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-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 Woods Dense 1. Surface Description (NEH table 15-1) Underbrush 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.40 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 0.066 0.8 6. Compute Tt 0.007 (nL) hr 0.213 + + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.213 hours Shallow Concentrated Flow Segment ID 2 7. Surface Description Woodlands 8. Flow Length, L ft 100 9. Watercourse Slope, s ft/ft 0.081 10. Average Velocity, V (NEH table 15-3) ft/s 1.43 11. Compute Tt L hr 0.019 + +

ft/s 1.43 11. Compute Tt L hr 0.019 + + Tt = 3600 V Shallow Conc. Flow Sub-Total 0.019 hours Channel Flow Segment ID 3 4 12. Flow Length, L ft 191 125 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 0.013 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 6.14 5.13 19. Compute Tt L hr 0.009 + 0.007 + Tt = 3600 V Channel Flow Sub-Total 0.015 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.248 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 15 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site

steps) Total Tc (minutes) = 15 minutes \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Stormwater\Time of Concentration Calcs\Current Existing TC EX-2-D Pervious v1.2