Illicit Discharge Detection & Elimination (IDDE) Flashcards
7 cards from real CSM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Illicit Discharge Detection & Elimination (IDDE) flashcards as text
NPDES MS4 permits typically require municipalities to prohibit illicit discharges through a local regulatory mechanism. What is the most common tool used to establish this legal authority?
Answer: A local stormwater ordinance or municipal code provision that prohibits non-stormwater discharges to the MS4
A local stormwater ordinance is the standard legal mechanism that grants the municipality authority to prohibit illicit discharges, investigate suspected violations, and enforce corrective actions.
Which of the following entities is NOT typically subject to IDDE inspections by an MS4 operator?
Answer: Federally owned facilities with their own stormwater permits
Federally owned facilities with their own separate NPDES stormwater permits are regulated independently and are generally not subject to MS4 IDDE inspections by the local municipality.
A field crew finds ammonia levels elevated at a storm drain outfall during dry weather. Which type of illicit discharge source is MOST consistent with this finding?
Answer: Sanitary sewage or septic system effluent cross-connected to the storm drain
Elevated ammonia in dry-weather outfall flows is a strong indicator of sewage contamination, as ammonia is a breakdown product of urea in human waste and is characteristic of sanitary sewage.
What is the recommended minimum dry period (no measurable rainfall) before conducting valid dry-weather outfall screening for illicit discharges?
Answer: 72 hours
A 72-hour (3-day) dry period is the standard minimum recommended before dry-weather outfall screening, allowing most legitimate stormwater to drain away and making illicit flows more detectable.
Which of the following best describes the role of public education and outreach in an effective IDDE program?
Answer: It reduces illicit discharges by informing residents and businesses about what can legally enter storm drains and how to report illegal dumping
Public education and outreach reduce illicit discharges by raising awareness of proper disposal practices and creating a community reporting network that extends the reach of limited inspection staff.
When documenting an IDDE field investigation, which of the following is MOST important to record for potential enforcement action?
Answer: Photographic evidence, GPS coordinates, field measurements, time and date of observation, and the name of the inspector
Thorough documentation including photos, GPS location, field measurements, timestamps, and inspector identification is essential for creating a defensible enforcement record and tracking investigation status.
A municipality discovers that a private restaurant has been discharging grease trap waste directly into a storm drain inlet for several months. Under a typical NPDES MS4-mandated IDDE program, what sequence of actions should the municipality take?
Answer: Document the discharge, notify the discharger to cease immediately, issue a formal notice of violation, require elimination within a specified timeframe, and conduct a follow-up inspection to confirm compliance
IDDE enforcement requires documentation, immediate cessation order, formal notice of violation, a compliance deadline, and follow-up verification — this sequence satisfies both permit obligations and due process requirements.