J_2024 05 09_West Orange Stormwater Management Plan

PSE&G Mav 17.2011 Page 3 ranging from 13 to 14 feet below grade. The locations of the test borings and test pits performed for this study are shown on the Plot Plan, Plate 2. In addition MTA has previously performed test pits within the switching station. Copies of the previous exploration logs and plans showing their approximate locations are attached in Appendix I. All field work was performed under the direct technical supervision of a representative from MTA. Our representative located the test borings in the field from existing surface features and maintained continuous logs of the explorations as the work proceeded. After hand excavating for the first three feet, continuous split spoon samples were obtained to 15 feet below grade and at five foot intervals thereafter in general accordance with the procedures of the Standard Penetration Test (ASTM D-1586). Detailed descriptions of the encountered subsurface conditions are presented on the Logs of Borings, Plates 3A through 3E. The results of the test pits are presented on Plates 4A and 4B. The soils encountered in the borings were visually classified in general accordance with the procedures of the Unified Soil Classification System shown on Plate 5A, while the soils in the test pits were described in accordance with the USDA Soil Classification System presented on Plate 5B. All soil samples obtained from the borings and test pits performed for this study were brought to our office where they were further examined by a project manager in our soil mechanics laboratory. Laboratory tests consisting of natural moisture content determinations (ASTM D-2216), grain-size analyses (ASTM D-422), Atterberg Limits determinations (ASTM D-2318), soil box resistivity tests (ASTM G-187) and pH tests (ASTM G-51) were performed on selected samples to aid in their engineering classification and evaluation. The results of the moisture content tests are indicated on the individual test boring logs, while the mechanical grain-size analyses are shown on the Gradation Curves, Plates 6A and 6B. The results of the Atterberg limits determinations are

PSE&G Mav 17.2011 Page 4 shown on Plate 7. The results of the soil box and pH tests are presented on Plate 8. In addition, selected soil samples were submitted to an NJDEP certified laboratory to perform testing for chloride ion and soluble sulfate. The results of these tests are also presented on Plate 8. Two test pits and field pit bail permeability tests were performed in the southwestern portion of the improvement areas. In addition two in-place percolation tests were attempted at depths of three and one-half feet, however no visible drop in the water levels were observed. Tube samples of the upper soils were also obtained that were subjected to laboratory tube permeameter testing. Further discussions of the testing will be presented later in this report. The results of our field explorations and the laboratory testing program 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 II to this report. General Site Geology The West Orange Switching Station is located in the Piedmont Geomorphic Province of the Appalachian Mountain System. The Piedmont Province is characterized by Mesozoic sedimentary rock interbedded with basaltic lava flows and diabase intrusions. According to the NJDEP-GIS, I-Map webpage, the substation is underlain by basalt bedrock of the Orange Mountain Formation. The surficial geology is identified as being the Rahway Glacial Till. The Rahway is a gravelly silty sand to sandy silt with cobbles and boulders. The NJDOT Geotechnical Data Management Website reports that about 70 borings are present within one-half mile of the site. The borings were generally performed along the Route 280 alignments to the north of the switching station. These borings show till over bedrock at variable depths. The logs can be viewed from the website: www.state.ni.us/transportation/refdata/geologic/map.shtm.

PSE&G Page 5 Mav 17.2011 Site Conditions Surface Features: The subject site is a fenced switching station with existing equipment at the surface, on-site buildings and below-grade utilities. Topographic information shown on the plans provided to us indicates the surface grades range from about +615 to +630 feet in the northern portions of the site and slope downward to the south and southwest to a low of about +580 feet in the southwest comer of the site adjacent to Mt. Pleasant Avenue. Subsurface Conditions: The subsurface conditions encountered in the test borings performed for this study consisted of the following generalized strata, listed in order of increasing depth: 1) Surface Materials: A thin layer of crushed stone on the order of two inches in thickness was encountered at test boring SBH-1. At SBH-2 the surface materials were comprised of a three inch thick asphalt layer which was underlain by about eight inches of stone. At SBH-3 and 4, a light grass cover over the underlying natural soils was present and at SBH-5, six inches of topsoil was encountered. 2) Fill: The surface materials were underlain by clayey sand and sandy clay fill in Borings SBH-1 and 2 which extended to depths on the order of two and one-half feet below the existing surface grades. At SBH-5, loose clayey silts and clayey sands were encountered to about nine feet that likely represent fill materials from past site grading activities. 3) Clavev Silt and Siltv Clav: The surface materials and fill where present were underlain by stiff clayey silts and silty clays that extended to about 3 to 13 feet below grade. .._ < .• • 4) Clavev Sands: The silts and clays were generally underlain by medium dense to very dense clayey or silty sands extending to depths ranging from about 9 to 23 feet below grade. The clayey sand soils were typically medium dense to dense in relative density. Loose soils were observed in Boring SBH-5 at a depth of about 13 feet. 5) Decomposed and Weathered Basalt Bedrock: The clayey sands were typically underlain by decomposed and weathered basalt bedrock. At SBH-2 decomposed sandstone bedrock as observed above the basalt bedrock at about 9 to 13 feet below grade.

PSE&G Mav 17.2011 Page 6 The area of the test pits is a depressed area which appears to receive surface runoff from the higher areas of the site. At the test pits performed in the southwest portion of the site, a layer of topsoil on the order of ten to twelve inches in thickness was present typically underlain by sandy clay loam soils. In Test Pit 2, a layer of silty clay was observed at 11 to 13 feet followed by loamy sand/sandy loam. Groundwater seepage was observed in borings SBH-2, 4 and 5 at depths ranging from approximately 7 to 14 feet below grade at the completion of the drilling. Light seepage was observed in the test pits at depths of about 1 to 2.5 feet below grade with moderate to rapid seepage observed at depths of 11.5 and 13 feet. Soil mottling was observed in the test pits at depths on the order of one to one and one-half feet below grade. A subsurface profile depicting the generalized subsurface conditions is presented on Plate 9. Findings and Recommendations General: Based on the subsurface conditions encountered in the borings performed for this study, it is our opinion that the existing near surface fill where present is not suitable for direct support of new structures on spread foundations due to the unknown nature of the placement and compaction of the material. Further, the SPT blow counts indicate the fill to be loose in relative density to about eight feet in Boring SBH-5. Therefore, any existing fill extending below the foundations should be completely removed to the surface of the undisturbed natural soils and the foundations established directly on the natural soils, or the excavations could be backfilled to conventional foundation levels with clean crushed stone. The new structures could then be supported on conventional spread foundations that would derive their support from the undisturbed natural soil or crushed stone backfill and could be designed to impose maximum allowable net bearing pressures of up to 4,000 pounds per square foot.

PSE&G Mav 17.2011 Eagel Site Preparation and Earthwork: Site preparation activities within the area of the improvements should include the excavation of the existing fill materials to the surface of the natural soils. The fill materials observed in our recent explorations typically extended to depths of approximately two and one half feet in SBH-1 and 2 to nine feet below the surface in SBH-5. As such, it is likely that the fill would extend to below conventional foundation levels in some portions of the site and would have to be removed. However, variations in the depth to the bottom of the fill soils should be anticipated between the exploration locations. After removal of any existing fill below the new foundations, crushed stone backfill could be installed to reach the design bottom of footing levels. If crushed stone backfill is used, the excavation should be widened on all sides one foot laterally for each two foot depth of overexcavation. A graphic representation of the overexcavation limits is presented on the Suggested Foundation Overexcavation Detail shown on Plate 10. Groundwater was encountered in the borings at depths ranging from approximately 7 to 14 feet below grade at the time of our study. However, perched seepage was observed as shallow as one foot in the test pits and could also be present trapped within the fill or at the interface of the fill and natural soils. As such temporary control of seepage and surface runoff will likely be required during construction. It is anticipated that seepage could be controlled by pumping from a series of sumps. If deeper excavations extend below the observed groundwater levels, more formal dewatering methods could be necessary such as wellpoints or temporary wells. It should be the contractor’s responsibility to provide whatever labor and equipment is necessary to control seepage. If seepage is not properly controlled, the natural subgrade soils will likely become softened and disturbed, and additional overexcavation could be required. We also recommend that the site be graded during construction to prevent surface water from entering the site excavations.

PSE&G May 17.2011 Page 8 Temporary construction excavations should comply with the most recent OSHA Excavation Guidelines (29 CFR Part 1926) assuming that the existing fill materials and natural clay sands soils prevalent at the site are Type “C” soils. The guidelines indicate for Type “C” soils, simple excavations less than 20 feet in depth shall have a maximum allowable slope of 1.5 horizontal to 1 vertical. Sloughing of the excavation sidewalls could occur and flattening of the slopes or use of plates, sheets, trench boxes or other types of temporary excavation support may be required to minimize the size of the excavations or to prevent undermining of adjacent equipment. 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 existing structures and equipment. The near surface excavated fill is expected to consist primarily of clayey sand and silts and clays. The sandier soils 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. Any encountered 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. Occasional cobbles and boulders were encountered and weathered basalt was encountered at nine feet in SBH-2 and as shallow as five feet in a previous test pit performed by MTA. As such, large excavation equipment with rock teeth could be required to penetrate the surface of the weathered basalt if excavations extend to these levels.

PSE&G Mav 17.2011 Page 9 Following excavation of the fill materials the exposed natural subgrade soils should be observed by a qualified geotechnical engineer to confirm that all softened or disturbed soils or deleterious materials have been removed. If excavations required to remove fill extend below the design foundation levels, as expected in some areas, the excavations could be backfilled with crushed stone to the design bottom of foundation levels. 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. Backfill around the foundations should consist of approved granular soils, on-site or imported, that are free of debris and deleterious materials, and which are at moisture contents suitable for compaction to the required densities. Any imported fill materials should consist of uncontaminated, granular soils containing less than 15 percent by weight of material passing a U.S. Standard No. 200 sieve and having a maximum particle size of four inches. NJDOT dense graded aggregate or recycled concrete could be used for this purpose. The backfill should be spread in layers on the order of twelve inches or less in loose thickness and should be uniformly compacted to at least 95 percent of its maximum dry density as determined by the ASTM D-1557 test procedure. Shallow Foundation Design Criteria: It is our recommendation that the new equipment be supported by conventional spread foundations that derive their support from the undisturbed natural soils 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. We recommend all foundation bearing soils be observed by a qualified geotechnical engineer to confirm that

PSE&G Mav 17.2011 Paee 10 adequate bearing materials are present. All foundations should extend to a depth of at least three feet below the adjacent finished exterior grade to provide frost protection. 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, 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 silts and clays and the clayey sand soils. 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 32 degrees (Kp = 3.25) 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. A subgrade modulus of 150 pounds per cubic inch would be appropriate for design of slabs supported by the natural clayey sand soils while a subgrade modulus of 200 pci could be used for imported granular soils as previously specified which are compacted to at least 95 percent of their ASTM D-1557 maximum dry density. Post-construction foundation settlements were estimated using the loads provided to us which are attached as Plate 11 and estimating a footing size based on the recommended bearing pressure of 4,000 pounds per square foot. As the site soils consist primarily of granular materials,

PSE&G Mav 17. 2011 Page 11 the majority of the settlement is expected to occur rapidly, practically upon application of load. Based on the information provided to us, it is our opinion that the lightly loaded foundations designed and installed in accordance with our recommendations would experience post construction settlements of about one-half of one inch. Information provided to us indicates that the transformers could weigh as much as 500 kips and would be supported on a mat with dimensions of 12 feet by 15 feet resulting in an applied pressure of about 2,800 pounds per square foot. The transformer pad would experience total settlements which are estimated to be about three-quarters of one inch. Calculations are presented in Appendix III. Seismic Design Criteria: Based on the results of our explorations and our review of the regional geology, it is our opinion that seismic design of the proposed improvements could be based on Site Class “C” as defined in the International Building Code 2009, New Jersey Edition. Lateral Earth Pressures: If required, excavation support systems, below grade structures or site retaining walls should be designed to resist lateral earth pressures imposed by the adjacent soils, as well as surcharge loads due to adjacent equipment, traffic, floor slabs or foundation loads, etc. We estimate that the following soil parameters could be used to design these systems: Soil Type .SISiw®:' S’" T?’-: Existing sandy and clayey fill materials Clean crushed stone backfill Natural silty and clayey sands or imported granular controlled compacted fill Total Unit Weight (pcf) AMpJjf fit internal friction (degrees) 120 30 0 0.333 105 38 0 0.238 125 34 0 0.307 Active Earth Pressure Coefficient (Ka> “ Corrosivity and pH Testing: Five samples of the soils in close proximity to the anticipated levels for shallow foundations (±2 to 2.5 feet) were submitted to an NJDEP certified laboratory and were subjected to laboratory tests to determine chloride, and sulfate levels to evaluate their potential

PSE&G Mav 17.2011 Page 12 for corrosion of below grade concrete. Also, several samples of the soils were subjected to pH testing. The results of these tests are attached on Plate 8. Sulfates were not detected to the method detection limit in any of the samples. Chlorides were detected in SBH-1 and SBH-2 at concentrations of 52.4 and 103 parts per million and not detected to the method detection limit in the remaining samples. The pH test results ranged from 4.7 to 7.4. Based on American Concrete Institute (AC1) 318 guidelines, sulfate levels of less than 1000 parts per million indicate a negligible exposure for corrosion of concrete and ACI recommends the use of Type I cement. However, United States Department of Agriculture (USDA) guidelines indicate sandy soils with a pH of <5.5 are considered to have a high risk of corrosion potential and soils with a pH of 5.5 to 6.5 are considered to have a moderate risk of corrosion potential for concrete. Therefore, it may be prudent to use Type H cement in the construction which would provide at least a moderate resistance to attack. Pavement Design Criteria: Immediately prior to pavement construction, all exposed subgrades should be recompacted to a dense and stable consistency, and the upper twelve inches of the subgrade soils should be recompacted to at least 95 percent of the maximum dry density as determined by ASTM D-1557 test procedure. Any subgrade materials that cannot be compacted to the required densities should be excavated to stable subgrade materials and replaced with granular controlled compacted fill. Following compaction, new pavements may be supported by the recompacted existing near surface silty sand fill soils or by controlled compacted granular fill. Pavement subgrades consisting of the silty sand fill materials would provide a "medium" subgrade support condition for pavements, with an estimated California Bearing Ratio (CBR) value of approximately seven percent. No traffic data was provided to us. We have assumed areas would be subjected to sporadic automobile and