and general quality of the rock samples from the cores obtained in the borings are visually described in accordance with the Engineering Rock Classification and Core Description Chart shown on Plate 7. All soil and rock samples were brought to our office where they were further examined in our soil mechanics laboratory. A geotechnical laboratory testing program consisting of mechanical grain-size analyses, natural moisture content determinations, tube permeameter permeability, and soil box resistivity tests were performed on selected samples to assist in estimating and evaluation of their engineering properties. The results of the mechanical grain-size tests are presented on Plates 8A and 8B, Gradation Curves. The results of the natural moisture content determinations and laboratory tube permeameter permeability tests are shown on the appropriate boring and test pit logs. In addition, three samples of the near surface soils were submitted to an NJDEP certified laboratory to perform testing for pH, sulfates, chloride ion, electric resistivity, redox potential, and sulfides. The results of the chemical tests and GZA soil box resistivity tests are presented on Plate 9. Rock core samples were also submitted to an independent laboratory for unconfined compressive strength testing, the results of which are attached in Appendix II. In addition, GZA sent samples collected for geothermal testing to an outside laboratory, Geotherm USA. The geothermal report is attached as Appendix III to this report. As discussed with the engineering team, An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 5 Proactive by Design the field resistivity testing will be performed at a later date and the results submitted as an addendum to this report. The results of our field explorations and laboratory testing programs have provided the basis for our engineering analyses and design recommendations. The following discussions of our findings and recommendations are subject to the Limitations attached as Appendix IV to this report. Site Conditions Surface Features: The subject site is the existing fenced-in West Orange Switching Station. The station is bound by Mt. Pleasant Avenue (State Route 10) to the south and Prospect Avenue to the east. A medical office complex is located to the west, and an LA Fitness and additional medical office building is located to the north of the station. Marion substation is located at the northwest corner of the station. The station contains various electrical equipment, control houses and other improvements typical of PSE&G stations, however the proposed improvement area would be located at the southeast corner of the site, within unimproved lawn and wooded areas. Topographic information provided to us indicates that the site generally slopes steeply downward from Mt. Pleasant Avenue and Prospect Avenue into the site where grades generally level off and gradually slope downward towards the existing station equipment which is established near Elevation +599 feet to +603 feet. Subsurface Conditions: The subsurface conditions encountered in the explorations performed for this study consisted of the following generalized strata, listed in order of increasing depth: An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 6 Proactive by Design 1) Surface Materials: A layer of crushed stone on the order of 10 to 12 inches in thickness was encountered at test boring SBH-1 and SBH-2. At the remaining three explorations, 8 to 11 inches of topsoil was encountered. The test pits were all performed within the lawn areas and encountered 6 to 20 inches of topsoil at the ground surface. 2) Fill: The surface materials were underlain by clayey silt and silty sand fill in the borings which extended to depths on the order of 2.5 feet to 8 feet below the existing surface grades. Fill and possible fill was also encountered in the three test pits and extended the full depth explored in the test pits. A layer of buried topsoil was encountered at the base of the fill in SBH-2, SBH-3, and SBH-5. 3) Clayey Silts and Silty Clays: The surface materials, fill and buried topsoil, where present were underlain by stiff clayey silts and silty clays. The silts and clays typically extended to depths of about 15 to 24 feet below the ground surface in the explorations to the underlying weathered basalt bedrock except for SBH-3 and SBH-4. 4) Clayey Sands: The silts and clays in SBH-3 and SBH-4 were generally underlain by medium dense to very dense clayey or silty sands at about 15 feet below the ground surface The clayey sands extending to depths ranging from about 25 to 28 feet below grade. Gravel, cobbles, boulders or weathered rock were encountered in the deeper portions of this layer and may represent weathered bedrock. 5) Decomposed and Weathered Basalt Bedrock: The clayey sands and/or clays and silts were typically underlain by decomposed/weathered and fractured basalt bedrock. Groundwater seepage was encountered in the three test pits at depths ranging from 4 to 9 feet below the ground surface. Groundwater levels were not recorded in the soil borings as the borings used rotary wash techniques which use water to facilitate the drilling, however, water levels were estimated to be between 10 to 15 feet in the borings based on review of the soil samples. Groundwater was also encountered at 7 feet below the ground surface in a prior boring (SBH-5) from our 2011 sutyd, and is also shown on the Plot Plan. Groundwater seepage conditions should be expected to vary seasonally. An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 7 Proactive by Design Note that fluctuations in the level of the groundwater may occur due to variations in rainfall, temperature and other factors occurring since the time measurements were made. Findings and Recommendations General: Based on the results of our study, it is our opinion that: 1) The existing fill materials and buried topsoil, where present, cannot be relied upon, in their current condition, to provide direct support for the foundations for the proposed station improvements. Following the site preparation procedures described in subsequent sections of this report, the proposed lightly loaded improvements could be supported by conventional shallow foundations which derive their support from the undisturbed natural soils or controlled compacted fill installed after removal of the existing fill. Foundations may be designed for maximum net allowable bearing pressures of up to 4,000 pounds per square foot. The undisturbed natural soils and properly placed and compacted controlled fill would also provide adequate support for the control building floor slab and other slabs. Any lightning masts, towers or H-frames and any other structures subject to high lateral loads could be supported by either drilled shaft foundations or conventional spread foundations set at depths necessary to accommodate overturning forces. 2) Groundwater seepage was encountered at depths ranging from approximately 4 to 9 feet in the test pits at the time of this study and estimated to be near about 10 feet in several borings. As such, construction dewatering could be required, especially during the removal and replacement of existing fill materials. The site contractor should be responsible to provide whatever means and methods are necessary to dewater excavations and maintain control of surface runoff during construction. 3) The predominately near surface silty and clayey soils, which would represent the bulk of the excavated materials, would generally be poorly suited for reuse as fill or backfill as they would be highly susceptible to moisture-related stability and compaction problems. The following sections of this report present further discussion of each of these items. Site Preparation and Earthwork: Site preparation activities should initially include the removal of any existing equipment,

g sections of this report present further discussion of each of these items. Site Preparation and Earthwork: Site preparation activities should initially include the removal of any existing equipment, utilities, or improvements that are not incorporated in the Lifecycle project. Following An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 8 Proactive by Design any demolition, the existing fill and any buried topsoil should be removed to the surface of the natural soils. The fill and buried topsoil in our recent explorations extended to depths ranging from 2.5 to 9 feet bgs. Based on our explorations, it is likely that excavations necessary to reach the plan foundation levels may not extend completely below the fill and buried topsoil into the natural soils. In areas where existing fill remains at the plan foundation bottom level, it should be removed to the surface of the natural bearing soils. Once it is confirmed that all existing fill materials have been removed, the foundations could be lowered to bear directly on the natural soils or the excavations backfilled with controlled compacted fill or crushed stone to the bottom of the foundation in accordance with the Suggested Foundation Overexcavation Detail presented on Plate 9. Excavations could be performed in a mass excavation, or depending on the proximity of other improvements, could be excavated in a series of isolated excavations. Following excavation of the fill materials and buried topsoil, the exposed natural subgrade soils should be observed by a qualified geotechnical engineer to confirm that all unsuitable soils have been removed. When excavations for new foundations are performed adjacent to existing foundations, the new foundations should be located so that a line drawn between the lower edges of adjoining footings shall not have a slope steeper than 30 degrees with the horizontal, unless the material supporting the higher footing is braced or retained or otherwise laterally supported. If some fill is left in-place in areas where new improvements are not proposed, in order to reduce the risk of excessive settlement in these areas, the existing fill should be proofrolled and recompacted to a relatively dense and stable condition and if observed, soft areas could be selectively excavated and replaced with An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 9 Proactive by Design controlled compacted fill to achieve the final desired subgrades. However, it should be understood that if existing fill is left in-place, even with a recompacted subgrade, some post-construction settlement could potentially be experienced. Controlled compacted fill or backfill should consist of dry, suitable portions of the excavated on-site soils or imported granular soils placed under the observation of the inspecting geotechnical engineer. The near surface excavated fill is expected to consist primarily of silts and clays with occasional sandier zones. The sandier soils, if encountered, would be considered suitable for reuse as controlled compacted fill and backfill provided they are at and maintained at moisture contents which would allow them to be properly compacted. The silty and clayey soils would be poorly suited for reuse due to their moisture sensitive nature. Variations in the nature and composition of the fill materials present at the site should be anticipated. A determination regarding the suitability of excavated fill materials for reuse as structural backfill adjacent to the foundations should be made at the time of construction by a qualified geotechnical engineer. Weathered basalt was encountered at depths ranging from about 15 to 28 feet below the ground surface and as such would not be a concern for the anticipated shallow foundations. Imported fill, if required, should consist of uncontaminated relatively well-graded sand and gravel soils containing less than 15 percent by weight of material passing a U.S. Standard No. 200 sieve and a maximum particle size of 4 inches. Documentation of the environmental quality of the fill should include a written certification from the fill supplier stating that the fill is virgin material from a commercial or non-commercial source. An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 10 Proactive by Design Any controlled compacted fill and backfill should be placed at appropriate moisture contents and in layers of no more than 12 inches in loose thickness. All controlled fill and backfill should be compacted to at least 95 percent of its maximum dry density as determined by the ASTM D-1557 test procedure. Backfill placed and compacted using manual equipment in confined areas such as foundation or utility trench excavations should be spread in layers of 6 to 8 inches or less in loose thickness as necessary to achieve the required compaction. Construction excavations should be performed in accordance with the applicable safety codes, including the latest OSHA Excavation Regulations. Based on the soils encountered in the test pits and borings, it is our opinion that the natural soils and fill are typical of Type "C" soils as defined by the OSHA Excavation Regulations. It should be the contractor’s responsibility to evaluate and provide a properly designed excavation support system, maintain safe excavations at all times, and prevent undermining of or damage to nearby existing structures and equipment to remain, if any. The contractor should be responsible for any damage caused by their work. Shallow Foundation Design Criteria: Following the site preparation procedures outlined above, it is our recommendation that equipment may be supported by conventional spread foundations that derive their support from the undisturbed natural soils, controlled compacted fill or stone backfill placed over the undisturbed natural soils in accordance with our above recommendations. Foundations for the proposed new improvements could be designed to impose maximum allowable net bearing pressures of up to 4,000 pounds per square foot. All foundations should extend to a depth of at least 3 feet below the adjacent finished exterior grade to provide frost protection. An Equal Opportunity Employer M/F/V/H

August 8, 2022 File No. 26.0092704.00 PSE&G – West Orange, NJ Page 11 Proactive by Design As previously indicated, when excavations for new foundations are performed adjacent to any existing foundations or other improvements to remain, if any, the new foundations should be located so that a line drawn between the lower edges of adjoining footings shall not have a slope steeper than 30 degrees with the horizontal, unless the material supporting the higher footing is braced or retained or otherwise laterally supported. Uplift loads may be resisted by the weight of the foundation, structure and soil within a prism defined by extending a line up and out from the edge of the foundation at an angle of 20 degrees from vertical. A total unit weight of 125 pounds per cubic foot could be assumed for the natural granular soils, excavated sandy fill, if any, or imported granular fill as previously specified to be used as backfill, provided the materials are compacted to at least 95 percent of their ASTM D-1557 maximum dry density. Horizontal loads may be resisted by friction between the concrete and soil, and passive pressure. An ultimate coefficient of friction of 0.35 for sliding may be assumed between the foundation concrete and the near surface silts and clays prevalent at the site. The coefficient of friction could be increased to 0.55 if crushed stone is provided below the foundations. Assuming the backfill is compacted as recommended, passive pressures may be calculated assuming a friction angle of 34 degrees (Kp = 3.5) and unit weight of 125 pounds per cubic foot. The designer should account for potential loss of support from freeze-thaw effects or future adjacent excavation if relying on passive pressures for shallow foundations. As such, we recommend that passive pressures be discounted for the upper two feet of soils due to potential disturbance. An Equal Opportunity Employer M/F/V/H