TEXAS OSSF INSTALLER II COMPREHENSIVE
EXAM ACTUAL PREP QUESTIONS AND WELL
REVISED ANSWERS - LATEST AND COMPLETE
UPDATE WITH VERIFIED SOLUTIONS –
ASSURES PASS
1. When installing a conventional septic system, the minimum separation
distance between the bottom of the absorption trench and the limiting zone
(e.g., bedrock, clay layer, seasonal high water table) is:
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: Texas Administrative Code requires at least 18 inches of
suitable soil between the trench bottom and the limiting zone to allow
adequate treatment and soil absorption.
2. A soil evaluation indicates a soil with a percolation rate of 45 minutes per
inch. According to Texas OSSF rules, this site:
A. Can use any type of absorption system
B. Requires a mound system
C. May require a raised bed system
D. Is unsuitable for any OSSF
Rationale: Soils with slow percolation rates (greater than 30 minutes/inch)
may require modified systems such as raised beds or mounds to achieve
proper effluent treatment.
3. What is the primary function of a distribution box in a conventional septic
system?
, A. To treat effluent biologically
B. To evenly distribute effluent to absorption trenches
C. To aerate effluent before discharge
D. To measure effluent volume
Rationale: A distribution box ensures uniform flow to multiple trenches,
preventing overloading in any single trench.
4. Which of the following is an approved effluent filter location in a Texas
OSSF?
A. At the septic tank inlet
B. At the septic tank outlet
C. Inside the absorption trench
D. At the lateral ends of the drainfield
Rationale: Outlet filters prevent solids from leaving the tank and entering
the absorption system, protecting soil from clogging.
5. During a site evaluation, the installer observes perched water above a
restrictive clay layer. The best action is to:
A. Excavate deeper trenches to bypass the water
B. Consider an alternative system design, such as a mound or elevated
sand filter
C. Ignore the perched water
D. Reduce trench length
Rationale: Perched water can lead to system failure. Alternative systems
are designed to maintain separation from water tables.
6. In Texas, what is the maximum allowable daily design flow for a single-
family residence using a conventional septic system without requiring an
engineering design?
A. 150 gallons
, B. 200 gallons
C. 250 gallons
D. 300 gallons
Rationale: The TCEQ rules set a maximum of 250 gallons per day for
standard single-family OSSF systems.
7. Which of the following soil textures provides the most reliable treatment for
effluent in a conventional absorption trench?
A. Sand with >85% coarse particles
B. Clay
C. Loamy sand or sandy loam
D. Gravel
Rationale: Loamy sand balances permeability and treatment capacity. Too
coarse drains too fast; clay drains too slowly.
8. A homeowner calls you to report sewage backing up into their house. On
inspection, you find the absorption field saturated. The most immediate
corrective action is to:
A. Add more water to dilute solids
B. Pump the septic tank and restrict water use
C. Excavate new trenches immediately
D. Apply chemical treatment to the tank
Rationale: Pumping relieves tank and field overload. Controlling water
use prevents further stress while assessing permanent repair.
9. The Texas OSSF rules define a "limiting zone" as:
A. A soil or geologic layer that restricts the downward movement of
effluent
B. The maximum property boundary for installation
C. The distance from the septic tank to the house
, D. A regulatory buffer between systems
Rationale: Limiting zones, such as bedrock, clay, or seasonal high water
tables, affect design depth and system type.
10.When constructing trenches for a conventional system, the recommended
trench width is typically:
A. 6–8 inches
B. 12–18 inches
C. 24 inches
D. 36–48 inches
Rationale: Texas OSSF guidelines recommend trenches 24 inches wide
for standard gravel trenches to ensure proper effluent distribution.
11.Which factor most directly influences the sizing of an absorption field?
A. Tank brand
B. House square footage
C. Soil type and daily flow rate
D. Pump model
Rationale: Soil permeability and wastewater flow are the primary
determinants for trench length and system sizing.
12.A mound system is indicated when:
A. Soil is deep and sandy
B. Groundwater is very low
C. The natural soil lacks sufficient depth or permeability
D. The lot size is extremely large
Rationale: Mounds provide additional treatment media where native soil is
shallow or restrictive.
13.The primary mechanism of effluent treatment in soil absorption systems is:
A. Filtration, adsorption, and microbial degradation
EXAM ACTUAL PREP QUESTIONS AND WELL
REVISED ANSWERS - LATEST AND COMPLETE
UPDATE WITH VERIFIED SOLUTIONS –
ASSURES PASS
1. When installing a conventional septic system, the minimum separation
distance between the bottom of the absorption trench and the limiting zone
(e.g., bedrock, clay layer, seasonal high water table) is:
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: Texas Administrative Code requires at least 18 inches of
suitable soil between the trench bottom and the limiting zone to allow
adequate treatment and soil absorption.
2. A soil evaluation indicates a soil with a percolation rate of 45 minutes per
inch. According to Texas OSSF rules, this site:
A. Can use any type of absorption system
B. Requires a mound system
C. May require a raised bed system
D. Is unsuitable for any OSSF
Rationale: Soils with slow percolation rates (greater than 30 minutes/inch)
may require modified systems such as raised beds or mounds to achieve
proper effluent treatment.
3. What is the primary function of a distribution box in a conventional septic
system?
, A. To treat effluent biologically
B. To evenly distribute effluent to absorption trenches
C. To aerate effluent before discharge
D. To measure effluent volume
Rationale: A distribution box ensures uniform flow to multiple trenches,
preventing overloading in any single trench.
4. Which of the following is an approved effluent filter location in a Texas
OSSF?
A. At the septic tank inlet
B. At the septic tank outlet
C. Inside the absorption trench
D. At the lateral ends of the drainfield
Rationale: Outlet filters prevent solids from leaving the tank and entering
the absorption system, protecting soil from clogging.
5. During a site evaluation, the installer observes perched water above a
restrictive clay layer. The best action is to:
A. Excavate deeper trenches to bypass the water
B. Consider an alternative system design, such as a mound or elevated
sand filter
C. Ignore the perched water
D. Reduce trench length
Rationale: Perched water can lead to system failure. Alternative systems
are designed to maintain separation from water tables.
6. In Texas, what is the maximum allowable daily design flow for a single-
family residence using a conventional septic system without requiring an
engineering design?
A. 150 gallons
, B. 200 gallons
C. 250 gallons
D. 300 gallons
Rationale: The TCEQ rules set a maximum of 250 gallons per day for
standard single-family OSSF systems.
7. Which of the following soil textures provides the most reliable treatment for
effluent in a conventional absorption trench?
A. Sand with >85% coarse particles
B. Clay
C. Loamy sand or sandy loam
D. Gravel
Rationale: Loamy sand balances permeability and treatment capacity. Too
coarse drains too fast; clay drains too slowly.
8. A homeowner calls you to report sewage backing up into their house. On
inspection, you find the absorption field saturated. The most immediate
corrective action is to:
A. Add more water to dilute solids
B. Pump the septic tank and restrict water use
C. Excavate new trenches immediately
D. Apply chemical treatment to the tank
Rationale: Pumping relieves tank and field overload. Controlling water
use prevents further stress while assessing permanent repair.
9. The Texas OSSF rules define a "limiting zone" as:
A. A soil or geologic layer that restricts the downward movement of
effluent
B. The maximum property boundary for installation
C. The distance from the septic tank to the house
, D. A regulatory buffer between systems
Rationale: Limiting zones, such as bedrock, clay, or seasonal high water
tables, affect design depth and system type.
10.When constructing trenches for a conventional system, the recommended
trench width is typically:
A. 6–8 inches
B. 12–18 inches
C. 24 inches
D. 36–48 inches
Rationale: Texas OSSF guidelines recommend trenches 24 inches wide
for standard gravel trenches to ensure proper effluent distribution.
11.Which factor most directly influences the sizing of an absorption field?
A. Tank brand
B. House square footage
C. Soil type and daily flow rate
D. Pump model
Rationale: Soil permeability and wastewater flow are the primary
determinants for trench length and system sizing.
12.A mound system is indicated when:
A. Soil is deep and sandy
B. Groundwater is very low
C. The natural soil lacks sufficient depth or permeability
D. The lot size is extremely large
Rationale: Mounds provide additional treatment media where native soil is
shallow or restrictive.
13.The primary mechanism of effluent treatment in soil absorption systems is:
A. Filtration, adsorption, and microbial degradation
