OSSF DR TEST PRACTICE QUESTIONS AND ANSWERS |FALL 2026/2027 UPDATE | 100% CORRECT
LATEST
Question 1
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.
Correct Answer
6.67 cubic yards
Question 2
When a maintenance contract is required for a single-family residence OSSF, the minimum frequency of site visits and type
of testing is
Correct Answer
once every four months with chlorine residual or fecal coliform testing
Question 3
_____________ is a term describing the ability of water to migrate through a soil profile under either _________ or __________
conditions.
Correct Answer
Hydraulic conductivity, saturated, unsaturated
Page 1 of 38
,Question 4
List the equipment and procedures to protect a work site.
Correct Answer
signs, regulated speed, cones, barricade, high level flags
Question 5
Which of the following is a likely cause of a "rotten egg" odor from an aerobic treatment plant?
Correct Answer
Mechanical aerator failure, hydraulic overload caused by leaking toilet
Question 6
Overall site suitability factors include ________, ________, ___________, and ____________.
Correct Answer
site factor, soil factors, groundwater evaluation, and surface drainage analysis
Question 7
In an unlined ET system, wastewater is disposed of by which of the following?
Correct Answer
evaporation, transpiration, soil absorption
Page 2 of 38
,Question 8
A mound or soil substitution drainfield is often used
Correct Answer
when existing soils will not provide adequate treatment due to depth or texture
Question 9
The area of a lot is 20,076 square feet. What is the area of this lot in acres?
Correct Answer
0.46 acres
Question 10
Grease interceptors are needed
Correct Answer
on wastewater lines from commercial kitchens
Question 11
When would an intermittent sand filter with disinfection system be selected over a properly designed and installed septic
tank system?
Correct Answer
For a standard drainfield in class Ia soil
Page 3 of 38
, Question 12
If a soil forms a ribbon greater than 2 inches, and neither smooth or gritty consistency predominates, the soil is _______,
class _____.
Correct Answer
clay, IV
Question 13
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
Question 14
An LPD system for a new three-bedroom home with 2200 Sq ft (having water-saving devices) with 9-inch-wide trenches
with 1 foot of gravel depth installed in Class III soil would require __________ linear feet of dosing pipe.
Correct Answer
400
Question 15
To determine if a proprietary aerobic treatment unit is appropriate for use with surface application disposal it must
Correct Answer
be on the TCEQ's most recently approved list
Page 4 of 38
LATEST
Question 1
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.
Correct Answer
6.67 cubic yards
Question 2
When a maintenance contract is required for a single-family residence OSSF, the minimum frequency of site visits and type
of testing is
Correct Answer
once every four months with chlorine residual or fecal coliform testing
Question 3
_____________ is a term describing the ability of water to migrate through a soil profile under either _________ or __________
conditions.
Correct Answer
Hydraulic conductivity, saturated, unsaturated
Page 1 of 38
,Question 4
List the equipment and procedures to protect a work site.
Correct Answer
signs, regulated speed, cones, barricade, high level flags
Question 5
Which of the following is a likely cause of a "rotten egg" odor from an aerobic treatment plant?
Correct Answer
Mechanical aerator failure, hydraulic overload caused by leaking toilet
Question 6
Overall site suitability factors include ________, ________, ___________, and ____________.
Correct Answer
site factor, soil factors, groundwater evaluation, and surface drainage analysis
Question 7
In an unlined ET system, wastewater is disposed of by which of the following?
Correct Answer
evaporation, transpiration, soil absorption
Page 2 of 38
,Question 8
A mound or soil substitution drainfield is often used
Correct Answer
when existing soils will not provide adequate treatment due to depth or texture
Question 9
The area of a lot is 20,076 square feet. What is the area of this lot in acres?
Correct Answer
0.46 acres
Question 10
Grease interceptors are needed
Correct Answer
on wastewater lines from commercial kitchens
Question 11
When would an intermittent sand filter with disinfection system be selected over a properly designed and installed septic
tank system?
Correct Answer
For a standard drainfield in class Ia soil
Page 3 of 38
, Question 12
If a soil forms a ribbon greater than 2 inches, and neither smooth or gritty consistency predominates, the soil is _______,
class _____.
Correct Answer
clay, IV
Question 13
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
Question 14
An LPD system for a new three-bedroom home with 2200 Sq ft (having water-saving devices) with 9-inch-wide trenches
with 1 foot of gravel depth installed in Class III soil would require __________ linear feet of dosing pipe.
Correct Answer
400
Question 15
To determine if a proprietary aerobic treatment unit is appropriate for use with surface application disposal it must
Correct Answer
be on the TCEQ's most recently approved list
Page 4 of 38
