Report 4 13 2026

Runoff Depth=11.28" 2 Tc=5.0 min CN=98 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours)

​ENSURPLAN, INC.​ ​ ww.Ensurplan.​​net​ w ​ ivil Engineers & Land Surveyors C Ph: (732) 469-0400​ ​Certificate of Authorization 24GA27997700​ ​STORMWATER DRAINAGE REPORT​ ​04/13/26​ ​Minor Subdivision 15 Ridgeway Ave West Orange, NJ​ ​Routed Hydrographs and Pond Information​ ​37​ ​Mailing Address: Post Office Box 4304, Warren, NJ 07059​

29906 15 Ridgeway West Orange Final NOAA 24-hr D 2-Year-2020 Rainfall=3.47", P2=3.47" Prepared by Ensurplan Inc Printed 4/20/2026 HydroCAD® 10.20-8a s/n 11646 © 2025 HydroCAD Software Solutions LLC Page 38 Summary for Pond 12P: Infiltration basin Inflow Area = 0.381 ac,100.00% Impervious, Inflow Depth = 3.24" for 2-Year-2020 event Inflow = 1.30 cfs @ 12.12 hrs, Volume= 0.103 af Outflow = 0.21 cfs @ 12.57 hrs, Volume= 0.103 af, Atten= 84%, Lag= 27.1 min Discarded = 0.03 cfs @ 12.57 hrs, Volume= 0.033 af Primary = 0.18 cfs @ 12.57 hrs, Volume= 0.070 af Routed to Reach 12R : Study Point At Inlet Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 564.32' @ 12.57 hrs Surf.Area= 1,600 sf Storage= 1,378 cf Plug-Flow detention time= 59.4 min calculated for 0.103 af (100% of inflow) Center-of-Mass det. time= 59.4 min ( 815.0 - 755.6 ) Volume Invert Avail.Storage Storage Description #1A 563.00' 1,582 cf 12.75'W x 125.50'L x 4.00'H Field A 6,401 cf Overall - 2,444 cf Embedded = 3,956 cf x 40.0% Voids #2A 563.50' 2,444 cf Cultec R-360HD x 66 Inside #1 Effective Size= 54.9"W x 36.0"H => 9.99 sf x 3.67'L = 36.6 cf Overall Size= 60.0"W x 36.0"H x 4.17'L with 0.50' Overlap 66 Chambers in 2 Rows Cap Storage= 6.5 cf x 2 x 2 rows = 25.8 cf 4,027 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 563.00' 0.500 in/hr Exfiltration over Horizontal area Conductivity to Groundwater Elevation = 560.30' #2 Primary 563.00' 2.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 564.40' 6.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 565.10' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary

0' 6.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 565.10' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 566.95' 4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.03 cfs @ 12.57 hrs HW=564.32' (Free Discharge) 1=Exfiltration ( Controls 0.03 cfs) Primary OutFlow Max=0.18 cfs @ 12.57 hrs HW=564.32' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.18 cfs @ 5.31 fps) 3=Orifice/Grate ( Controls 0.00 cfs) 4=Orifice/Grate ( Controls 0.00 cfs) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

29906 15 Ridgeway West Orange Final NOAA 24-hr D 2-Year-2020 Rainfall=3.47", P2=3.47" Prepared by Ensurplan Inc Printed 4/20/2026 HydroCAD® 10.20-8a s/n 11646 © 2025 HydroCAD Software Solutions LLC Page 39 Pond 12P: Infiltration basin Hydrograph 1.30 cfs Inflow Outflow Inflow Area=0.381 ac Discarded Primary Peak Elev=564.32' Storage=1,378 cf 1 Flow (cfs) 0.21 cfs 0.18 cfs 0.03 cfs 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours)

29906 15 Ridgeway West Orange Final NOAA 24-hr D 10-Year-2020 Rainfall=5.38", P2=3.47" Prepared by Ensurplan Inc Printed 4/20/2026 HydroCAD® 10.20-8a s/n 11646 © 2025 HydroCAD Software Solutions LLC Page 40 Summary for Pond 12P: Infiltration basin Inflow Area = 0.381 ac,100.00% Impervious, Inflow Depth = 5.14" for 10-Year-2020 event Inflow = 2.03 cfs @ 12.12 hrs, Volume= 0.163 af Outflow = 0.67 cfs @ 12.27 hrs, Volume= 0.163 af, Atten= 67%, Lag= 9.2 min Discarded = 0.03 cfs @ 12.27 hrs, Volume= 0.039 af Primary = 0.64 cfs @ 12.27 hrs, Volume= 0.125 af Routed to Reach 12R : Study Point At Inlet Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 564.85' @ 12.27 hrs Surf.Area= 1,600 sf Storage= 2,029 cf Plug-Flow detention time= 60.9 min calculated for 0.163 af (100% of inflow) Center-of-Mass det. time= 60.9 min ( 808.0 - 747.1 ) Volume Invert Avail.Storage Storage Description #1A 563.00' 1,582 cf 12.75'W x 125.50'L x 4.00'H Field A 6,401 cf Overall - 2,444 cf Embedded = 3,956 cf x 40.0% Voids #2A 563.50' 2,444 cf Cultec R-360HD x 66 Inside #1 Effective Size= 54.9"W x 36.0"H => 9.99 sf x 3.67'L = 36.6 cf Overall Size= 60.0"W x 36.0"H x 4.17'L with 0.50' Overlap 66 Chambers in 2 Rows Cap Storage= 6.5 cf x 2 x 2 rows = 25.8 cf 4,027 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 563.00' 0.500 in/hr Exfiltration over Horizontal area Conductivity to Groundwater Elevation = 560.30' #2 Primary 563.00' 2.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 564.40' 6.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 565.10' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 566.95'

Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 565.10' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 566.95' 4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.03 cfs @ 12.27 hrs HW=564.85' (Free Discharge) 1=Exfiltration ( Controls 0.03 cfs) Primary OutFlow Max=0.64 cfs @ 12.27 hrs HW=564.85' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.22 cfs @ 6.36 fps) 3=Orifice/Grate (Orifice Controls 0.42 cfs @ 2.28 fps) 4=Orifice/Grate ( Controls 0.00 cfs) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

29906 15 Ridgeway West Orange Final NOAA 24-hr D 10-Year-2020 Rainfall=5.38", P2=3.47" Prepared by Ensurplan Inc Printed 4/20/2026 HydroCAD® 10.20-8a s/n 11646 © 2025 HydroCAD Software Solutions LLC Page 41 Pond 12P: Infiltration basin Hydrograph 2.03 cfs Inflow Outflow Inflow Area=0.381 ac Discarded Primary 2 Peak Elev=564.85' Storage=2,029 cf Flow (cfs) 1 0.67 cfs 0.64 cfs 0.03 cfs 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours)

29906 15 Ridgeway West Orange Fina NOAA 24-hr D 100-Year-2020 Rainfall=9.18", P2=3.47" Prepared by Ensurplan Inc Printed 4/20/2026 HydroCAD® 10.20-8a s/n 11646 © 2025 HydroCAD Software Solutions LLC Page 42 Summary for Pond 12P: Infiltration basin Inflow Area = 0.381 ac,100.00% Impervious, Inflow Depth = 8.94" for 100-Year-2020 event Inflow = 3.47 cfs @ 12.12 hrs, Volume= 0.284 af Outflow = 1.78 cfs @ 12.20 hrs, Volume= 0.284 af, Atten= 49%, Lag= 4.8 min Discarded = 0.04 cfs @ 12.20 hrs, Volume= 0.043 af Primary = 1.74 cfs @ 12.20 hrs, Volume= 0.241 af Routed to Reach 12R : Study Point At Inlet Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 565.80' @ 12.20 hrs Surf.Area= 1,600 sf Storage= 3,105 cf Plug-Flow detention time= 55.2 min calculated for 0.284 af (100% of inflow) Center-of-Mass det. time= 55.2 min ( 794.6 - 739.4 ) Volume Invert Avail.Storage Storage Description #1A 563.00' 1,582 cf 12.75'W x 125.50'L x 4.00'H Field A 6,401 cf Overall - 2,444 cf Embedded = 3,956 cf x 40.0% Voids #2A 563.50' 2,444 cf Cultec R-360HD x 66 Inside #1 Effective Size= 54.9"W x 36.0"H => 9.99 sf x 3.67'L = 36.6 cf Overall Size= 60.0"W x 36.0"H x 4.17'L with 0.50' Overlap 66 Chambers in 2 Rows Cap Storage= 6.5 cf x 2 x 2 rows = 25.8 cf 4,027 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 563.00' 0.500 in/hr Exfiltration over Horizontal area Conductivity to Groundwater Elevation = 560.30' #2 Primary 563.00' 2.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 564.40' 6.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 565.10' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 566.95'

Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 565.10' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 566.95' 4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.04 cfs @ 12.20 hrs HW=565.80' (Free Discharge) 1=Exfiltration ( Controls 0.04 cfs) Primary OutFlow Max=1.74 cfs @ 12.20 hrs HW=565.80' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.27 cfs @ 7.91 fps) 3=Orifice/Grate (Orifice Controls 1.01 cfs @ 5.16 fps) 4=Orifice/Grate (Orifice Controls 0.46 cfs @ 3.38 fps) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)