Which of the following are pretreatment options for small-scale infiltration?

• A. Vegetated filter strip, grass channel, or forebay
• B. Concrete curb
• C. Chemical dosing
• D. No pretreatment

Answer: (A)

Pretreatment before small-scale infiltration focuses on removing sediment and debris so the infiltrative soil isn’t clogged and its capacity isn’t reduced. Vegetated filter strips, grass channels, and forebays accomplish this by using plants and gentle flow to trap sediment, promote settling, and filter runoff before it reaches the infiltration area. This helps protect the infiltration surface and maintain performance.

Concrete curb isn’t a pretreatment device—it mainly handles conveyance and edge work and doesn’t remove sediments or pollutants before infiltration. Chemical dosing isn’t used as a pretreatment for infiltration either; it alters water chemistry and isn’t about physically removing solids before infiltration. No pretreatment would allow sediments and debris to reach the infiltrative soil, increasing the risk of clogging and reduced infiltration rates.