Above ground storage tanks (ASTs) are containers used to store various substances, such as fuel, chemicals, and water, above the ground surface. They are often found in industries such as oil and gas, chemical manufacturing, agriculture, and transportation, providing a cost-effective and convenient solution for storing large volumes of these substances.The importance of these tanks in these industries cannot be overstated as they play a vital role in the operations of such sectors. The article discusses a 290 gallon steel AST used for storing and dispensing gasoline.

The integrity and design of these tanks are critical as they hold substances that could pose a risk if not stored correctly. Therefore, selecting the right type of tank is paramount to ensure compliance with regulations and meet specific operational needs. There are several types of ASTs, but in this article, we will zero in on two main types: single wall and double wall tanks. We will explore the differences between these two, their advantages, safety considerations, and how they comply with regulations.

Additionally, it is important to note that ASTs are subject to stringent regulations and guidelines to ensure the safe storage and handling of hazardous materials. These regulations are put in place by environmental and safety bodies to protect the environment and the people working around these tanks. Compliance with these regulations is not just a legal requirement, but it's also an ethical obligation to safeguard our environment.

Single Wall Tanks: An Overview

Single wall tanks, as the name suggests, consist of a single layer of metal that directly holds the stored substance.This design is straightforward and effective, fulfilling the basic requirement of a storage tank, which is to safely contain substances.Single wall tanks are commonly used in situations where [secondary containment](http://www.epacinc.com/single-wall-vs-double-wall-fuel-tanks-need) , such as a concrete structure coated with epoxy, is already in place to prevent leaks. Single wall tanks offer several benefits, including affordability and flexibility in placement.

One specific type of single wall tank worth mentioning is the diked tank. Diked tanks are a subtype of single wall tanks that come with an integral steel containment structure in the form of an open-top dike. This design provides secondary containment in the event of a leak, thereby minimizing the risk of environmental contamination. This is an excellent example of how the single wall tank design can be augmented to increase safety.

While single wall tanks are often used when there is an existing concrete structure available for containment, it should be noted that this structure must meet specific requirements to be considered effective. This concrete structure needs to be coated with a substance such as epoxy to prevent the corrosive action of the stored substances. Besides, it should be inspected regularly for any signs of wear or damage that could compromise its effectiveness. This underscores the need for additional safety measures when dealing with single wall tanks.

Double Wall Tanks: An Overview

Double wall tanks take safety and environmental protection a notch higher with their innovative design. Unlike their single-wall counterparts, double wall tanks are designed with two layers of metal, with the primary tank surrounded by a secondary containment layer. This design essentially provides a tank within a tank, significantly increasing the level of safety and protection against leaks.

The secondary containment layer in double wall tanks offers an extra level of protection. Should there be a leak in the primary tank, the secondary containment layer is ready to catch the leaked substance before it can enter the environment, offering a fail-safe mechanism. This is especially crucial when storing substances that are potentially harmful to the environment or pose a fire risk.

An important feature of double wall tanks is their monitoring systems. These systems are designed to detect leaks and prevent rainwater from entering the tank, further enhancing the safety and efficiency of these tanks. For instance, a vacuum gauge is often installed between the two walls to monitor the space. Any change in the vacuum level could indicate a leak, prompting immediate action.

Double wall tanks also offer resistance to inclement weather conditions. Their robust construction can withstand high winds and heavy rainfall, ensuring that the stored substance remains safe even in harsh weather conditions. This is a critical feature as exposure to adverse weather conditions could cause damage to the tank and potentially lead to leaks.

Comparison: Single Wall vs Double Wall Tanks

When comparing single wall and double wall tanks, several factors should be taken into account. These factors include cost, space and existing structures, compliance with regulations, placement and flexibility, leak monitoring systems, and resistance to weather conditions.

When it comes to cost, single wall tanks generally have a lower initial cost than double wall tanks. This can make them an attractive option for businesses operating on a tight budget. However, it's important to note that while single wall tanks may have a lower upfront cost, additional expenses may be incurred for secondary containment systems, such as concrete structures or other approved methods [3, 4].

Space and existing structures also play a key role in the decision-making process. While single wall tanks require additional concrete structures for containment, double wall tanks do not. This can make double wall tanks a more convenient option in situations where space is limited or there is no existing containment structure [3, 4].

Compliance with Environmental Protection Agency (EPA) regulations is a crucial consideration in the choice between single wall and double wall tanks. Double wall tanks automatically comply with EPA regulations due to their built-in secondary containment. In contrast, single wall tanks may require additional measures, such as secondary containment systems, to achieve compliance [3, 4].

When it comes to placement and flexibility, single wall tanks offer more flexibility, especially if there is an existing concrete structure available. However, double wall tanks, with their built-in secondary containment, may not require specific placement to ensure containment.

Leak monitoring is another important factor in the comparison. Double wall tanks have built-in leak monitoring systems, providing an added layer of protection and peace of mind. Single wall tanks, on the other hand, may require additional leak detection systems to ensure safety.

Finally, weather resistance can be a key factor, especially in areas prone to severe weather conditions. Double wall tanks offer resistance to inclement weather conditions, ensuring the stored substance remains safe.

In summary, when choosing between single wall and double wall tanks, it's crucial to consider all these factors. The decision should be based on a thorough assessment of the specific needs, budget, and regulatory requirements of the operation.

Safety Considerations for Above Ground Storage Tanks

When it comes to above ground storage tanks, safety is paramount. For single wall tanks, the absence of a built-in secondary containment means it is critical to have an effective secondary containment measure in place, such as a concrete structure coated with epoxy. This is to ensure that in the event of a leak, the leaked substance is contained and does not seep into the environment.

Additionally, regular inspections of the tank and the secondary containment structure are crucial to ensure their integrity. This is particularly important for single wall tanks where the risk of leaked substances reaching the environment is higher due to the absence of a built-in secondary containment. Regular inspections can help detect any signs of wear or damage early, allowing for timely repairs and prevention of potential leaks.

Double wall tanks, on the other hand, have an inherent secondary containment system. This design is a significant safety feature as it provides a built-in safeguard against leaks. However, this does not eliminate the need for regular inspections and maintenance. The secondary containment layer should be routinely inspected to ensure its integrity and functionality.

Furthermore, double wall tanks often come equipped with leak monitoring systems. These systems provide an added layer of safety by detecting leaks early, allowing for prompt action to prevent environmental damage. Regular testing and calibration of these systems are necessary to ensure they remain effective in detecting leaks.

In summary, regardless of the type of tank, adherence to safety guidelines and regulations is crucial in ensuring the safe storage and handling of substances. Regular inspections, routine maintenance, and effective leak detection and containment measures are key in ensuring the safety of above ground storage tanks.

Importance of EPA Compliance and Regulations

Compliance with Environmental Protection Agency (EPA) regulations is a critical aspect of operating above ground storage tanks. The EPA has specific guidelines and requirements in place to ensure the safe storage and handling of hazardous substances.These regulations are designed to protect the environment from potential contamination that can result from leaks or spills.

Double wall tanks are designed to automatically meet these EPA regulations. Their built-in secondary containment provides an added layer of protection, minimizing the risk of leaks and environmental contamination. This makes double wall tanks an attractive option for businesses looking to ensure regulatory compliance with minimal additional measures [3, 4, 5].

Single wall tanks, on the other hand, may require additional measures to achieve compliance with EPA regulations. This could include the installation of secondary containment systems or other approved methods to prevent leaks [3, 4]. It is essential to understand these requirements and ensure that they are met when choosing and operating single wall tanks.

In addition to federal regulations, state and local regulations may also apply to above ground storage tanks. These can vary from one location to another and may have specific requirements regarding tank design, installation, operation, and maintenance. It is essential to understand these regulations and ensure compliance to avoid penalties and ensure environmental protection.

Cost Analysis and Budget Considerations

The financial aspect of installing and maintaining above ground storage tanks is a significant consideration. When it comes to upfront costs, single wall tanks generally have a lower initial cost compared to double wall tanks. This can make them an attractive option for businesses operating on a tight budget. However, it is crucial to also consider the long-term costs associated with each type of tank.

For single wall tanks, additional expenses may be incurred for secondary containment systems, such as concrete structures or other approved methods. These costs can add up over time, potentially offsetting the initial cost savings [3, 4]. Furthermore, if a leak occurs and the secondary containment fails, the cost of clean-up and potential fines for environmental damage can be substantial.

Double wall tanks, on the other hand, come with a higher initial cost. However, their built-in secondary containment eliminates the need for additional containment measures, potentially saving costs in the long run [3, 4]. Furthermore, in the event of a leak, the secondary containment can prevent the leaked substance from entering the environment, potentially saving on clean-up costs and avoiding fines.

Therefore, when considering the cost of single wall vs. double wall tanks, it's important to look beyond the initial investment. A comprehensive cost analysis should include both upfront and long-term costs, including potential clean-up costs and fines in case of leaks. This will provide a more accurate picture of the total cost of ownership, enabling an informed decision to be made.

Environmental Impact and Sustainability

The decision between single wall and double wall tanks can have significant implications for the environment. Single wall tanks, if not equipped with effective secondary containment, carry a higher risk of environmental damage in the event of a leak. This can lead to soil and water contamination, which can have serious consequences for local ecosystems and public health.

On the other hand, double wall tanks, with their built-in secondary containment, provide an added layer of protection, minimizing the potential for environmental contamination. In the event of a leak, the secondary containment layer acts as a barrier, preventing the leaked substance from escaping into the environment.

By choosing double wall tanks, businesses can demonstrate their commitment to environmental stewardship. These tanks offer a higher level of safety and reduce the risk of environmental damage, contributing to the long-term sustainability of operations. This can enhance a business's reputation as an environmentally responsible entity and can potentially contribute to customer trust and loyalty.

Moreover, as environmental regulations become more stringent and public awareness of environmental issues increases, the use of double wall tanks can help businesses stay ahead of the curve. By investing in double wall tanks, businesses can not only meet current regulations but also be prepared for potential future regulatory changes aimed at further protecting the environment.

Real-World Examples and Recommendations

In a real-world example discussed on the AST Forum, a 290-gallon steel AST used for storing and dispensing gasoline raises questions about determining if the tank is single wall or double wall just by observing the vents. In this case, without visible markings or labels to provide information about the tank's construction, it can be challenging to determine if the tank is single or double-walled.

One recommendation in such situations is to consult the manufacturer's specifications or seek professional advice. Visual indicators, such as a slightly larger size, a vacuum gauge to monitor the vacuum between the layers, and the absence of a separate epoxy-coated concrete structure, may suggest a double wall tank. However, these indicators are not foolproof, and it is always best to seek professional advice or consult the manufacturer's specifications to confirm the type of tank.

In addition to observing the physical characteristics of the tank, regular inspections and maintenance can also provide insights into the tank's construction. For instance, during maintenance, the presence of a secondary containment layer or a leak detection system may indicate a double wall tank. Therefore, regular inspections and maintenance are not only important for ensuring the safe operation of the tank but can also provide valuable insights into its construction.

Maintenance and Longevity of Tanks

The maintenance of above ground storage tanks is crucial for ensuring their longevity and safe operation. Regular inspections, leak monitoring, and adherence to maintenance guidelines provided by the manufacturer are key aspects of tank maintenance, regardless of whether they are single wall or double wall tanks.

For single wall tanks, regular inspections of the tank and the secondary containment structure are essential. Any signs of wear or damage should be promptly addressed to prevent leaks and environmental contamination. Regular maintenance also includes checking for signs of corrosion, which can compromise the integrity of the tank and lead to leaks.

For double wall tanks, both the primary and secondary containment layers should be regularly inspected for signs of corrosion or leaks. The monitoring systems, if present, should be tested and calibrated to ensure accurate detection of any leaks. While the built-in secondary containment of double wall tanks provides an added layer of protection, it does not eliminate the need for regular inspections and maintenance.

With proper maintenance, both single and double wall tanks can provide long-term reliability and cost-effectiveness. In fact, with proper maintenance, double-wall oil tanks can last up to 50 years. This underlines the importance of regular inspections and maintenance in ensuring the longevity of above ground storage tanks.

Future Trends and Innovations in Tank Design

The field of above ground storage tanks is continually evolving, with ongoing advancements in materials, design, and technology. Future trends and innovations may include improved corrosion-resistant materials, enhanced leak detection systems, and more sustainable and environmentally-friendly designs.

For example, advancements in material technology can lead to the development of more corrosion-resistant materials, enhancing the longevity and durability of above ground storage tanks. Improved leak detection systems, capable of detecting even the smallest leaks in real-time, can provide early warning of potential issues, allowing for prompt action to prevent environmental damage.

Sustainable and environmentally-friendly designs are another potential area of innovation. As environmental regulations become more stringent and public awareness of environmental issues increases, the demand for sustainable and environmentally-friendly storage solutions is likely to grow. This could lead to the development of tanks made from recycled or eco-friendly materials, or designs that minimize the risk of leaks and environmental contamination.



As technology continues to evolve, it is essential to stay updated on the latest innovations and trends in tank design and technology. By embracing new technologies and sustainable practices, businesses can ensure the safe and efficient storage of substances while minimizing their environmental footprint and meeting regulatory requirements.