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-2B-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 2 Dense Grasses Smooth Surfaces 1. Surface Description (NEH table 15-1) 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.24 0.011 3. Design Flow Length, Ldes (Total Ldes < 100 ft) ft 34 55 4. Two-year 24-hr rainfall, P2 in 3.46 3.46 5. Land Slope, s ft/ft 0.072 0.037 6. McCuen-Spiess Limit, Lmcs (max. 100 ft) Lmcs = (100 s0.5)/n ft 100 100 7. Compute Tt 0.007 (nLdes)0.8 hr 0.058 + 0.009 + Tt = 0.5 0.4 P2 s Sheet Flow Sub-Total 0.067 hours Shallow Concentrated Flow Segment ID 3 Pavement 8. Surface Description 9. Flow Length, L ft 41 10. Watercourse Slope, s ft/ft 0.020 11. Average Velocity, V (NEH table 15-3) ft/s 2.87 12. Compute Tt L

ft/ft 0.020 11. Average Velocity, V (NEH table 15-3) ft/s 2.87 12. Compute Tt L hr 0.004 + + Tt = 3600 V Shallow Conc. Flow Sub-Total 0.004 hours Channel Flow Segment ID 13. Flow Length, L ft 14. Cross Sectional flow area, a ft2 15. Wetted Perimeter, Pw ft 16. Hydraulic Radius, r r = a / Pw ft 17. Channel Slope, s ft/ft 18. Manning's Roughness Coeff., n 19. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 20. Compute Tt L hr + + Tt = 3600 V Channel Flow Sub-Total 0.000 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.071 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 4 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-2B-D Pervious v1.4