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

LAND DEVELOPMENT CONSULTING ● PERMITTING GEOTECHNICAL ● ENVIRONMENTAL TRAFFIC● SURVEY● PLANNING & ZONING 245 Main Street, Suite 110 Chester, NJ 07930 T: 908.879.9229 | F: 908.879.0222 Offices conveniently located at: Lake Como, New Jersey ● T: 732.974.0198 Chester, New Jersey ● T: 908.879.9229 Newark, New Jersey ● T: 973.755.7200 Toms River, New Jersey ● T: 732.974.0198 Newtown, Pennsylvania ● T: 267.685.0276 Philadelphia, Pennsylvania ● T: 215.253.4888 Bethlehem, Pennsylvania ● T: 610.598.4400 Allen, Texas ● T: 972.534.2100 Houston, Texas ● T: 281.789.6400 Austin, Texas● T: 512.646.2646 Delray Beach, Florida ●561.921.8570 T: www.dynamicec.com ROBERT J. COLUCCO III JOSEPH C. SPARONE ã

LAND DEVELOPMENT CONSULTING ● PERMITTING GEOTECHNICAL ● ENVIRONMENTAL TRAFFIC● SURVEY● PLANNING & ZONING 245 Main Street, Suite 110 Chester, NJ 07930 T: 908.879.9229 | F: 908.879.0222 Offices conveniently located at: Lake Como, New Jersey ● T: 732.974.0198 Chester, New Jersey ● T: 908.879.9229 Newark, New Jersey ● T: 973.755.7200 Toms River, New Jersey ● T: 732.974.0198 Newtown, Pennsylvania ● T: 267.685.0276 Philadelphia, Pennsylvania ● T: 215.253.4888 Bethlehem, Pennsylvania ● T: 610.598.4400 Allen, Texas ● T: 972.534.2100 Houston, Texas ● T: 281.789.6400 Austin, Texas● T: 512.646.2646 Delray Beach, Florida ●561.921.8570 T: www.dynamicec.com ROBERT J. COLUCCO III JOSEPH C. SPARONE ã

LAND DEVELOPMENT CONSULTING ● PERMITTING GEOTECHNICAL ● ENVIRONMENTAL TRAFFIC● SURVEY● PLANNING & ZONING 245 Main Street, Suite 110 Chester, NJ 07930 T: 908.879.9229 | F: 908.879.0222 Offices conveniently located at: Lake Como, New Jersey ● T: 732.974.0198 Chester, New Jersey ● T: 908.879.9229 Newark, New Jersey ● T: 973.755.7200 Toms River, New Jersey ● T: 732.974.0198 Newtown, Pennsylvania ● T: 267.685.0276 Philadelphia, Pennsylvania ● T: 215.253.4888 Bethlehem, Pennsylvania ● T: 610.598.4400 Allen, Texas ● T: 972.534.2100 Houston, Texas ● T: 281.789.6400 Austin, Texas● T: 512.646.2646 Delray Beach, Florida ●561.921.8570 T: www.dynamicec.com ROBERT J. COLUCCO III JOSEPH C. SPARONE ã

Refuse (Front Load) LAND DEVELOPMENT CONSULTING ● PERMITTING GEOTECHNICAL ● ENVIRONMENTAL TRAFFIC● SURVEY● PLANNING & ZONING 245 Main Street, Suite 110 Chester, NJ 07930 T: 908.879.9229 | F: 908.879.0222 Offices conveniently located at: Lake Como, New Jersey ● T: 732.974.0198 Chester, New Jersey ● T: 908.879.9229 Newark, New Jersey ● T: 973.755.7200 Toms River, New Jersey ● T: 732.974.0198 Newtown, Pennsylvania ● T: 267.685.0276 Philadelphia, Pennsylvania ● T: 215.253.4888 Bethlehem, Pennsylvania ● T: 610.598.4400 Allen, Texas ● T: 972.534.2100 Houston, Texas ● T: 281.789.6400 Austin, Texas● T: 512.646.2646 Delray Beach, Florida ●561.921.8570 T: www.dynamicec.com ROBERT J. COLUCCO III JOSEPH C. SPARONE ã

STORMWATER MANAGEMENT REPORT for Altera 769, LLC Proposed Office Building Block 166.15, Lot 9 769 Northfield Avenue (CR 508) Township of West Orange Essex County, New Jersey Prepared by: 245 Main Street Suite 110 Chester, NJ 07930 (908) 879-9229 Robert J. Colucco, PE NJ Professional Engineer License #55851 January 2022 Revised August 2022 DEC #2530-99-006

TABLE OF CONTENTS I. Introduction ............................................................................................... 3 II. Existing Site Conditions ............................................................................. 3 III. Proposed Site Conditions ........................................................................... 5 IV. Design Methodology .................................................................................. 6 V. Aboveground Stormwater Management Basin Design ................................ 7 VI. Runoff Rates .............................................................................................. 8 VII. Water Quality ............................................................................................ 8 VIII. Groundwater Recharge .............................................................................. 9 IX. Conclusion ................................................................................................. 9 APPENDIX • NRCS Web Soil Survey • Runoff Curve Number (CN) Calculations • Time of Concentration (Tc) Calculations • Existing & Proposed Hydrographs 2yr, 10yr, & 100yr Design Storms (Hydrographs created using Hydrology Studio 2020 Computer Software) • Existing & Proposed Hydrographs 1yr Water Quality Design Storm (Hydrographs created using Hydrology Studio 2020 Computer Software) • Rip Rap Calculations • Inlet Area Calculations and Stormwater Collection System Calculations (Pipe Sizing) • Basin Drain Time Calculation • Stormwater Basin Area Investigation Report prepared by Dynamic Earth, LLC, dated January 14, 2022 • Drainage Area Maps Altera 769, LLC 2 Revised August 2022 DECPC #2530-99-006

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

Based upon the Essex County Soil Survey the soil types native to the site include: HYDRAULIC SOIL TYPE SOIL TYPE NAME SOIL GROUP* BogB Boonton Loam, 3 to 8 percent slopes C Boonton Loam, 0 to 8 percent slopes, BogBc C extremely stony Boonton – Urban Land, Boonton BouB C Substratum Complex, 0 to 8 percent slopes Urban Land, Boonton Substratum, 0 to 8 URBONB C percent slopes *A field investigation of the existing on-site soils was performed by Dynamic Earth, LLC to evaluate subsoil conditions to estimate depth to the seasonal high groundwater levels and permeability rates. Based on laboratory testing, permeability rates were less than 0.06 inches per hour, which is consistent with a hydrologic soil group (HSG) D. For the purposes of the design, the site has been modeled as HSG D in the Runoff Curve Number calculations. A copy of the Runoff Curve Number calculations as well as the Stormwater Basin Area Investigation Report prepared by Dynamic Earth, LLC are provided within the Appendix of this report. The existing site conditions have been evaluated using the following drainage sub-watershed areas as depicted on the Existing Drainage Area Map included within the Appendix within this report: Existing DA-1: This area consists of the wooded area at the northern most part of the site. Stormwater runoff generated by this area sheet flows overland in a westerly direction, where it is collected by an existing stormwater pipe (POI-1) along the western property line. A time of concertation of 18.5 minutes has been calculated and utilized for this drainage area. Existing DA-2: This area consists of the northern portion of

(POI-1) along the western property line. A time of concertation of 18.5 minutes has been calculated and utilized for this drainage area. Existing DA-2: This area consists of the northern portion of the existing rear parking area and a portion of the wooded areas. Stormwater runoff generated by this area sheet flows overland to the west where it is collected by a series of existing inlets where is it ultimately conveyed to the existing stormwater management structure (POI-2). A time of concentration of 16.1 minutes has been calculated and utilized for this drainage area. Existing DA-3: This area consists of the remainder of the subject site which includes the existing office building, remaining parking areas and open space (lawn) areas. Stormwater runoff generated by this area sheet flows overland in a southerly direction where it is collected by a series of existing inlets. Ultimately, stormwater runoff is conveyed to the existing stormwater conveyance system within Northfield Avenue (CR 508) (POI-3). A minimum time of concentration of six (6) minutes has been utilized for this drainage area. Altera 769, LLC 4 Revised August 2022 DECPC #2530-99-006