Underground Storage Tanks Inspection (USTs)

Underground storage tanks are a crucial part of our country’s fueling infrastructure yet present significant health and environmental risks. Leaking tanks can lead to fire and explosion, as well as environmental contamination. Midwest Environmental Consulting Services Inc. (MEC) provides inspection for underground storage tanks (USTs) to ensure compliance with federal and state regulations.

According to the United States Environmental Protection Agency (EPA), “approximately 553,000 underground storage tanks (USTs) nationwide store petroleum or hazardous substances. The greatest potential threat from a leaking UST is contamination of groundwater, the source of drinking water for nearly half of all Americans.”



Majority of underground storage tanks were installed before EPA regulations. Modern-day environmental concerns may not have been anticipated during your tank installation, as many tanks today are defective. Many tanks are not designed to be stored underground and consequently become corrosive, causing leakage and contamination. In addition, the liability surrounding leaking tanks is the responsibility of the property owner.

USTs should be constructed, maintained, and operated in a way that regulated substances are stored safely. Likewise, a properly installed and managed UST system should not threaten human health or the environment. MEC’s experienced team can perform the testing necessary for USTs compliance.

Inspection and Testing Services

Cathodic Protection Systems (CP)

  • Protecting underground storage tanks and their components from corrosion

  • Needed for valves, piping, and connectors that are in contact with soil and contain regulated substances

  • Sacrificial anode CP: Magnesium or zinc anodes that will corrode over time instead of the tank or piping

  • Impressed current CP: Uses anodes to prevent corrosion with a weak electrical current to strengthen the effect

Tank and Line Tightness Testing

  • Analytical method to determine if a tank leaks a quantity as small as 0.1 gallons per hour (gph)

  • Used under special circumstances such as a failed leak detection test

  • Volumetric tightness test: Applying slight pressure to the tank and carefully measuring for any change in volume over time

  • Non-volumetric tightness test: Using other principles and methods to determine a leak

Automatic Tank Monitoring Testing

  • Monthly leak test using a properly installed and maintained automatic tank gauge (ATG) system

  • ATG systems are permanently installed in USTs

  • A probe is inserted into the tank, measuring the product level and temperature

  • ATG leak tests must meet minimum performance standards for detecting leaks

Stage II Vapor Recovery Testing

  • Required for many commercial gasoline dispensing facilities (GDF)

  • System designed to capture displaced vapors that emerge from inside a UST

  • Controls gasoline vapor emissions that occur when vehicles are fueled at GDFs

  • Vapors stored in the underground storage tank will later be transferred to the terminal for processing

Spill and Overfill Testing

  • To ensure fuel spills or overfills do not occur during fuel deliveries

  • Checking for drainage, obstructions, damage, or leaks

  • Containment around the fill pipe that catches small drips or spills using a spill bucket

  • Protecting from overfills through automatic shutoff, overfill alarms, and flow restrictors