CESSWI Stormwater Runoff Management 2

Question 1

Which hydrologic parameter represents the fraction of rainfall that becomes surface runoff?

Accepted Answer

Runoff coefficient (C)

Answer

The runoff coefficient (C) in the Rational Method represents the proportion of rainfall that converts to runoff, ranging from 0 to 1.

Question 2

A detention basin designed to reduce peak discharge by storing runoff temporarily is classified as which type of BMP?

Accepted Answer

Detention basin

Answer

A detention basin temporarily stores runoff and releases it at a controlled rate to reduce peak flows, unlike retention basins which hold water permanently.

Question 3

Under the NPDES Construction General Permit, a Stormwater Pollution Prevention Plan (SWPPP) must be prepared for sites disturbing at least how many acres?

Accepted Answer

1 acre

Answer

The NPDES CGP requires a SWPPP for construction sites disturbing 1 or more acres, or smaller sites in a common plan of development exceeding 1 acre.

Question 4

Which factor most directly increases the peak runoff rate from a developed watershed compared to pre-development conditions?

Accepted Answer

Shorter time of concentration

Answer

Development shortens time of concentration by replacing permeable surfaces with impervious ones and adding channels, causing runoff to reach the outlet faster and intensifying peak flows.

Question 5

What is the primary purpose of a level spreader at the outlet of a stormwater conveyance system?

Accepted Answer

Convert concentrated flow to sheet flow

Answer

A level spreader converts concentrated pipe or channel flow into diffuse sheet flow, reducing erosive velocities before runoff enters a vegetated buffer.

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

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

CESSWI Stormwater Runoff Management 2