Foundation Design for Above-Ground Storage Tanks

Engineer Your Foundation to Last

At Phillips Tank & Structure, our engineers will work with you to review geotechnical reports and project requirements to engineer and construct a durable foundation. If you have issues with an existing tank foundation, consider our storage tank foundation repair services.

The foundation of a storage tank is critical to its stability and longevity. An appropriately engineered foundation will withstand the structural load of the tank, the product stored in it, and natural forces like high winds, rain, and earthquakes. We can provide engineering services per customer requirements or industry standards, including API 650 tank foundation design, AWWA D-100, and AWWA D-103 tank foundation design.

Compacted soil tank foundation

This type of foundation is substantially lower cost than concrete ring or slab foundations, but is not recommended for most installations. Excavation for a compacted soil tank foundation is relatively quick, and the gravel used as a support and drainage layer can be compacted without heavy machinery. However, compacted soil tank foundations are not durable, and require regular maintenance to stabilize the gravel base. If a compacted soil tank foundation is not properly drained, water will seep into and under the foundation, causing ongoing settlement and erosion. Edge settlement will be an issue if the soil cannot support the weight of the tank shell.

Reinforced Concrete Slab Foundation

A reinforced concrete slab will provide a level surface to support a storage tank. However, like a compacted soil foundation, the slab may not protect from edge settlement under the tank shell. Where the soil is stable enough to protect from edge settlement, reinforced concrete slab foundations are the least expensive concrete foundation. Foundations of bolted water storage tanks often use a concrete slab as the tank bottom, and are sealed to prevent water infiltration. While reinforced concrete is strong and durable, it can still crack over time. Minor cracks are not an issue, but uneven settlement from inadequate soil support or poor groundwater drainage can damage the tank.

Reinforced Concrete Ringwall Foundation

Ringwall foundations are the most common type for storage tanks installed at ground-level, and are designed to fit a specific size of storage tank. The interior area of the ringwall can use compacted sand or a concrete slab to support the tank bottom. A reinforced concrete ringwall provides a stable base because the weight of the storage tank and product are spread out evenly across the full area of the tank bottom. Ringwall foundation construction requires specialized skills and equipment available from concrete contractors. In some cases, a thickened concrete ringwall is needed to resist uneven settlement. Like any other foundation, reinforced concrete ringwall foundations require maintenance over time. This can include repairing cracks, releveling foundations that have not settled evenly, and repainting.

Steel Pier Concrete Ringwall Foundation

In locations with poor soil, steel piers must be driven into the ground to provide additional stability. The concrete ringwall supports the tank shell, and the piers carry the weight of the tank product. Designing steel pier concrete ring foundations can be complex, and requires the appropriate engineering knowledge. Piles are an expensive solution, making them more suited for large storage tanks that must be constructed in a specific location, such as bulk fuel terminals.

Storage Tank Bottom Types

Welded Steel: Chemical, petroleum, and other storage tanks require a welded steel bottom supported by concrete or compacted soil.
Concrete Slab: Bolted water tanks commonly use a sealed concrete slab foundation with an embedded bolting ring.

Flat Bottom: A flat bottom tank is used where it is not necessary to drain water from a single low point. This will include water tanks and smaller oil tanks.
Cone Up at Center: A cone up bottom allows water to drain from the center of the tank to collect in a water-draw sump near the shell.
Cone Down at Center: A cone down bottom directs water to a sump near the tank center. This design ensures complete removal of water without any remaining at the tank shell.

Shovel Bottom: A flat bottom with a single continuous slope can be used to direct the stored product to one edge of the tank. This type of bottom allows the tank to be fully drained with a shell nozzle at the low point.
Hopper Bottom: The steep cone of a hopper bottom tank provides gravity-fed unloading, reducing the need for transfer pumps or material conveyers.

Trusted, Responsive, Nationwide Tank Contractor

PTS has over 130 employees and specializes in designing, engineering, repairing, and constructing above-ground metal storage tanks and related structures. PTS has active projects in various industries, such as petroleum, power, chemical, and renewable fuels markets throughout the United States and the Pacific Island nations.

At PTS, our commitment to our customers shapes everything we do. We have served companies across an array of industries, handling new tanks, repairs, and modifications. Our collective methodology, industry knowledge, and exhaustive range of abilities permit us to meet one-of-a-kind needs of our customers as they react to industry expectations. We believe in good quality and on-time delivery. We provide an excellent working relationship based on integrity and professionalism.

PTS is your trusted tank advisor and provides The PTS Guarantee: if you find a less expensive engineered solution to your tank needs, our engineering work is free. PTS has developed custom, proprietary business systems that help it have the most accurate design drawings and competitive lead times in the industry. Also, PTS is a nationwide tank contractor that is willing and able to go anywhere, anytime to service your tank needs.