What Are The Requirements For Hazardous Substance USTs?

Underground storage tank (UST) systems that store substances identified as being hazardous under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) are subject to the same requirements as petroleum UST systems except that hazardous substance tanks must have secondary containment. Hazardous wastes are already regulated under Subtitle C of the Resource Conservation and Recovery Act (RCRA) and therefore are not covered by the UST regulations.

Currently about 1,200 substances (excluding radionuclides) are identified as hazardous under CERCLA see 40 CFR 302, section 302.4).

Additional information on the CERCLA hazardous substances is available on the CERCLA Web site http://www.epa.gov/superfund/programs/er/hazsubs/cercsubs.htm

What Requirements Apply To Hazardous Substance USTs?

Hazardous substance USTs have to meet the same requirements for petroleum USTs concerning correct installation, spill, overfill and corrosion protection, corrective action, and closure.

In addition, hazardous substance USTs must have secondary containment and interstitial monitoring for leak detection, as described below.

What Is Secondary Containment?

All hazardous substance USTs must have "secondary containment." A single-walled tank is the first or "primary" containment. Using only primary containment, a leak can escape into the environment. But by enclosing an UST within a second wall, leaks can be contained and detected quickly before harming the environment.

There are several ways to construct secondary containment:

Placing one tank inside another tank or one pipe inside another pipe (making them double-walled systems).
Placing the UST system inside a concrete vault.
Lining the excavation zone around the UST system with a liner that cannot be penetrated by the hazardous substance.

What Is Interstitial Monitoring?

The hazardous substance UST must have a leak detection system that can indicate the presence of a leak in the confined space between the first and the second wall. Several devices are available to monitor this confined "interstitial" space. ("Interstitial" simply means "between the walls.") The UST regulations describe these various methods and the requirements for their proper use.

You can apply for an exception, called a variance, from the requirement for secondary containment and interstitial monitoring. To obtain a variance you must demonstrate to the regulatory authority that your alternative leak detection method will work effectively by providing detailed studies of your site, proposed leak detection method, and available methods for corrective action.

What About Leak Detection?

All UST systems are required to have leak detection, and the method must be properly operated and maintained.

What About Spill, Overfill, and Corrosion Protection?

All UST systems are required to have spill, overfill, and corrosion protection.

What If You Have A Hazardous Substance Release?

Whether you have a confirmed release, or even if you suspect that you might have a release, you must follow the basic actions described below:

You must take necessary and appropriate steps to stop further release and contain what has been released to ensure that there are no immediate threats to the safety and health of those nearby.
You must immediately report hazardous substance spills or overfills that meet or exceed their "reportable quantities" to the National Response Center at 800 424-8802 or 202 267-2675.
You must also report hazardous substance spills or overfills that meet or exceed their "reportable quantities" to the regulatory authority within 24 hours. However, if these spills or overfills are smaller than their "reportable quantities" and are immediately contained and cleaned up, they do not need to be reported.
Based on the information you have provided, the regulatory authority will decide if you must take further action at your site. You may need to develop and submit a Corrective Action Plan that shows how you will meet requirements established for your site by the regulatory authority. Make sure you implement the corrective action steps approved by the regulatory authority for your site.

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