Scour is the removal of sediment around piers due to flowing water. Which of the following is a typical countermeasure?

• A. Riprap armor around piers with protective aprons and scour-depth monitoring.
• B. Increased deck thickness.
• C. Painting the pier.
• D. Raising the abutments only.

Answer: (A)

Scour around piers is addressed by protecting the foundation from flowing water. The best countermeasure is to place rock armor (riprap) around the pier, with a protective apron downstream and monitoring of scour depth. The rock armor dissipates flow energy and shields the base from erosion, while the apron helps spread and reduce scour in front of and around the pier, and monitoring allows timely maintenance if scour progresses. Other options don’t tackle the erosion mechanism: increasing deck thickness changes only the superstructure, not the foundation protection; painting the pier offers no protective effect against sediment removal; and raising the abutments target areas away from the pier foundation in the main flow, so it doesn’t mitigate scour at the pier itself.