Distribution System Components
cThe fire insurance underwriters recommend that residential areas should have a minimum pipe size of?
a. 3-4 in.
b. 4-6 in.
c. 6-8 in.
d. 9-10 in.
c. 6-8 in.
Reference: Water System Operations (WSO) Series (AWWA)
To use cathodic protection for protecting steel and iron pipe, what two sacrificial anodes could be used?
a. brass or aluminum
b. brass or zinc
c. zinc or magnesium
d. magnesium or copper
c. Zinc or magnesium
Reference: Water System Operations (WSO) Series (AWWA)
When using the slug method to disinfect a new pipeline, if the PH goes above ______, virtually all the chlorine residual is present as hypochlorite ion, which is much less effective than hypochlorous acid.
a. 9.5
b. 10
c. 10.5
d. 11
b.10
Reference: Water Distribution Operator Training Handbook (AWWA)
Which of the following is a chemical warfare agent?
a. Arsenic Fluoride
b. Dieldren
c. Tabun
D. Parathion
c. Tabun
Reference: Water System Operations (WSO) Series (AWWA)
You are driving through Kansas at 90 mph. What is this in feet per second?
132 fps
If a hydrant needs to be throttled, one of the nozzles should be fitted with a ______ and the hydrant fully opened.
a. plug valve
b. ball valve
c. butterfly valve
d. gate valve
d. gate valve
Reference: Water System Operations (WSO) Series (AWWA)
Before a new main is put into service, what should be completed and used as a basis for the final inspection?
a. Engineering plans
b. As-built plans
c. Site plans
d. Construction plans
b. As-built plans
Reference: Water System Operations (WSO) Series (AWWA)
Utilities that use chloramines as _______ disinfectants should establish ______ and have response plans to control nitrification.
a. primary, an MCL
b. secondary, action levels
c. primary, action levels
d. secondary, an MCL
b. secondary, action levels
Reference: Water Distribution Operator Training Handbook (AWWA)
What is lacking if a supervisor micromanages his or her employees?
a. Teamwork
b. Communication
c. Confidence in the available talent
d. Efficiency
a. Teamwork
Reference: Water System Operations (WSO) Series (AWWA)
A pipe carries 2.3 MGD. How much is this in cfs?
3.56 cfs
The distribution system design should include equal emphasis on _____ and ______.
a. pressure, flow velocity
b. fire protection, domestic peak demand
c. quantity, quality
d. disinfection residual, disinfectant by product potential
c. quantity, quality
Reference: Water System Operations (WSO) Series (AWWA)
When good-quality material is used to backfill a trench for a new pipe up to the springline, it is best to add a second layer of the same material that is at least _____ over the top of a pipe that is 8 in. in diameter and more if a larger pipe is covered.
a. 4 in.
b. 6 in.
c. 8 in.
d. 12 in.
b. 6 in.
Reference: Water Distribution Operator Training Handbook (AWWA)
If bacterial regrowth and disinfectant by products are persistent in the distribution system, what is recommended as a possible solution?
a. Carbon filtration
b. Ozone biofiltration
c. Source water treatment
d. Enhanced coagulation
c. Source water treatment
Reference: Water System Operations (WSO) Series (AWWA)
Permanent and conspicuous warning signs should be installed for panels carrying more than ______.
a. 400 V
b. 400 A
c. 600 V
d. 600 A
7. c. 600 V
A force main necks down from 12-inches to 6-inches. The velocity in the 12-inch pipe was 2 fps.
What will the velocity be in the 6-inch pipe?
8 fps
What type of pipe has high tensile strength, is low cost, and is good hydraulically when lined but is subject to general corrosion if installed unprotected in a corrosive environment?
a. steel pipe
b. ductile-iron pipe
c. cast-iron pipe
d. asbestos-cement pipe
a. Steel pipe
Reference: Water System Operations (WSO) Series (AWWA)
How many pounds of lime are needed to make a 10.0% slurry if exactly 100 gal of slurry are required?
a. 90.9 lb of lime
b. 92.7 lb of lime
c. 93.0 lb of lime
d. 93.4 lb of lime
b. 92.7 lb of lime
Reference: Math for Distribution System Operators (AWWA)
Let x = the number of pounds of lime needed.
1 o 001 limA= (x lb)(100%)
- (x lb)+ (8.34 lb/gal)(100 gal)
To solve this problem, we have to use a little more complex algebra than what we have been using so far. It is not that difficult, just follow the steps, and always remember that whatever we do to one side of the equation, we have to do to the other side.
First, multiply both sides by (x lb)+ (8.34 lb/gal)(100 gal)
(x lb)(10.0% lime)+ (8.34 lb/gal)(100 gal)(10.0% lime) =
(x lb)(100%){(x lb)+ (8.34 lb/gal}(100 gal)}
{(x lb)+ (8.34 lb/gal)(100 gal)}
The terms in the {} will cancel each other in the numerator (top) and the denominator (bottom) to get the following:
(x lb)(10.0% lime)+ (8.34 lb/gal)(100 gal)(10.0% lime) = (x lb)(100%)
Next, divide both sides by 100%
(x lb}(10.0% lime) (8.34 lb/gal)(100 gal)(10.0% lime) (x lb)(100%) 100% + 100% 100%
The 100% will cancel on the right side of the equation to get the following: (x lb)(10.0% lime) (8.34 lb/gaI)(100 gal)(10.0% lime) _ lb
100% + 100% - X
Next, reduce the problem by solving the multiplication and division of
(8.34 lb/gal)(100 gal)(10.0% lime)/100% and division of (x lb)(10.0% lime)/100%
0.1x lb of lime+ 83.4 lb of lime = x lb
Next, subtract 0.1x lb of lime from both sides to get the following: 0.1x lb of lime - 0.1x lb of lime+ 83.4 lb of lime = x lb - 0.1 lb of lime Add the like terms (the x terms) to get the following:
83.4 lb = 0.9x lb of lime
Last, divide both sides by 0.9.
83.4 lb 0.9 x lb of lime
--=
0.9 0.9
x lb of lime = 92.67 lb of lime, round to 92.7 lb of lime
How many gallons of sodium hypochlorite solutions that contain 11.7% available chlorine are needed to disinfect a water main ( where the main is 14.0 in. in diameter and the pipeline is 1,002 ft long) if the dosage required is 25.0 mg/L? Assume the sodium hypochlorite solution weighs 10.12lb/gal.
a. 1.40 gal of sodium hypochlorite
b. 1.41 gal of sodium hypochlorite
c. 1.44 gal of sodium hypochlorite
d. 1.47 gal of sodium hypochlorite
b. 1.41 gal of sodium hypochlorite
Reference: Math for Distribution System Operators (AWWA)
First, convert 14 in. to feet: 14 in./12 in. per foot = 1.167 ft
Next, find the volume of the pipe using: Volume, gal = (0.785)(Diameter, ft)2(Length, ft)(7.48 gal/ft3) Volume = (0.785)(1.167 ft)(1.167 ft)(1,002 ft)(7.48 gal/ft3) = 8,012.7 gal
Next, find the number of MG.
MG = (16,448 gaI)(1 M/1,000,000) = 0.0080127 MG
Then use the "pound" equation:
. .
SodI.urnh ypochion·te, lb = (MG)(Dosage, rng/L)(8.34 lb/gal)
% available chlonne/100%
0 14 279I
S d" h hi ·t lb )0.0080127 MG)(25.0 rng/L)(8.34 lb/gal)= b iurn ypoc one, 11.7% available chlorine/100% ·
Last, calculate the number of gallons of sodium hypochlorite.
Sodium hypochlorite, gal= 14.279 lb/10.12 lb/gal = 1.41 gal of sodium hypochlorite
Temporary pipelines used during an extended water outage also need to be chlorinated according to ____.
a. ANSI/NSF Standard C650
b. ANSI/NSF Standard C651
c. ANSI/ AWWA Standard C650
d. ANSI/AWWA Standard C651
d. ANSI/AWWA Standard C651
Reference: Water Distribution Operator Training Handbook (AWWA)
Water is pumped from a wet well fifty feet uphill to the next gravity line. The pump rate is 50 GPM. The pump is 85% efficient and the motor is 90% efficient. Find the wire to water horsepower.
0.825 motor HP
What type of transmission allows signals to pass in only one direction?
a. Uniplex
b. Simplex
c. Full simplex
d. Half simplex
b. Simplex
Reference: Water Distribution Operator Training Handbook (AWWA)
What is the curing time for a pipe that is lined with epoxy resin?
a. at least 4 hours
b. at least 12 hours
c. at least 16 hours
d. at least 24 hours
c. At least 16 hours
Reference: Water Distribution Operator Training Handbook (AWWA)
If 7 lb, 12 oz of soda ash is added to 50.0 gal of water, what is the percentage of soda ash in the slurry?
a. 1.78% soda ash slurry
b. 1.80% soda ash slurry
c. 1.2% soda ash slurry
d. 1.86% soda ash slurry
c. 1.82% soda ash slurry
Reference: Water System Operations (WSO) Series (AWWA)
First, convert ounces to pounds.
Number of lb= (12 ounces) (1 lb/16 ounces)= 0.75 lb
Total number of lb= 7 lb+ 0.75 lb= 7.75 lb
S d h o/c (7.75 lb) (100%) (7.75 lb) (100%) (7.75 lb) (100%) =
o aas' o-7.751b+(50.0gal)(8.341b/gal) 7.751b+4171b 424.751b
_ %
1 82
Who is ultimately responsible for ensuring employees are trained and advised of relevant situations?
a. The employee
b. The supervisor of that employee
c. The employee's union
d. The operational manager
b. The supervisor of that employee
Reference: Water System Operations (WSO) Series (AWWA)
A four cylinder positive displacement pump has a cylinder bore of 4.5 inches and a stroke length of 5.5 inches. The pump operates at 1700 rpm. How long will it take to empty a 72-inch diameter wet well, 33 feet deep, if it has an inflow of 2500 gpm?
98 minutes
If sodium hypochlorite is used to disinfect a storage tank, the total volume of the entire tank should have a free chlorine residual of at least _____ after the proper detention time.
a. 5 mg/L
b. 10 mg/L
c. 25 mg/L
d. 50 mg/L
b. 10 mg/L
Reference: Water System Operations (WSO) Series (AWWA)
What type of pump requires careful installation to ensure proper alignment of all shafting and impeller stages throughout its length and has the drive unit located under the surface?
a. Submersible pump
b. Deep-well pump
c. Booster pump
d. Centrifugal- jet pump
b. Deep well pump
Reference: Water System Operations (WSO) Series (AWWA)
The major source of organic chemicals in drinking water is from ____.
a. industrial and synthetic wastes
b. domestic waste, including landfills and urban runoff
c. reactions that take place during water treatment and distribution
d. breakdown of naturally occurring organic chemicals
d. breakdown of naturally occurring organic chemicals
Reference: Water System Operations (WSO) Series (AWWA)
Collapsible shoring assemblies are _____ panels of _______ or ______ that are available in various panel sizes.
a. lightweight, steel, alumimum
b. lightweight, wood, steel
c. heavy, iron, wood
d. heavy, steel, wood
a. lightweight, steel, aluminum
Reference: Water Distribution Operator Training Handbook (AWWA)
A centrifugal pump delivers 1890 liters per minute against a head of 300 feet with a combined pump and motor efficiency of 70 percent. What is the cost of the electrical power required to operate the pump 12 hours per day for 2 months? Assume each month has 31 days. Electricity costs $0.09 per kWh.
$2698.49