CPESC Stormwater Management 2

Question 1

What is the primary purpose of a stormwater detention basin?

Accepted Answer

Temporarily store runoff to reduce peak discharge rates

Answer

Detention basins temporarily hold stormwater to attenuate peak flow rates before releasing water at a controlled rate.

Question 2

Which hydrologic method is most commonly used to estimate peak runoff rates for small watersheds in the US?

Accepted Answer

Rational Method (Q = CiA)

Answer

The Rational Method (Q = CiA) is the most widely used approach for small urban watersheds to estimate peak runoff rates.

Question 3

A Curve Number (CN) of 98 indicates what type of land surface?

Accepted Answer

Nearly impervious surface such as pavement or rooftops

Answer

A CN of 98 represents nearly impervious surfaces where almost all rainfall becomes runoff with minimal infiltration.

Question 4

What is the function of an outlet control structure's emergency spillway?

Accepted Answer

Handle flows exceeding the principal spillway capacity to prevent dam failure

Answer

The emergency spillway safely passes extreme storm flows that exceed the principal spillway's capacity, preventing overtopping and dam failure.

Question 5

Under the EPA's NPDES Construction General Permit, what rainfall threshold typically triggers a site inspection requirement?

Accepted Answer

0.25 inch

Answer

The EPA CGP typically requires site inspections after any storm event of 0.25 inch or greater within a 24-hour period.

(CPESC) Certified Professional in Erosion and Sediment Control Practice Test