A$)$ Design a longitudinal$-$serpentine contact chamber for a conventional filtration plant with a design

flow of $25,000\frac{m^3}{d}$ and a residual chlorine concentration of $2m\frac{g}{L}.$ Assume that the raw water

microorganism concentration is between $1$ and $10/100$L and there is no evidence of cryptosporidium

oocysts. Design criterion is a performance of $\frac{t_{10}}{t_0}=0\mathrm{.}8.$ Use $H=3W$ for the depth of water

estimate.

B$)$ Now, assume that the chlorine contact chamber is followed by a distribution pipe that can serve

as a contact chamber. It is a straight pipe, $500mm$ in diameter, and it has no service connections

for $1\mathrm{.}5km.$ Assume $\frac{t_{10}}{t_0}=1\mathrm{.}0$ for the pipe. Redesign the contact chamber, considering the contact

time provided by the pipe. Compare the basin footprint to the design for part A$.$