Underground Storage Tank: A Comprehensive Guide

An underground storage tank (UST) is a specialized container designed to store hazardous materials, petroleum products, or chemicals beneath the ground’s surface. These tanks are constructed using steel or fiberglass and vary in size, with capacities ranging from a few hundred gallons to several million gallons. USTs are subject to federal regulations in the United States, which specify that a UST must consist of a tank, along with any connected underground piping, and at least 10 percent of its combined volume must be situated underground.

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The use of underground storage tanks serves multiple purposes, such as minimizing the risk of environmental contamination, conserving space above ground, and protecting the contents from extreme temperature fluctuations. Proper installation, maintenance, and monitoring of USTs are crucial to ensure their integrity and prevent leaks that could result in significant environmental damage, costly clean-up operations, and potential harm to human health.

As awareness about the potential hazards associated with USTs continues to grow, stricter regulatory guidelines and comprehensive training programs are being implemented to ensure the proper management and operation of these crucial storage systems. This article will delve into the essential aspects of USTs, including their design, applications, and the development of relevant regulations to address potential concerns.

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What Is an Underground Storage Tank (UST)?

An Underground Storage Tank (UST) refers to a storage tank and any underground piping connected to the tank. These tanks usually store either petroleum or certain hazardous substances, with at least 10 percent of their combined volume underground. The purpose of USTs is to safely store substances while helping to protect the environment and public health.

Types of USTs

There are several types of USTs, each designed for different purposes and substances. Some common examples include:

  • Motor fuel USTs: Used to store automotive fuels such as gasoline, diesel, and aviation fuels.
  • Heating oil USTs: Designed for storing heating oil for use in furnaces, boilers, and other heating appliances.
  • Hazardous substances USTs: Used to store chemicals and other hazardous substances that require proper containment and handling.
  • Septic tanks: Wastewater treatment systems that receive and treat domestic sewage from households.
  • Flow-through process tanks: Tanks that are part of a larger process where fluids flow through and are temporarily held before moving on to the next stage in the process.

Certain tanks, like septic tanks and flow-through process tanks, are generally not regulated as USTs since they serve different purposes and are not primarily focused on long-term storage.

It is essential to select the appropriate type of UST based on the substance being stored and the specific requirements for safe and compliant storage. This helps avoid potential environmental and health risks associated with improper storage and containment.

In order to provide maximum safety and reduce environmental risks, USTs are subject to strict regulations and guidelines by the Environmental Protection Agency (EPA).

UST Regulations and Programs

UST Program

Underground storage tanks (USTs) are widely used to store petroleum and hazardous substances, and proper management is essential to protect the environment and public safety. The Environmental Protection Agency (EPA) established the UST Program to oversee the implementation of regulations and requirements concerning the operation, maintenance, and monitoring of these tanks. The program aims to minimize the environmental and health risks associated with leaking tanks and to ensure proper tank disposal.

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The EPA partners with state, local, and tribal governments to administer the UST program by providing technical assistance, educational resources, and funding for inspection and enforcement activities.

UST Regulations

The federal UST regulations are described in the Code of Federal Regulations (CFR), Title 40, Part 280. Requirements include design, construction, installation, notification, release detection, release reporting, corrective action, and closure. The regulations also outline financial responsibility and operator training requirements to ensure proper management and prevent releases.

In addition to federal regulations, states may have their own UST regulations that supplement or supersede the EPA’s requirements. Owners and operators must adhere to both federal and state regulations to maintain compliance.

Energy Policy Act of 2005

The Energy Policy Act of 2005 amended Subtitle I of the Solid Waste Disposal Act, enhancing the federal UST program by:

  • Mandating state implementation of operator training programs
  • Requiring secondary containment for new and replaced tanks and piping
  • Requiring financial responsibility for installation and closure of tanks
  • Establishing guidelines for delivery prohibition if a tank is found to be non-compliant.

Subtitle I of the Solid Waste Disposal Act

Subtitle I of the Solid Waste Disposal Act established the regulatory framework for the EPA’s UST program. It requires EPA to develop and implement regulations related to the storage of petroleum and hazardous substances, as well as guidelines for states to gain approval to operate their own UST programs.

As part of this regulation, the EPA issues a UST Technical Compendium containing interpretations and clarifications of federal UST regulations, which can guide owners, operators, and inspectors in understanding and implementing the requirements.

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Overall, the UST regulations and programs work in tandem to protect public health and the environment from potential contamination stemming from underground storage tanks. Ensuring compliance and proper management practices helps maintain a safer, cleaner environment for all.

Installation and Inspection

Secondary Containment

Underground Storage Tanks (USTs) are designed to store hazardous substances like petroleum or other chemicals. As a crucial preventive measure, secondary containment systems are installed around the main storage tank. Secondary containment helps prevent hazardous substance leaks into the environment by capturing any released substances.

These containment systems may include double-walled tanks or external barriers surrounding the tank to provide additional protection. Proper installation of secondary containment ensures the durability and effectiveness of the storage system.

Spill Prevention

A critical aspect of UST installation is preventing spills during operation. Several techniques ensure that spills, overfills, and corrosion are avoided. These include:

  • Installing overfill prevention devices, such as alarms and shut-off valves, to stop the flow of substances when the tank reaches its maximum capacity
  • Following correct filling practices, such as monitoring fill levels and using appropriate equipment
  • Implementing corrosion protection methods, like cathodic protection or using corrosion-resistant materials

Adhering to these practices helps maintain the integrity of the tank and protect the environment from accidental spills and leaks.

Periodic Inspections

Regular inspections of UST systems are essential to ensure their continued safe operation. Inspection guidelines may differ depending on local regulations, but they generally cover aspects such as:

  • Checking for leaks or signs of corrosion in the tank, piping, and ancillary equipment
  • Assessing the functionality of overfill prevention devices and alarms
  • Confirming the integrity of secondary containment systems
  • Monitoring tanks for the presence of water, which could indicate a leak or other issues

Periodic inspections help identify potential problems in the early stages and facilitate timely interventions to maintain the safety and efficiency of UST systems.

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Leaking USTs and Enforcement

Leaking USTs

An underground storage tank (UST) system consists of a tank and any underground piping connected to the tank, having at least 10% of its combined volume underground. Leaking USTs (LUSTs) are a major concern due to the potential release of petroleum or hazardous substances into the environment.

Corrective Action

To address leaking USTs, corrective actions are taken in accordance with the 2015 UST regulations. These actions include:

  • Investigating the extent of environmental contamination
  • Cleaning up contaminated soil and groundwater
  • Ensuring proper operation and maintenance of UST systems

Local governments and communities play a crucial role in supporting these corrective actions, ensuring that environmental and public health risks are minimized.

Enforcement and Compliance

The U.S. Environmental Protection Agency (EPA) enforces the regulations governing UST systems, as authorized by Title 42, Chapter 82, Subchapter IX of the U.S. Code. This law integrates amendments to Subtitle I of the Solid Waste Disposal Act, UST provisions of the Energy Policy Act of 2005, and grants the EPA authority to regulate and enforce compliance of UST systems.

Enforcement and compliance efforts involve:

  • Regular inspections of UST systems
  • Providing technical assistance and resources to owners and operators
  • Ensuring adherence to regulatory requirements, such as leak detection and prevention, as well as proper system closure procedures.

State and local governments, along with the EPA, work closely in implementing and enforcing these regulations. The Arizona Department of Environmental Quality (ADEQ), for example, is responsible for overseeing UST compliance in Arizona.

Environmental and Public Health Impacts

Groundwater Contamination

Underground storage tanks (USTs) can pose a significant threat to environmental and public health due to their potential for leaking toxic substances. For example, leaked petroleum or hazardous substances can contaminate groundwater, which serves as a source of drinking water for nearly half of all Americans. When UST contents seep into the soil, they can potentially contaminate groundwater, affecting both private and municipal drinking water wells.

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Soil Contamination

Leaking USTs can also result in soil contamination. Toxic materials, such as gasoline and waste oil, contain dangerous substances that can quickly move through the soil and pollute surrounding areas. If left unchecked, these contaminants can eventually reach rivers, lakes, reservoirs, and other water bodies, negatively impacting aquatic life and ecosystems.

Human Health Risks

The harmful substances commonly found in USTs pose considerable risks to human health. Exposure to these materials can lead to various health conditions, including cancer and developmental problems in children. Moreover, the contamination of groundwater and soil directly affects public health, as exposure to these pollutants can occur through ingestion, inhalation, or dermal contact.

In summary, the environmental and public health impacts associated with underground storage tanks warrant serious consideration. Preventing leakage and contamination is essential to preserving groundwater, soil, and human health.

Types of Tanks and Facilities

Residential Tanks

Residential tanks are typically used for storing heating oil for home purposes, and their capacity tends to be smaller than that of other tank types. These tanks are usually exempt from federal underground storage tank (UST) regulations, as long as they are used on the premises where the oil is stored.

Farm and Residential Tanks

Farm and residential tanks are commonly used to store motor fuel for noncommercial purposes on farms or in residential settings. These tanks have a capacity of 1,100 gallons or less, and like residential tanks, they are usually exempt from federal UST regulations.

Some types of exempt tanks include:

  • Tanks storing heating oil used on the premises where it is stored
  • Tanks on or above the floor of underground areas, such as basements or tunnels
  • Septic tanks and systems for collecting stormwater and wastewater
  • Flow-through process tanks
  • Tanks of 110 gallons or less capacity
  • Emergency spill and overfill tanks
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Aboveground Storage Tanks

Aboveground storage tanks (ASTs) are another common type of storage facility, and they store materials like natural gas or petroleum. While ASTs are not considered USTs, they still need to comply with specific regulations and safety standards, as their contents can pose hazards to the environment and human health.

Natural gas can be stored in both liquid and gaseous forms in ASTs. Underground gas storage is primarily held in three types of facilities:

  • Depleted reservoirs in oil and/or natural gas fields
  • Aquifers
  • Salt cavern formations

These facilities store the gas under pressure, helping to ensure a steady and reliable supply of natural gas when needed.

In summary, there are various types of storage tanks and facilities, including residential, farm and residential, and aboveground storage tanks. Each type serves specific purposes and is regulated accordingly to ensure safety and environmental protection.

Specific Locations and Industries

Service Stations

Service stations are one of the primary users of underground storage tanks (USTs). USTs at service stations store a variety of fuels like gasoline, diesel, and sometimes alternative fuels. These tanks help meet the storage and dispensing needs of customers by ensuring a constant supply of fuel at the pump. As the fuels are hazardous materials, these tanks need to comply with federal regulations to prevent environmental contamination and ensure safety.

Convenience Stores

Convenience stores that sell fuel also utilize UST systems to store petroleum products. Similar to service stations, the tanks are needed for storing fuel that can be dispensed at the pump. Besides gasoline and diesel, some convenience stores may offer additional fuel types like ethanol or biodiesel. Adherence to federal regulations is crucial for the safe functioning of the USTs and the environment.

Fleet Service Operators

Fleet service operators utilize USTs to store fuel to power their fleet of vehicles, such as trucks, vans, or buses. These operators often have their own fueling stations on-site, allowing them to easily access and monitor fuel consumption. The use of USTs in this scenario promotes efficiency within the fleet operations by making fuel readily available. Similar to other industries, fleet service operators are required to follow federal regulations when it comes to UST management.

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Pipeline Facilities

Pipeline facilities store and transport hazardous materials such as petroleum products or chemicals. USTs play a vital role in some of these facilities by storing the materials before they are transported through the pipeline system. Additionally, intrastate pipeline facilities, which operate within one state, may also use USTs for this purpose. Compliance with federal regulations is crucial not only for the safety of these storage systems but also for reducing potential environmental impact from leaks or spills.

Storage Methods and Structures


Pits are excavated depressions in the ground, commonly used for the temporary storage of liquid materials, such as water, crude oil, or even waste products. Pits can take different forms depending on their intended use and local soil conditions, but they generally have:

  • Earthen walls reinforced with gravel or rocks
  • Liners or other impermeable barriers to prevent leaks, if storing hazardous materials
  • Covers or fences to deter wildlife and unauthorized access

Some typical uses for pits include:

  • Retention ponds for stormwater management
  • Emergency spill containment
  • Temporary storage for drilling fluids in oil and gas operations


Lagoons are shallow, pond-like structures used to store or treat liquid waste, especially in wastewater treatment and agricultural settings. They can be natural or man-made, and their design typically includes:

  • An excavated or bermed basin
  • A liner, often made from clay or synthetic materials, to prevent leakage
  • Aeration or other treatment equipment, if necessary

Lagoons can serve different purposes, such as:

  • Storing and treating wastewater from industrial processes, human settlements, or agricultural operations
  • Stabilizing organic matter in animal waste or sludge
  • Providing temporary storage and treatment before transfer to another facility
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Impoundments, also known as surface impoundments, are earthen or concrete structures that hold water or other liquid materials. Generally, impoundments have one or more raised embankments to contain the stored materials and prevent leakage. Some features of impoundments include:

  • Levees, dikes, or other embankments for containment
  • Liners, such as clay or synthetic materials, to prevent leaks
  • Monitoring systems to detect potential issues, like leaks or structural failures

Impoundments can fulfill different roles depending on their size, location, and contents, including:

  • Storing water for irrigation, power generation, or human consumption
  • Containing toxic or hazardous materials, like mine tailings or industrial waste
  • Facilitating sedimentation and settling processes in wastewater treatment plants

Regulatory Amendments and Acts

Hazardous and Solid Waste Amendments

The Hazardous and Solid Waste Amendments (HSWA) were passed in 1984, amending the Resource Conservation and Recovery Act (RCRA). These amendments expanded and strengthened the regulatory system, focusing on:

  • Improved hazardous waste management
  • Increased enforcement authority against non-compliant facilities
  • Enhancing state involvement in waste regulation

The HSWA granted authority to the EPA to regulate Underground Storage Tanks (USTs) and set guidelines to prevent hazardous substance leaks and contamination.

Superfund Amendments and Reauthorization Act

The Superfund Amendments and Reauthorization Act (SARA) was enacted in 1986. It amended the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and reauthorized the Superfund program. SARA aimed to:

  • Provide for quicker and efficient cleanup of hazardous waste sites
  • Improve public participation in the cleanup process
  • Increase attention to the potential health risks

SARA addressed the problem of leaking USTs by establishing programs to oversee their operation, maintenance, and closure to protect human health and the environment.

American Recovery and Reinvestment Act of 2009

The American Recovery and Reinvestment Act of 2009 (ARRA) included funding for environmental cleanup, including UST cleanups. It allocated funds for:

  • Assessment and cleanup of leaking UST sites
  • Supporting state UST programs
  • Research, development, and demonstration projects related to UST leaks
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The ARRA helped address the backlog of UST sites requiring cleanup, while also promoting job creation and advancing environmental protection efforts.

Regulated Substances and Storage Facilities

Underground storage tanks (USTs) are systems that consist of a tank and any underground piping connected to it, with at least 10 percent of their combined volume underground. These tanks are used for storing regulated substances, which are primarily petroleum or certain hazardous substances.

Regulated Substances

Regulated substances in USTs can include:

  • Petroleum: Gasoline, diesel, jet fuel, and other petroleum-based products
  • Hazardous substances: Certain chemicals or compounds classified as hazardous by federal regulations

It is important to ensure the proper storage and handling of these substances to prevent environmental contamination, leaks, and spills.

Storage Facilities

UST storage facilities need to adhere to federal regulations and standards to ensure safety and prevent leaks. Key aspects of these facilities include:

  • Design and construction: Tanks and connected piping should be constructed using materials that are resistant to the stored substance’s potential corrosive effects.
  • Leak detection: Storage facilities must have leak detection systems in place to monitor for potential leaks, spills, or other issues.
  • Corrosion protection: USTs and their piping must have corrosion protection systems to prevent damage and leaks over time.

Liquid Trap

A liquid trap is a safety feature in some UST systems designed to contain regulated substances, particularly hazardous liquids. These traps can prevent the release of hazardous substances into the environment in case of a tank leak or system failure. Liquid traps can be standalone devices or integrated within the UST system itself.

By adhering to federal regulations and ensuring proper design, construction, and maintenance, underground storage tank systems can effectively store regulated substances while minimizing the risk of leaks and spills that could harm the environment.

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Underground Pipes and Systems

An underground storage tank (UST) is a storage system that includes a tank, as well as any connected underground piping. The system has at least 10 percent of its combined volume underground, which means that the tank and the underground pipes together contribute to this volume.

USTs are designed for storing substances such as petroleum or certain hazardous chemicals. They are constructed using high-quality materials like horizontal cylindrical steel and coated with factory-applied protective layers, preventing corrosion and leaks. This combination of materials and layering ensures the longevity and safety of underground storage tank systems.

Underground Pipes

A critical component of UST systems is the underground pipes connecting the tanks. These pipes are responsible for safely transporting substances between the storage tank and other ancillary equipment. Just like the tanks, these pipes are also designed to be durable and prevent leakages into the surrounding environment.

Materials and Construction

Underground pipes used in UST systems are typically made of corrosion-resistant materials such as fiberglass, steel, or a combination of both. They are also equipped with secondary containment systems, like a double-wall piping structure, to ensure no leaks occur.

Maintenance and Monitoring

To maintain the safety and longevity of UST systems, regular inspections and maintenance of underground pipes are essential. Leak detection methods, like interstitial monitoring and monthly inventory control, can help detect problems early and prevent serious environmental hazards.

Regular maintenance checks typically include:

  • Inspections for signs of corrosion and leaks
  • Assessment of pipe supports, connections, and associated ancillary equipment
  • Testing of any leak detection devices present in the system

By ensuring the integrity of underground pipes and the overall UST system, underground storage tank operators can minimize the risks associated with potential leaks or spills, ultimately ensuring a safer and environmentally friendly storage solution.


Hello! I'm Nikita, the creator of Abodenation, a blog dedicated to home improvement, troubleshooting, advice, and decor. With years of hands-on experience and a keen eye for detail, I love sharing my passion for creating functional, beautiful, and comfortable living spaces with others. Join me on my journey to transform houses into homes, one project at a time.

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