Which sequence best describes standard actions when scour depth is detected near a pier?

• A. Ignore readings until deterioration occurs.
• B. Wait for natural sediment build-up.
• C. Use countermeasures such as riprap, concrete aprons, grouted sleeves, and, if needed, deep foundations extensions.
• D. Only repair the deck.

Answer: (C)

When scour depth is detected near a pier, the priority is to stop further erosion and protect the foundation, not to ignore the reading or wait for sediment buildup. Scour eats away at the soil supporting the pier, which can progressively undermine bearing capacity and lead to failure if left unaddressed. The best approach is to apply protective countermeasures that shield the foundation from ongoing scour. This includes rock armor (riprap) to dissipate flow energy around the base, concrete aprons to spread protection and limit local scour, and grouted sleeves to secure exposed piles. If these measures aren’t sufficient or the scour has already weakened the foundation, extending the foundation deeper into more stable soil or bedrock provides a more reliable load path. Repairing only the deck doesn’t address the subsurface vulnerability, and waiting for natural sediment buildup offers no proactive protection.