J_2024 05 09_West Orange Stormwater Management Plan

PSE&G Mav 17.2011 Page 13 light truck traffic and recommend the following generalized flexible asphalt pavement and aggregate sections be used. Pavement Type .XI: / : ; Bituminous Asphalt Aggregate only Surface Course (inches) •> 2 NJDOT Dense Graded Aggregate -vi (inches) 4 15 BaS(inches)Se 2 - If provided with more specific traffic loading, we would be pleased to reevaluate these general sections. Soil Permeability Testing: Two test pits were excavated in the area being considered for stormwater management. At these locations, in-place field percolation tests were initiated at three and one-half feet below grade at each test pit and experienced little or no water movement and seepage began to emanate around the test levels after the start of the testing. Additionally, our representative collected tube samples of the near surface soils which were subjected to laboratory tube permeameter testing, the results of which also exhibited low permeability rates of less than 0.2 . . . V - • • • * . ‘ ' . I . . . ‘ ♦ ’ inches per hour. Since groundwater seepage was encountered in the test pits, our representative also , tv. .v;. ' jfij ■-(, , H ■■ ■ ■ :':/•) : v : . ' p performed field pit bail permeability tests in each of the test pits to estimate the permeability of the subsoils below the seepage levels. Based on the measured inflow and assuming a stabilized water level equal to the observed soil mottling levels encountered in the test pits, permeability rates of 1.6 inches per hour and 0.3 inches per hour were recorded at depths of 11.5 to 13.5 feet below grade in Test Pits 1 and 2, respectively. The low permeability rates and high soil mottling levels and seepage levels should be considered when evaluating the type of stormwater management system which may be appropriate at the site. Please contact us if you have any questions regarding this report.