CE 4313: CE CAD---Exam 3 Notes

These are some supporting notes and calculations for the exam 3.

These are now in a spreadsheet: OOo xls.

• Assume each storm sewer branch collects from 400' laterally.
• The central branch has two sags
  • The further sag at 24+00 collects runoff from 39+00 - 17+00
    • 2200'x400' = 20.2 acres
    • average L ≈ 1500'
    • average slope ≈ 30/1500 = 2% ⇒ v= 1.0 ft/s
    • 
  • The nearer sag at 9+00 from 17+00 - 0+00
    • 15.6 acres
    • average L ≈ 800'
    • average slope ≈ 10/800 = 1.25% ⇒ v=0.7
    • 
• The western branch also has two sags
  • the further sag at 21+00 collects 24+00 - 18+00
    • 5.5 acres
    • average L ≈ 300'
    • average slope ≈ 1% ⇒ v=0.6
    • → Use 10
  • the near sag at 5+00 collects 18+00 - 0+00
    • 16.5 acres
    • average L ≈ 1600'
    • average slope ≈ 20/1600 = 1.25% ⇒ v=0.7
    • 
• The eastern branch has only one sag at 11+00
  • collects 24+00 - 0+00
    • 22.0 acres
    • average L ≈ 1200'
    • average slope ≈ 20/1200= 1.7% ⇒ v=0.8
    • 

c = 0.3

b₂₅ = 95 ; d₂₅ = 9.6 ; e₂₅ = 0.781

b₅₀ = 103 ; d₅₀ = 9.6 ; e₅₀ = 0.781

(in/hr)