J_2024 05 09_West Orange Stormwater Management Plan

Stormwater Management Plan Revision 0 Hydrology and Hydraulics The post-developed peak runoff rates for watershed PO-DA N, which drains to an existing inlet manhole similar to watershed PO-DA 1, thus providing no adverse impact to Outfall O-2. The HydroCAD calculations show the post-construction runoff hydrographs for the current and projected 2-, 10-, and 100year storm events, do not exceed, at any point in time, the pre-construction runoff hydrographs through hydrologic and hydraulic analysis for stormwater leaving the site, for the same storm events. This is summarized in Table 2.7 below. The bioretention basins with underdrains will provide runoff quantity control in accordance with N.J.A.C. 7:8-5.6. This regulation requires the peak post developed runoff rates to not exceed the peak preconstruction runoff rates for 50% of the 2-year, 75% of the 10-year, and 80% of the 100-year storm events. Table 2.7 below summarizes the stormwater flow conditions for the project. Both the Current and Future Precipitation Change Factors for Essex County have been considered as per the July 2023 N.J.A.C. 7:8 updates and section . Table 2.6: Site Flow Results Pre Q(2-YR) Current (cfs) 4.09 3.34<4.09 OK 1.59 Q(2-YR) Future (cfs) 5.27 4.32<5.27 OK 2.25 Q(10-YR) Current (cfs) 7.37 6.09<7.37 OK 3.53 Q(10-YR) Future (cfs) 9.33 7.73<9.33 OK 4.74 Q(100-YR) Current (cfs) 14.11 11.79<14.11 OK 7.72 Q(100-YR) Future (cfs) 18.67 15.60<18.67 OK 10.46 Post 1.59 2.25 3.53 4.74 7.72 10.46 Pre 2.66*50% = 1.33 3.49*50% = 1.75 5.20*75% = 3.90 6.61*75% = 4.96 10.52*80% = 8.42 13.89*80% = 11.11 Post 0.87<1.33 OK 1.04<1.75 OK 1.31<3.90 OK 1.81<4.96 OK 3.61<8.42 OK 5.00<11.11 OK Outfall Discharge Point O-AquaShield (PO-DA 6 / A, DA 8 / M) O-1A (PO-DA K, noncontributory areas (L, H, F, D, B)) O-1Bb (bioretention areas totals (PODA 6 / C, 7 / E, G, J, I)) Pre Post 2.45 3.19 4.81 6.07 9.80 12.86 2.06<2.45 2.75<3.19 4.02<4.81 5.21<6.07 8.18<9.80 11.03<12.86 Post OK OK OK OK OK OK b N.J.A.C. 7:8-5.6 requires post-construction peak runoff rates for the 2-, 10-, and 100-year storm events to be 50%, 75%, and 80%, respectively, of the pre-construction peak runoff rates. O-2 (PO-DA 1 / N) Pre Public Service Electric & Gas Company 2-7 Burns & McDonnell

Stormwater Management Plan 2.5 Revision 0 Hydrology and Hydraulics Other Stormwater Conveyance Table 2.8 summarizes the results for the proposed subsurface pipe network, conveying flow for the newly developed areas from the bioretention basins and non-contributory trench drains to the project outfall. Storm drainage piping was designed to accommodate the 25-year storm as required by PSE&G. The subsurface conveyance calculations were conducted using CivilStorm software. Refer to Appendix C for the calculations. Table 2.7: Stormwater Conveyance Results Pipe 25 Year Flow (cfs) SD-01 SD-02 SD-03 SD-04 SD-05 SD-06 SD-07 SD-08 SD-09 SD-10 SD-11 SD-12 SD-21 SD-22 SD-23 SD-24 SD-25 SD-26 5.75 5.75 1.40 7.15 7.15 0.83 7.98 8.22 2.20 10.42 1.75 12.17 5.07 7.85 9.18 10.20 11.42 11.42 Public Service Electric & Gas Company Pipe Length (ft) 31.63 78.00 5.00 19.06 38.91 5.00 18.81 135.70 5.00 83.62 5.00 158.11 64.50 127.26 93.73 111.26 262.39 29.44 Diameter (in) Slope (%) 12” dia. 12” dia. 12” dia. 12” dia. 18” dia. 12” dia. 18” dia. 18” dia. 12” dia. 18” dia. 12” dia. 18” dia. 12” dia. 12” dia. 15” dia. 15” dia. 15” dia. 18” dia. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.50 1.50 1.50 1.50 1.50 1.50 2-8 25 Year Velocity (ft/s) 7.32 7.32 4.27 9.10 9.10 3.70 6.57 6.56 4.77 5.90 4.52 6.89 6.46 9.99 11.69 12.99 14.54 14.54 Full Flow Capacity (cfs) 3.58 3.54 3.56 3.56 3.57 3.56 10.56 10.48 3.56 10.53 3.56 10.50 4.37 4.36 4.35 4.36 4.37 4.36 Burns & McDonnell

Stormwater Management Plan 3.0 3.1 Revision 0 Best Management Practices BEST MANAGEMENT PRACTICES NJDEP’s Low Impact Development Checklist NJDEP requires the identification of the nonstructural stormwater management strategies that are incorporated into the design of the project and provides several nonstructural strategies as follows: 1. Protect areas that provide water quality benefits or areas particularly susceptible to erosion and sediment loss; The station improvements will install new stormwater management facilities to mitigate the increase in runoff from the site and enhance water quality. There will be no exposed areas of soil and no areas susceptible to erosion and sediment loss. Additionally, retaining walls are to be installed to stabilize areas where steep slopes would otherwise be encountered. 2. Minimize impervious surfaces and break up or disconnect the flow of runoff over impervious surfaces; The areas of new impervious surface have been minimized to only what is necessary for the station expansion. New impervious surfaces consist primarily of gravel to surround the proposed electrical equipment and associated structures. 3. Maximize the protection of natural drainage features and vegetation; Existing vegetation will only be disturbed to the maximum extent necessary to complete construction. 4. Minimize the decrease in the pre-construction time of concentration; Due to station safety requirements, the land coverage cannot be altered to increase the time of concentration post-construction. 5. Minimize land disturbance including clearing and grading; Extents of construction and grading are limited to requirements for the station expansion, driving paths, and stormwater management and conveyance structures. 6. Minimize soil compaction; Low pressure construction equipment will be used wherever possible to minimize soil compaction where minimum compaction limits are not required. Public Service Electric & Gas Company 3-1 Prior to the Burns & McDonnell

Stormwater Management Plan Revision 0 Best Management Practices restoration and establishment of vegetated areas, the soil will be mechanically loosened to provide proper aeration and drainage through the topsoil and underlying soil layers. 7. Provide low maintenance landscaping that encourages retention and planting of native vegetation and minimizes the use of lawns, fertilizers, and pesticides. Landscaping installed at the site will not be used for stormwater purposes. 8. Provide vegetated open-channel conveyance systems discharge into and through stable vegetated areas; N/A – Due to the industrial nature of the site and station safety requirements, open channel conveyance systems cannot be installed on site. 9. Provide preventative source controls; Pollution source control measures, other than soil sediment control measures, have not been provided due to the nature of the proposed project. The station will not generate any pollution in the form of trash, debris, garbage and pet waste. Public Service Electric & Gas Company 3-2 Burns & McDonnell

Stormwater Management Plan 4.0 Revision 0 Soil Erosion and Sediment Control Measures SOIL EROSION AND SEDIMENT CONTROL MEASURES A soil erosion and sediment control plan and associated details have been developed to control sediment during construction activities. Silt sock and/or silt fence will be installed around the perimeter of the areas to be disturbed prior to beginning construction. Newly graded areas will be stabilized with erosion control blanket during construction and the project entrance will be stabilized with 1.5” to 2.5” stone tracking pads. Filter protection will be provided at existing and proposed inlets as indicated on the soil erosion control drawings to minimize sediment from entering the subsurface storm drainage system. Upon completion of earthwork activities, the station yard within the fenced area will be rocked with a sacrificial rock working surface to temporarily stabilize the site. Public Service Electric & Gas Company 4-1 Burns & McDonnell

Stormwater Management Plan Revision 0 5.0 Conclusions CONCLUSIONS N.J.A.C. 7:8 defines a Major Development as any development that disturbs an acre of land or greater since February 2004, provides an additional quarter acre of impervious area since February 2, 2004, adds one quarter acre of regulated motor vehicle surface since March 2, 2021, or a quarter acre consisting of a combination of impervious and regulated motor vehicle surfaces. As this project disturbs more than one acre, it is classified as a Major Development. However, it does not add an additional 0.25 acres to vehicular traffic and is located within an urban redevelopment area, thus the project is not required to treat water quality or provide groundwater recharge. However, because bioretention basins are implemented for the station expansion areas, water quality will be improved by reducing the average annual total suspended solids load in the runoff. The bioretention basin system with underdrains will address the stormwater quantity requirements, ultimately reducing the combined system outfalls, into the existing municipal storm drain infrastructure, located along Mount Pleasant Avenue. There will be no adverse impact to the public or private lands adjacent to the site. Temporary on-site erosion control measures have been designed in accordance with the New Jersey Department of Environmental Protection’s standards set forth in the New Jersey Stormwater BMP Manual and the New Jersey Department of Agriculture’s Standards for Soil Erosion and Sediment Control. Public Service Electric & Gas Company 5-1 Burns & McDonnell

EXHIBIT A - PRE-DEVELOPED WATERSHED PLAN

1 2 3 5 4 6 7 8 9 10 11 12 13 14 no. LEGEND date by ckd description A 05/07/24 SJM MJB ISSUED FOR REVIEW BASIN DELINEATION TIME OF CONCENTRATION NON-CONTRIBUTORY AREAS A County 20' 40' Road 5 0 80' 77 SCALE IN FEET B C R=544.44 L=154.39 =15°40'20" CH=S21°22'54"W 153.91 Millimeters PO-DA 6 2.93 AC CN=82 D Scale For Microfilming E F G PO-DA 7 2.33 AC CN=81 County Road 57 7 Inches PO-DA 8 0.44 AC CN=94 9400 WARD PARKWAY KANSAS CITY, MO 64114 816-333-9400 date detailed S. MACALUSO COPYRIGHT © 2024 BURNS & McDONNELL ENGINEERING COMPANY, INC. 3/22/24 PO-DA 1 1.21 AC CN=80 H designed S. MACALUSO checked M. BLAKE WEST ORANGE SWITCHING STATION 230/26/4KV OUTDOOR SUBSTATION I PRE-DEVELOPED WATERSHED MAP WEST ORANGE, NJ J State Highway Rt. 10 project contract 144507 drawing rev. EXHIBIT A MICHAEL J. BLAKE LIC NO. 24GE05521600 COA NO. 24GA28066400 sheet file of A sheets

EXHIBIT B - POST-DEVELOPED WATERSHED PLAN

1 2 3 5 4 6 7 8 9 10 11 12 13 14 no. LEGEND date by ckd description A 05/07/24 SJM MJB ISSUED FOR REVIEW 149.3' BASIN DELINEATION TIME OF CONCENTRATION NON-CONTRIBUTORY AREAS A County 20' 40' Road 5 0 80' 77 SCALE IN FEET B PO-DA A 1.84 AC CN=83 C UD PO-DA B 0.66 AC CN=74 D Millimeters UD Scale For Microfilming UD PO-DA C 0.57 AC CN=87 E H0 H3 H2 H1 PO-DA D 0.15 AC CN=77 Inches UD PO-DA M 0.48 AC CN=95 PO-DA E 0.35 AC CN=88 County Road 57 9400 WARD PARKWAY KANSAS CITY, MO 64114 816-333-9400 PO-DA H 0.24 AC CN=73 PO-DA J 0.32 AC CN=89 311.2' 285.9' UD UD COPYRIGHT © 2024 BURNS & McDONNELL ENGINEERING COMPANY, INC. G 7 UD PO-DA F 0.09 AC CN=75 PO-DA G 0.39 AC CN=88 PO-DA N 1.32 AC CN=81 F date detailed S. MACALUSO 3/22/24 designed S. MACALUSO PO-DA I 0.24 AC CN=88 PO-DA L 0.18 AC CN=74 H checked M. BLAKE WEST ORANGE SWITCHING STATION 230/26/4KV OUTDOOR SUBSTATION UD I POST-DEVELOPED WATERSHED MAP UD WEST ORANGE, NJ State Highway Rt. 10 J PO-DA K 0.10 AC CN=82 project contract 144507 drawing rev. EXHIBIT B MICHAEL J. BLAKE LIC NO. 24GE05521600 COA NO. 24GA28066400 sheet file of A sheets