DRAINAGE 107 



Number of acres drained by open ditches. 



Depth of water 7 feet. Depth of ditch at least 9 feet. 



Grade 



Average width of water 



QUESTIONS 



1. When may it be necessary to use open ditches as drains? 



2. What are some of the disadvantages of open ditches or drains? 



3. What slope is usually given the sides of open ditches? 



4. What is the "waste bank"? The "berm"? 



5. How much does the digging of open ditches cost per cubic yard? 



6. What factors influence the capacity of open ditches? 



7. What formula is generally used in computing the capacity of 

 open ditches? 



