CTC 440 - Homework 15 (Hydraulic Radius/Size Pipe)

1. Determine by hand (using the attached Table) the hydraulic radius of a pipe (24” in diameter) flowing:

· 1/4 full

· half full

· 3/4 full

· almost completely full (but not under pressure)

Check your answers by using “Flowmaster”. Print out the results.

2. Given:

· 32l-acre watershed

· Time of concentration = 40 minutes

· Single family residential neighborhood near Stewart Airport (see IDF Curve here)

· Round concrete pipe

· 2% pipe slope

Size the pipe for a 25-year storm and check the approximate velocity. (Note: Although the drainage area is greater than 200 acres use the rational formula to determine the peak flow).

3. Read the following article: Lessons From Katrina, Todd Litman (Draft) 2005