J_2024 05 09_West Orange Stormwater Management Plan

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.