2025 12 19 Stormwater Report Rev 1

STORMWATER MANAGEMENT REPORT FOR THE ESTATE BLOCK 151 LOT 17.01 TOWNSHIP OF WEST ORANGE ESSEX COUNTY, NEW JERSEY SUBMITTED TO: TOWNSHIP OF WEST ORANGE PLANNING BOARD PREPARED FOR: THE ESTATE 111 PROSPECT AVENUE WEST ORANGE, NEW JERSEY 07052 PREPARED BY: PETRY ENGINEERING, LLC 155 PASSAIC AVENUE FAIRFIELD, NEW JERSEY 07004 973-227-7004

STORMWATER MANAGEMENT REPORT FOR THE ESTATE BLOCK 151 LOT 17.01 TOWNSHIP OF WEST ORANGE ESSEX COUNTY, NEW JERSEY SUBMITTED TO: TOWNSHIP OF WEST ORANGE PLANNING BOARD PREPARED FOR: THE ESTATE 111 PROSPECT AVENUE WEST ORANGE, NEW JERSEY 07052 PREPARED BY: PETRY ENGINEERING, LLC 155 PASSAIC AVENUE FAIRFIELD, NEW JERSEY 07004 973-227-7004 J. Michael Petry J. MICHAEL PETRY, PE NJ PROFESSIONAL ENGINEER # 36662 DATED: DECEMBER 27, 2024 REVISED: DECEMBER 19, 2025 1

TABLE OF CONTENTS Introduction ..................................................................................................................................... 3 Proposed Improvements.................................................................................................................. 3 Methodology ................................................................................................................................... 4 Existing Conditions......................................................................................................................... 5 Drainage area 1 (DA-1) .............................................................................................................. 5 Drainage area 2 (DA-2) .............................................................................................................. 5 Curve Numbers ........................................................................................................................... 5 Peak Flows .................................................................................................................................. 5 Proposed Conditions ....................................................................................................................... 6 Drainage area 1 (DA-1) .............................................................................................................. 6 Drainage area 2 (DA-2) .............................................................................................................. 6 Curve Numbers ........................................................................................................................... 7 Peak Flows .................................................................................................................................. 7 Water Quality .................................................................................................................................. 8 Groundwater Recharge ................................................................................................................... 8 Storm Sewer Computations ............................................................................................................ 8 Conclusion

................................................... 8 Storm Sewer Computations ............................................................................................................ 8 Conclusion ...................................................................................................................................... 9 Existing Conditions Hydrographs Proposed Conditions Hydrographs Appendix - Web Soil Survey - Essex County Soils Information - New Jersey 24 Hour Rainfall Frequency Data - Table 2-2a Runoff Curve Numbers for Urban Data - Figure 10-B Rainfall Intensity – Duration Frequency Curve – Northern Region - Table 7 – DA-1 Existing Vs. Proposed Runoff Rates – Current Adjusted Rainfall - Table 8 – DA-2 Existing Vs. Proposed Runoff Rates – Current Adjusted Rainfall - Table 9 – DA-1 Existing Vs. Proposed Runoff Rates – Future Projected Rainfall - Table 10 – DA-2 Existing Vs. Proposed Runoff Rates – Future Projected Rainfall - Time of Concentration Calculations - Storm Sewer Calculations - Drainage Area Maps (Fig.-1 – Fig.-3) 2

INTRODUCTION The subject property is located at 111 Prospect Avenue, at the corner of Prospect Avenue and Woodland Avenue in the Township of West Orange, NJ. The property consists of 8.29± acres of land. It is located within the B-2 General Business Zone. The adjacent properties to the south and west are residential. To the north of the property is the Residence Inn. Finally, to the east of the property, across Prospect Avenue, is the Eagle Rock Reservation. Currently, the site contains a catering hall and restaurant consisting of 3 buildings and multiple paved parking lots that service the buildings. The property slopes from elevation 555 to elevation 505, from the southeast to the northwest. The main building has a footprint of approximately 36,100 square feet and contains 2 stories. There are also 2 smaller buildings on the lot, located in the center and rear of the site. Three large parking lots are located throughout the site. An employee parking lot is located at the southwestern corner. A valet parking lot is located to the east of the main building, and a public parking lot is located to the north. The public parking lot is also partially contained by a cross-access easement and connects to the Residence Inn parking lot. The NRCS Websoil survey mapping indicates that the portion of the site subject to development contains Hydrologic Group “D” soils, Urban land, Boonton Substratum, (URBONB) with Urban Land. The stormwater analysis considers this soil group type D. (See attached Websoil Survey Mapping.) PROPOSED IMPROVEMENTS Phase 1 of the project was previously approved in May of 2025. This approval included the renovation of the main building, the front garden area, a new porte cochere, and the reconstruction of the front parking lot. The applicant is submitting this application as an Amended Site Plan to include Phase 2. This scope of work includes an addition to the rear of the main building, the renovation of the existing restaurant, and the reconstruction of the rear parking lot. The new parking lot will contain more landscape islands throughout which will help to guide traffic as well as allow for additional plantings. The proposed development will reduce the overall impervious on the site. The previously approved site plan had 5.02 acres of impervious coverage and 3.39 acres of motor vehicle surface. The proposed impervious coverage for

nt will reduce the overall impervious on the site. The previously approved site plan had 5.02 acres of impervious coverage and 3.39 acres of motor vehicle surface. The proposed impervious coverage for the site is 4.96 acres and the proposed motor vehicle surface is 3.31 acres. The entirety of the proposed disturbance is limited to previously developed areas. In order to accurately assess the impacts of stormwater on the subject property, this stormwater report used the existing conditions prior to the approval of Phase 1 and the proposed improvements include both Phase 1 and Phase 2. 3

METHODOLOGY The USDA Natural Resources Conservation Service (NRCS) methodology described in the Technical Release 55 – Urban Hydrology for Small Water Sheds (TR-55) is used for computing stormwater runoff rates, volumes, and hydrographs for both existing and proposed conditions. In computing stormwater runoff from all design storms, the relative stormwater runoff rates and volumes of pervious and impervious surfaces are analyzed separately. The rainfall-duration- frequency data was taken from the NOAA National Weather Service. (See attached.) The NRCS Type D Design Storm Rainfall Distribution was used to analyze both pre- and post-conditions for both current adjusted and future projected rainfall projections. Hydraflow Hydrographs Extension 2024 Modeling Software was used to compute the site's pre- and post-development runoff of the site. Table 1 – Rainfall Data Current Rainfall Current Adjusted Future Rainfall Storm Event (in) Rainfall (in) (in) 2-Yr 3.44 3.47 4.09 10-Yr 5.22 5.38 6.37 100-Yr 8.66 9.18 11.52 According to the Township of West Orange Stormwater Management Rules and the NJDEP Stormwater Management regulations, the proposed development is considered a major development since there is more than one acre of disturbance. For major developments, stormwater management measures designed to provide groundwater recharge, stormwater runoff quantity control, and stormwater runoff quality treatment, utilizing green infrastructure. The development does not have to meet the groundwater recharge requirement since it is located within the Metropolitan Planning Area. Also, since the proposed development does not result in a net increase of ¼ of an acre or more of impervious surface, the water quality aspect of the Stormwater Management Rules is not required. Therefore, the stormwater management measures have been designed to meet only the stormwater runoff quantity requirements. According to Section 7:8-5.6(b)1. the design must “demonstrate through hydrologic and hydraulic analysis that for stormwater leaving the site, post-construction runoff

r runoff quantity requirements. According to Section 7:8-5.6(b)1. the design must “demonstrate through hydrologic and hydraulic analysis that for stormwater leaving the site, 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.” The proposed development calls for a decrease in the amount of impervious on the site, the amount of runoff will be reduced. Since the stormwater quantity is satisfied through the use of non-structural strategies, green infrastructure requirements are not required. 4

EXISTING CONDITIONS The existing site has been modeled as two drainage areas totaling 4.86 acres. (See Fig.1 Existing Drainage Area Map.) The point of analysis for Drainage Area 1 is the Type Double “B” Inlet at the rear of the site, which connects to the municipal storm sewer system within Deerfield Drive. The point of analysis for Drainage Area 2 is the rear property line that bypasses. The drainage areas include all areas of disturbance, as well as any other areas that drain to the point of analyses. DRAINAGE AREA 1 (DA-1) Drainage Area 1 consists of 4.68 acres of both pervious and impervious surfaces. The impervious area, 3.32 acres, consists of the existing parking lot and associated improvements. The pervious area, 0.27 acres, is comprised of landscaped and lawn areas that are in good condition. Two times of concentration have been calculated for this drainage area, one based on the current adjusted rainfall total and one for the future projected rainfall total. The times of concentration are 13.6 and 12.7 minutes, respectively. DRAINAGE AREA 2 (DA-2) Drainage Area 2 consists of 0.18 acres of both pervious and impervious surfaces. The impervious area, 0.04 acres, consists of walkways. The pervious area, 0.14 acres, is comprised of landscaped and lawn areas that are in good condition. Two times of concentration have been calculated for this drainage area, one based on the current adjusted rainfall total and one for the future projected rainfall total. The times of concentration are 11.8 and 10.9 minutes, respectively. CURVE NUMBERS The CN values used have been taken from the TR-55 Manual “Urban Hydrology for Small Watersheds,” Table 2-2a and Table 2-2c, based on land cover and hydrologic soil groups. Table 2 – Curve Number (Existing Conditions) Description Hydrologic Group Curve Number Landscaped Islands D 80 (Open Space-Good Conditions) Impervious D 98 PEAK FLOWS Using the information described above, the peak flows during the 2-, 10-, and 100-year storm events where calculated. Table 2 below summarizes the peak flows during

98 PEAK FLOWS Using the information described above, the peak flows during the 2-, 10-, and 100-year storm events where calculated. Table 2 below summarizes the peak flows during each 5