Did you know that underground gas tanks play a crucial role in our daily lives, from fueling our vehicles to powering industrial machinery? Ensuring their safety, inspection, and maintenance is not only vital for the environment but also for public safety and compliance with industry regulations. In this blog post, we’ll guide you through the essential aspects of underground gas tanks and help you understand how to select a qualified tank testing service. Southern Tank Testers provides services for nearly any type of underground tank.

Key Takeaways

Underground gas tanks are essential components for reliable fuel supply.

Safety and compliance must be ensured through industry standards, inspections, testing, leak prevention/detection methods and cathodic protection systems.

Choosing a qualified tank testing service with relevant qualifications is necessary to ensure safe operation of underground gas tanks.

Understanding Underground Gas Tanks

Underground gas tanks, as the name suggests, are storage tanks installed beneath the ground’s surface to store fuel or other substances. They are typically made from concrete and steel, with an increasing preference for fiberglass reinforced plastic (FRP) due to its corrosion resistance and lower maintenance requirements.

The primary purpose of these tanks is to supply fuel for vehicles or power industrial machinery, ensuring the smooth functioning of our day-to-day activities.

Types of Underground Gas Tanks

There are several types of underground gas tanks available, including:

Aluminum or steel tanks

Composite overwrapped tanks

Thermoplastic tanks

Cisterns

Fiberglass tanks, for instance, range in size from 4-foot to 12-foot diameter and can store up to 50,000 gallons of fuel, biofuels, biodiesels, ethanol, and ethanol blends, meeting the Underwriters Laboratories (UL) Standard for Safety 1316.

Steel tanks, on the other hand, vary in capacity, length, and fittings, adhering to specifications published by the Steel Tank Institute (STI) and UL standards.

Common Uses for Underground Gas Tanks

Underground gas tanks serve various applications, such as:

Storing heating oil

Storing petroleum products

Storing chemicals and hazardous materials

Acting as septic systems

At gas stations, they securely store fuel, with access to the fuel provided through locked hatches that require a key to open. For emergency generators, underground tanks store diesel or gasoline, ensuring a continuous fuel supply during power outages.

Other applications include storing water, wastewater, compressed air, and natural gas.

Safety Considerations for Underground Gas Tanks

The safety of underground gas tanks is of utmost importance. Maintaining their integrity and preventing leaks is critical for environmental protection and compliance with industry standards and regulations. Staying informed about industry trends can help ensure the best practices are followed.

Techniques such as corrosion testing and line tightness testing help assess the tank’s integrity, while reporting any failed tests to the relevant authorities is mandatory.

Leak Prevention and Detection

Various methods exist for preventing and detecting leaks in underground gas tanks, including the use of double-walled tanks, leak detection sensors, and monitoring systems. For tanks with a capacity of less than 1,000 gallons, weekly or monthly tank gauging and annual tightness testing can satisfy leak detection requirements. Automatic Tank Gauges (ATGs) using the ‘Continuous In-Tank Leak Detection Method’ also fulfill EPA leak detection requirements.

To prevent water accumulation in the UST sump, installing a manway larger than the sump diameter with a covered spill bucket is recommended.

Cathodic Protection

Cathodic protection is a fundamental technique for preventing corrosion in underground gas tanks. By supplying a direct current (DC) from an external source, the tank acts as the cathode, shielding it from corrosion. Sacrificial anode CP (galvanic CP) and impressed current systems are the types of cathodic protection used in underground gas tanks.

Proper installation and maintenance of cathodic protection, adhering to applicable industry codes and guidelines, ensure the system operates correctly and provides effective corrosion protection to the tank. The cost of implementing cathodic protection ranges from $10,000 to $48,000 for retrofitting existing tanks.

Inspection and Maintenance of Underground Gas Tanks

Frequent inspection and maintenance of underground gas tanks are necessary for safety assurance and regulatory compliance. Companies like ATS Environmental offer comprehensive inspections for underground storage tanks, heating oil tanks, and aboveground storage tanks.

Genesis Environmental Solutions, with extensive experience and specialty training in environmental services, provide state-of-the-art equipment for inspecting any type of tank.

Visual Inspection

Visual inspection of underground gas tanks includes:

Routine walkthrough inspections of the release detection equipment

Scrutinizing visible components of the UST system

Examining the tank’s interior and exterior shell plates

Assessing the containment area

Probes and sensors, along with inspection of bolts and hardware, can help identify signs of damage during visual inspections.

Detecting leaks during visual inspections may also involve monitoring for any liquid or vapor around the tank, although additional techniques like periodic tightness testing or vapor monitoring may be necessary for a more comprehensive evaluation.

Periodic Testing

Periodic testing for underground gas tanks includes:

Tightness testing: assesses the integrity of the tank and its piping system, ensuring that no leaks are present.

Pressure testing: involves pressurizing the tank and monitoring it for fluctuations that may suggest a leak, detecting leaks as small as 0.1 gallons per hour (gph).

Ultrasonic testing: uses sound waves to detect any structural defects or weaknesses in the tank.

These tests are important for ensuring the safety and compliance of underground gas tanks.

Ultrasonic testing uses sound waves to detect defects and measure thickness, helping identify signs of corrosion or improper operation.

Repairs and Upgrades

Repairs and upgrades are required to ensure that underground gas tanks align with the current safety standards and regulations. Typical repairs include:

Repairing tank damage

Replacing fittings and manways

Installing collars and tank sumps

Adding or replacing anodes

Steel, fiberglass, and concrete are the common materials used for the repair and improvement of underground gas tanks.

Inspecting underground gas tanks for potential repairs and upgrades should be done at least once every five years.

Industry Standards and Regulations

The American Petroleum Institute (API) and the Environmental Protection Agency (EPA) are responsible for setting industry standards and regulations governing underground gas tanks. These requirements guarantee the safe and dependable functioning of underground gas tanks, addressing aspects such as:

Tank design

Installation

Leak detection

Spill control

Corrective actions

American Petroleum Institute (API) Standards

The American Petroleum Institute (API) establishes several standards for underground gas tanks, including API 650 for welded tanks for oil storage and API RP 1631 for the interior lining of existing underground tanks. These standards help ensure that underground gas tanks are designed, constructed, and operated with optimal safety and compliance. API standards are revised periodically, with the most up-to-date information available on the API website or through direct contact with API.

Environmental Protection Agency (EPA) Requirements

The EPA’s requirements for the installation and maintenance of underground gas tanks include:

Secondary containment and interstitial monitoring for all tanks installed or replaced after April 11, 2016

Design and construction in accordance with a nationally recognized code of practice

Operating requirements and technical standards for tank design and installation

The EPA conducts inspections of UST facilities to ensure compliance, with non-compliance resulting in penalties and fines.

EPA guidelines for leak detection require leak tests upon pump activation, tank tightness testing methods, and leak detection systems for regulated tanks and piping.

Choosing a Qualified Tank Testing Service

Choosing a qualified tank testing services provider is imperative for the safety and compliance of your underground gas tank. Technicians employed by tank testing companies should be certified by the manufacturer and authorized by the state in which they operate. Additionally, they should have the necessary training and certifications for the equipment they use. Southern Tank Testers is trusted, nationwide, for our expertise and experience.

Industry Leader Qualities

An industry-leading tank testing service should possess the following qualifications:

An engineering degree or an associate degree in engineering

Relevant work experience in testing and inspecting tanks

API 653 certification

Certificate of Proficiency for conducting tank inspections

Knowledgeable about tank inspection requirements and regulations

A strong safety record is also crucial as it reflects the company’s dedication to ensuring the safety of the tanks they inspect, giving clients confidence in their ability to execute meticulous and precise inspections.

Questions to Ask Potential Providers

Verifying the qualifications and certifications of a tank testing provider is a critical step in the selection process. Asking questions about their certifications, such as Certified Underground Storage Tank Tester and UST Tank Tightness Testing Certification, can help you gauge their expertise.

Additionally, inquire about their insurance coverage for pollution liability and third-party bodily injury and property damage. Southern Tank Testers can provide all of these services with the proper licensing and insurance necessary.

Case Studies: Successful Underground Gas Tank Installations and Maintenance

Successful case studies exemplify best practices and learned lessons in the installation and maintenance of underground gas tanks. Some examples of successful installations include:

Propane companies offering underground tank installations as a competitive advantage

Certified installers of Xerxes, Containment Solutions, and Highland underground tanks

Installations in areas with limited space or obstructions

These case studies highlight the importance of:

Regular inspection of tank base and supporting structures

Ensuring a level base

Checking isolation valves

Monitoring for corrosion

Following proper installation and maintenance practices.

Summary

In conclusion, underground gas tanks play an essential role in our daily lives, and ensuring their safety, inspection, and maintenance is crucial for environmental protection, public safety, and regulatory compliance. By understanding the different types of tanks, their uses, safety considerations, inspection and maintenance practices, and industry standards and regulations, you can make informed decisions when choosing a qualified tank testing service to safeguard your underground gas tank investment.

Frequently Asked Questions

What is the life expectancy of an underground gas tank?

Underground fuel tanks can last an average of 20 to 30 years, depending on the construction process, material, installation system, maintenance and soil condition. Proper installation and maintenance help extend the life of the tank.

Can gas tanks be stored underground?

Yes, gas tanks can be stored underground in depleted reservoirs, aquifers, or salt cavern formations. Above ground storage is also an option.

How do I know if I have an underground gas tank?

If you find a fill valve near your gas meter or see supply pipes or concrete patches in your walls, you may have an underground storage tank (UST). Additionally, check your yard for pipes, hidden in bushes and shrubs as well as your lawn.

How much gas is in an underground tank?

On average, a gasoline station has 30,000 to 40,000 gallons of fuel in their underground tanks. They come in different sizes ranging from 10,000 to 60,000 gallons and have systems in place to reduce risk from spills and leaks.

What is a tank test?

Tank testing is a process to assess a tank's integrity and safety. It ensures that tanks are suitable for the safe storage of fuel oil, water or other products. If not, Southern Tank Testers can recommend necessary repairs or removal of the tank to prevent damage to building, soil and groundwater.