Minnesota Subsurface Sewage
Treatment System Soil Evaluator Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a soil evaluation for SSTS design?
A. To determine property value
B. To identify suitable soil conditions for wastewater treatment
C. To locate underground utilities
D. To test drinking water quality
Answer: B
Rationale: Soil evaluation determines if soil can properly treat and
disperse wastewater before it reaches groundwater or bedrock.
2. The most important soil property affecting wastewater treatment is:
A. Soil color
B. Soil texture and structure
C. Soil temperature
, D. Soil odor
Answer: B
Rationale: Texture and structure control water movement, oxygen
flow, and treatment capacity.
3. A mottled soil profile typically indicates:
A. Excessive drainage
B. Seasonal saturation or high water table
C. Sandy soil only
D. Volcanic soil origin
Answer: B
Rationale: Mottling is caused by fluctuating groundwater levels and
reducing conditions.
4. Soil texture refers to:
A. Soil color variation
B. Proportion of sand, silt, and clay
C. Organic matter content
D. Soil density only
Answer: B
Rationale: Texture is defined by the relative percentages of mineral
particle sizes.
5. Which soil horizon is most important for wastewater treatment?
A. O horizon
B. A and upper B horizons
, C. C horizon only
D. Bedrock layer
Answer: B
Rationale: These layers provide biological and physical filtration of
effluent.
6. A limiting layer in soil evaluation refers to:
A. Fertile soil zone
B. Layer restricting wastewater movement or treatment
C. Topsoil layer only
D. Organic mulch layer
Answer: B
Rationale: Limiting layers include bedrock, high water tables, or
dense till.
7. Percolation rate measures:
A. Soil color change
B. Water absorption speed in soil
C. Soil nutrient content
D. Air temperature in soil
Answer: B
Rationale: It determines how quickly water moves through soil.
8. Soil structure refers to:
A. Soil chemical composition
B. Arrangement of soil particles into aggregates
, C. Soil depth only
D. Soil moisture level
Answer: B
Rationale: Structure affects pore space and water movement.
9. The best indicator of seasonal high water table is:
A. Dry soil surface
B. Redoximorphic features (mottling)
C. Soil smell
D. Vegetation type alone
Answer: B
Rationale: Redoximorphic features form under saturated conditions.
10. Which soil texture drains fastest?
A. Clay
B. Silt
C. Sand
D. Loam
Answer: C
Rationale: Sand has large particles and high permeability.
11. Clay soils are problematic because they:
A. Drain too quickly
B. Restrict water movement and oxygen flow
C. Contain too much gravel
D. Have no organic matter
Treatment System Soil Evaluator Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a soil evaluation for SSTS design?
A. To determine property value
B. To identify suitable soil conditions for wastewater treatment
C. To locate underground utilities
D. To test drinking water quality
Answer: B
Rationale: Soil evaluation determines if soil can properly treat and
disperse wastewater before it reaches groundwater or bedrock.
2. The most important soil property affecting wastewater treatment is:
A. Soil color
B. Soil texture and structure
C. Soil temperature
, D. Soil odor
Answer: B
Rationale: Texture and structure control water movement, oxygen
flow, and treatment capacity.
3. A mottled soil profile typically indicates:
A. Excessive drainage
B. Seasonal saturation or high water table
C. Sandy soil only
D. Volcanic soil origin
Answer: B
Rationale: Mottling is caused by fluctuating groundwater levels and
reducing conditions.
4. Soil texture refers to:
A. Soil color variation
B. Proportion of sand, silt, and clay
C. Organic matter content
D. Soil density only
Answer: B
Rationale: Texture is defined by the relative percentages of mineral
particle sizes.
5. Which soil horizon is most important for wastewater treatment?
A. O horizon
B. A and upper B horizons
, C. C horizon only
D. Bedrock layer
Answer: B
Rationale: These layers provide biological and physical filtration of
effluent.
6. A limiting layer in soil evaluation refers to:
A. Fertile soil zone
B. Layer restricting wastewater movement or treatment
C. Topsoil layer only
D. Organic mulch layer
Answer: B
Rationale: Limiting layers include bedrock, high water tables, or
dense till.
7. Percolation rate measures:
A. Soil color change
B. Water absorption speed in soil
C. Soil nutrient content
D. Air temperature in soil
Answer: B
Rationale: It determines how quickly water moves through soil.
8. Soil structure refers to:
A. Soil chemical composition
B. Arrangement of soil particles into aggregates
, C. Soil depth only
D. Soil moisture level
Answer: B
Rationale: Structure affects pore space and water movement.
9. The best indicator of seasonal high water table is:
A. Dry soil surface
B. Redoximorphic features (mottling)
C. Soil smell
D. Vegetation type alone
Answer: B
Rationale: Redoximorphic features form under saturated conditions.
10. Which soil texture drains fastest?
A. Clay
B. Silt
C. Sand
D. Loam
Answer: C
Rationale: Sand has large particles and high permeability.
11. Clay soils are problematic because they:
A. Drain too quickly
B. Restrict water movement and oxygen flow
C. Contain too much gravel
D. Have no organic matter
