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

EX-1-UNDISTURBED WATERSHED

Project: Eagle Rock Avenue By: TEG Date: 10/20/2025 Location: West Orange, NJ Checked By: MJV Date Checked: 10/20/2025 Circle One: Present Developed Current Existing Watershed EX-1-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 1. Surface Description (NEH table 15-1) Smooth Surfaces 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.011 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 0.051 0.8 6. Compute Tt 0.007 (nL) hr 0.013 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.013 hours Shallow Concentrated Flow Segment ID 2 3 4 7. Surface Description Pavement Woodlands Pavement 8. Flow Length, L ft 239 117 463 9. Watercourse Slope, s ft/ft 0.048 0.207 0.018 10. Average Velocity, V (NEH table 15-3) ft/s 4.48 2.29

0.048 0.207 0.018 10. Average Velocity, V (NEH table 15-3) ft/s 4.48 2.29 2.75 11. Compute Tt L hr 0.015 + 0.014 + 0.047 Tt = 3600 V Shallow Conc. Flow Sub-Total 0.076 hours Channel Flow Segment ID 5 6 12. Flow Length, L ft 15 51 2 13. Cross Sectional flow area, a ft 0.61 0.61 14. Wetted Perimeter, Pw ft 2.00 2.00 15. Hydraulic Radius, r r = a / Pw ft 0.31 0.31 16. Channel Slope, s ft/ft 0.055 0.021 17. Manning's Roughness Coeff., n 0.013 0.013 2/3 1/2 18. Velocity, V V = (1.49 r s ) / n ft/s 12.14 7.59 19. Compute Tt L hr 0.000 + 0.002 + Tt = 3600 V Channel Flow Sub-Total 0.002 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.091 hours (Add Sub-Total Tt from prior steps)

Total Tc (hours) = 0.091 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 5 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Current Existing TC EX-1-U Impervious v1.2

Project: Eagle Rock Avenue By: TEG Date: 10/20/2025 Location: West Orange, NJ Checked By: MJV Date Checked: 10/20/2025 Circle One: Present Developed Current Existing Watershed EX-1-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 2 Woods Dense Woods Dense 1. Surface Description (NEH table 15-1) Underbrush Underbrush 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.40 0.40 3. Flow Length, L (total L < 100 ft) ft 40 60 4. Two-year 24-hr rainfall, P2 in 3.46 3.46 5. Land Slope, s ft/ft 0.094 0.305 0.8 6. Compute Tt 0.007 (nL) hr 0.089 + 0.077 + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.166 hours Shallow Concentrated Flow Segment ID 3 4 Grassed 7. Surface Description Pavement Waterways 8. Flow

Pavement Waterways 8. Flow Length, L ft 13 406 9. Watercourse Slope, s ft/ft 0.182 0.020 10. Average Velocity, V (NEH table 15-3) ft/s 6.89 2.87 11. Compute Tt L hr 0.001 + 0.039 + Tt = 3600 V Shallow Conc. Flow Sub-Total 0.040 hours Channel Flow Segment ID 5 6 12. Flow Length, L ft 15 51 2 13. Cross Sectional flow area, a ft 0.61 0.61 14. Wetted Perimeter, Pw ft 2.00 2.00 15. Hydraulic Radius, r r = a / Pw ft 0.31 0.31 16. Channel Slope, s ft/ft 0.055 0.021 17. Manning's Roughness Coeff., n 0.013 0.013 2/3 1/2 18. Velocity, V V = (1.49 r s ) / n ft/s 12.14 7.59 19. Compute Tt L hr 0.000 + 0.002 + Tt = 3600 V

hr 0.000 + 0.002 + Tt = 3600 V Channel Flow Sub-Total 0.002 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.208 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 12 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Current Existing TC EX-1-U Pervious v1.2

Hydrograph Report File: Eagle Rock Existing (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 EX-1-U Open Space C Hyd. No. 13 Hydrograph Type = NRCS Runoff Peak Flow = 1.491 cfs Storm Frequency = 2-yr Time to Peak = 12.18 hrs Time Interval = 1 min Runoff Volume = 5,892 cuft Drainage Area = 1.36 ac Curve Number = 74.00 Tc Method = User Time of Conc. (Tc) = 12.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 1.491 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 Existing (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 EX-1-U Woods C Hyd. No. 14 Hydrograph Type = NRCS Runoff Peak Flow = 0.600 cfs Storm Frequency = 2-yr Time to Peak = 12.20 hrs Time Interval = 1 min Runoff Volume = 2,460 cuft Drainage Area = 0.7 ac Curve Number = 70.00 Tc Method = User Time of Conc. (Tc) = 12.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 0.600 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 Existing (Current).hys Hydrology Studio v 3.0.0.39 10-21-2025 EX-1-U Impervious Hyd. No. 15 Hydrograph Type = NRCS Runoff Peak Flow = 9.916 cfs Storm Frequency = 2-yr Time to Peak = 12.12 hrs Time Interval = 1 min Runoff Volume = 35,511 cuft Drainage Area = 2.94 ac Curve Number = 98.00 Tc Method = User Time of Conc. (Tc) = 5.0 min Total Rainfall = 3.46 in Design Storm = NOAA-D Storm Duration = 24 hrs Shape Factor = 484 Qp = 9.916 cfs 11 10 9 8 7 6 Q (cfs) 5 4 3 2 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)