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

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-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 100 4. Two-year 24-hr rainfall, P2 in 3.46 5. Land Slope, s ft/ft 0.034 6. Compute Tt 0.007 (nL)0.8 hr 0.016 + + Tt = P20.5s0.4 Sheet Flow Sub-Total 0.016 hours Shallow Concentrated Flow Segment ID 2 Pavement 7. Surface Description 8. Flow Length, L ft 48 9. Watercourse Slope, s ft/ft 0.024 10. Average Velocity, V (NEH table 15-3) ft/s 3.16 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 65 110 66 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 0.026 0.005 0.070 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 9.11 3.98 14.89 19. Compute Tt L hr 0.002 + 0.008 + 0.001 Tt = 3600 V Channel Flow Sub-Total 0.011 hours Channel Flow Segment ID 6 20. Flow Length, L ft 96 21. Cross Sectional flow area, a ft2 0.61 22. Wetted Perimeter, Pw ft 2.00 23. Hydraulic Radius, r r = a / Pw ft 0.31 24. Channel

meter, Pw ft 2.00 23. Hydraulic Radius, r r = a / Pw ft 0.31 24. Channel Slope, s ft/ft 0.080 25. Manning's Roughness Coeff., n 0.012 26. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 15.91 27. Compute Tt L hr 0.002 + + Tt = 3600 V Channel Flow Sub-Total 0.002 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.032 hours (Add Sub-Total Tt from prior steps) Software Limitations Require Minimum Tc = 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-U Impervious v1.2