12 2026 02 12 Crestmont CC Stormwater Management Report

STORMWATER MANAGEMENT REPORT for CRESTMONT COUNTRY CLUB & EAGLE ROCK AVE IMPROVEMENTS BLOCK No. 174, LOT No. 1.01 TOWNSHIP OF WEST ORANGE, ESSEX COUNTY, NEW JERSEY Prepared For: Crestmont Country Club, Inc. 750 Eagle Rock Avenue West Orange, New Jersey 07052 Prepared By: Langan Engineering & Environmental Services, LLC 300 Kimball Drive Parsippany, New Jersey 07054 NJ Certificate of Authorization No: 24GA27996400 Michael Vitello, P.E. John Coté, P.E. New Jersey Professional Engineer Lic. No. 24GE03705800 February 12, 2026 101049802

TABLE OF CONTENTS EXECUTIVE SUMMARY.............................................................................................................................. 1 1.0 INTRODUCTION .................................................................................................................................... 1 2.0 PROJECT DESCRIPTION ....................................................................................................................... 2 2.1 EXISTING SITE DESCRIPTION .................................................................................................................... 2 2.2 SUBSURFACE CONDITIONS ...................................................................................................................... 2 2.3 FLOOD HAZARD AREA ............................................................................................................................ 4 2.4 PROPOSED DEVELOPMENT...................................................................................................................... 4 3.0 STORMWATER MANAGEMENT .......................................................................................................... 4 3.1 STORMWATER QUANTITY DESIGN ............................................................................................................ 5 3.1.1 Design Criteria ............................................................................................................................. 5 3.1.2 Design Methodology ................................................................................................................... 5 3.1.3 Points of Analysis ........................................................................................................................ 7 3.1.4 Existing Watersheds ................................................................................................................... 8 3.1.5 Allowable Peak Discharges ......................................................................................................... 8 3.1.6 Proposed Watersheds ............................................................................................................... 11 3.1.7 Proposed Detention Routing ..................................................................................................... 12

............................................... 11 3.1.7 Proposed Detention Routing ..................................................................................................... 12 3.1.8 Quantity Control BMP Design Summary .................................................................................. 13 3.1.9 Stormwater Quantity Summary ................................................................................................ 15 3.2 STORMWATER QUALITY DESIGN ............................................................................................................ 16 3.2.1 Design Criteria ........................................................................................................................... 16 3.2.2 Design Methodology ................................................................................................................. 17 3.2.3 Design Summary ....................................................................................................................... 17 3.2.4 Trash and Waste ....................................................................................................................... 18 3.3 GROUNDWATER RECHARGE .................................................................................................................. 18 3.3.1 Design Criteria ........................................................................................................................... 18 3.3.2 Design Methodology ................................................................................................................. 18 3.3.3 BMP Design .............................................................................................................................. 18 3.3.4 Design Summary ....................................................................................................................... 19 3.4 NON-STRUCTURAL STORMWATER MANAGEMENT STRATEGIES ................................................................. 19 3.5 STORMWATER CONVEYANCE DESIGN ..................................................................................................... 19 3.5.1 Design Criteria ........................................................................................................................... 19

.................................... 19 3.5.1 Design Criteria ........................................................................................................................... 19 3.5.2 Design Methodology ................................................................................................................. 20 4.0 SOIL EROSION AND SEDIMENT CONTROL ..................................................................................... 21 5.0 STORMWATER MAINTENANCE PLAN ............................................................................................. 21 6.0 CONCLUSION ...................................................................................................................................... 21 7.0 REFERENCES ....................................................................................................................................... 21 i

LIST OF FIGURES FIGURE DESCRIPTION 1 Site Location Map 2 FEMA Flood Insurance Rate Map 3 Soils Map 4 Existing Watershed Map 5 Proposed Watershed Map 6 Existing Drainage Subarea Map 7 Proposed Drainage Subarea Map 8 Required Water Quality Treatment Map 9 Proposed Water Quality Treatment Map 10 Test Pit Location Plan LIST OF DRAWINGS DRAWING DESCRIPTION CG101 Partial Grading Plan CG102 Partial Grading Plan CG103 Partial Drainage Plan CG104 Partial Drainage Plan CG501 Drainage Details CG502 Drainage Details LIST OF APPENDICES APPENDIX DESCRIPTION A Existing Stormwater Discharge Calculations B Proposed Stormwater Discharge Calculations C Pond Routing Calculations D Stormwater Conveyance Calculations E Stormwater Quality Calculations F Geotechnical Investigation Information ii

EXECUTIVE SUMMARY The proposed stormwater management and conveyance systems for the proposed Crestmont Country Club & Eagle Rock Ave Improvements project have been designed in accordance with the New Jersey Department of Environmental Protection stormwater rules (NJAC 7:8), and the Township of West Orange stormwater regulations. The proposed development includes the construction of: • Installation of a new traffic signal at Eagle Rock Avenue & Oval Road intersection; • Widening along Eagle Rock Avenue to support the new lane geometry required at the new signal; • Re-alignment of the Crestmont egress driveway to connect into the new intersection; and, • Onsite improvements to both increase the number of parking spaces and re-design the parking around the new egress driveway. The proposed development disturbs more than one acre of land; therefore, this project is considered a “major development” from a stormwater management perspective, and the proposed design is required to address stormwater quantity, quality, and groundwater recharge requirements. The proposed stormwater management system consists of the following: • A subsurface conveyance system consisting of inlets, manholes, and pipes to convey stormwater runoff from the 25-year design storm event; • 2 small-scale bioretention basins; and, • 1 porous asphalt pavement system. By using the stormwater management measures identified above and reviewing the results of the detailed calculations provided in this report, the stormwater management design is in accordance with the Township of West Orange and NJDEP stormwater rules, regulations, and ordinance requirements in effect at the time of the preparation of this report. 1.0 INTRODUCTION This report addresses the engineering design of the stormwater conveyance and management system for proposed improvements within Eagle Rock Avenue and Crestmont Country Club in West Orange, New Jersey. The proposed stormwater management system is designed in accordance with: • New Jersey Department of Environmental Protection (NJDEP) stormwater rules (NJAC 7:8), last amended July 17, 2023; 1

• New Jersey Standards for Soil Erosion and Sediment Control, last revised July 2017; and, • Township of West Orange Code of Ordinances Chapter 240: Stormwater Management. . 2.0 PROJECT DESCRIPTION 2.1 Existing Site Description The project site is comprised of Block No. 174, Lot No. 1.01 in the Township of West Orange, Essex County, New Jersey. The 146.76± acre tract is the location of Crestmont Country Club and predominantly covered by the grassed golf course, along with some wooded areas. The site is bound by Laurel Avenue and Eagle Rock Avenue to the north, undeveloped wooded area to the east and south, and a continuation of the Crestmont Country Club golf course to the west; refer to Figure 1 – Site Location Map. The proposed work will only impact 3.93± acres of the site, located along Eagle Rock Avenue and Laurel Avenue in the north side of the property. The disturbed site topography generally slopes from south to north, with existing grades across the disturbed site ranging from approximately EL. 570 to EL. 532. 2.2 Subsurface Conditions According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service Soil Survey Map for Essex County, New Jersey, there are 4 predominant soils within the area of redevelopment. A brief description of each soil type is provided below. • Boonton – Urban land, Boonton substratum complex (BouB): The natural soil typically consists of loam to silt loam to gravelly fine sandy loam to fine sandy loam loamy sand. The soil mapping unit is reported to be Hydrologic Soil Group C. • Udorthents, Haledon substratum (UdhalB): The natural soil typically consists of loam to gravelly fine sandy loam. The soil mapping unit is reported to be Hydrologic Soil Group D. • Boonton loam, 0 to 8 percent slopes, extremely stony (BogBc): These areas are typically covered with slightly decomposed plant material to highly decomposed plant material. The natural soil typically consists of loam to silt loam to gravelly fine sandy loam to fine sandy loam to loamy sand. The soil mapping unit is reported to be Hydrologic Soil Group C. • Haledon silt loam (HanBc): These areas are typically covered with moderately decomposed plant material. The natural soil typically consists of silt loam to loam to gravelly

C. • Haledon silt loam (HanBc): These areas are typically covered with moderately decomposed plant material. The natural soil typically consists of silt loam to loam to gravelly fine sandy loam. The soil mapping unit is reported to be Hydrologic Soil Group C. 2

A geotechnical investigation was performed in the area of redevelopment in April 2024; refer to Appendix F for the supporting geotechnical memorandum. As part of this investigation, soil samples were collected at 19 test pit locations for laboratory permeability tests. The purpose of this testing was to confirm the hydrologic soil group classification of the in-situ soils within the proposed limit of disturbance area, which is approximately 3.93± acres. Soil type UdhalB is already classified as Hydrologic Soil Group D; therefore, not reclassification testing was performed within this soil. The number and location of these test pits is based upon the regulations set forth in Chapter 12 of the New Jersey Stormwater BMP Manual. A summary of the required and proposed geotechnical testing is summarized in Table 1 below: Table 1 – Hydrologic Soil Group Reclassification Summary Approximate Area Required Number Soil Number of Test of Disturbance of Test Pits / Mapping Pits / Permeability Test Pit IDs Within Soil Permeability Unit Tests Performed Mapping Unit (AC) Tests TP-9, TP-14, TP-15, BouB 1.20 5 5 TP-16, TP-17 HanBc 0.27 2 2 TP-11, TP-12 TP-1, TP-4, TP-5, TP-6, TP-8, TP-7, TP-10, TP- BogBc 2.37 8 12 13, TP-18, TP-19, TP- 20, TP-21 Notes: 1. Chapter 12 of the BMP Manual requires that soil profile

8, TP-19, TP- 20, TP-21 Notes: 1. Chapter 12 of the BMP Manual requires that soil profile test pits and soil borings be performed as part of the HSG reclassification. In accordance with Chapter 12 Subsection 1C, soil profiles test pits may be conducted in place of a required soil boring in all testing instances. 2. Refer to the Test Pit Location Plan, Figure 10, for BMP and test pit locations. Refer to Appendix F for supporting geotechnical investigation information including test pit and boring logs. The full geotechnical analysis and supporting laboratory data is contained in Appendix F of this report. In summary, the laboratory permeability testing at all 19 test pit locations supports the reclassification of soils within the project area’s limit of disturbance to HSG D in accordance with the New Jersey Stormwater Best Practices Manual and the NRCS National Engineering Handbook, Part 630 – Hydrology, Chapter 7 Hydrologic Soil Groups, Table 7-1: Criteria for Assignment of Hydrologic Soil Group. For the purpose of the stormwater management calculations in this report, all underlying soil within the project area’s limit of disturbance is assumed to be HSG D. All soil outside the limit of disturbance is assumed to retain its respective NRCS Web Soil Survey hydrologic soil group classification. It should be noted that the project site is located in an area of the state containing known karst 3