J_2024 05 09_West Orange Stormwater Management Plan

PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report 2. Soil Types Review of the Natural Resource Conservation Service (NRCS) Web Soil Survey data and information indicates that there are six (6) principal soil types present in the site vicinity. Table II-1 provides a tabular listing of soil types present and summarizes their hydrologic characteristics. A copy of the NRCS Soils Map and other key soil characteristics are included in Appendix A. Table II-l Table of Soil Characteristics Map Unit BogBc BogCc DuuB UdbonB URBONB USBONB Soil Name Boonton loam, 0 to 8% slopes, extremely stony Boonton loam, 8 to 15% slopes, extremely stony Dunellen - Urban land, Dunellen substratum complex, 0 to 8 % slopes Udorthents, Boonton substratum, 0 to 8 % slopes Urban Land, Boonton substratum, 0 to 8% slopes Urban Land, Boonton substratum-Boonton complex, 0 to 8% slopes Water Table (cm) >200 Depth to Restrictive Layer (cm) 76 Hydrologic Soils Group C Slope 0-8% >200 76 C 8-15% >200 >200 A 0-8% >200 >200 D 0-8% >200 >200 N/A 0-8% >200 >200 N/A 0-8% The existing West Orange Switching Station, as well as the proposed expansion area, is located within soils designated by the NRCS as Urban-Boonton substratum soils (URBONB) and Urban-Boonton substratum-Boonton complex soils (USBONB) with 08% slopes. Urban soils are described by the NRCS as soils where 80 percent of the surface is covered by asphalt, concrete, buildings, or other impervious areas. Although the NRCS does not assign a hydrologic soil group to urban soils, to be conservative and to reflect the low infiltration capacity at the site, runoff curve numbers (i.e., CN values) corresponding to hydrologic soils group “D” were assigned to the various cover types identified within the area of interest. The geotechnical report provided in Appendix A also shows a solid clay layer underlying the site which shows that there is not much infiltration capacity. Surface materials in Borings SBH-1 and 2 are underlain by clayey sand and sandy clay fill which extend to depths on the order of two and one-half feet below existing 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. TRC Engineers, Inc. 5 March 2012