2023 06 Drainage Statement

DRAINAGE STATEMENT for MPB Realty, LLC Proposed Popeyes Restaurant & Sonic Restaurant 470 Eagle Rock Avenue (CR 611) Block 153, Lot 38 Township of West Orange Essex County, NJ Prepared by: 1904 Main Street Lake Como, NJ 07719 (732) 974-0198 Matthew J. Bersch, PE NJ Professional Engineer License #54522 October 2022 Last Revised June 2023 DEC# 1021-99-025

TABLE OF CONTENTS Page No. I. Introduction ............................................................................................... 3 II. Existing Drainage Conditions ..................................................................... 3 III. Proposed Drainage Conditions ................................................................... 4 IV. Runoff Rate Reduction Performance .......................................................... 4 V. Groundwater Recharge .............................................................................. 4 VI. Water Quality ............................................................................................ 4 VII. Conclusion ................................................................................................. 5 APPENDIX • Location Map • USGS Map • NRCS Web Soil Survey • Time of Concentration (Tc) Calculations • Runoff Curve Number (CN) Calculations – Existing • Runoff Curve Number (CN) Calculations – Proposed • Hydrograph Summary Reports – Existing and Proposed Conditions 2 yr. 10 yr. & 100 yr. • Multi-Hydrograph Plot – Existing and Proposed Conditions Superimposed 2 yr. 10 yr. & 100 yr. • Stormwater Collection System Calculations (Pipe Sizing) • Drainage & Inlet Area Maps MPB Realty, LLC October 2022 DEC# 1021-99-025 2 Last Revised June 2023

I. Introduction This Drainage Statement has been prepared to define and analyze the stormwater drainage conditions that would occur as a result of the improvements to Block 153, Lot 38, as shown on the Township of West Orange Tax Map Sheet No. 84, located in the Township of West Orange, Essex County, New Jersey. In existing conditions, the subject site consists of 1.07 acres (45,713 SF) and is located at 470 Eagle Rock Avenue. Under existing conditions, the site is developed as a restaurant with associated parking, landscaping and lighting. The existing development has an impervious coverage of 80.5% (36,974 SF) and is located in the B-2 – General Business Zone. The proposed development consists of the demolition of the existing restaurant and the construction of a 2,525 SF Popeyes restaurant with a drive-thru and a 1,484 SF Sonic restaurant with a drive-thru. Additional site amenities include parking, landscaping, lighting and a trash enclosures. The proposed development will provide a total impervious coverage of 68.8% (31,436 SF), resulting in a 5,538 SF (11.7%) reduction. In addition, the project will result in a decrease in motor vehicle surface area of approximately 4,133 SF from 28,325 SF to 24,192 SF. Per the Natural Resources Conservation Service Web Soil Survey, a portion of the property is located within unclassified Urban Land soil. To be conservative, the analysis utilized HSG B in existing conditions and HSG D in proposed for disturbed areas within the Urban Land soil. Based upon the fact that the proposed improvements will result in more than one (1) acre of land disturbance, this project is classified as a “major development” and is subject to compliance with the Stormwater Regulations set forth in NJAC 7:8. However, the project will result in a decrease in motor vehicle surface area and impervious coverage from existing to proposed conditions. As such, the project does not increase regulated motor vehicle surface by more than one-quarter acre and is therefore not required to meet the stormwater runoff quality standards under NJAC 7:8-5.5 and Township of West Orange Ordinance §25-29.4.q. A hydrological evaluation is provided for the 2-, 10-, and 100-year storm events utilizing the Urban Hydrology for Small Watersheds TR55 Method to confirm compliance with the stormwater runoff quantity and groundwater recharge standards set forth by

10-, and 100-year storm events utilizing the Urban Hydrology for Small Watersheds TR55 Method to confirm compliance with the stormwater runoff quantity and groundwater recharge standards set forth by the Township of West Orange Land Development Ordinance and NJAC 7:8. II. Existing Drainage Conditions In existing conditions, a majority of the stormwater runoff from the area to be disturbed is conveyed via overland flow to the proposed onsite inlets which connect to the existing stormwater infrastructure within Rosney Terrace. Stormwater runoff from Rosney Terrace ultimately discharges into the existing stormwater infrastructure within Eagle Rock Avenue. The remaining stormwater runoff from the site discharges directly to the existing inlet along Eagle Rock Avenue via overland flow. As such, one point of analysis can be considered for the overall development. MPB Realty, LLC October 2022 DEC# 1021-99-025 3 Last Revised June 2023

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

VII. Conclusion In conclusion, the proposed project has been designed to ensure the safe and efficient control of stormwater runoff in a manner that will not adversely impact the existing drainage patterns or adjacent properties. The project is designed to comply with the stormwater runoff quantity and groundwater recharge requirements set forth under NJAC 7:8 and the Township of West Orange Land Use Ordinance. With this stated, it is evident that the proposed development will not have a negative impact on or within the vicinity of the site, and the increase in pervious coverage will benefit the area. MPB Realty, LLC October 2022 DEC# 1021-99-025 5 Last Revised June 2023

APPENDIX

LOCATION MAP

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