2023 06 Drainage Statement

III. Proposed Drainage Conditions In proposed conditions, stormwater runoff from the project area has been designed to maintain existing drainage patterns. The project proposes to remove the existing onsite inlets and provide six (6) new inlets within the site to assist in collecting stormwater runoff from impervious areas. The proposed inlets are connected via an underground conveyance system consisting of 12” and 15” reinforced concrete pipes discharging to the existing inlet within Rosney Terrace. Stormwater runoff from the building roofs are collected and conveyed underground via 6” PVC roof leaders to the proposed inlets. IV. Runoff Rate Reduction Performance Due to the reduction in impervious coverage, the volume and peak discharge runoff rates for the 2-, 10- & 100-year design storms have been reduced. As such, there shall be no adverse impacts to the properties located upstream and downstream of the site. Study Area Site Design Storm Ex. Peak Flow (cfs) Prop. Peak Flow (cfs) 2 2.913 2.803 10 4.640 4.553 100 8.056 8.012 Per NJAC 7:8-5.6(b).1, the stormwater runoff quantity requirements are met through demonstration that the post-construction runoff hydrographs for the 2, 10- and 100-year storm events do not exceed at any point in time, the pre-construction runoff hydrographs for the same storm events. Appended are the superimposed hydrographs for reference. V. Groundwater Recharge Per NJAC 7:8-5.4(b).2, the project is not subject to the groundwater recharge requirement as it is within the Metropolitan Planning Area (PA1) which is classified as an Urban Redevelopment Area. VI. Water Quality Per NJAC 7:8-5.5(a), the project is not required to meet the stormwater runoff quality standards as the project results in a decrease in motor vehicle surface area. This reduction provides a decrease in total suspended solid (TSS) generation for the site, improving the quality of stormwater runoff leaving the site. MPB Realty, LLC October 2022 DEC# 1021-99-025 4

ter runoff leaving the site. MPB Realty, LLC October 2022 DEC# 1021-99-025 4 Last Revised June 2023