2026 02 12 Crestmont CC and Eagle Rock Ave Stormwater Management Report

PR-2C-UNDISTURBED WATERSHED

Project: Eagle Rock Avenue By: TEG Date: 10/21/2025 Location: West Orange, NJ Checked By: MJV Date Checked: 10/21/2025 Circle One: Present Developed Current Proposed Watershed PR-2C-U Impervious Circle One: Tc Tt through subarea Include a map, schematic, or description of flow segments. Sheet Flow (Applicable to Tc Only) Segment ID 1 Smooth Surfaces 1. Surface Description (NEH table 15-1) 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.011 3. Flow Length, L (total L < 100 ft) ft 89 4. Two-year 24-hr rainfall, P2 in 3.46 5. Land Slope, s ft/ft 0.089 6. Compute Tt 0.007 (nL)0.8 hr 0.010 + + Tt = P20.5s0.4 Sheet Flow Sub-Total 0.010 hours Shallow Concentrated Flow Segment ID 2 Pavement 7. Surface Description 8. Flow Length, L ft 29 9. Watercourse Slope, s ft/ft 0.010 10. Average Velocity, V (NEH table 15-3) ft/s 2.05 11. Compute Tt L hr 0.004 + + Tt = 3600 V

+ Tt = 3600 V Shallow Conc. Flow Sub-Total 0.004 hours Channel Flow Segment ID 3 4 5 12. Flow Length, L ft 157 36 139 13. Cross Sectional flow area, a ft2 0.61 0.61 0.61 14. Wetted Perimeter, Pw ft 2.00 2.00 2.00 15. Hydraulic Radius, r r = a / Pw ft 0.31 0.31 0.31 16. Channel Slope, s ft/ft 0.028 0.080 0.040 17. Manning's Roughness Coeff., n 0.012 0.012 0.012 18. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 9.34 15.91 11.25 19. Compute Tt L hr 0.005 + 0.001 + 0.003 Tt = 3600 V Channel Flow Sub-Total 0.009 hours Channel Flow Segment ID 6 7 8 20. Flow Length, L ft 79 54 195 21. Cross Sectional flow area, a ft2 0.61 0.61 0.88 22. Wetted Perimeter, Pw

ow area, a ft2 0.61 0.61 0.88 22. Wetted Perimeter, Pw ft 2.00 2.00 2.40 23. Hydraulic Radius, r r = a / Pw ft 0.31 0.31 0.37 24. Channel Slope, s ft/ft 0.020 0.015 0.013 25. Manning's Roughness Coeff., n 0.012 0.012 0.013 26. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 7.96 6.89 6.71 27. Compute Tt L hr 0.003 + 0.002 + 0.008 Tt = 3600 V Channel Flow Sub-Total 0.013 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.035 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 2 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Proposed Tc Calcs\Current Proposed TCs\Current Proposed TC PR-2C-U Impervious v1.2

Project: Eagle Rock Avenue By: TEG Date: 10/21/2025 Location: West Orange, NJ Checked By: MJV Date Checked: 10/21/2025 Circle One: Present Developed Current Proposed Watershed PR-2C-U Pervious Circle One: Tc Tt through subarea Include a map, schematic, or description of flow segments. Sheet Flow (Applicable to Tc Only) Segment ID 1 Woods Dense 1. Surface Description (NEH table 15-1) Underbrush 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.40 3. Flow Length, L (total L < 100 ft) ft 100 4. Two-year 24-hr rainfall, P2 in 3.46 5. Land Slope, s ft/ft 0.060 6. Compute Tt 0.007 (nL)0.8 hr 0.222 + + Tt = P20.5s0.4 Sheet Flow Sub-Total 0.222 hours Shallow Concentrated Flow Segment ID 2 3 4 Grassed Woodlands Pavement 7. Surface Description Waterways 8. Flow Length, L ft 155 68 15 9. Watercourse Slope, s

Waterways 8. Flow Length, L ft 155 68 15 9. Watercourse Slope, s ft/ft 0.049 0.055 0.055 10. Average Velocity, V (NEH table 15-3) ft/s 1.12 3.80 4.78 11. Compute Tt L hr 0.039 + 0.005 + 0.001 Tt = 3600 V Shallow Conc. Flow Sub-Total 0.044 hours Channel Flow Segment ID 5 6 12. Flow Length, L ft 10 125 13. Cross Sectional flow area, a ft2 0.61 0.61 14. Wetted Perimeter, Pw ft 1.96 1.96 15. Hydraulic Radius, r r = a / Pw ft 0.31 0.31 16. Channel Slope, s ft/ft 0.113 0.009 17. Manning's Roughness Coeff., n 0.013 0.013 18. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 17.69 5.11 19. Compute Tt L hr 0.000 + 0.007 + Tt = 3600 V Channel Flow Sub-Total 0.007 hours Watershed or subarea Tc or Tt Total Tc (hours)

Channel Flow Sub-Total 0.007 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.273 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 16 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Proposed Tc Calcs\Current Proposed TCs\Current Proposed TC PR-2C-U Pervious v1.2

Hydrograph Report File: Eagle Rock Proposed (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2C-U Open Space C Hyd. No. 63 Hydrograph Type = NRCS Runoff Peak Flow = 0.690 cfs Storm Frequency = 2-yr Time to Peak = 12.23 hrs Time Interval = 1 min Runoff Volume = 3,030 cuft Drainage Area = 0.68 ac Curve Number = 74.00 Tc Method = User Time of Conc. (Tc) = 16.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 0.690 cfs 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 Q (cfs) 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Time (hrs)

Hydrograph Report File: Eagle Rock Proposed (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2C-U Woods C Hyd. No. 64 Hydrograph Type = NRCS Runoff Peak Flow = 0.609 cfs Storm Frequency = 2-yr Time to Peak = 12.23 hrs Time Interval = 1 min Runoff Volume = 2,783 cuft Drainage Area = 0.77 ac Curve Number = 70.00 Tc Method = User Time of Conc. (Tc) = 16.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 0.609 cfs 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 Q (cfs) 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Time (hrs)

Hydrograph Report File: Eagle Rock Proposed (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2C-U Gravel C Hyd. No. 65 Hydrograph Type = NRCS Runoff Peak Flow = 0.223 cfs Storm Frequency = 2-yr Time to Peak = 12.10 hrs Time Interval = 1 min Runoff Volume = 632 cuft Drainage Area = 0.08 ac Curve Number = 89.00 Tc Method = User Time of Conc. (Tc) = 2.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 0.223 cfs 0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 Q (cfs) 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Time (hrs)