Question points$]$

A$.$ Evaluate the travel time associated with the $24-$in diameter, $300-ft$ long cast iron

pipe flowing just full and laid on a slope of $0\mathrm{.}004f\frac{t}{f}t.$

B$.$ A new $7-$acres suburban development is to be drained by a storm sewer that

connects to a municipal drainage system. The time of concentration for the basin

is $15$ minutes, and the local intensity$-$duration$-$frequency relationship can be

approximated as $(i=5\mathrm{.}6-0\mathrm{.}2t_d),$ where $t_d$ is rainfall duration in hours. Estimate the

peak runoff using the rational method. Make reasonable assumption for runoff

coefficient.

C$.$ Evaluate how peak flow changes if the development described in Question B

consists of two smaller subbasins: one has a drainage area of $5-$acres and a runoff

coefficient of $0\mathrm{.}4,$ while the other drains $2-$acres and has a runoff coefficient of

$0\mathrm{.}7.$ Compare the answer to that if the entire basin is characterized by a median

runoff coefficient of $0\mathrm{.}55.$