12 2026 02 12 Crestmont CC 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-1C-U 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 Dense Grasses 1. Surface Description (NEH table 15-1) 2. Manning's Roughness Coeff., n (NEH table 15-1) 0.24 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 0.090 6. Compute Tt 0.007 (nL)0.8 hr 0.126 + + Tt = P20.5s0.4 Sheet Flow Sub-Total 0.126 hours Shallow Concentrated Flow Segment ID 2 3 4 Grassed Pavement Pavement 7. Surface Description Waterways 8. Flow Length, L ft 178 207 164 9. Watercourse Slope, s ft/ft 0.078 0.067

ft 178 207 164 9. Watercourse Slope, s ft/ft 0.078 0.067 0.016 10. Average Velocity, V (NEH table 15-3) ft/s 4.50 5.27 2.60 11. Compute Tt L hr 0.011 + 0.011 + 0.017 Tt = 3600 V Shallow Conc. Flow Sub-Total 0.039 hours Channel Flow Segment ID 5 6 12. Flow Length, L ft 36 67 13. Cross Sectional flow area, a ft2 0.88 0.88 14. Wetted Perimeter, Pw ft 2.40 2.40 15. Hydraulic Radius, r r = a / Pw ft 0.37 0.37 16. Channel Slope, s ft/ft 0.032 0.042 17. Manning's Roughness Coeff., n 0.013 0.013 18. Velocity, V V = (1.49 r2/3 s1/2 ) / n ft/s 10.43 11.98 19. Compute Tt L hr 0.001 + 0.002 + Tt = 3600 V Channel Flow Sub-Total 0.003 hours Watershed or subarea Tc or Tt Total Tc (hours) = 0.167 hours (Add Sub-Total Tt from prior steps)

Total Tc (hours) = 0.167 hours (Add Sub-Total Tt from prior steps) Total Tc (minutes) = 10 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-1C-U Pervious v1.2