QUESTION $1$

A $1\mathrm{.}88m{i}^2$ service area within a municipal wastewater collection system is currently served by a lift station. Right$-$of$-$way and easement have been obtained by the municipality to construct gravity interceptor sewer to collect the wastewater from the service area and abandon the lift station. The service area is completely developed and has an average population density of $10.$ persons per acre. The terrain in the right$-$of$-$way and easement provides for a minimum sewer slope of $0\mathrm{.}25$ feet per $100$ feet. The inflow and infiltration for the area can be estimated at $650$ gallons per day per acre of service area. The peak flow can be estimated using Curve G from the Sewage Flow Ratio Curves published in Design and Construction of Sanitary and Storm Sewers by the American Society of Civil Engineers and the average flow is $100$ gallons per capita per day. The minimum size of plastic pipe in inches needed for the interceptor is most nearly:

a$)$

$12$

b$)$

$15$

c$)$

$18$

d$)$

$21$

Instructions:

Calculate the population

Determine the average flow rate

Calculate the peaking factor,

$F_P=\frac{18+\sqrt[\phantom{2}]{P_1}}{4+\sqrt[\phantom{2}]{P_1}}$

determine the Peak flow

calculate the allowance for inflow and infiltration

Compute the design flow

Compute the pipe diameter,

$D=[\frac{2\mathrm{.}16Qn}{\sqrt[\phantom{2}]{S}}{]}^{\frac{3}{8}}$

$$ The pipe diameter $(D)=15$ inches

The pipe diameter $(D)=18$ inches

The pipe diameter $(D)=12$ inches

The pipe diameter $(D)=21$ inches