ICC ECP Soils Plans Module Practice
Exam with Practice Questions And
Correct
1. A site's geotechnical report classifies the native soil as CH (high-plasticity clay) with
a liquid limit of 65 and plasticity index of 35. The erosion control plan proposes using
the excavated clay as a compacted fill for a structural pad. Which of the following best
explains why this material is unsuitable without treatment?
A. High plasticity clays are prone to significant volume change with moisture
fluctuation, leading to differential settlement and structural distress.
B. CH soils have low permeability, which prevents proper compaction and requires
excessive water during construction.
C. High-plasticity clays are highly erodible and will fail under concentrated stormwater
flows, causing sediment discharge.
D. CH soils have low shear strength and cannot achieve the required bearing capacity
even when compacted.
Answer: A. High plasticity clays are prone to significant volume change with moisture
fluctuation, leading to differential settlement and structural distress.
Rationale: CH clays exhibit high shrink-swell potential due to their plasticity, causing
volume changes that can damage structures. Option B is incorrect because low
permeability does not prevent compaction; it affects drainage. Option C mischaracterizes
erodibility-clays are generally less erodible but dispersive clays can be an exception.
Option D is false; compacted CH can have adequate shear strength if moisture-controlled.
Page 1 of 81
,2. During a plan review, you notice that the proposed sediment basin has a volume of
3,600 cubic feet and a drainage area of 5 acres. Local regulations require a sediment
basin to provide at least 3,600 cubic feet per acre of drainage area. Which of the
following is the most appropriate action?
A. Approve the plan because the basin volume meets the minimum requirement for the
given drainage area.
B. Require the basin volume to be increased to 18,000 cubic feet to comply with the
regulation.
C. Request a variance because the basin is oversized for the site's soil type.
D. Recommend adding a forebay to compensate for the volume deficit without resizing
the basin.
Answer: B. Require the basin volume to be increased to 18,000 cubic feet to comply
with the regulation.
Rationale: The regulation requires 3,600 ft³ per acre, so for 5 acres the minimum is 18,000
ft³. The proposed 3,600 ft³ is only one-fifth of the requirement. Option A is incorrect
because the volume is far below the minimum. Option C is wrong because the basin is
undersized, not oversized. Option D does not address the volume deficiency and forebays
do not replace required storage.
Page 2 of 81
,3. A developer proposes a stormwater management plan that relies solely on a dry
detention basin to meet peak flow attenuation requirements. The site is underlain by
karst geology with known sinkholes. Which of the following is the most significant
concern with this approach?
A. Dry detention basins are ineffective at removing pollutants and will violate NPDES
permit limits.
B. Karst geology increases the risk of sinkhole formation and groundwater contamination
due to concentrated infiltration.
C. The basin will not provide adequate peak flow reduction because karst soils have high
permeability.
D. Karst geology requires the use of wet detention basins to maintain a permanent pool
for treatment.
Answer: B. Karst geology increases the risk of sinkhole formation and groundwater
contamination due to concentrated infiltration.
Rationale: In karst areas, concentrated stormwater infiltration can trigger sinkholes and
allow contaminants to enter groundwater rapidly. Option A is not the most significant
concern; pollutant removal is secondary to geotechnical risk. Option C is incorrect
because karst permeability does not negate peak flow attenuation; the basin still detains
surface runoff. Option D is not universally required; wet basins may also pose risks in
karst.
4. A plan reviewer must determine the appropriate Soil Loss Ratio (SLR) for a
construction site using the Revised Universal Soil Loss Equation (RUSLE). The site
has a cover-management factor (C) of 0.15 and a support practice factor (P) of 0.8. If
the baseline C for bare soil is 1.0 and P is 1.0, what is the SLR?
A. 0.12
B. 0.15
C. 0.80
D. 0.95
Answer: A. 0.12
Rationale: SLR is calculated as C × P divided by the baseline C × P (1.0 × 1.0). Thus SLR =
(0.15 × 0.8) / 1.0 = 0.12. Options B, C, and D are incorrect because they do not multiply
both factors or misapply the baseline.
Page 3 of 81
, 5. During a site inspection, you observe that a silt fence has been installed along a
property line at the top of a 3:1 slope. The fence is 18 inches high with a 6-inch
compost filter sock placed at its base. Which of the following is the most critical
deficiency?
A. Silt fence should be placed at the toe of the slope, not the top, to intercept
sediment-laden runoff.
B. The fence height is insufficient; silt fence must be at least 24 inches high.
C. The compost filter sock is redundant and will reduce the fence's structural integrity.
D. Silt fence is not appropriate for slopes steeper than 4:1; a sediment basin is required.
Answer: A. Silt fence should be placed at the toe of the slope, not the top, to intercept
sediment-laden runoff.
Rationale: Silt fence is designed to intercept sheet flow; placing it at the top of a slope
allows runoff to concentrate and bypass it. It should be installed at the toe or along the
contour. Option B is incorrect; typical silt fence height is 16-18 inches, though some specs
require 24 inches. Option C is false; compost socks can enhance filtration without
compromising integrity. Option D is false; silt fence can be used on steep slopes if properly
entrenched and spaced.
6. A site's SWPPP includes a sequence of construction activities. The plan states:
'Install perimeter controls, then clear and grub, then construct sediment basin, then
install stabilized construction entrance.' Which of the following best evaluates this
sequence?
A. The sequence is correct because perimeter controls must be installed before any land
disturbance.
B. The sequence is incorrect because the sediment basin should be constructed before
clearing and grubbing.
C. The sequence is correct because the construction entrance is needed only after
clearing.
D. The sequence is incorrect because the stabilized construction entrance must be
installed first to prevent tracking.
Answer: B. The sequence is incorrect because the sediment basin should be
constructed before clearing and grubbing.
Rationale: Sediment basins should be installed early in the construction sequence, before
major clearing, to provide immediate sediment capture. Perimeter controls are also early,
Page 4 of 81
Exam with Practice Questions And
Correct
1. A site's geotechnical report classifies the native soil as CH (high-plasticity clay) with
a liquid limit of 65 and plasticity index of 35. The erosion control plan proposes using
the excavated clay as a compacted fill for a structural pad. Which of the following best
explains why this material is unsuitable without treatment?
A. High plasticity clays are prone to significant volume change with moisture
fluctuation, leading to differential settlement and structural distress.
B. CH soils have low permeability, which prevents proper compaction and requires
excessive water during construction.
C. High-plasticity clays are highly erodible and will fail under concentrated stormwater
flows, causing sediment discharge.
D. CH soils have low shear strength and cannot achieve the required bearing capacity
even when compacted.
Answer: A. High plasticity clays are prone to significant volume change with moisture
fluctuation, leading to differential settlement and structural distress.
Rationale: CH clays exhibit high shrink-swell potential due to their plasticity, causing
volume changes that can damage structures. Option B is incorrect because low
permeability does not prevent compaction; it affects drainage. Option C mischaracterizes
erodibility-clays are generally less erodible but dispersive clays can be an exception.
Option D is false; compacted CH can have adequate shear strength if moisture-controlled.
Page 1 of 81
,2. During a plan review, you notice that the proposed sediment basin has a volume of
3,600 cubic feet and a drainage area of 5 acres. Local regulations require a sediment
basin to provide at least 3,600 cubic feet per acre of drainage area. Which of the
following is the most appropriate action?
A. Approve the plan because the basin volume meets the minimum requirement for the
given drainage area.
B. Require the basin volume to be increased to 18,000 cubic feet to comply with the
regulation.
C. Request a variance because the basin is oversized for the site's soil type.
D. Recommend adding a forebay to compensate for the volume deficit without resizing
the basin.
Answer: B. Require the basin volume to be increased to 18,000 cubic feet to comply
with the regulation.
Rationale: The regulation requires 3,600 ft³ per acre, so for 5 acres the minimum is 18,000
ft³. The proposed 3,600 ft³ is only one-fifth of the requirement. Option A is incorrect
because the volume is far below the minimum. Option C is wrong because the basin is
undersized, not oversized. Option D does not address the volume deficiency and forebays
do not replace required storage.
Page 2 of 81
,3. A developer proposes a stormwater management plan that relies solely on a dry
detention basin to meet peak flow attenuation requirements. The site is underlain by
karst geology with known sinkholes. Which of the following is the most significant
concern with this approach?
A. Dry detention basins are ineffective at removing pollutants and will violate NPDES
permit limits.
B. Karst geology increases the risk of sinkhole formation and groundwater contamination
due to concentrated infiltration.
C. The basin will not provide adequate peak flow reduction because karst soils have high
permeability.
D. Karst geology requires the use of wet detention basins to maintain a permanent pool
for treatment.
Answer: B. Karst geology increases the risk of sinkhole formation and groundwater
contamination due to concentrated infiltration.
Rationale: In karst areas, concentrated stormwater infiltration can trigger sinkholes and
allow contaminants to enter groundwater rapidly. Option A is not the most significant
concern; pollutant removal is secondary to geotechnical risk. Option C is incorrect
because karst permeability does not negate peak flow attenuation; the basin still detains
surface runoff. Option D is not universally required; wet basins may also pose risks in
karst.
4. A plan reviewer must determine the appropriate Soil Loss Ratio (SLR) for a
construction site using the Revised Universal Soil Loss Equation (RUSLE). The site
has a cover-management factor (C) of 0.15 and a support practice factor (P) of 0.8. If
the baseline C for bare soil is 1.0 and P is 1.0, what is the SLR?
A. 0.12
B. 0.15
C. 0.80
D. 0.95
Answer: A. 0.12
Rationale: SLR is calculated as C × P divided by the baseline C × P (1.0 × 1.0). Thus SLR =
(0.15 × 0.8) / 1.0 = 0.12. Options B, C, and D are incorrect because they do not multiply
both factors or misapply the baseline.
Page 3 of 81
, 5. During a site inspection, you observe that a silt fence has been installed along a
property line at the top of a 3:1 slope. The fence is 18 inches high with a 6-inch
compost filter sock placed at its base. Which of the following is the most critical
deficiency?
A. Silt fence should be placed at the toe of the slope, not the top, to intercept
sediment-laden runoff.
B. The fence height is insufficient; silt fence must be at least 24 inches high.
C. The compost filter sock is redundant and will reduce the fence's structural integrity.
D. Silt fence is not appropriate for slopes steeper than 4:1; a sediment basin is required.
Answer: A. Silt fence should be placed at the toe of the slope, not the top, to intercept
sediment-laden runoff.
Rationale: Silt fence is designed to intercept sheet flow; placing it at the top of a slope
allows runoff to concentrate and bypass it. It should be installed at the toe or along the
contour. Option B is incorrect; typical silt fence height is 16-18 inches, though some specs
require 24 inches. Option C is false; compost socks can enhance filtration without
compromising integrity. Option D is false; silt fence can be used on steep slopes if properly
entrenched and spaced.
6. A site's SWPPP includes a sequence of construction activities. The plan states:
'Install perimeter controls, then clear and grub, then construct sediment basin, then
install stabilized construction entrance.' Which of the following best evaluates this
sequence?
A. The sequence is correct because perimeter controls must be installed before any land
disturbance.
B. The sequence is incorrect because the sediment basin should be constructed before
clearing and grubbing.
C. The sequence is correct because the construction entrance is needed only after
clearing.
D. The sequence is incorrect because the stabilized construction entrance must be
installed first to prevent tracking.
Answer: B. The sequence is incorrect because the sediment basin should be
constructed before clearing and grubbing.
Rationale: Sediment basins should be installed early in the construction sequence, before
major clearing, to provide immediate sediment capture. Perimeter controls are also early,
Page 4 of 81
