CLARB Sustainable Design and Environmental Stewardship 2 — Questions and Answers
Question 1: Which design element is a key component of a constructed wetland used for stormwater treatment?
- Emergent wetland vegetation planted in a shallow engineered basin to biologically filter pollutants (Correct answer)
- A concrete-lined basin with no vegetation
- A deep water reservoir for potable water storage
- An underground cistern with mechanical filtration
Correct answer: Emergent wetland vegetation planted in a shallow engineered basin to biologically filter pollutants
Constructed wetlands use emergent macrophytes and microbial communities in the root zone to uptake nutrients, trap sediment, and biologically treat stormwater pollutants.
Question 2: A CLARB exam scenario asks how to minimize light pollution from a new park lighting system. Which approach is most appropriate?
- Use full-cutoff luminaires aimed downward with motion sensors and warm color temperature LEDs (Correct answer)
- Install the tallest poles possible to spread light widely
- Use upward-facing spotlights on trees and structures
- Maximize lumen output to ensure safety at all hours
Correct answer: Use full-cutoff luminaires aimed downward with motion sensors and warm color temperature LEDs
Full-cutoff fixtures direct light only downward, eliminating sky glow and glare, while motion sensors reduce unnecessary nighttime illumination and dark-sky LEDs minimize ecological disruption.
Question 3: What is the primary goal of a 'carbon sequestration' planting strategy in landscape architecture?
- Increasing biomass through vegetation to capture and store atmospheric carbon dioxide long-term (Correct answer)
- Reducing vehicle emissions in parking areas
- Eliminating the need for mechanical HVAC systems
- Capturing methane from decomposing organic matter
Correct answer: Increasing biomass through vegetation to capture and store atmospheric carbon dioxide long-term
Carbon sequestration plantings maximize biomass accumulation — particularly through large-canopy trees and healthy soils — to absorb and store atmospheric CO₂ over decades.
Question 4: According to EPA's green infrastructure guidance, what is the primary benefit of street tree trenches or silva cells in urban streetscapes?
- They provide expanded soil volume for tree root growth while managing stormwater through structural soil cells beneath pavement (Correct answer)
- They eliminate the need for tree grates
- They replace underground utility infrastructure
- They are used exclusively in rural highway medians
Correct answer: They provide expanded soil volume for tree root growth while managing stormwater through structural soil cells beneath pavement
Silva cells and structural soil systems support pavement loads while creating rooting space and stormwater storage beneath paved surfaces, enabling healthy urban trees and reducing runoff.
Question 5: A landscape architect is asked to restore a degraded native prairie. Which site preparation method is ecologically preferred before seeding?
- Kill existing invasive vegetation through herbicide application or prescribed burn, then scarify soil minimally before seeding native seed mixes (Correct answer)
- Rototill deeply and apply synthetic fertilizer before seeding
- Install an impermeable barrier to prevent weed growth
- Overseed directly into existing vegetation without preparation
Correct answer: Kill existing invasive vegetation through herbicide application or prescribed burn, then scarify soil minimally before seeding native seed mixes
Controlling existing invasive species and lightly disturbing the soil reduces competition and creates seedbed conditions for native prairie species without over-preparing the site.
Question 6: What does 'on-site stormwater retention' mean in the context of low-impact development (LID)?
- Capturing and holding stormwater on the project site to allow infiltration, evapotranspiration, or reuse rather than discharging it off-site (Correct answer)
- Building a large concrete cistern for municipal water supply
- Routing all runoff directly to the nearest storm drain
- Elevating the site to prevent flooding
Correct answer: Capturing and holding stormwater on the project site to allow infiltration, evapotranspiration, or reuse rather than discharging it off-site
LID's core principle is to manage stormwater as close to where it falls as possible through infiltration, ET, and reuse, replicating predevelopment hydrology.
CLARB Sustainable Design and Environmental Stewardship 2
Which design element is a key component of a constructed wetland used for stormwater treatment?