Geotech Report 04 19 2021

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 11 West Orange, NJ Access Roads Automobile Parking | Bituminous Concrete Surface Course 2 inches 2 inches Bituminous Concrete Base Course 4 inches 2 inches Dense Graded Aggregate Subbase 6 inches 6 inches Total Section Thickness 12 inches 10 inches For a rigid pavement, a modulus of subgrade reaction of 200 pounds per cubic inch may be used. Proposed Detention Basins: An exploration program consisting of six backhoe excavated test pits was performed at the site. Four test pits were performed in the proposed basin area. The area of basin is currently grass/vegetation covered. The existing ground surface elevation is approximately +538 to +546 feet. The area of second infiltration area is at TP-14 and 15 locations and is currently grass/vegetation covered or wooded. The existing ground surface elevation is approximately +594 to +598 feet. The test pits, TP-24, 25, 26 and 27 performed at basin area encountered 8 inches of topsoil. Light brown silt loam to clay loam was encountered beneath the topsoil at test pits and extended to depths of 3 to 5.5 feet below surface. Loam was encountered beneath the silt or clay loam and extended to maximum depths explored, 6 to 13 feet. At TP-25 bedrock was encountered at a depth of 6 feet. Groundwater or seasonal high groundwater was not encountered to the maximum depths explored. The test pits, TP-14 and 15, performed at the infiltration area encountered 8 to 12 inches of topsoil. Brown loam material was encountered beneath the topsoil and extended to depths of 10 to 11 feet below surface where bedrock was encountered. Water seepage was encountered at a depth of 9 feet in TP-15 location. The tube samples collected during the field investigation were returned to our soil mechanics laboratory. Five mechanical grain-size analyses and falling head tube permeability tests were performed on the samples. The test results are included with this report. The falling head permeability test results for the basin indicate that the loam has a permeability rate ranging from 0.81 to 1.58 in/hr (K2 soils). Test results on silt loam (TP-25) has a permeability rate of 0.18 in/hr (KO soils) which is hydraulically restrictive.