ILLICIT DISCHARGE DETECTION AND ELIMINATION (IDDE)
CERTIFICATION EXAM PRACTICE QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALE Q&A INSTANT DOWNLOAD PDF
110 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze stormwater regulations and IDDE program requirements under federal and state law
2 Design and evaluate dry-weather screening and monitoring protocols for outfall detection
3 Apply chemical, biological, and physical indicators to trace illicit discharges to their sources
4 Develop and justify enforcement and remediation strategies for various discharge scenarios
5 Synthesize data from multiple sources to prioritize and manage IDDE program resources
6 Illicit Discharge Detection and Elimination
7 IDDE
8 Certification Exam Practice Questions And Correct Answers
9 Verified Answers
10 Plus Rationale Q&A Instant Download Pdf
11 Foundations of Environmental Engineering & Stormwater Management
12 Applied Environmental Engineering & Stormwater Management
13 Advanced Environmental Engineering & Stormwater Management
14 Environmental Engineering & Stormwater Management Review
Page 1
,Q1 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A municipality's MS4 permit requires IDDE but allows flexibility in outfall
screening frequency. Which approach best balances legal compliance and
resource efficiency for a large watershed with 200 outfalls?
A. Screen all outfalls annually during dry weather regardless of land use.
B. Prioritize high-risk outfalls (industrial, commercial) for quarterly screening; screen others
biannually. CORRECT
C. Screen only outfalls with known historical illicit discharges.
D. Conduct continuous automated monitoring at all outfalls.
RATIONALE: Prioritizing high-risk areas aligns with EPA guidance and common permit language
that requires screening 'as necessary' based on risk. Annual screening of all outfalls is not
required and wastes resources; only screening known discharges misses new ones; continuous
monitoring is cost-prohibitive.
Q2 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
During dry-weather screening, an outfall shows a chlorine residual of 0.2 mg/L and
a pH of 9.0. Which illicit discharge is most likely?
A. Sanitary sewage
B. Industrial cooling water
C. Swimming pool water CORRECT
D. Vehicle wash water
RATIONALE: Chlorine residual and elevated pH are classic indicators of swimming pool
discharge. Sanitary sewage typically has high BOD and bacteria but no chlorine; cooling water
may have elevated temperature but not chlorine; wash water often has surfactants.
Page 2
,Q3 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A dye test is being used to trace an illicit connection. Which condition is essential
to ensure the test's validity?
A. Dye is introduced upstream and observed at the suspected outfall during dry weather.
CORRECT
B. Dye is introduced at the outfall and observed upstream.
C. Dye is visible in the receiving water within 30 minutes.
D. Dye is non-toxic and biodegradable.
RATIONALE: Dye testing involves introducing dye at a suspected source (upstream) and
observing its appearance at the outfall (downstream) to confirm a connection. Introducing at the
outfall would not trace the source. Visibility time is not a validity criterion; non-toxicity is important
but not the essential condition for tracing.
Q4 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A municipality has a Phase II MS4 permit. Which activity is NOT required by the
EPA's IDDE minimum control measure?
A. Develop a storm sewer map showing all outfalls and receiving waters.
B. Prohibit non-stormwater discharges through ordinance or other regulatory mechanism.
C. Implement a program to detect and address illicit discharges.
D. Require all commercial car washes to obtain a wastewater discharge permit. CORRECT
RATIONALE: The IDDE minimum control measure requires mapping, prohibition, and
detection/elimination programs. It does not specifically require permitting commercial car washes;
that is a local decision. The other options are explicit requirements under 40 CFR 122.34(b)(3).
Page 3
, Q5 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
During a sanitary sewer inspection, smoke testing is used to identify illicit
connections. What is a primary limitation of this method?
A. It cannot detect leaks in private laterals.
B. It requires dry weather conditions and can be affected by wind. CORRECT
C. It is ineffective in identifying roof drain connections.
D. It requires excavation to confirm each connection.
RATIONALE: Smoke testing relies on visible smoke escaping through connections; wind can
disperse smoke, and wet weather can prevent smoke from moving. It can detect private lateral
issues, roof drains, and does not require excavation-those are not limitations.
Q6 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A municipality is developing an IDDE program. Which activity is most effective for
preventing illicit discharges in the long term?
A. Conducting annual outfall screening
B. Implementing a public education and outreach program CORRECT
C. Increasing fines for violations
D. Hiring more inspectors
RATIONALE: Public education addresses the root cause by changing behavior, reducing the
number of discharges. Screening and enforcement are reactive; education is proactive and
cost-effective.
Page 4
CERTIFICATION EXAM PRACTICE QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALE Q&A INSTANT DOWNLOAD PDF
110 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze stormwater regulations and IDDE program requirements under federal and state law
2 Design and evaluate dry-weather screening and monitoring protocols for outfall detection
3 Apply chemical, biological, and physical indicators to trace illicit discharges to their sources
4 Develop and justify enforcement and remediation strategies for various discharge scenarios
5 Synthesize data from multiple sources to prioritize and manage IDDE program resources
6 Illicit Discharge Detection and Elimination
7 IDDE
8 Certification Exam Practice Questions And Correct Answers
9 Verified Answers
10 Plus Rationale Q&A Instant Download Pdf
11 Foundations of Environmental Engineering & Stormwater Management
12 Applied Environmental Engineering & Stormwater Management
13 Advanced Environmental Engineering & Stormwater Management
14 Environmental Engineering & Stormwater Management Review
Page 1
,Q1 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A municipality's MS4 permit requires IDDE but allows flexibility in outfall
screening frequency. Which approach best balances legal compliance and
resource efficiency for a large watershed with 200 outfalls?
A. Screen all outfalls annually during dry weather regardless of land use.
B. Prioritize high-risk outfalls (industrial, commercial) for quarterly screening; screen others
biannually. CORRECT
C. Screen only outfalls with known historical illicit discharges.
D. Conduct continuous automated monitoring at all outfalls.
RATIONALE: Prioritizing high-risk areas aligns with EPA guidance and common permit language
that requires screening 'as necessary' based on risk. Annual screening of all outfalls is not
required and wastes resources; only screening known discharges misses new ones; continuous
monitoring is cost-prohibitive.
Q2 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
During dry-weather screening, an outfall shows a chlorine residual of 0.2 mg/L and
a pH of 9.0. Which illicit discharge is most likely?
A. Sanitary sewage
B. Industrial cooling water
C. Swimming pool water CORRECT
D. Vehicle wash water
RATIONALE: Chlorine residual and elevated pH are classic indicators of swimming pool
discharge. Sanitary sewage typically has high BOD and bacteria but no chlorine; cooling water
may have elevated temperature but not chlorine; wash water often has surfactants.
Page 2
,Q3 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A dye test is being used to trace an illicit connection. Which condition is essential
to ensure the test's validity?
A. Dye is introduced upstream and observed at the suspected outfall during dry weather.
CORRECT
B. Dye is introduced at the outfall and observed upstream.
C. Dye is visible in the receiving water within 30 minutes.
D. Dye is non-toxic and biodegradable.
RATIONALE: Dye testing involves introducing dye at a suspected source (upstream) and
observing its appearance at the outfall (downstream) to confirm a connection. Introducing at the
outfall would not trace the source. Visibility time is not a validity criterion; non-toxicity is important
but not the essential condition for tracing.
Q4 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A municipality has a Phase II MS4 permit. Which activity is NOT required by the
EPA's IDDE minimum control measure?
A. Develop a storm sewer map showing all outfalls and receiving waters.
B. Prohibit non-stormwater discharges through ordinance or other regulatory mechanism.
C. Implement a program to detect and address illicit discharges.
D. Require all commercial car washes to obtain a wastewater discharge permit. CORRECT
RATIONALE: The IDDE minimum control measure requires mapping, prohibition, and
detection/elimination programs. It does not specifically require permitting commercial car washes;
that is a local decision. The other options are explicit requirements under 40 CFR 122.34(b)(3).
Page 3
, Q5 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
During a sanitary sewer inspection, smoke testing is used to identify illicit
connections. What is a primary limitation of this method?
A. It cannot detect leaks in private laterals.
B. It requires dry weather conditions and can be affected by wind. CORRECT
C. It is ineffective in identifying roof drain connections.
D. It requires excavation to confirm each connection.
RATIONALE: Smoke testing relies on visible smoke escaping through connections; wind can
disperse smoke, and wet weather can prevent smoke from moving. It can detect private lateral
issues, roof drains, and does not require excavation-those are not limitations.
Q6 ANALYZE STORMWATER REGULATIONS AND IDDE PROGRAM REQUIREMENTS UNDER
FEDERAL AND STATE LAW
A municipality is developing an IDDE program. Which activity is most effective for
preventing illicit discharges in the long term?
A. Conducting annual outfall screening
B. Implementing a public education and outreach program CORRECT
C. Increasing fines for violations
D. Hiring more inspectors
RATIONALE: Public education addresses the root cause by changing behavior, reducing the
number of discharges. Screening and enforcement are reactive; education is proactive and
cost-effective.
Page 4
