2026 02 12 Crestmont CC and Eagle Rock Ave Stormwater Management Report

Stormwater Management Field Testing Results MEMO Eagle Rock Ave and Oval Road Improvements 750 Eagle Rock Avenue, West Orange, New Jersey Langan Project No. - 101049802 25 August 2025 - Page 2 of 4 The locations of all test pits are shown on Figures 1A and 1B. Logs of the profile test pits and test pit photographs are provided in Appendix A and B, respectively. Profile Test Pits A total of twenty-one (21) exploratory profile test pits were excavated by Frank Semeraro Construction, Inc. throughout the project site. Profile test pits identified as TP-1 through TP-10 were excavated between 25 and 26 April 2024 using a CAT 306 excavator. Profile test pits identified as TP-11 through TP-21 were excavated between 14 and 15 April 2025 using a Hitachi Excavator 7X85. The profile test pits extended between 1.75 ft and 12 ft below existing surface grade. Upon completion, the profile test pits were backfilled with excavated materials and compacted with the excavator bucket. Laboratory Tube Permeameter Tests A total of twenty (20) tube permeameter samples were collected and tested during the 2024 and 2025 subsurface investigation. These samples were collected within the upper 40 inches of the existing surface grade in compliance with the latest version of the New Jersey Stormwater Best Management Practices Manual, Chapter 12, Subsection A2: Tube Permeameter Test. The tube permeameter samples, identified using the corresponding profile test pit identification number, were collected in close proximity to the respective profile test pit location. The samples were tested to determine the soil hydraulic conductivity, which was used to determine the Hydrologic Soil Group (HSG). SUBSURFACE CONDITIONS The generalized subsurface conditions consist of surficial materials over sand and silt material underlain by bedrock. Significant amounts of gravel and cobbles were observed to be intermixed in the overburden soil layer. A generalized description of the subsurface conditions is provided below. Surficial Material Surficial materials consisted of grass and topsoil. An approximately 0.5-ft to 3-ft-thick

den soil layer. A generalized description of the subsurface conditions is provided below. Surficial Material Surficial materials consisted of grass and topsoil. An approximately 0.5-ft to 3-ft-thick layer of fill material, generally consisting of gravel, sand, or silt was encountered in the majority of the test pits beneath the surficial materials. In test pit TP-17, a 10-ft thick layer of fill material consisting of silty sand was encountered beneath the surficial materials. A buried topsoil layer approximately 1.25 ft thick was encountered in test pit TP-18 at approximately 3 ft below surface grade. Natural Soils Natural soils generally consisting of intermixed layers of sand and silt with varying amounts of gravel, clay, cobbles and boulders were encountered below the surficial and fill materials. The thickness of this natural overburden soil layer generally ranged from approximately 1 ft to 10 ft. = = =