Geotech Report 02 12 2024

SOR CONSULTING ENGINEERS, INC. Garden Homes/West Essex Highlands, Inc. Report No. 24-C-02 Subsurface Stormwater Management System Page 5 West Orange, NJ beneath the clayey material at depths of 4 to 5 feet. Groundwater was not encountered to the maximum depth explored. Due to the presence of clayey soils which is hydraulically restrictive and shallow bedrock presence, the area is not suitable for stormwater infiltration design. Basin (TP-23, TP-24): The area is presently a wooded site. Topographic data provided to us indicate that ground surface elevations range from approximately +582 feet to +583 feet. The subsurface conditions revealed in the test pits performed for this study encountered 6 inches of topsoil/vegetation. The topsoil was underlain by clayey soil and extended to depths of 2 to 5 feet below the surface. The clayey soil was underlain by silty gravelly sand (loam material) at TP-23 and extended to the maximum depths explored, 7 feet. Bedrock was encountered beneath the clay loam or loam at depths of 5 to 7 feet below surface. Groundwater seepage was encountered at depths immediately above the bedrock. Laboratory tube permeameter testing performed on the silty gravelly sand or silty clayey sand stratum (loam to clay loam material) resulted in permeability rates of 0.20 to 0.88 inches per hour (K1to K2 soils). We recommend that the stormwater management system be hydraulically connected to these materials found at a depth of 2 feet. The system should be designed in accordance with the NJDEP Stormwater BMP Manual based on the specific measured permeability rates in each area. We also recommend that the infiltrative surface be covered with a geotextile filter fabric or properly graded soil/aggregate filter material to provide a unform separation layer and infiltrative surface to minimize the transmission of fines and possible soil clogging. Basin (TP-25, TP-26): The area is presently a wooded site. Topographic data provided to us indicate that ground surface elevations range from approximately +591 feet to +593 feet. The subsurface conditions revealed in the test pits performed for this study encountered 4 to 6 inches of topsoil/vegetation. The topsoil was underlain by clayey soil and extended to depths of 2.5 to 3.0 feet below the surface. The clayey soil was underlain by reddish brown silty gravelly sand (loam material) extended to

on. The topsoil was underlain by clayey soil and extended to depths of 2.5 to 3.0 feet below the surface. The clayey soil was underlain by reddish brown silty gravelly sand (loam material) extended to the maximum depths explored, 5.5 to 6 feet where bedrock was encountered. Groundwater