CPD CPD Storm Drainage & Site Utilities 2 — Questions and Answers
Question 1: What is a retention pond's primary function in site stormwater management?
- To hold stormwater permanently and release it at a controlled rate (Correct answer)
- To supply potable water to the building's plumbing system
- To collect sanitary waste from exterior restrooms
- To pressurize the site fire hydrant system
Correct answer: To hold stormwater permanently and release it at a controlled rate
A retention pond holds a permanent pool of stormwater and releases excess volume slowly, reducing peak runoff and allowing sediment to settle.
Question 2: What distinguishes a detention basin from a retention pond in stormwater design?
- A detention basin temporarily holds stormwater and drains completely between storms (Correct answer)
- A detention basin permanently holds water like a lake
- A detention basin is used only for potable water storage
- A detention basin is required only for rooftop drainage
Correct answer: A detention basin temporarily holds stormwater and drains completely between storms
A detention basin temporarily stores stormwater during a storm event and drains completely afterward, while a retention pond maintains a permanent water pool.
Question 3: Which US federal regulation governs stormwater discharge from construction sites larger than one acre?
- NPDES Construction General Permit under the Clean Water Act (Correct answer)
- Safe Drinking Water Act (SDWA) Section 1401
- Resource Conservation and Recovery Act (RCRA) Subtitle D
- Occupational Safety and Health Act (OSHA) 29 CFR 1926
Correct answer: NPDES Construction General Permit under the Clean Water Act
The EPA's NPDES Construction General Permit, issued under the Clean Water Act, requires stormwater pollution prevention plans for construction sites disturbing one or more acres.
Question 4: What is the purpose of a roof drain overflow (secondary) drain in plumbing design?
- To handle excess rainwater if the primary roof drain becomes blocked, preventing structural overload (Correct answer)
- To provide a backup supply line for rooftop cooling towers
- To serve as a cleanout access point for roof drain maintenance
- To equalize air pressure between the roof drain and the vent stack
Correct answer: To handle excess rainwater if the primary roof drain becomes blocked, preventing structural overload
Secondary (overflow) roof drains protect the roof structure from ponding overload if the primary drain is blocked, directing excess water to a safe discharge point.
Question 5: What is an area drain used for in exterior plumbing design?
- To collect surface water in paved or landscaped areas and direct it to the storm system (Correct answer)
- To supply water to outdoor hose bibs and irrigation zones
- To receive condensate discharge from rooftop HVAC units
- To vent the underground storm piping to atmosphere
Correct answer: To collect surface water in paved or landscaped areas and direct it to the storm system
Area drains are installed at low points in paved plazas, courtyards, or landscaped areas to collect surface runoff and route it into the underground storm drainage system.
Question 6: In CPD exam contexts, what does 'time of concentration' (Tc) refer to in stormwater hydrology?
- The time for runoff to travel from the most remote point in a watershed to the design outlet (Correct answer)
- The duration of a design storm event used in sizing calculations
- The lag time between pipe installation and full flow capacity
- The reaction time required for a sump pump to activate
Correct answer: The time for runoff to travel from the most remote point in a watershed to the design outlet
Time of concentration (Tc) is the travel time for runoff from the hydraulically most remote point of the drainage area to reach the design point, and it determines the critical storm duration for peak flow calculations.
CPD CPD Storm Drainage & Site Utilities 2
What is a retention pond's primary function in site stormwater management?