StormVault Simplifies Installation and Maximizes Storage at San Bernardino ARCO

A new ARCO gas station along West Highland Avenue in San Bernardino, California, needed an effective way to manage stormwater runoff without sacrificing valuable space at the surface.

Like many commercial developments in Southern California, the project required a stormwater management system that could capture runoff and allow it to infiltrate naturally into the surrounding soil.

To meet these requirements, Jensen Infrastructure supplied a precast concrete StormVault system designed to store thousands of cubic feet of stormwater beneath the development while maximizing available storage capacity.

For this project, the challenge went beyond simply providing underground stormwater storage. The system needed to encourage infiltration, maximize storage volume, and provide a way for excess water to safely exit during significant storm events.

One consideration was the placement of the overflow outlet. Traditional designs often use an internal weir to control when stormwater exits the system. However, this approach can leave valuable space between the top of the weir and the vault ceiling unused, reducing the amount of available storage.

The project also called for a practical installation solution that would minimize the need for specialized equipment and help keep construction moving efficiently.

Jensen’s engineering team needed to develop a solution that addressed these challenges while making the most of the available underground space.

Jensen supplied a modular precast concrete StormVault featuring a six-foot interior height and a total storage capacity of 9,540 cubic feet, including 300 cubic feet of gravel storage.

The system was designed to prioritize infiltration, allowing captured stormwater to gradually return to the surrounding soil rather than relying solely on downstream drainage infrastructure. Six infiltration openings cast into the bottom slabs allow water to pass through the underlying gravel and into the native soil.

One of the project’s most distinctive features was a custom-designed rectangular riser that positioned the overflow pipe above the main storage chamber.

Rather than installing a traditional internal weir that would limit usable storage, Jensen’s engineering team incorporated the overflow connection into the elevated riser. This allowed stormwater to fill more of the vault’s interior before reaching the overflow elevation, maximizing storage capacity within the system’s existing footprint.

During larger storm events, when water rises beyond the system’s storage capacity, the elevated outlet provides a pathway for excess stormwater to flow into the downstream drainage system.

The StormVault’s modular design also provided a significant advantage during installation. Instead of requiring a large crane, the contractor was able to set the precast components using an excavator, a piece of equipment commonly found on construction sites. This eliminated the need to bring in a separate crane and helped simplify the installation process.

The result was a stormwater management solution that combined efficient underground storage, natural infiltration, and straightforward installation, demonstrating how thoughtful precast engineering can deliver added value beyond the structure itself.

Want to install your next stormwater detention system with only an excavator? Contact Jensen Infrastructure today.