J_2024 05 09_West Orange Stormwater Management Plan

January 17, 2023 File No. 26.0092704.00 PSE&G – West Orange Station Page 2 underlain by buried topsoil in Test Pits 204 and 205. The fill and buried topsoil extended to depths of approximately 2 to 4.5-feet bgs. Proactive by Design Native soils consisting primarily of silts and clays with occasional silty sand layers were encountered below the fill and surface materials and extended to the underlying basalt bedrock in Test Pit 201 to Test Pit 205 at which point refusal to further excavation was encountered. The native soils in Test Pit 205 extended to the maximum reach of the excavator, 10 feet bgs. Groundwater seepage was observed in Test Pit 201 and 204 at depths of 6 feet and 7 feet respectively, atop of or within 1 foot of the underlying bedrock. Groundwater levels will vary based on seasonal changes. Permeability Test Results Field single ring infiltration tests were initiated at approximately 3.5 to 4 feet bgs in the test pits. In addition, tube samples were collected from each test pit for laboratory tube permeameter permeability testing. The results of the field single ring infiltration and laboratory tube permeameter tests are presented in the table below and are shown on the appropriate exploration logs. The infiltration test rates from the single ring tests were used to calculate a permeability rate using the formula provided in Chapter 12 of the NJDEP BMP manual. Summary of Permeability Test Results Test Permeability Type of Test Depth USDA Description of Soil Tested (in/hr.) (1) Performed (ft, bgs) TP-201 1.5 <0.06 Loam Fill Tube Permeameter TP-201 6 >20 Loamy Sand Tube Permeameter TP-202 1.5 0.2 Sandy Clay Loam Tube Permeameter TP-202 4 <0.06 Clay Loam Tube Permeameter TP-202 4 <0.06 Clay Loam Single Ring TP-203 2 0.2 Silt Loam Tube Permeameter TP-203 4 <0.06 Silty Clay Loam Single Ring TP-203 5 0.1 Clay Tube Permeameter TP-204 4 <0.06 Silt Loam Single Ring TP-204 4 <0.06 Silt Loam Tube Permeameter TP-204 6 <0.06 Clay Loam Tube Permeameter TP-204 8 <0.06 Clay Loam Tube Permeameter TP-205 3.7 <0.06 Silt Loam Topsoil/Fill Single Ring TP-205 4 <0.06 Silt Loam Topsoil/Fill Tube Permeameter TP-205 5 <0.06 Loam Single Ring TP-205 7 <0.06 Clay Loam Tube Permeameter (1) Slowest of two test replicates reported for laboratory tube permeameter tests. Exploration No. An Equal Opportunity Employer M/F/V/H