TCEQ Class B Surface Water Exam 2026 NEWEST
Test Material Questions & ANSWERS
What happens to dissolved solids on contact with chlorine? -
ANSWER- Dissolved solids are oxidized on contact further
reinforcing the importance of contact time.
No residual is formed until reducing agents are destroyed.
What are examples of reducing agents? - ANSWER-
Manganese, iron, turbidity, organic matter, ammonia, or
nitrates
What the 4 stages of the Chlorine Demand Curve chart? -
ANSWER- Stage 1: No residual is formed because inorganic
demand destroys the chlorine. (Flat Line)
Stage 2: Monochloramines are formed as chlorine combines
with organics containing ammonia (rising curve). The chlorine
to ammonia weight ratio at this point is 5:1. Combined and
total residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a
chlorine/ammonia weight ratio of 7.6:1 destroys chloramines
and chloro-organics. Combined decreases and free chlorine
increases.
,Stage 4: Enough chlorine is added to reduce all demand. The
combined residual remains the same, but free residual
increases with dosage. This stage is called "breakpoint"
chlorination. The chlorine to ammonia ratio of 10:1 satisfies
all demand and disinfects the distribution system. ( second
rising curve)
What is the difference between free chlorine and combined
chlorine (chloramines/chlorine-ammonia) systems? -
ANSWER- Free chlorine is more powerful than combined
chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time
while free chlorine requires 10 minutes.
-If combined residual is replaced by a free residual, less taste
and odor in the water usuals occurs.
- if combined residual is used : ph and temperature must be
monitored closely and the residual adjusted accordingly. For
example, as the temperature decreases the combines
residual must be increased. Free residual does not require
such monitoring in the 6.0 - 8.0 pH range. Free chlorine
residual concentration is not affected by temperature
changes.
,What is the minimum chlorine residual at the far reaches of
the system for both free and combined? - ANSWER- Free
chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free
chlorine or chloramine residual of 4 mg/L as a running
average. Limiting residuals reduces disinfection byproducts
such as trihalomethanes and haloacetic acids. These
byproducts, consumed over a long period of time, may cause
cancer.
What are the proper techniques for chlorine cylinder
storage? - ANSWER- - secure the ton cylinders in a horizontal
position and move with a lifting bar and hoist. Never roll
them
- 150lbs cylinders shall be chained to rigid support and keep
capped unless in use.
- Check all chlorine systems for leaks before putting into
service with a 10% ammonia solution. Household ammonia is
not approved. When ammonia contacts chlorine gas white
smoke results.
What are the steps to do before entering a room with a
chlorine leak? - ANSWER- 1: notify other operators and have
, standby help for possible notification of emergency
personnel
2: Be trained in emergency procedures and have knowledge
of chlorinators, tools, and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
What is the maximum withdrawal rate for 150lbs chlorine
cylinders? - ANSWER- The maximum sustained gas
withdrawal rate for 150lbs cylinders (vacuum transmission) is
1lbs per day per degree F.
The equivalent rate for ton cylinders (vacuum transmission) is
8 lb per day per degree F.
Pressure transmission rates are 42 lbs per day for 140lb
cylinders and 336 lb per day for ton containers, based on an
air temp of 70 degrees F.
Test Material Questions & ANSWERS
What happens to dissolved solids on contact with chlorine? -
ANSWER- Dissolved solids are oxidized on contact further
reinforcing the importance of contact time.
No residual is formed until reducing agents are destroyed.
What are examples of reducing agents? - ANSWER-
Manganese, iron, turbidity, organic matter, ammonia, or
nitrates
What the 4 stages of the Chlorine Demand Curve chart? -
ANSWER- Stage 1: No residual is formed because inorganic
demand destroys the chlorine. (Flat Line)
Stage 2: Monochloramines are formed as chlorine combines
with organics containing ammonia (rising curve). The chlorine
to ammonia weight ratio at this point is 5:1. Combined and
total residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a
chlorine/ammonia weight ratio of 7.6:1 destroys chloramines
and chloro-organics. Combined decreases and free chlorine
increases.
,Stage 4: Enough chlorine is added to reduce all demand. The
combined residual remains the same, but free residual
increases with dosage. This stage is called "breakpoint"
chlorination. The chlorine to ammonia ratio of 10:1 satisfies
all demand and disinfects the distribution system. ( second
rising curve)
What is the difference between free chlorine and combined
chlorine (chloramines/chlorine-ammonia) systems? -
ANSWER- Free chlorine is more powerful than combined
chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time
while free chlorine requires 10 minutes.
-If combined residual is replaced by a free residual, less taste
and odor in the water usuals occurs.
- if combined residual is used : ph and temperature must be
monitored closely and the residual adjusted accordingly. For
example, as the temperature decreases the combines
residual must be increased. Free residual does not require
such monitoring in the 6.0 - 8.0 pH range. Free chlorine
residual concentration is not affected by temperature
changes.
,What is the minimum chlorine residual at the far reaches of
the system for both free and combined? - ANSWER- Free
chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free
chlorine or chloramine residual of 4 mg/L as a running
average. Limiting residuals reduces disinfection byproducts
such as trihalomethanes and haloacetic acids. These
byproducts, consumed over a long period of time, may cause
cancer.
What are the proper techniques for chlorine cylinder
storage? - ANSWER- - secure the ton cylinders in a horizontal
position and move with a lifting bar and hoist. Never roll
them
- 150lbs cylinders shall be chained to rigid support and keep
capped unless in use.
- Check all chlorine systems for leaks before putting into
service with a 10% ammonia solution. Household ammonia is
not approved. When ammonia contacts chlorine gas white
smoke results.
What are the steps to do before entering a room with a
chlorine leak? - ANSWER- 1: notify other operators and have
, standby help for possible notification of emergency
personnel
2: Be trained in emergency procedures and have knowledge
of chlorinators, tools, and ammonia use.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
What is the maximum withdrawal rate for 150lbs chlorine
cylinders? - ANSWER- The maximum sustained gas
withdrawal rate for 150lbs cylinders (vacuum transmission) is
1lbs per day per degree F.
The equivalent rate for ton cylinders (vacuum transmission) is
8 lb per day per degree F.
Pressure transmission rates are 42 lbs per day for 140lb
cylinders and 336 lb per day for ton containers, based on an
air temp of 70 degrees F.
