Glossary: Petroleum Product Storage

These terms may help you make more accurate assessments when completing the Petroleum Product Storage Fact/Worksheet. They may also help clarify some of the terms used.

Cathodic protection: One of several techniques to prevent corrosion of a metal surface by reversing the electric current that causes corrosion. A tank system can be protected by sacrificial anodes or impressed current (See sacrificial anodes and impressed current).

Certified installer/remover: A person certified by the state to install, repair, or remove petroleum storage tanks.

Corrosion: Deterioration of a metallic material ("rust") due to a reaction with its environment.

Corrosion protection: Measures taken to prevent corrosion on a steel tank.

Galvanized: The result of coating an iron or steel structure with zinc. Galvanized materials do not meet corrosion protection requirements for underground tanks.

Impressed current: A protection system that introduces an electric current into the ground through a series of anodes that are not attached to the underground tank. Because the electric current flowing from these anodes to the tank system is greater than the corrosive current attempting to flow from it, the underground tank is protected from corrosion.

Interior liner: A tank liner made of noncorrosive synthetic materials that are effective in preventing leaks in metal tanks when they corrode.

Inventory control: Measuring and comparing the volume of tank contents regularly with product delivery and withdrawal records to help detect leaks.

Protected tank: A tank approved by the underground storage tank regulatory authorities for use underground if installed according to the manufacturer's instructions. An unprotected tank has not been installed to the manufacturer's instructions.

Regulated tank: A tank, which because of its size, use and/or location, requires registration with a state or local agency. Not all tanks are subject to regulation.

Sacrificial anodes: Pieces of metal attached directly to an underground tank to prevent corrosion. Sacrificial anodes deflect corrosion-causing electrical currents from the underground storage tank.

Secondary containment: A system designed to catch and hold the contents of a tank if it leaks or ruptures.

Soil permeability: Characteristic of a soil to transmit water or air. Slowly permeable soils have fine-textured materials (clays) that permit only slow movement. Moderately or highly permeable soils have coarse-textured materials (sands) that permit rapid movement.

Spill and overfill protection: Spill protection usually consists of a catch basin for collecting spills when the tank is filled. Overfill protection is a warning which helps prevent an overfill, such as an automatic shutoff or buzzer. These precautions can prevent the pollution of the ground water.

Tank tightness testing: A procedure for testing a tank for leaks to identify any accidental release of any stored substance into the environment, or intrusion of ground water into an underground tank.