CESSWI Stormwater Runoff Management 3

Question 1

Which curve number (CN) value in the TR-55 method indicates the LEAST runoff potential from a given soil and land use combination?

Accepted Answer

35

Answer

Lower curve numbers indicate greater infiltration and less runoff potential; a CN of 35 represents a highly permeable soil with dense vegetation, while 98 represents nearly impervious surfaces.

Question 2

What term describes the practice of directing rooftop downspouts away from impervious surfaces and toward vegetated areas to promote infiltration?

Accepted Answer

Downspout disconnection

Answer

Downspout disconnection redirects roof drainage to lawns, gardens, or rain gardens rather than directly into the storm sewer, reducing runoff volume.

Question 3

A permeable pavement system fails to drain adequately after several years of use. What is the most likely cause?

Accepted Answer

Clogging of pores by fine sediments and debris

Answer

Fine sediment and organic debris accumulate in the pores of permeable pavement over time, reducing infiltration rates and requiring vacuum sweeping maintenance.

Question 4

Which NRCS hydrologic soil group has the HIGHEST runoff potential due to very slow infiltration rates?

Accepted Answer

Group D

Answer

Hydrologic Soil Group D soils (such as clays) have very slow infiltration rates, high runoff potential, and are typically wet, shallow, or have impermeable layers.

Question 5

During a CESSWI inspection, you observe that a site's temporary sediment basin outlet riser is submerged with no freeboard remaining. What is your immediate concern?

Accepted Answer

Potential overtopping and embankment failure

Answer

When freeboard is lost, the embankment is at risk of overtopping, which can cause rapid erosion and catastrophic failure of the sediment basin.

(CESSWI) Certified Erosion, Sediment, and Storm Water Inspector Practice Test

(CESSWI) Certified Erosion, Sediment, and Storm Water Inspector Practice Test

CESSWI Stormwater Runoff Management 3