MARK THE FOLLOWING TRUE OR FALSE

$(3$ PTS$)$ Presence of total coliform bacteria in water means water is definitely contaminated by salmonella, E$.$coli, or some other type of pathogenic bacteria.

$(3$ PTS$)$ Plastic containers are commonly used for storage of chlorine gas.

$(3$ PTS$)$ When a water sample is positive for total coliform, the sample must be analyzed for fecal coliform or E$.$coli.

$(3$ PTS$)$ The number of monthly distribution samples bacteriological samples required by Total Coliform Rule is based on the number of water sources serving customers.

$(3$ PTS$)$ At any sample point in the distribution system, the presence of HPC more than or equal to $500$ colony forming units per milliliter is equivalent to a detectable disinfectant residual.

$(3$ PTS$)$ Water delivered to the distribution system shall not contain a disinfectant residual of less than $0\mathrm{.}2m\frac{g}{L}$ for more than $4$ hours in any $24-$hour period $($continuous disinfection$).$

CIRCLE THE CORRECT ANSWER

$7.(3$ PTS$)$ Which one of the following factors affects CT$?$

a$.$ Alkalinity

c$.$ Color

b$.$ Hardness

d$.pH$ value

$8.(3$ PTS$)$ Conventional filtration combined filter effluent turbidity shall:

a$.$ be less than or equal to $0\mathrm{.}5$ NTU $95\%$ of time

b$.$ never exceed $5\mathrm{.}0$ NTU

c$.$ not exceed $1\mathrm{.}5$NTU for more than one continuous hour

d$.$ none of these

SHOW ALL YOUR WORK

$9.(5$ PTS$)$ Determine Contact Time $(T_{10})$ in minutes of the $60-$inch pipeline that is $1,600$ feet long, when peak hourly flow rate through the pipeline is $8,851gpm.$ Assumes plug flow. $($Use formula: $T_{10}=$ Volume of Pipe Section$/$Flow Rate$).$