What type of storage systems must be provided with cathodic protection when in contact with soil?

Metallic underground storage systems require cathodic protection when in contact with soil due to their susceptibility to corrosion. When metal is buried in soil, it is exposed to moisture, pH changes, and various soil characteristics that can accelerate corrosion processes. Cathodic protection serves as a safeguard by employing a means (usually an impressed current or sacrificial anode) to provide electrons to the metal surface, effectively reducing the anodic reaction that leads to corrosion.

This protective measure is essential for maintaining the integrity and longevity of metallic storage systems, ensuring the safety and reliability of the stored materials. In contrast, composite and plastic underground storage systems do not have the same corrosion concerns due to their non-metallic nature. Surface storage systems are also not in direct contact with soil, thus not presenting the same risks for corrosion and, consequently, requiring cathodic protection.