1240815StormWaterManagementReportrcd 3 12 2026

Development Engineering, LLC 550 Colfax Road Wayne, NJ 07470 (973) 835-0340 Soil Percolation Report June 30, 2025 Isaac Lefkowitz 127 Mitchell LLC 516 Pleasant Valley Way West Orange, NJ RE: Percolation Test Seepage Pit/Drywell for Proposed Office Building 512 & 516 Pleasant Valley Way West Orange, NJ Percolation Rate by Soil Category Percolation speed or percolation rate, measured in inches per hour, depends greatly on the soil type as described below:  Sandy soils usually have very high percolation rates, measured in the range of 1 to 8 inches or more per hour. That means sandy soils dry out very quickly, heat up very quickly.  Silty soils, including loam, have moderate percolation speeds, ranging from 0.1 to 1 inch per hour.  Clay soils have notoriously slow percolation speeds of 0.1 inch or less per hour. These soils easily become waterlogged, and plant roots can suffocate as a result.  Any soil can vary significantly from the percolation rate averages. This variation can be due to factors that include soil compaction, organic matter content and/or soil temperature. Yet soil types are by far the single biggest determinant for percolation rates. Percolation Rate Field Measurement Estimating percolation speed is based on general knowledge of soil's type and/or through observation of how well it drains. Also, however, a simple percolation test can easily be done to determine a more precise percolation rate following the steps below to conduct the field tests: Field Tests 6