OSSF DR EXAM PRACTICE 150 QUESTIONS &
CORRECT ANSWERS LATEST 2025
_______ and ________ soil textural classes are always unsuitable for standard
absorptive OSSF - ANSWER-class IA and IV
List each of the major soil horizons - ANSWER-surface soil A, surface soil B, and
parent material
_____________ is a term describing the ability of water to migrate through a soil
profile under either _________ or __________ conditions. - ANSWER-Hydraulic
conductivity, saturated, unsaturated
Interconnected pores in the soil profile allow ______ and _______ to enter the
soil at its surface and migrate downward - ANSWER-air, water
List the four components of soil - ANSWER-air, water, organics, inorganics
A drainfield is 50 feet by 90 feet and must be covered with an average of 15
inches of sand loam. How many cubic yards of sandy loam soil must be purchased
(find the volume of a rectangular object)? - ANSWER-208.3 cubic yards
What would be the volume of a 5-foot-diameter pump tank that is 5 feet tall with
the inlet 1 foot below the rim? - ANSWER-587 gals
,What would be the percent slope on a lot 250 feet deep that drops 20 feet in
elevation over the depth of the lot? - ANSWER-8%
How many cubic yards of gravel would be needed to fill a ditch 3 feet deep, 10
feet wide, and 12 feet long with 18 inches of gravel? 1 cubic yard = 27 cubic feet. -
ANSWER-6.67 cubic yards
A septic tank is 6 feet in diameter and is 8 feet deep. How many gallons will it hold
if the overflow line is located half way up from the bottom? - ANSWER-846 gals
Calculate the working liquid capacity (volume) for this septic tank. SEE PAGE 2-
39!! - ANSWER-1077gals
What is the surface area (area in square feet) of an evapotranspiration system 40
feet wide and 65 feet long? - ANSWER-2,600 sqft
Figure the acreage for a piece of property that measures 256 feet on each of four
sides. - ANSWER-1.5 acres
Figure the area of a lot that measures 60ft by 280ft - ANSWER-16,800sqft ,0.39
acres
A disposal option that might be considered in a clay soil would be a ________. -
ANSWER-drip or spray irrigation
The primary treatment device providing the least or poorest treatment of
domestic wastewater would be _______. - ANSWER-septic tank
, Nitrogen or nitrate removal in soil occurs by _________. - ANSWER-vegetation
uptake
The factors influencing the survival of bacteria in soil are _______. - ANSWER-
moisture, temperature, pH, and organic matter.
Physical removal of bacteria by straining occurs when _______. - ANSWER-the
bacteria are larger than the pore openings in the soil
A solid that can be filtered out of the wastewater is a _________. - ANSWER-
suspended solid
Which of the following describes domestic wastewater as it leaves a home? -
ANSWER-fresh, light in color, has dissolved oxygen
Which of the following are problems caused by malfunctioning septic tank
systems? - ANSWER-surface water pollution, groundwater contamination, and
standing sewage in neighborhoods
An inorganic chemical that affects human health is - ANSWER-nitrate
Parasites (helminths) found in untreated sewage include ________. - ANSWER-
hookworm, round worms, and tapeworms
Viruses are responsible for such diseases as - ANSWER-poliomyelitis and
infectious hepatitis
CORRECT ANSWERS LATEST 2025
_______ and ________ soil textural classes are always unsuitable for standard
absorptive OSSF - ANSWER-class IA and IV
List each of the major soil horizons - ANSWER-surface soil A, surface soil B, and
parent material
_____________ is a term describing the ability of water to migrate through a soil
profile under either _________ or __________ conditions. - ANSWER-Hydraulic
conductivity, saturated, unsaturated
Interconnected pores in the soil profile allow ______ and _______ to enter the
soil at its surface and migrate downward - ANSWER-air, water
List the four components of soil - ANSWER-air, water, organics, inorganics
A drainfield is 50 feet by 90 feet and must be covered with an average of 15
inches of sand loam. How many cubic yards of sandy loam soil must be purchased
(find the volume of a rectangular object)? - ANSWER-208.3 cubic yards
What would be the volume of a 5-foot-diameter pump tank that is 5 feet tall with
the inlet 1 foot below the rim? - ANSWER-587 gals
,What would be the percent slope on a lot 250 feet deep that drops 20 feet in
elevation over the depth of the lot? - ANSWER-8%
How many cubic yards of gravel would be needed to fill a ditch 3 feet deep, 10
feet wide, and 12 feet long with 18 inches of gravel? 1 cubic yard = 27 cubic feet. -
ANSWER-6.67 cubic yards
A septic tank is 6 feet in diameter and is 8 feet deep. How many gallons will it hold
if the overflow line is located half way up from the bottom? - ANSWER-846 gals
Calculate the working liquid capacity (volume) for this septic tank. SEE PAGE 2-
39!! - ANSWER-1077gals
What is the surface area (area in square feet) of an evapotranspiration system 40
feet wide and 65 feet long? - ANSWER-2,600 sqft
Figure the acreage for a piece of property that measures 256 feet on each of four
sides. - ANSWER-1.5 acres
Figure the area of a lot that measures 60ft by 280ft - ANSWER-16,800sqft ,0.39
acres
A disposal option that might be considered in a clay soil would be a ________. -
ANSWER-drip or spray irrigation
The primary treatment device providing the least or poorest treatment of
domestic wastewater would be _______. - ANSWER-septic tank
, Nitrogen or nitrate removal in soil occurs by _________. - ANSWER-vegetation
uptake
The factors influencing the survival of bacteria in soil are _______. - ANSWER-
moisture, temperature, pH, and organic matter.
Physical removal of bacteria by straining occurs when _______. - ANSWER-the
bacteria are larger than the pore openings in the soil
A solid that can be filtered out of the wastewater is a _________. - ANSWER-
suspended solid
Which of the following describes domestic wastewater as it leaves a home? -
ANSWER-fresh, light in color, has dissolved oxygen
Which of the following are problems caused by malfunctioning septic tank
systems? - ANSWER-surface water pollution, groundwater contamination, and
standing sewage in neighborhoods
An inorganic chemical that affects human health is - ANSWER-nitrate
Parasites (helminths) found in untreated sewage include ________. - ANSWER-
hookworm, round worms, and tapeworms
Viruses are responsible for such diseases as - ANSWER-poliomyelitis and
infectious hepatitis
