CSM Sustainable Practices & Conservation 3 — Questions and Answers
Question 1: A developer proposes a cluster development design that preserves 40% of a site as open space. How does this primarily benefit stormwater management?
- It increases the overall site impervious area
- It maintains natural infiltration and reduces runoff-generating surfaces (Correct answer)
- It eliminates the need for detention facilities
- It increases the runoff curve number
Correct answer: It maintains natural infiltration and reduces runoff-generating surfaces
Clustering development concentrates impervious surfaces, preserving natural areas that maintain pre-development infiltration capacity and reduce runoff volume.
Question 2: What is the term for the practice of restoring a stream to a more natural meandering pattern to slow water, increase habitat, and reduce erosion?
- Stream channelization
- Stream naturalization or remeandering (Correct answer)
- Grade stabilization
- Bank armoring
Correct answer: Stream naturalization or remeandering
Stream remeandering restores natural sinuosity, slowing flow velocity, reducing bank erosion, and improving aquatic habitat and water quality.
Question 3: Under the EPA's National Pollutant Discharge Elimination System (NPDES), what stormwater practice is considered a best management practice (BMP) for construction sites?
- Removing all vegetation before grading
- Installing silt fences to trap sediment (Correct answer)
- Increasing grading slope to accelerate drainage
- Eliminating all on-site retention
Correct answer: Installing silt fences to trap sediment
Silt fences are a standard erosion and sediment control BMP required under NPDES Construction General Permit to prevent sediment from leaving the site.
Question 4: A green roof reduces stormwater runoff primarily through which two mechanisms?
- Filtration and disinfection
- Retention in growing media and evapotranspiration (Correct answer)
- Detention and slow release
- Infiltration and percolation to groundwater
Correct answer: Retention in growing media and evapotranspiration
Green roofs store water in their soil media and return it to the atmosphere via plant evapotranspiration, reducing both volume and peak discharge.
Question 5: Which soil amendment practice most improves the infiltration capacity of compacted urban soils, thereby enhancing stormwater performance?
- Adding sand to clay soils only
- Incorporating compost to increase organic matter and porosity (Correct answer)
- Compacting topsoil further for uniformity
- Applying herbicide to reduce root competition
Correct answer: Incorporating compost to increase organic matter and porosity
Adding compost increases soil organic matter, improving soil structure, macropore development, and infiltration capacity in compacted urban soils.
Question 6: Which water quality parameter is MOST commonly associated with excess stormwater runoff from agricultural fields?
- Heavy metals
- Nitrogen and phosphorus (Correct answer)
- Petroleum hydrocarbons
- Chlorinated solvents
Correct answer: Nitrogen and phosphorus
Agricultural runoff is a major source of nitrogen and phosphorus from fertilizers, which cause eutrophication in receiving water bodies.
Question 7: A stormwater manager is evaluating whether to use biofiltration strips along a highway. What is the PRIMARY water quality benefit of this practice?
- Groundwater recharge through deep infiltration
- Sediment and pollutant removal through filtration and settling (Correct answer)
- Peak flow attenuation
- Thermal cooling of runoff
Correct answer: Sediment and pollutant removal through filtration and settling
Vegetated filter strips slow runoff velocity and allow sediment and associated pollutants to settle out or be filtered by dense vegetation.
CSM Sustainable Practices & Conservation 3
A developer proposes a cluster development design that preserves 40% of a site as open space.
How does this primarily benefit stormwater management?