What method reduces underground fuel storage tank corrosion activity related to soil resistivity?

• A. Cathodic protection
• B. Anodic protection
• C. Ground-penetrating radar
• D. Regular painting

Answer: (A)

Cathodic protection reduces corrosion on buried metal structures by driving the tank surface to a cathodic (negatively charged) potential, which suppresses the anodic reactions that cause metal dissolution. In soil, corrosion relies on electrochemical reactions at the steel-soil interface, and the amount of protective current that can flow depends on soil resistivity. When soil resistivity is higher, the path for current is more resistive, so you design the system to supply sufficient current or use more effective anodes to maintain the protective potential. The result is a significant drop in corrosion activity, even as soil resistivity changes.

Anodic protection would do the opposite and accelerate corrosion, so it’s not used for buried tanks. Ground-penetrating radar detects buried objects, not corrosion control. Regular painting isn’t reliable for buried tanks, since the coating and paint degrade in soil and moisture, leaving the steel exposed to corrosion.