Which of the following two factors are primary for making a risk determination?

Which of the following two factors are primary for making a risk determination?

• A. Flow rate and turbulence
• B. Soil type and vegetation
• C. Receiving Waters and Sediment Risk
• D. Runoff volume and duration

Answer: (C)

The key idea here is that risk determination is driven by where the stormwater is discharging to and how much sediment-related risk it poses to that receiving water. If the discharge goes into a sensitive or protected receiving water and has a high potential for sediment impact, the overall risk is higher and controls must be more stringent. “Receiving Waters” identifies the endpoint being protected, and “Sediment Risk” captures the potential for sediment to carry pollutants and harm aquatic life, clog habitats, or degrade water quality. These two factors together set the baseline risk category and guide the appropriate controls. Other site characteristics like flow rate and turbulence, soil type and vegetation, or runoff volume and duration influence how much sediment could be moved or how quickly, but they do not by themselves define the risk category. They affect severity or management complexity, not the primary basis for risk determination.

The key idea here is that risk determination is driven by where the stormwater is discharging to and how much sediment-related risk it poses to that receiving water. If the discharge goes into a sensitive or protected receiving water and has a high potential for sediment impact, the overall risk is higher and controls must be more stringent. “Receiving Waters” identifies the endpoint being protected, and “Sediment Risk” captures the potential for sediment to carry pollutants and harm aquatic life, clog habitats, or degrade water quality. These two factors together set the baseline risk category and guide the appropriate controls.

Other site characteristics like flow rate and turbulence, soil type and vegetation, or runoff volume and duration influence how much sediment could be moved or how quickly, but they do not by themselves define the risk category. They affect severity or management complexity, not the primary basis for risk determination.