CESSWI ACTUAL EXAM – QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED ANSWERS | PLUS
RATIONALES | DOWNLOAD AND PASS | LATEST EXAM UPDATE 2026/2027
1. What is the primary purpose of a Stormwater Pollution Prevention Plan (SWPPP)?
A. To provide a detailed site map for local emergency responders
B. To identify potential sources of pollution and outline best management practices to prevent their discharge
C. To serve as a public document for community review of construction activities
D. To calculate the total maximum daily load for a receiving waterbody
Correct Answer: B. To identify potential sources of pollution and outline best management practices to prevent their
discharge
Rationale: The SWPPP is the foundational document of the National Pollutant Discharge Elimination System (NPDES)
construction permit. Its core function is to identify all potential pollutant sources on a site and detail the specific Best
Management Practices (BMPs) that will be implemented to control erosion, sedimentation, and other pollutants,
preventing their discharge into waters of the U.S. Option A is incorrect as the SWPPP is not an emergency response
map, though it may contain contact information. Option C is incorrect as it is not primarily a public document for
review, though it can be subject to public inspection. Option D is incorrect because TMDLs are a separate regulatory
calculation, not the purpose of a SWPPP.**
,2. A CESSWI is conducting a site inspection and observes that a silt fence is installed along a contour. What is the
most significant issue with this installation?
A. It will be more difficult to maintain
B. The fence will be less visible to equipment operators
C. Water will pond in front of the fence, creating a safety hazard
D. Water is likely to flow around the ends of the fence, rendering it ineffective
Correct Answer: D. Water is likely to flow around the ends of the fence, rendering it ineffective
Rationale: Silt fences are designed to intercept and slow overland sheet flow, allowing sediment to settle. For this to
work effectively, they must be installed on the contour so water is directed into the fence's length, not around it. If
installed on a steep grade or without proper end treatment, water will concentrate and flow around the ends, bypassing
the filtration system. While ponding (C) can occur behind a properly installed fence, it's not the primary issue of a
contour installation. Visibility (B) and maintenance (A) are secondary concerns.**
3. For a typical construction site, which of the following is classified as an authorized non-stormwater discharge?
A. Water from fire hydrant flushing
B. Discharge from a concrete truck washout area
C. Pumped groundwater from a dewatering operation
D. Sanitary wastewater from an on-site portable toilet
,Correct Answer: C. Pumped groundwater from a dewatering operation
Rationale: EPA's NPDES regulations define certain non-stormwater discharges as "authorized" if they are essential to
the construction activity and do not contain pollutants. Dewatering (pumping groundwater) is generally an authorized
discharge, provided it meets specific water quality criteria and is managed to prevent sediment discharge. Fire hydrant
flushing (A) is not a standard construction activity and would require authorization. Concrete washout (B) and sanitary
wastewater (D) are prohibited non-stormwater discharges that must be contained and disposed of off-site.**
4. Which factor most directly influences the erosivity of rainfall on a construction site?
A. The total annual precipitation in the region
B. The intensity and duration of a storm event
C. The soil's organic matter content
D. The type of vegetation present
Correct Answer: B. The intensity and duration of a storm event
Rationale: The erosivity of rainfall is the potential for rain to cause erosion, which is primarily a function of the storm's
intensity (how hard it rains) and duration (how long it rains). High-intensity, short-duration storms produce the most
erosive energy because raindrops impact the soil with great force, detaching particles, and generate large amounts of
, runoff. While total annual precipitation (A) contributes to overall climate, it is not a direct factor for a single event. Soil
organic matter (C) and vegetation (D) are factors of erodibility, not erosivity.**
5. What is the primary function of a sediment basin in a stormwater management system?
A. To intercept and divert runoff away from disturbed areas
B. To provide temporary storage of runoff to allow sediment to settle out
C. To convey concentrated flows down a slope without erosion
D. To filter runoff through a vegetated area
Correct Answer: B. To provide temporary storage of runoff to allow sediment to settle out
Rationale: A sediment basin is a large depression that collects stormwater runoff from the site. Its primary purpose is to
detain the runoff for a sufficient period to allow the force of gravity to settle out suspended soil particles before the
water is discharged. This is a structural, gravity-based BMP. Option A describes a diversion dike or swale. Option C
describes a lined channel or chute. Option D describes a vegetated filter strip or biofilter.**
6. An inspector notices that a temporary diversion dike has a small breach. What is the most appropriate
immediate action?
RATIONALES | DOWNLOAD AND PASS | LATEST EXAM UPDATE 2026/2027
1. What is the primary purpose of a Stormwater Pollution Prevention Plan (SWPPP)?
A. To provide a detailed site map for local emergency responders
B. To identify potential sources of pollution and outline best management practices to prevent their discharge
C. To serve as a public document for community review of construction activities
D. To calculate the total maximum daily load for a receiving waterbody
Correct Answer: B. To identify potential sources of pollution and outline best management practices to prevent their
discharge
Rationale: The SWPPP is the foundational document of the National Pollutant Discharge Elimination System (NPDES)
construction permit. Its core function is to identify all potential pollutant sources on a site and detail the specific Best
Management Practices (BMPs) that will be implemented to control erosion, sedimentation, and other pollutants,
preventing their discharge into waters of the U.S. Option A is incorrect as the SWPPP is not an emergency response
map, though it may contain contact information. Option C is incorrect as it is not primarily a public document for
review, though it can be subject to public inspection. Option D is incorrect because TMDLs are a separate regulatory
calculation, not the purpose of a SWPPP.**
,2. A CESSWI is conducting a site inspection and observes that a silt fence is installed along a contour. What is the
most significant issue with this installation?
A. It will be more difficult to maintain
B. The fence will be less visible to equipment operators
C. Water will pond in front of the fence, creating a safety hazard
D. Water is likely to flow around the ends of the fence, rendering it ineffective
Correct Answer: D. Water is likely to flow around the ends of the fence, rendering it ineffective
Rationale: Silt fences are designed to intercept and slow overland sheet flow, allowing sediment to settle. For this to
work effectively, they must be installed on the contour so water is directed into the fence's length, not around it. If
installed on a steep grade or without proper end treatment, water will concentrate and flow around the ends, bypassing
the filtration system. While ponding (C) can occur behind a properly installed fence, it's not the primary issue of a
contour installation. Visibility (B) and maintenance (A) are secondary concerns.**
3. For a typical construction site, which of the following is classified as an authorized non-stormwater discharge?
A. Water from fire hydrant flushing
B. Discharge from a concrete truck washout area
C. Pumped groundwater from a dewatering operation
D. Sanitary wastewater from an on-site portable toilet
,Correct Answer: C. Pumped groundwater from a dewatering operation
Rationale: EPA's NPDES regulations define certain non-stormwater discharges as "authorized" if they are essential to
the construction activity and do not contain pollutants. Dewatering (pumping groundwater) is generally an authorized
discharge, provided it meets specific water quality criteria and is managed to prevent sediment discharge. Fire hydrant
flushing (A) is not a standard construction activity and would require authorization. Concrete washout (B) and sanitary
wastewater (D) are prohibited non-stormwater discharges that must be contained and disposed of off-site.**
4. Which factor most directly influences the erosivity of rainfall on a construction site?
A. The total annual precipitation in the region
B. The intensity and duration of a storm event
C. The soil's organic matter content
D. The type of vegetation present
Correct Answer: B. The intensity and duration of a storm event
Rationale: The erosivity of rainfall is the potential for rain to cause erosion, which is primarily a function of the storm's
intensity (how hard it rains) and duration (how long it rains). High-intensity, short-duration storms produce the most
erosive energy because raindrops impact the soil with great force, detaching particles, and generate large amounts of
, runoff. While total annual precipitation (A) contributes to overall climate, it is not a direct factor for a single event. Soil
organic matter (C) and vegetation (D) are factors of erodibility, not erosivity.**
5. What is the primary function of a sediment basin in a stormwater management system?
A. To intercept and divert runoff away from disturbed areas
B. To provide temporary storage of runoff to allow sediment to settle out
C. To convey concentrated flows down a slope without erosion
D. To filter runoff through a vegetated area
Correct Answer: B. To provide temporary storage of runoff to allow sediment to settle out
Rationale: A sediment basin is a large depression that collects stormwater runoff from the site. Its primary purpose is to
detain the runoff for a sufficient period to allow the force of gravity to settle out suspended soil particles before the
water is discharged. This is a structural, gravity-based BMP. Option A describes a diversion dike or swale. Option C
describes a lined channel or chute. Option D describes a vegetated filter strip or biofilter.**
6. An inspector notices that a temporary diversion dike has a small breach. What is the most appropriate
immediate action?
