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

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-2-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 0.043 0.8 6. Compute Tt 0.007 (nL) hr 0.014 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.014 hours Shallow Concentrated Flow Segment ID 2 3 4 7. Surface Description Pavement Woodlands Pavement 8. Flow Length, L ft 340 109 187 9. Watercourse Slope, s ft/ft 0.074 0.058 0.048 10. Average Velocity, V (NEH table 15-3) ft/s 5.54 1.21

0.074 0.058 0.048 10. Average Velocity, V (NEH table 15-3) ft/s 5.54 1.21 4.47 11. Compute Tt L hr 0.017 + 0.025 + 0.012 Tt = 3600 V Shallow Conc. Flow Sub-Total 0.054 hours Channel Flow Segment ID 5 6 12. Flow Length, L ft 56 125 2 13. Cross Sectional flow area, a ft 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 0.027 0.009 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 8.67 5.13 19. Compute Tt L hr 0.002 + 0.007 + Tt = 3600 V Channel Flow Sub-Total 0.009 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.077 hours (Add Sub-Total Tt from prior steps)

Total Tc (hours) = 0.077 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-2-U Impervious v1.2