Drainage & Stormwater Management Flashcards
7 cards from real NETTCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Drainage & Stormwater Management flashcards as text
Which type of culvert pipe material is most resistant to corrosion in acidic soil environments common in New England?
Answer: High-density polyethylene (HDPE) pipe
HDPE pipe is highly resistant to corrosion from acidic soils and is commonly specified in New England where acidic glacial soils are prevalent.
What is the primary purpose of a catch basin in a highway drainage system?
Answer: To collect surface runoff and trap sediment before it enters the storm sewer
Catch basins are designed to intercept surface runoff and allow sediment and debris to settle before water enters the storm sewer system.
Manning's equation is used in drainage design primarily to calculate:
Answer: Flow velocity and discharge in open channels and pipes
Manning's equation relates channel geometry, roughness coefficient, slope, and hydraulic radius to determine flow velocity and discharge.
During a culvert inspection, you observe headwater depth approaching the crown of the inlet. This condition indicates:
Answer: The culvert barrel is undersized or partially blocked and flow is restricted
When headwater approaches the crown, it signals the culvert is near or at hydraulic capacity, indicating potential undersizing or blockage that requires attention.
What minimum pipe bedding material gradation is typically required beneath drainage pipe to provide uniform support and prevent settlement?
Answer: Clean crushed stone or gravel free of fines, typically 3/4" to 1-1/2"
Clean, well-graded crushed stone or gravel free of fines provides uniform bearing, promotes drainage around the pipe, and prevents point loading that causes cracking.
The rational method formula Q = CiA is used to estimate peak stormwater runoff. What does the variable 'C' represent?
Answer: Runoff coefficient reflecting land use and soil type
The runoff coefficient C accounts for the fraction of rainfall that becomes surface runoff, varying by land use, soil type, and surface cover.
Under federal NPDES Phase II regulations, which of the following highway construction activities requires a stormwater pollution prevention plan (SWPPP)?
Answer: Any project disturbing more than 1 acre of land
NPDES Phase II requires a SWPPP and permit coverage for construction sites that disturb one or more acres of land, regardless of proximity to water or project cost.