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-1-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 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 85 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 0.013 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.013 hours Shallow Concentrated Flow Segment ID 2 3 7. Surface Description Woodlands Pavement 8. Flow Length, L ft 117 465 9. Watercourse Slope, s ft/ft 0.207 0.018 10. Average Velocity, V (NEH table 15-3) ft/s 2.29 2.75 11. Compute Tt L hr 0.014 +

ft/s 2.29 2.75 11. Compute Tt L hr 0.014 + 0.047 + Tt = 3600 V Shallow Conc. Flow Sub-Total 0.061 hours Channel Flow Segment ID 4 5 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) = 0.076 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 5 minutes \\langan.com\data\PAR\data8\101049801\Project

b-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-D Impervious v1.2