CESSWI Cheat Sheet 2026

The 30 highest-yield CESSWI facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What minimum ground cover percentage is typically required before temporary erosion controls can be removed from a stabilized slope? → 85%
2. A 'perched water table' on a construction site is most likely caused by: → An impermeable soil or rock layer that impedes downward percolation of water
3. A construction site inspector finds that discharge from the site during a storm event is visibly turbid and brown. The first step should be: → Document the discharge, assess BMP performance, and determine the source
4. Which situation requires an inspector to amend the SWPPP and update documentation before construction resumes? → A new phase of grading exposes additional acreage not reflected in the original plan
5. What should inspectors check for in BMPs? → Installation and maintenance status
6. When should erosion control measures be implemented? → Before or during land disturbance
7. An inspector observes that fiber rolls installed on a slope have gaps larger than 1 inch between the roll and the soil surface. What problem does this create? → Runoff bypasses the roll by flowing underneath rather than being slowed
8. How should a CESSWI inspector communicate a significant permit violation that poses an immediate threat to water quality? → Notify the regulatory agency immediately per the permit's reporting requirements
9. Which design element of a wet detention pond is specifically intended to increase sediment removal efficiency? → Forebay at the inlet
10. What is the primary purpose of an extended detention basin compared to a standard dry detention basin? → Provide longer residence time to settle fine sediments
11. Why inspect during storm events? → Assess runoff and erosion controls
12. What does the letter 'D' represent in NRCS Hydrologic Soil Group (HSG) classification? → Very slow infiltration rate — highest runoff potential
13. Under good housekeeping practices, construction site dumpsters used for general solid waste should be: → Covered or lidded to prevent stormwater from contacting and mobilizing waste materials
14. What documentation must be retained on-site or made available during a regulatory inspection under the EPA CGP? → The SWPPP, all inspection reports, and records of corrective actions
15. Why monitor stormwater discharges? → To assess pollutant levels
16. Permeable pavement is classified as which type of Low Impact Development (LID) stormwater practice? → Volume reduction / green infrastructure BMP
17. A slope with a 3:1 (horizontal:vertical) gradient is considered what relative to erosion risk compared to a 4:1 slope? → Higher risk because a 3:1 slope is steeper than a 4:1 slope
18. What is the primary purpose of the 'implementation schedule' section of a SWPPP? → To sequence BMP installation relative to the phases of construction activity
19. Which pollutant is most effectively removed from stormwater by a vegetated filter strip? → Coarse sediment and associated particulate pollutants
20. What does the term 'common plan of development' mean in the context of SWPPP and permit coverage requirements? → Any contiguous area where multiple construction activities will occur under a single plan
21. Which of the following is a required element of a site map included in most SWPPPs? → Locations of all drainage patterns and receiving waters
22. Why is documentation important in compliance? → To provide evidence during audits
23. Which of the following is an example of a 'non-stormwater discharge' that must be identified and addressed in a SWPPP? → Water used to wash out concrete trucks
24. When inspecting a steep slope with unstable soil during a storm water inspection, what is the FIRST safety action an inspector should take? → Assess slope stability before approaching and use fall protection if required
25. Under the NPDES CGP, who is responsible for ensuring the SWPPP is implemented and updated throughout the construction project? → The operator(s) with day-to-day site control
26. Which document is the primary communication tool between the inspector and the contractor regarding required corrective actions? → A Notice of Deficiency or Corrective Action Report
27. Which NRCS hydrologic soil group has the HIGHEST runoff potential due to very slow infiltration rates? → Group D
28. Which soil texture is generally considered the most erodible under typical rainfall conditions? → Silt loam
29. What is a retention basin used for? → Store stormwater temporarily
30. What is the recommended maximum ponding depth behind a silt fence before the fabric is considered overstressed? → 12 inches