OSSF DR TEST PRACTICE EXAM QUESTIONS WITH
SOLVED ANSWERS.
_______ adopted the current OSSF Rules in 1997 and revised them several times -
CORRECT ANSWER✅✅TCEQ
_______ and ________ soil textural classes are always unsuitable for standard
absorptive OSSF - CORRECT ANSWER✅✅class IA and IV
_____________ is a term describing the ability of water to migrate through a soil profile
under either _________ or __________ conditions. - CORRECT
ANSWER✅✅Hydraulic conductivity, saturated, unsaturated
A common reason for wastewater system failure is __________. - CORRECT
ANSWER✅✅hydraulic overloading (due to modernized tank usually)
A disposal option that might be considered in a clay soil would be a ________. -
CORRECT ANSWER✅✅drip or spray irrigation
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)? - CORRECT ANSWER✅✅208.3 cubic yards
A drip irrigation system must - CORRECT ANSWER✅✅be equipped with mechanisms
to flush from the drainfield back to the treatment unit or pump tank
A gravelless pipe drainfield - CORRECT ANSWER✅✅can be backfilled with Class Ib,
II, or III soil
A leaching chamber system - CORRECT ANSWER✅✅requires 25% less absorptive
area than a standard system for new construction
A maintenance provider for a surface application OSSF using a proprietary aerobic
plant must have an employee who is - CORRECT ANSWER✅✅a licensed
maintenance provider or a registered maintenance technician
A minimum lot size of _______ acre is required for subdivisions serviced by _________
water. The minimum size is ______ acre for those serviced by ___________. -
CORRECT ANSWER✅✅0.5, public, 1, private well
, A mound or soil substitution drainfield is often used - CORRECT ANSWER✅✅when
existing soils will not provide adequate treatment due to depth or texture
A particular hazard that OSSF installers face that most construction workers do not is
_______. - CORRECT ANSWER✅✅infectious waterborne diseases
A pumped effluent drainfield - CORRECT ANSWER✅✅is an alternative for well-
drained clay soils on nearly level sites, has a 2% or less slope for single-family
dwellings only
A septic tank had a working volume of 31 cubic feet. How many gallons does this septic
tank hold? - CORRECT ANSWER✅✅approx. 232 gals
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? - CORRECT ANSWER✅✅846
gals
A septic tank serving a new five-bedroom home with 3800 sqft must have a minimum
capacity of - CORRECT ANSWER✅✅1,250 gallons
A soil color pattern of orange and brown on a background of gray or bluish color is
called - CORRECT ANSWER✅✅mottling
A solid that can be filtered out of the wastewater is a _________. - CORRECT
ANSWER✅✅suspended solid
A standard drainfield excavation should - CORRECT ANSWER✅✅be level within 1
inch per 25 feet or a maximum of 3 inches whichever is less
A standard perforated drainline should be which of the following? - CORRECT
ANSWER✅✅3 inches to 4 inches in diameter, a maximum length of 150 feet, laid
parallel in multiple-line system
A trench measures 30 inches wide. How wide is the trench in feet? - CORRECT
ANSWER✅✅2.5'
A trench requires 430 cubic feet of gravel. How many cubic yards must be purchased? -
CORRECT ANSWER✅✅16 cubic yards
A type of bacteria that indicates sewage contamination is ________. - CORRECT
ANSWER✅✅fecal coliform
Aerobic treatment units - CORRECT ANSWER✅✅utilize aerobic bacteria and oxygen
to break down complex organics and produce carbon dioxide
SOLVED ANSWERS.
_______ adopted the current OSSF Rules in 1997 and revised them several times -
CORRECT ANSWER✅✅TCEQ
_______ and ________ soil textural classes are always unsuitable for standard
absorptive OSSF - CORRECT ANSWER✅✅class IA and IV
_____________ is a term describing the ability of water to migrate through a soil profile
under either _________ or __________ conditions. - CORRECT
ANSWER✅✅Hydraulic conductivity, saturated, unsaturated
A common reason for wastewater system failure is __________. - CORRECT
ANSWER✅✅hydraulic overloading (due to modernized tank usually)
A disposal option that might be considered in a clay soil would be a ________. -
CORRECT ANSWER✅✅drip or spray irrigation
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)? - CORRECT ANSWER✅✅208.3 cubic yards
A drip irrigation system must - CORRECT ANSWER✅✅be equipped with mechanisms
to flush from the drainfield back to the treatment unit or pump tank
A gravelless pipe drainfield - CORRECT ANSWER✅✅can be backfilled with Class Ib,
II, or III soil
A leaching chamber system - CORRECT ANSWER✅✅requires 25% less absorptive
area than a standard system for new construction
A maintenance provider for a surface application OSSF using a proprietary aerobic
plant must have an employee who is - CORRECT ANSWER✅✅a licensed
maintenance provider or a registered maintenance technician
A minimum lot size of _______ acre is required for subdivisions serviced by _________
water. The minimum size is ______ acre for those serviced by ___________. -
CORRECT ANSWER✅✅0.5, public, 1, private well
, A mound or soil substitution drainfield is often used - CORRECT ANSWER✅✅when
existing soils will not provide adequate treatment due to depth or texture
A particular hazard that OSSF installers face that most construction workers do not is
_______. - CORRECT ANSWER✅✅infectious waterborne diseases
A pumped effluent drainfield - CORRECT ANSWER✅✅is an alternative for well-
drained clay soils on nearly level sites, has a 2% or less slope for single-family
dwellings only
A septic tank had a working volume of 31 cubic feet. How many gallons does this septic
tank hold? - CORRECT ANSWER✅✅approx. 232 gals
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? - CORRECT ANSWER✅✅846
gals
A septic tank serving a new five-bedroom home with 3800 sqft must have a minimum
capacity of - CORRECT ANSWER✅✅1,250 gallons
A soil color pattern of orange and brown on a background of gray or bluish color is
called - CORRECT ANSWER✅✅mottling
A solid that can be filtered out of the wastewater is a _________. - CORRECT
ANSWER✅✅suspended solid
A standard drainfield excavation should - CORRECT ANSWER✅✅be level within 1
inch per 25 feet or a maximum of 3 inches whichever is less
A standard perforated drainline should be which of the following? - CORRECT
ANSWER✅✅3 inches to 4 inches in diameter, a maximum length of 150 feet, laid
parallel in multiple-line system
A trench measures 30 inches wide. How wide is the trench in feet? - CORRECT
ANSWER✅✅2.5'
A trench requires 430 cubic feet of gravel. How many cubic yards must be purchased? -
CORRECT ANSWER✅✅16 cubic yards
A type of bacteria that indicates sewage contamination is ________. - CORRECT
ANSWER✅✅fecal coliform
Aerobic treatment units - CORRECT ANSWER✅✅utilize aerobic bacteria and oxygen
to break down complex organics and produce carbon dioxide
