PB 22 10 Altera 769 LLC Filed Application with Exhibits Final Site Plan Phase 2

I. INTRODUCTION The intention of this study is to analyze the stormwater drainage conditions that will occur as a result of the proposed site improvements. The proposed improvements consist of the renovation of the existing office building, modifications to the existing parking lot to satisfy current ADA regulations, the expansion of the rear parking area, and other associated site improvements. The subject site is located at 769 Northfield Avenue (CR 508) in the Township of West Orange, Essex County, New Jersey and is identified as Block 166.15, Lot 9 on the Township of West Orange Tax Maps. The scope of this study focuses on the overall drainage conditions that will result from the proposed improvements. The proposed site improvements shall result in an increase in impervious coverage of approximately 20,635 SF (9.7%). The primary design constraints for this project are based on requirements established in the Township of West Orange Land Use Ordinance, the State of New Jersey Stormwater Regulations outlined in NJAC 7:8, and State of New Jersey Soil Conservation Requirements. More specifically, the stormwater management design will serve to maintain existing drainage patterns and will not have a negative impact on downstream facilities. More specifically, the limit of disturbance for the development will exceed one (1) acre; therefore, the project meets the definition of a “major development” under NJAC 7:8. As such, the project has been designed to meet the applicable standards set forth by the Township of West Orange and NJAC 7:8. II. EXISTING SITE CONDITIONS The subject site consists of 212,742 SF (4.88 acres) of which is partially developed with one (3) three-story office building and associated paved parking areas and drive aisles. The site currently consists of 57.4% impervious surface area including building and pavement areas. Currently, stormwater runoff generated by the rear wooded area of the site sheet flows overland in a westerly direction where it is collected by on-site stormwater management structures (POI-1) and is tributary to the stormwater conveyance system located within the rear paved parking area. The majority of stormwater runoff generated by the pavement areas sheet flows in a westerly direction where it is collected by on-site inlets and conveyed to an on-site underground stormwater management structure

of stormwater runoff generated by the pavement areas sheet flows in a westerly direction where it is collected by on-site inlets and conveyed to an on-site underground stormwater management structure (POI-2). Ultimately stormwater runoff is tributary to the existing underground stormwater conveyance system within Northfield Avenue (POI-3). Altera 769, LLC 3 Revised August 2022 DECPC #2530-99-006