TCEQ CLASS B SURFACE WATER QUESTIONS WITH
DETAILED VERIFIED ANSWERS FOR ACCURACY
What is the most important factor affecting the useful life of
service lines?
ANS >>> It is the ability of the material to resist internal and
external corrosion
When does Suction Head exist?
ANS >>> Suction head exists when the source of supply is above
the centerline of the pump.
What is Net positive Suction Head (NPSH)
ANS >>> NPSH is the pressure under which water enters the
eye of the impeller in a centrifugal pump. Insufficient NPSH is
the main cause of pump cavitation
Explain and expand on Chlorine Dioxide (what it reacts with,
oxidizes, etc.)
ANS >>> Chlorine Dioxide is a gas used in small quantities to
disinfect water. It does not react with organics to form THMs
and HAAs. It oxidizes phenols, manganese, iron, sulfurous and
organic compounds which aids in the removal of tastes and
odors. It is a very effective bactericide and a superior virucide.
It dies not combine with ammonia. Chlorine Dioxide MRDL is
.8 mg/L and monitoring procedures are the same as for
chlorine. The Chlorite MCL is. q mg/L and must be monitored
daily.
,What is Texas drinking water pH requirements?
ANS >>> The Texas drinking water requirements require a pH
> 7.0 for the water treatment plant finished water. EPA
requires that pH analysis be performed within 15 minutes of
the sample being caught.
How does pH affect Chlorine activity?
ANS >>> When chlorine is added to water it forms
hypochlorous acid (HOCL) and hydrochloric acid (OCL). The
hypochlorous acid is the effective disinfectant. At a pH of 4.0
there is 100% hypochlorous acid. At a pH of 11 there is 100%
hypochlorite ion. At a pH of 7, the hypochlorous acid is at about
80% and the hypochlorite ion makes up about 20% of the
chlorine content.
The lower the pH is more effective chlorine is because you have
more hypochlorous acid.
What is meant by water stability?
ANS >>> Stable water is defined as water that will neither
deposit or dissolve a calcium carbonate film or scale. Since no
water is stable indefinitely, chemical treatment of water usually
is intended to produce water that is slightly scale forming
without being liable to cause stoppages in small lines and
services.
Bayliss curve is the simplest determination of stability. The
Langelier saturation index is also used.
What/how are above ground tanks and piping protected from
corrosion?
, ANS >>> Corrosion protection for above ground tanks and
piping is prevented by: cathodic protection, use if protective
linings/coatings, eliminating different types of metals in the
distribution system, and treating the water with chemicals to
make it less corrosive
How do you test fir alkalinity?
ANS >>> The two initiation methods of analysis are a standard
acid to titrate a sample. The end point of the titration is
determined by the following: an indicator that changes color at
a certain pH, or potentiometric titration to end - point ph.
Using either of the methods, a measured amount of sample is
titrated with a standard sulfuric acid to a predetermined ph.
Nomograph are a graphical form of determining alkalinity. If
the pH, total alkalinity, temperature and total dissolved solids
are known, any or all of the alkalinity forms may be estimated.
What is Turbidity?
ANS >>> Turbidity can be described as a measure of the
relative clarity of water. Turbidity is an expression of the
optical property that causes light to be scattered and absorbed
rather than transmitted in straight lines through the sample.
What causes Turbidity?
ANS >>>Turbidity is caused by clay, slit, finely divided organic
and inorganic material. Other suspended matter and
microscopic organisms can also cause turbidity. There is one
approved method for running turbidity - the Nephelometric
Method (NTU)
What is chlorine Demand?
, ANS >>> The amount of chlorine used up to completely react
with the water and its suspended or dissolve material
What is chlorine residual?
ANS >>>When all the demand of the water is met any
additional chlorine produces a chlorine residual
What is chlorine dosage?
ANS >>>Demand plus residual is the chlorine dosage. Chlorine
Dosage = Demand + Residual
What determines rate of disinfection?
ANS >>> Chlorine concentration and contact time determines
the rate and degree of disinfection. If concentration increases,
the time can be reduced; if concentration is reduced the time
must be increased.
How does temperature effect chlorine effectiveness?
ANS >>>Chlorine effectiveness is greater at higher
temperatures, up to the point that chlorine volatizes. At low
temperature, chlorine is more stable, but disinfection time
increases.
Is removing turbidity important for disinfection?
ANS >>>Turbidity must be removed to low levels by
sedimentation and filtration to allow chlorine to contact
pathogens.
What happens to dissolved solids on contact with chlorine?
DETAILED VERIFIED ANSWERS FOR ACCURACY
What is the most important factor affecting the useful life of
service lines?
ANS >>> It is the ability of the material to resist internal and
external corrosion
When does Suction Head exist?
ANS >>> Suction head exists when the source of supply is above
the centerline of the pump.
What is Net positive Suction Head (NPSH)
ANS >>> NPSH is the pressure under which water enters the
eye of the impeller in a centrifugal pump. Insufficient NPSH is
the main cause of pump cavitation
Explain and expand on Chlorine Dioxide (what it reacts with,
oxidizes, etc.)
ANS >>> Chlorine Dioxide is a gas used in small quantities to
disinfect water. It does not react with organics to form THMs
and HAAs. It oxidizes phenols, manganese, iron, sulfurous and
organic compounds which aids in the removal of tastes and
odors. It is a very effective bactericide and a superior virucide.
It dies not combine with ammonia. Chlorine Dioxide MRDL is
.8 mg/L and monitoring procedures are the same as for
chlorine. The Chlorite MCL is. q mg/L and must be monitored
daily.
,What is Texas drinking water pH requirements?
ANS >>> The Texas drinking water requirements require a pH
> 7.0 for the water treatment plant finished water. EPA
requires that pH analysis be performed within 15 minutes of
the sample being caught.
How does pH affect Chlorine activity?
ANS >>> When chlorine is added to water it forms
hypochlorous acid (HOCL) and hydrochloric acid (OCL). The
hypochlorous acid is the effective disinfectant. At a pH of 4.0
there is 100% hypochlorous acid. At a pH of 11 there is 100%
hypochlorite ion. At a pH of 7, the hypochlorous acid is at about
80% and the hypochlorite ion makes up about 20% of the
chlorine content.
The lower the pH is more effective chlorine is because you have
more hypochlorous acid.
What is meant by water stability?
ANS >>> Stable water is defined as water that will neither
deposit or dissolve a calcium carbonate film or scale. Since no
water is stable indefinitely, chemical treatment of water usually
is intended to produce water that is slightly scale forming
without being liable to cause stoppages in small lines and
services.
Bayliss curve is the simplest determination of stability. The
Langelier saturation index is also used.
What/how are above ground tanks and piping protected from
corrosion?
, ANS >>> Corrosion protection for above ground tanks and
piping is prevented by: cathodic protection, use if protective
linings/coatings, eliminating different types of metals in the
distribution system, and treating the water with chemicals to
make it less corrosive
How do you test fir alkalinity?
ANS >>> The two initiation methods of analysis are a standard
acid to titrate a sample. The end point of the titration is
determined by the following: an indicator that changes color at
a certain pH, or potentiometric titration to end - point ph.
Using either of the methods, a measured amount of sample is
titrated with a standard sulfuric acid to a predetermined ph.
Nomograph are a graphical form of determining alkalinity. If
the pH, total alkalinity, temperature and total dissolved solids
are known, any or all of the alkalinity forms may be estimated.
What is Turbidity?
ANS >>> Turbidity can be described as a measure of the
relative clarity of water. Turbidity is an expression of the
optical property that causes light to be scattered and absorbed
rather than transmitted in straight lines through the sample.
What causes Turbidity?
ANS >>>Turbidity is caused by clay, slit, finely divided organic
and inorganic material. Other suspended matter and
microscopic organisms can also cause turbidity. There is one
approved method for running turbidity - the Nephelometric
Method (NTU)
What is chlorine Demand?
, ANS >>> The amount of chlorine used up to completely react
with the water and its suspended or dissolve material
What is chlorine residual?
ANS >>>When all the demand of the water is met any
additional chlorine produces a chlorine residual
What is chlorine dosage?
ANS >>>Demand plus residual is the chlorine dosage. Chlorine
Dosage = Demand + Residual
What determines rate of disinfection?
ANS >>> Chlorine concentration and contact time determines
the rate and degree of disinfection. If concentration increases,
the time can be reduced; if concentration is reduced the time
must be increased.
How does temperature effect chlorine effectiveness?
ANS >>>Chlorine effectiveness is greater at higher
temperatures, up to the point that chlorine volatizes. At low
temperature, chlorine is more stable, but disinfection time
increases.
Is removing turbidity important for disinfection?
ANS >>>Turbidity must be removed to low levels by
sedimentation and filtration to allow chlorine to contact
pathogens.
What happens to dissolved solids on contact with chlorine?
