Water Distribution Flashcards
The difference between the static groundwater level and the pumping level is the
Drawdown
A customer complaint about the presence of brown floc in tap water can best be handled by
Investigating the problem as soon as possible
The term aquifer relates to which of the following
Groundwater
On indication of corrosive water is a high concentration of
Carbon dioxide
Catholic protection means protection against
Corrosion
The primary reason for the use of a dry barrel fire hydrant is to
Keep the hydrant from freezing
The component parts of a well include all of the following except
Included ( sanitary seal, well screen, cement grout)
Pressure switch
At the same barometric pressure, the amount of dissolved oxygen in cold water tends to be ____ the amount of dissolved oxygen in warm water
More than
Which of the following is the principal constituent in water that causes corrosion of metals>
Dissolved oxygen
Which component of a centrifugal pump moves the water?
Impeller
A record containing the size, location, and ties of water mains, valves, hydrants, tanks reservoirs, and pump stations is called a
Comprehensive map
What term describes water that is suitable for drinking?
Potable
Velocity of flow in mains is usually expressed in terms of
Feet per second
A “competent person” at an excavation site
Is capable of identity hazards and has the authority to take corrective measures
Hydrogen sulfide has smells like
Rotten eggs
Which of the following methods can be used to remove high iron content from a well supply
Oxidation and filtration
Hardness may be expressed in
Milligrams per liter as CaCo3
The basic unit of electrical power is the
Watt
Check valves are used to
Permit flow in only one direction
Standard pumper connection fire hydrants should not be installed on water mains smaller than __ inches in diameter
6
Beards of long sideburns prohibit and operation from safely
Wearing the face mask of a self contained breathing apparatus
The water table is defined as the
Upper surface of the groundwater
The shaft speed of an electric motor is most commonly expressed in units of
Revolutions per minute
A coupon test installation in a distribution system is used to
Determine the rate of scaling or corrosion
Disease-causing bacteria are known as
Pathogenic
Normally surface water and groundwater have a pH range of
6.8 — 8.5
What is the best definition of turbidity in water
Anything in water that scatters light
A “competent person” must inspect excavations and adjacent areas for hazards
Daily, prior to the start of work, and as needed through shift
The component of a centrifugal pump sometimes installed on the end of a suction pipe to hold priming is known as a
Foot valve
The principal purpose of an altitude valve on an elevated tank is to
Control maximum filling level in distribution storage
The term “primacy” means the
Primary authority for the implementation and enforcement of drinking water regulations
Reciprocating positive-displacement pumps are also known as
Piston pumps
Moderately hard water will have a hardness range of ___ mg/l as calcium carbonate
61 to 120
A common method of removing hydrogen sulfide from water is
Aeration
The treatment process designed to kill pathogenic organisms is
Disinfection
Lead in drinking water can result in
Impaired mental functioning in children
A disease that might be transferred to a new victim through water is
Typhoid
An average percentage range for unaccounted for water in a fully metered system is
11 to 15 %
A cross connection is defined as a connection between
A potable water system and a non potable system
Backsiphonage is caused by
Partial vacuum in the line
When the pumping rate is increased, the effect on the cone of depression is to
Lower the pumping level
Which chemical is most often used to disinfect public water supplies
Chlorine or chlorine compounds
The purpose of a surge tank is to
Control water hammer
The presence of total coliforms in drinking water indicates
The potential presence of pathogens
The term “MCL” means
Maximum contaminant level
the primary origin of coliforms in water supplies is
Fecal contamination by warm-bodied animals
The primary source of trihalomethanes (THMs) in drinking water is
The reaction of chlorine compounds and organic matter
An air-gap device is used to
Prevent backflow of non potable water into a drinking water supply
The primary health risk associated with trihalomethanes (THMs) is
Cancer
The purpose of the fusible plug on a chlorine tank is to
Prevent the cylinder from exploding at high temperatures
The primary health risk associated with synthetic organic compounds (SOCs) is
Cancer
Which is the most accurate statement concerning potable water lines?
They must never be connected to a contaminated water source
The primary source(s) of synthetic organic compounds (SOC) contamination in water supplies is (are)
Industrial solvents and agricultural pesticides
water samples are analyzed for the coliform group of bacteria because these bacteria
Indicate the possible presence of disease-causing organisms
Lead in drinking water is primarily the result of
Corrosion within the distribution system and residential plumbing
pressure in a pipeline may be caused by
friction and elevation
what is the difference between a maximum contaminant level and a secondary maximum contaminant level
MCLs relate to health effects, while SMCls relate to aesthetic concerns
the purpose of an electrical lock-out device is to
positively prevent the operation of an electrical circuit
the maximum contaminant level goal (MCLG) of a known or probable carcinogen is
zero
a public water system must comply with safe drinking water act regulations baed on
population range, size of community and financial ability
an objectionable feature of iron and manganese in water is
staining of fixtures
the pressure that a pump must operate against is measure in
pounds per square inch
if the peed of a centrifugal pump is increased, and the head remains the same, the gallons per minute output will
increase
a suspension of very minute particles that cause an appearance of cloudiness is called
turbidity
hardness in water is caused by
calcium and magnesium
contaminant monitoring requirements can depend on
previous violations of MCLs, the results of a vulnerability assessment, the size of the water system
sodium hypochlorite is
a compound that can be purchased in liquid solution and can be used for disinfection
the abbreviation “DO” stands for
dissolved oxygen
high nitrate concentrations in water can affect
infants
a corporation stop is used to
connect the service line to the main water line under pressure
when installing service lines, it is a good practice to provide for movement due to soil settling by installing which of the following?
bend or gooseneck in the pipe
how many pounds of pressure (ponds per square inch) equals 100 feet of head?
43 pounds
the metal trip in an electrical fuse will melt from the heat caused by
high amperage demands
a trench must be shored if it is ____ feet deep or deeper
5 feet
an approved device used to prevent backflow and back siphonage is a
vacuum breaker
disc-type meters are classified as ____ meters
positive-displacement
distribution system components from various manufactures are compatible because of
AWWA standards
the performance curve of a pump reflects
pump capacity, pump efficiency, pump horsepower
if the pump bearings on horizontal centrifugal pumps are overlubricated, the most important effect is that the extra lubricant
may cause overheating and possible failure of the bearings
flexible couplings used to connect the motor and the pump shaft transmit
power efficiently and effectively from one shaft transmit
a major break in a water main can assist the distribution operator to
observe the interior condition of the distribution systems piping
a portable ladder must extend ___ feet above the upper surface of an excavated trench
3 feet
a vacuum is formed in the chlorinator by the
pressure differential through the ejector
the rated flow of a water meter, as stated by the manufacturer, is based on ___ flow
continuous
on a switch that has been tagged and locked out, the warning tag must have
name and signature of person who locked out the switch
in general, a pH of treated water below 6.5 indicates
corrosive water
when comparing friction loss in various types of pumps, a larger Hazen-Williams C value indicates the pipe
is smoother inside
generally, a valve exercising program recommends valves be exercised
one a year
if water flowing in a 6 in diameter pipe is discharged diameter pipe, the velocity will
increase approximately twice
a manganese level of about 0.2 mg/l can result in
staining of toilet fixtures and laundry
which of the following safe drinking water act rules provides for action levels instead of maximum contaminant levels
lead and copper
the most widely used type of prime mover in a pumping station is a
electric motor
an illness in infants known as methemoglobinemia is attributed to
high nitrate content in the water
hydrostatic pressure testing is the process used to test
leakage in the pipe
water leaking to the surface after operating an old valve probably is caused by
dried out packing
water hammer is most likely caused by
closing a valve too fast
to repack a buried gate valve, the valve must be
fully open
centrifugal pump parts include
volute
thrust blocks are installed to
prevent movement of pipes
in order to comply with safety regulations, all couplings on pumps must be
guarded
is is essential to ventilate a valve vault before entry in order to
remove dangerous gases and/or ensure proper oxygen levels
according to the SDWA bacteriological samples should be collected at
representative points in the distribution system
in making a household service connection, the employee finds the 8-inch water main wall is too thin and has to use a ___ to complete the installation
service clamp
a noisy and vibrating gate valve idicated
cavitation is happening
how often should a sealed ball bearing in an electrical motor be lubricated?
never
a maintenance and inspection program for storage tanks and reservoirs is performed
ever other year
the term MCL means
level of contaminant in drinking water below which there are no known or suspected adverse health effects with a margin of safety
wht flow can be expected from a standard 5/8inch by 3/4inch meter
20 gallons per minute
the difference between tier and tier 2 violations
Tier 1 violations potentially impose direct and adverse health effects, Tier 2 violations do not pose a direct threat to public health
water hammer can be minimized by
air release valves and surge tanks
maintenance required of bubbler tube level indicators includes checking the
air tube
a device used to check flows in a distribution system is called a
pitot gage
which of the following would be classified as a positive displacement pump
reciprocating pump
the pH of water may be reduced by adding
carbon dioxide
proper alignment between two shafts can be checked using a
straight edge and feeler gauge
two fundamental treatment requirements for public water systems using surface water sources are
disinfection and filtration
water with high turbidity will also have a high concentration of
fine suspended materials
the MCL for trihalomethanes is
0.10mg/l
for household use, what size of displacement meter is best?
5/8 to 2 inches
an amperometric titrator is used to measure
chlorine residual
a direct water connection to a boiler containing a scale prevention compound must be protected by an
air gap
the multiple tube fermentation test method consists of three tests – the presumptive, the completed and the ___ test
confirmed
a characteristic that distinguishes a strong acid from a week acid is the
degree of ionization
final determination of vulnerability is made by
the primacy agency
when a water main repair can be made with a repair clamp and the main is under continuous pressure, the concern for ___ is reduced
disinfecting
if solids in water have an average specific gravity of 1.20 they are
20% heavier than water
static head is the
pressure due to the depth of elevation of water
what is the maximum length of time water must remain motionless in pipes prior to the first-draw residential lead sampling
6 hours
according to the lead and copper rule, the action level for the 90th percentile lead level is
0.015mg/l
a tank containing industrial solvent is under 10 pounds per square inch pressure. An employee accidentally opens a valve that is connected to the potable water. pressure in the potable water system drops to 5 pounds per square inch. This condition is called
back pressure
the lead and copper rule specifies that all public water systems must initially monitor for lead content by collecting samples from
high risk residences
which of the following is most likely to corrode steel
acid conditions
the SDWA requires ___ to develop comprehensive coliform monitoring plan
all public water systems
THMs are primarily a concern in
water after chlorine disinfection treatment
wearing rings are installed in a pump to
minimize internal water leakage
if an initial sample is positive for total coliforms and a subsequent sample is positive for fecal coliform or E. coli an ___ violation is triggered
acute tier 1
material safety data sheets are required for
all chemicals used in the workplace regardless of hazard
cavitation in pumps is caused by pumping
flow rates considerably higher than design flows
when the static level of the groundwater is 50 feet below the ground surface, the most suitable type of pump is a
turbine pump
Flammable liquids are those that have flash points
below 100 degrees F
under the SDWA “lead free” means
up to 8% lead content in pipes/fixtures and 0.2% lead content in solder
when a nonpotable water is connected directly to a potable water system, the minimum acceptable method of eliminated the cross connection is
an air gap between the two systems or a reduced pressure zone device
a potable water supply discharges into an irrigation water storage tank. the pipe should be
above the overflow level of the tank by several pipe diameters
the minimum pressure required in a water distribution system is
20 pounds per square inch
which valve is most suitable for a throttling application
ball
where should an air release valve be placed on a water main
top
under the lead and copper rule, all large public water systems (serving > 50,000 people) are required to
conduct corrosion control studies
community water systems that add a disinfectant to water and serve a population of ___ or more are required to monitor for total trihalomethane
10,000
a chain of custody for a sample legally proves that
responsible people had possession of the sample at all times
the minimized iron from precipitating in the distribution system ___ is decreased
carbo dioxide
an altitude valve is a device used to
regulate the water surface level in a storage tank
when using a fire hydrant the valve should be open
to the full open position
the discharge flow rate of a piston-type pump
is constant at a constant speed
single phasing of a motor means
loss of one power phase
the angle of repose is the angle of slope of
unsupported lose soil
what affects the flow capacity of an installed pipeline
pipe size, pipe material, and grade
alkalinity in water serves as
a measure of the water capacity to neutralize and acid
3-log removal means ___ precent removal/inacaivation
99.9%
the advantage of a balanced mechanical seal is that
the wearing force between the ground surface does not vary regardless of the suction head
disinfection residuals for surface water supplies must be measured at the entry point to the distribution system. the minimum acceptable residual is
0.2 mg/l
which of the following is an example of an acute violation?
a positive sample for total coliforms when Ecoli are present
what happens to a pump if the back pressure on the pump is allowed to drop too low and the pump is operated for a prolonged period of time?
efficiency will drop off and the pump will heat up
treatment techniques rather than a maximum contaminant level are established for Giardia, viruses and legionella because
no commonly available test exists for these microorganisms
which of the following must be checked when doing maintenance on pneumatic controllers
air supply availability
under the SDWA if the MCL for nitrate or nitrite is exceeded, notice must be given to the public by broadcast media (television and radio) within
72 hours
when a pump is leaking excessively around the packing gland, the operator should first turn the pump off and
tighten the packing gland
the MCL for copper is based on the concern that excessive copper ingestion may cause
stomach and intestinal distress
what should an operator do when entering a room containing a high concentration of chlorine gas
use self-contained air or oxygen and have help standing by
as water temperature decrease, the disinfecting action of cholrine
decreases
