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

CURRENT HYDROGRAPH CALCULATIONS

PR-1A-DISTURBED 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-1A-D - 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. Design Flow Length, Ldes (Total Ldes < 100 ft) ft 85 4. Two-year 24-hr rainfall, P2 in 3.46 5. Land Slope, s ft/ft 0.034 6. McCuen-Spiess Limit, Lmcs (max. 100 ft) Lmcs = (100 s0.5)/n ft 100 7. Compute Tt 0.007 (nLdes)0.8 hr 0.014 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.014 hours Shallow Concentrated Flow Segment ID 2 Pavement 8. Surface Description 9. Flow Length, L ft 105 10. Watercourse Slope, s ft/ft 0.008 11. Average Velocity, V (NEH table 15-3) ft/s 1.86 12. Compute Tt L hr 0.016 + + Tt =

L hr 0.016 + + Tt = 3600 V Shallow Conc. Flow Sub-Total 0.016 hours Channel Flow Segment ID 3 4 5 13. Flow Length, L ft 30 66 96 14. Cross Sectional flow area, a ft2 0.61 0.61 0.61 15. Wetted Perimeter, Pw ft 2.00 2.00 2.00 16. Hydraulic Radius, r r = a / Pw ft 0.31 0.31 0.31 17. Channel Slope, s ft/ft 0.005 0.070 0.080 18. Manning's Roughness Coeff., n 0.012 0.012 0.012 19. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 3.98 14.89 15.91 20. Compute Tt L hr 0.002 + 0.001 + 0.002 Tt = 3600 V Channel Flow Sub-Total 0.005 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.034 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

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-1A-D Impervious v1.4

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-1A-D - 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 Dense Grasses 1. Surface Description (NEH table 15-1) 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.24 3. Design Flow Length, Ldes (Total Ldes < 100 ft) ft 100 4. Two-year 24-hr rainfall, P2 in 3.46 5. Land Slope, s ft/ft 0.095 6. McCuen-Spiess Limit, Lmcs (max. 100 ft) Lmcs = (100 s0.5)/n ft 100 7. Compute Tt 0.007 (nLdes)0.8 hr 0.123 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.123 hours Shallow Concentrated Flow Segment ID 2 Grassed 8. Surface Description Waterways 9. Flow Length, L ft 105 10. Watercourse Slope, s ft/ft 0.213 11. Average Velocity, V (NEH table 15-3) ft/s 7.45 12. Compute Tt L hr

.213 11. Average Velocity, V (NEH table 15-3) ft/s 7.45 12. Compute Tt L hr 0.004 + + Tt = 3600 V Shallow Conc. Flow Sub-Total 0.004 hours Channel Flow Segment ID 13. Flow Length, L ft 14. Cross Sectional flow area, a ft2 15. Wetted Perimeter, Pw ft 16. Hydraulic Radius, r r = a / Pw ft 17. Channel Slope, s ft/ft 18. Manning's Roughness Coeff., n 19. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 20. Compute Tt L hr + + Tt = 3600 V Channel Flow Sub-Total 0.000 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.127 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 8 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-1A-D Pervious v1.4

Hydrograph Report File: Eagle Rock Proposed (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-1A-D Grass D Hyd. No. 1 Hydrograph Type = NRCS Runoff Peak Flow = 0.575 cfs Storm Frequency = 2-yr Time to Peak = 12.13 hrs Time Interval = 1 min Runoff Volume = 1,874 cuft Drainage Area = 0.33 ac Curve Number = 80.00 Tc Method = User Time of Conc. (Tc) = 8.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 0.575 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-1A-D Imp Hyd. No. 2 Hydrograph Type = NRCS Runoff Peak Flow = 1.082 cfs Storm Frequency = 2-yr Time to Peak = 12.10 hrs Time Interval = 1 min Runoff Volume = 3,514 cuft Drainage Area = 0.32 ac Curve Number = 98.00 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 = 1.082 cfs 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 Q (cfs) 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 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-1A-D Hyd. No. 3 Hydrograph Type = Junction Peak Flow = 1.622 cfs Storm Frequency = 2-yr Time to Peak = 12.10 hrs Time Interval = 1 min Hydrograph Volume = 5,388 cuft Inflow Hydrographs = 1, 2 Total Contrib. Area = 0.65 ac Qp = 1.622 cfs 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 Q (cfs) 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 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) PR-1A-D Grass D PR-1A-D Imp PR-1A-D