CPD Storm Drainage & Site Utilities Flashcards
6 cards from real CPD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CPD Storm Drainage & Site Utilities flashcards as text
Which pipe material is most commonly specified for underground storm drainage piping on US commercial sites?
Answer: Reinforced concrete pipe (RCP) or high-density polyethylene (HDPE)
Reinforced concrete pipe and HDPE are the most common materials for underground site storm drainage due to their structural strength and resistance to soil loads.
What is the purpose of a flap gate (tide gate) on a storm drainage outfall?
Answer: To prevent backflow from a receiving water body into the storm system during high water events
A flap gate at a storm outfall prevents backflow from rivers, tidal channels, or detention basins from entering the storm system when external water levels are elevated.
What is the 'design storm' concept used in storm drainage design?
Answer: A specific return-period rainfall event (e.g., 10-year, 100-year) used to size drainage infrastructure
A design storm is a statistical rainfall event of a selected return period (e.g., 10-year storm) used as the basis for sizing storm drainage systems to handle expected peak flows.
Per the IPC, what is the required minimum horizontal distance between a storm drainage cleanout and a wall or obstruction?
Answer: 18 inches
The IPC requires a minimum clearance of 18 inches in front of storm and sanitary drainage cleanouts to allow access for rodding equipment.
What is 'impervious cover' and why is it significant to a CPD designing site utilities?
Answer: Hard surfaces like pavement that do not absorb rainfall, increasing runoff volume and rate
Impervious cover refers to hard, non-absorbing surfaces such as roofs and pavement that prevent infiltration, directly increasing the volume and peak rate of stormwater runoff that drainage systems must handle.
What role does the 'invert elevation' play in storm drainage system design?
Answer: It defines the lowest inside point of a pipe at a given location, controlling gravity flow direction and slope
The invert elevation is the inside-bottom elevation of a pipe, and designing correct invert elevations at each structure ensures positive gravity flow throughout the storm drainage system.