COLORADO WASTEWATER TREATMENT OPERATOR
CLASS D EXAMINATION ACTUAL EXAM COMPLETE
QUESTIONS AND DETAILED SOLUTIONS 2026/2027
Which pump is okay with pumping against a closed pipe? -
ANSWERCentrifugal pump
What is the most common disinfection byproduct when
adding chlorite to water containing natural AND inorganic
matter? - ANSWERChloroform
Why can rapid sand filters handle higher filtration rates
compare to slow sand filters? - ANSWERCoarser sand
(bigger grains of sand)
,Iron bacteria can interfere with ________ because the
bacteria produce ________ that prevents the stabilization
chemicals from reaching the pipe surface. -
ANSWERStabilization and a slime layer
Multiple-tube Fermentation Method (MTF) - ANSWERA lab
method used for coliform testing that uses a nutrient broth
placed in culture tubes
Membrane Filter (MF) Method - ANSWERA lab method
used to detect bacteria by capturing them on a membrane
filter
, Wells of __ feet are usually free of organisms? -
ANSWER50
What are most common reasons for groundwater
contamination? - ANSWERAccidents with fertilizer, sewer
leakage, unlined landfills, and septic tanks
What is sanitary seal (on a well)? - ANSWERA well feature
that prevents contamination from entering the well
What is a well casing? - ANSWERA concrete area placed
around the casing of wells to support pumps and to help
prevent surface water from contaminating the well water
CLASS D EXAMINATION ACTUAL EXAM COMPLETE
QUESTIONS AND DETAILED SOLUTIONS 2026/2027
Which pump is okay with pumping against a closed pipe? -
ANSWERCentrifugal pump
What is the most common disinfection byproduct when
adding chlorite to water containing natural AND inorganic
matter? - ANSWERChloroform
Why can rapid sand filters handle higher filtration rates
compare to slow sand filters? - ANSWERCoarser sand
(bigger grains of sand)
,Iron bacteria can interfere with ________ because the
bacteria produce ________ that prevents the stabilization
chemicals from reaching the pipe surface. -
ANSWERStabilization and a slime layer
Multiple-tube Fermentation Method (MTF) - ANSWERA lab
method used for coliform testing that uses a nutrient broth
placed in culture tubes
Membrane Filter (MF) Method - ANSWERA lab method
used to detect bacteria by capturing them on a membrane
filter
, Wells of __ feet are usually free of organisms? -
ANSWER50
What are most common reasons for groundwater
contamination? - ANSWERAccidents with fertilizer, sewer
leakage, unlined landfills, and septic tanks
What is sanitary seal (on a well)? - ANSWERA well feature
that prevents contamination from entering the well
What is a well casing? - ANSWERA concrete area placed
around the casing of wells to support pumps and to help
prevent surface water from contaminating the well water
