Missed Practice Exam

If a motor using Direct Current (DC) draws 4 amps at 440 volts, what will be the power used?

1,760 watts

What is the minimum chlorine residual entering the distribution system from the WTP?

1.0 mg/L

One part per million of lime [Ca(OH)2], will increase alkalinity and hardness by ________ part per million.

1.25

American Water Works Association (AWWA) recommends 5/8 inch meters be tested every

10 years

The Safe Drinking Water Act (SDWA) defines a public water system that supplies piped water for human consumption as one that has

15 service connections or serves 25 or more people for 60 or more days per year

If a operator wants to treat a flow of 1,200 gpm with 0.5 mg/L of 1.5% polymer working solution, how many millilitres per minute (mL's per minute) are needed?

151.4 mL's minute

Unless water cooled, the operating temperature of a mechanical seal in a pump should never exceed

160 degrees F (71 degrees C)

A chlorine evaporator maintains a water bath at

170 - 180 degrees F

1 cubic foot of water is equivalent to 7.48 gallons at normal temperature. If a meter registers in units of 100 cubic feet and 25 units of water have passed through the meter, how many gallons is this?

18,700 gallons

A rapid sand filter is 17.5 feet wide and 20 feet long. If the flow through the filter is 1 MGD, what is the filter loading rate in gpm/ft2 of filter media?

2.0 gpm/sq ft

An operator feeds activated carbon at a rate of 23 pounds per hour to treat a raw flow of 32 mgd. How many mg/L is fed?

2.1 mg/L

During a twenty four hour period a water treatment plant filters 1.6 million gallons. The surface area of the filters is 500 ft2. Determine the filtration rate in gallons per minute per square foot.

2.2 gpm/sq ft

The gas chlorinators at a water plant go out of service, so the operator decides to feed a hypochlorite solution that is 15% as available chlorine. If the operator needs to treat a flow of 1.6 mgd with 6 mg/L chlorine, how many gallons per hour hypochlorite solution are needed?

2.67 gph

In coliform analyses using the presence-absence test, a sample should be incubated for

24 and 48 hours @ 35 degrees C

When employees are working in trenches five feet deep or more, an adequate means of exit, such as a ladder or steps, must be located no further than ____ apart.

25 feet

If flow through a 10 inch pipe is 722 gpm, what is the velocity in feet per second (ft/sec)?

3 ft/sec

After initial full-service operation, grease-lubricated bearings should be regreased at what frequency?

3 to 6 months

A one-ton cylinder filled with chlorine weighs approximately:

3,700 pounds

What is the maximum theoretical suction lift of a centrifugal pump at sea level?

34 feet

If a water treatment plant is operating at 6.75 mgd, how many gpm is this? Select the most accurate.

4,687.5 gpm

Two solutions are being combined. 250 gallons of a solution containing 1.5 pounds of chemical per gallon of solution is being added to 1,500 gallons containing 4.8 pounds of chemical per gallon of solution. The weight of chemical in the new solution is __________ pounds per gallon.

4.33 lbs of chemical per gallon of solution

A trench must be shored if it is _____ feet deep or deeper.

5

Records of turbidity analyses should be kept for a minimum of

5 years

What is the recommended loading rate of copper sulfate for algae control at an alkalinity of greater than 50 mg/L?

5.4 pounds of copper sulfate per acre of surface area

If a 4.52 mgd pump is used to fill a rectangular basin that is 75 feet long and 36 feet wide, how long will it take to bring the water level from empty to a depth of 8 feet?

51.4 minutes

A solution is 5.8 percent hypochlorite. What is the mg/L of hypochlorite in the solution?

58,000 mg/L

A wash water recycle basin that measures 25 feet wide, 80 feet long, and 15 feet deep is emptied by a recycle pump operating at 560 gpm. Filters are being backwashed at the same time, and the flow from the backwash enters the recycle basin. Each filter backwash uses 54,600 gallons. How many filters can be backwashed over a 4 hour period, assuming the basin was empth to start?

6

What horsepower must a pump deliver to water that must be lifted 125 feet when the flow is 200 gpm?

6.31 HP

What is the pressure in pounds per square foot on the bottom of a tank when the water depth is 10 feet?

624 lbs/sq ft

An operator makes a 0.75% polymer solution in a day tank. How many milligrams per litre is this?

7,500 mg/L

Convert 67 pounds per million gallons to milligrams per liter.

8.0 mg/L

How many seconds are in one day?

86,400 seconds

How many pounds of 61% calcium hypochlorite are required for a 50 mg/L dose in a tank that is 110 feet in diameter and has a water level of 19 feet?

923 pounds

35o Celsius is equal to _______ on the Fahrenheit scale.

95

What is "clogging" of a filter?

A build up of head loss across the filter media until it reaches some predetermined design limit

Distribution system components from various manufacturers are compatible because of

AWWA Standards

How often should preventive maintenance for equipment be performed?

According to manufacturers recommendations

One part per million of soda ash (NaOH) will increase alkalinity by ______ part per million and hardness by ______ part per million.

Alkalinity = 0.94; Hardness = 0

Generally, a valve excersing program recommends valves be exercised

Annually

Where should bacteriological samples be collected in the distribution system?

At locations that are represetative of conditions within the system

What is a major cause of cross contamination?

Backpressure from private wells

How are particles removed by the slow sand filtration process?

By straining, adsorption, and biological action

Which of the following chemicals decreases corrosion rates?

Calcium carbonate

A component of a centrifugal pump sometimes installed on the end of a suction pipe to hold the priming is known as a

Casing

Which items should not be checked after start-up and during normal operation of sedimentation basin equipment?

Chlorine residual

Which chemical is used to make copper sulfate effective in highly alkaline waters, > 150 mg/L of alkalinity?

Citric acid

Total chlorine residual is:

Combined chlorine forms plus free chlorine

Which of the following is a primary function of couplings?

Compensate for alignment changes

A record containing the size, location, and ties of water mains, valves, hydrants, tanks, reservoirs, and pump stations is called a

Comprehensive map

The principal purpose of an altitude valve on an elevated tank is to

Control maximum filling level in distribution storage

Which type of valve on the discharge side of the pump is most effective in reducing pressure surges when starting or stopping the pump?

Controlled globe valves

The use of ammonia solution on a chlorine gas leak from the disinfection assembly may cause which of the following?

Dense white smoke

A coupon test installation in a distribution system is used to

Determine the rate of scaling or corrosion

When does the most serious threat of Cryptosporidium occur in a public water supply?

During periods of heavy rains or high snow melts

Cavitation in pumps is caused by pumping

Flow rates considerably higher than design flows

Why is sulfate of concern in drinking water?

Formation of scale on heat exchangers

To repack a buried gate valve, the valve must be

Fully open

Velocity of flow in water mains are usually expressed in terms of

Gallons per minute

The metal strip in an electrical fuse will melt from the heat caused by

High amperage demands

An illness in infants known as methemoglobinemia is attributed to

High nitrate content in the water

Which of the following contributes to the creation of algae blooms in reservoirs?

Increased nutrients

The discharge flow rate of a piston type pump

Is constant at a constant speed

What are the benefits of self-contained reservoirs?

Keep out flood rains

The primary reason for the use of a dry barrel fire hydrant is to

Keep the hydrant from freezing

If the limiting headloss is frequently a problem and turbidity breakthrough rarely occurs, what media change may be considered?

Larger size media

Hydrostatic pressure testing is the process used to test

Leakage in the pipe

Single phasing of a motor means

Loss of one power phase

If a water body has a high salinity and is warm, it will generally be

Low in dissolved oxygen

Which of the following is a characteristic of an ideal water distribution system sampling station?

Made of corrosion-resistant material

At a water treatment plant operating at 4 mgd, the dry alum feeder is set at an indicated feed rate of 17.3 mg/L. The operator runs a calibration check by catching 0.34474 kg of dry alum in 2 minutes. Is the dosimeter accurate?

No

A three phase motor looses one phase. What happens?

Noise and vibration until the sensor shuts the motor off

When testing for chlorine residuals at various points in the distribution system, it is most important to

Perform each test at the time the sample is collected

Static head is the

Pressure due to the depth of elevation of water

An altitude valve is a device used to

Regulate the water surface level in a storage tank

The chlorine gas feed rate is usually controlled by adjusting the

Rotameter control valve

The lead gasket in a chlorine cylinder

Should be replaced each time a new cylinder is connected

If turbidity breakthrough is frequently a problem and limiting headloss is rarely encountered, what media change may be considered?

Smaller size media

When comparing friction loss in various types of pipes, a larger Hazen-Williams "C" value indicates the pipe is

Smoother inside

Which of the following chemicals, used in water treatment, does not cause changes in alkalinity?

Sodium

Why are public health officials concerned regarding the application of compounds containing sodium to drinking water?

Sodium in drinking water may cause the development of high blood pressure in susceptible individuals

Which of the following chemicals can be activated for use as a coagulant aid with alum?

Sodium silicate

An alkalinity determination is needed when calculating chemical dosages used in what water treatment processes?

Softening

What type of motor is the simplist of all AC motors, with rotors consisting of a series of bars placed in slots?

Squirrel cage

Pipe fittings which are used to change the direction of flow are

Tees

What is the purpose of the coliform bacteria test?

Test for potential presence of pathogens

What is the Unit Filter Run Volume (UFRV)?

The volume of water produced by the filter during the course of the filter run divided by the surface area of the filter

When using a fire hydrant, the valve should be opened

To the full open position

Complaints of poor water quality will most likely occur in which type of water main layout?

Tree

How can buried, non-metallic pipe be located by electronic locators?

Use of metallic tracer tape

Centrifugal pump parts include

Volute

Which of the following best defines the term static water level?

Water level in a well when the well isn't in operation

Where is potassium permanganate (KMnO4) added to water to control taste and odor?

before filters

Where do you inject chlorine in a WTP?

before the clearwell

On an adapter, the ground wire which is connected under the screw on the receptacle cover plate is

green

Which of the following substances is the most effective disinfection residual?

hypochlorous acid

How are three-phased motors usually protected?

overload relays

Which piece of laboratory equipment is the most accurate way to measure a volume of liquid?

pipet

Fluoride chemical doses must never be metered against what type of head?

suction

The riparian doctrine is sometimes called the

the rule of reasonable sharing.

A gravometric feeder is run by

weight

Autoclaving will sterilize

with steam at 121 degrees C and 15 psi.