Which of the following actions can adversely affect a tank's coating?

Inadequate compaction of backfill materials can lead to issues that adversely affect a tank's coating. When backfill is not compacted properly, it can create voids and uneven pressures around the tank. This uneven support can result in movement or settling, which may crack, scrape, or wear down the protective coating of the tank. The tank's coating is designed to protect against corrosion and other environmental factors; therefore, any damage to this coating can compromise the tank's integrity and lead to potential leaks or environmental hazards.

Regular cleaning and proper sealing, on the other hand, are essential maintenance practices that help preserve the tank's condition. Using premium materials is a proactive measure that enhances the tank's durability and protection against corrosion, rather than detracting from it. Therefore, the correct focus is on the impact of inadequate compaction of backfill materials on the tank's coating.