12 2026 02 12 Crestmont CC Stormwater Management Report

• Groundwater recharge; and, • Nonstructural measures The following sections provided additional detail regarding each of the stormwater design regulations. 3.1 Stormwater Quantity Design 3.1.1 Design Criteria In accordance with N.J.A.C. 7:8-5.6.(b).3, stormwater management measures are to be designed so that the post-construction peak runoff rates for the 2-, 10-, and 100-year design storm events are 50, 75, and 80%, respectively, of the pre-construction runoff rates for the portion of the site on which the proposed development is to be constructed. The portions of the project site that are to remain undisturbed in the post-construction condition are not subject to rate control measures. Therefore, it shall be demonstrated in accordance with N.J.A.C. 7:8-5.6.(b).3 that the post- construction peak runoff rates for the 2-, 10-, and 100-year design storm events are 50, 75, and 80%, respectively, of the pre-construction runoff rates for the portion of the site on which the redevelopment is to take place and quantity control through the implementation of BMPs is required. In accordance with N.J.A.C. 7:8-5.7, the 2-, 10-, and 100-year design storm events must be analyzed for both the “current” and “future” rainfall events. 3.1.2 Design Methodology This study was prepared utilizing the Natural Resources Conservation Service (NRCS - formerly SCS) method to analyze the pre- and post-development stormwater runoff rates and volumes. This methodology meets the NJDEP stormwater calculation requirements presented in Section 7:8-5.7.(a).1 of the New Jersey Administrative Code (N.J.A.C.) recognizing existing conditions. Stormwater hydrographs were developed utilizing the NOAA Atlas 14 Region D 24-hour storm distribution, and precipitation depths are referenced from the NOAA Atlas 14, Volume 2, Version 3 Point Precipitation Frequency Estimates Table for West Orange, New Jersey, accessed on March 20, 2024, for the 2-, 10-, 25-, and 100-year return periods. The table below summarizes the rainfall event totals. 5