C-Well Practice Exam No. 2
When calcium hypochlorite is used for disinfecting a water supply, it should be: dissolved in water
allowed to settle and supernatant siphoned off and fed into the water system, dissolved in water as a dry
chemical then injected into the water system, fed as a dry chemical directly into the pipeline, fed as dry
powder into the clear well. - dissolved in water as a dry chemical, allow to settle , and the
supernatant siphoned off and fed into the water system
Which of the following best describes "chlorine demand": the difference between the amount of
chlorine added and turbidity, the difference between the amount of chlorine added and ph, the
difference between the total chlorine residual and the free chlorine risidual, the difference between the
amount of chlorine added and the amount of residual chlorine remaining after a given contact time. -
the difference between the amount of chlorine added and the amount of residual chlorine
remaining after a given contact time
In NC, the drinking water quality standards are enforced by - The N. C. Division of Water
Resourses, PWSS
The number of monthly samples required for bacteriological analyses is based on - Population
served
(NC) State Rules governing public water systems require records of bacteriological analyses be kept on or
near premises for a minimum of - 5 years
NC Division of Water Resourses-PWSS Rules require the control and upward adjustment of the ph of
drinking water if it is below a level of - 6.5
Which of the following well types is most protected from surface contamination? artesian well,
infiltration gallery, rock well, shallow well. - artesian well
a single sample taken without considering the time of day or rate of flow is called a - grab sample
, The Total Coliform Rule is based first on, presence or absence of coliforms in a sample, density of
coliform in a sample, type of coloforms in a sample, presence or absence of coliforms in a sample -
presence or absence of coliforms in a sample
The primary origin of coliforms in water supplies is, natural algae growth, industrial solvents, bacterial
contamination, acid rain - bacterial contamination
If an initial sample is positive for total coliforms and a repeat sample sample is positive for fecal or E-coli;
notice to the public must be given by broadcast media (television and radio) within: 24 hours, 48 hours,
72 hours, 14 days - 24 hours
Check valves are used to prevent: excessive pump pressure, priming, water from flowing backward,
water hammer - water from flowing backward
An operator hears a pinging sound coming from the pump. What is the probable cause: descaling,
cavitation, corrosion, hardness. - cavitation
Prepared water samples bottles used for collecting samples for bacteriological examination contain
sodium thiosulfate crystals. It is important not to rinse out the sample bottle because the sodium
thiosulfate: eliminates the need for refrigeration of the sample, neutralizes any chlorine present in the
sample, the test for it is relatively inexpensive and easy to perform, all of the above. - neutralize
any chlorine present in the sample
During a routine inspection on a centrifugal pump, the operator notices that the bearings are excessively
hot. This is most likely caused by: over lubrication, the speed being to slow, a worn impellar, a worn
packing - over lubrication
The leakage of seal water around the packing on a centrifugal pump is required because it acts as a(n):
ahesive, coolant, corrosive inhibitor, scale inhibitor. - coolant
Sodium Tiosulfate is used to: buffer chlorine solutions, neutralize chlorine residual, detect chlorine leaks,
sterilize sample bottles. - neutralize chlorine residuals
