Best Management Practices (BMPs) & Design Flashcards
7 cards from real CSM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Best Management Practices (BMPs) & Design flashcards as text
Which BMP type removes pollutants primarily through settling and sedimentation rather than biological uptake?
Answer: Wet detention pond
Wet detention ponds rely on extended hydraulic retention time to allow suspended solids and associated pollutants to settle out.
When sizing a bioretention cell, the typical ponding depth is limited to avoid anaerobic conditions in the media. What is the commonly accepted maximum ponding depth?
Answer: 12 inches
Most design guidelines limit bioretention ponding depth to 12 inches to prevent anaerobic conditions that inhibit plant survival and pollutant treatment.
A site designer wants to use a dry extended detention basin. Which pollutant removal mechanism is least effective in this BMP compared to a wet pond?
Answer: Biological nutrient uptake by aquatic plants
Dry basins drain between storms and lack a permanent pool, so aquatic vegetation cannot establish and biological nutrient uptake is minimal.
Under the 'runoff volume reduction' approach to stormwater management, which BMP best addresses the water quality volume by retaining and infiltrating the first flush?
Answer: Infiltration basin sized to drawdown within 72 hours
An infiltration basin that fully drawdowns the water quality volume within 72 hours achieves maximum volume reduction by returning runoff to groundwater.
Which soil characteristic most directly limits the feasibility of infiltration BMPs at a given site?
Answer: Saturated hydraulic conductivity (Ksat)
Saturated hydraulic conductivity determines how quickly water moves through soil; sites with Ksat below 0.5 in/hr are typically poor candidates for infiltration BMPs.
A constructed stormwater wetland differs from a wet detention pond primarily in that it:
Answer: Incorporates shallow marsh zones with emergent vegetation for enhanced treatment
Stormwater wetlands incorporate shallow emergent marsh zones (typically 0–18 inches deep) that support biological nutrient cycling and additional pollutant removal beyond simple settling.
For a permeable pavement system in a cold climate, which design modification is most important to maintain functionality during freeze-thaw cycles?
Answer: Selecting open-graded aggregate base course material instead of dense-graded
Open-graded aggregate base material drains freely and resists frost heave, maintaining the structural integrity and permeability of the system through freeze-thaw cycles.