2024 03 Drainage Statement

II. Design Methodology The intention of the design of the proposed stormwater management facility for this project is to provide measures as required to address applicable aspects of the Standards for Soil Erosion and Sediment Control in New Jersey and the Township of West Orange Stormwater Management Control Ordinance. The stormwater runoff from the project area is ultimately tributary to two points of analysis as previously described. The stormwater drainage for the proposed project has been designed to maintain existing runoff patterns on-site to the maximum extent practicable. A grading plan has been developed for the proposed site improvements with consideration to the existing drainage patterns. The project proposes an underground detention system located to the north of the dwelling. A proposed roof leader system will collect stormwater runoff from the dwelling and discharge into the basin. Two (2) yard inlets are proposed onsite to collect stormwater runoff from the project area. The proposed basin is designed with an outlet control structure which will release stormwater runoff at a controlled rate to the existing stormwater conveyance pipe located to the east of the proposed dwelling, which is ultimately tributary to the existing concrete channel. A portion of stormwater runoff from the project area will continue to flow undetained via overland to the existing headwall within the adjacent Lot 21. The hydrology for the site was calculated using the NRCS Runoff Equation and Dimensionless Unit Hydrograph as noted in Part 630, Hydrology National Engineering Handbook. The following particular references were used: • Curve Numbers were established via Chapter 9 – Hydrologic Soil-Cover Complexes • Time of Concentrations were calculated in accordance with Chapter 15 • Rainfall Distributions are based on NOAA Type D rainfall distributions • The SCS Dimensionless Unit Hydrograph was utilized. Aaron Friedman DEC# 5142-24-00053 March 2024 2