San Jose Strides Toward Stronger Stormwater Treatment

San Jose, California

Water is an integral part of the California lifestyle and ecosystem, playing a pivotal role in everything from recreation to agriculture. Yet, as trash produced by human activity makes its way into streams, rivers, and creeks, it inevitably finds its way into the ocean.

As part of backend engineering support for a stormwater system in the City of San Jose, located about 40 miles south of San Francisco, Jensen Precast assisted in the installation of a dual offline hydrodynamic separator system. The site was located on Quimby Road in San Jose, about 15 minutes from the city’s downtown area.

The initiative is part of California’s Trash Amendments, which apply to all municipal separate storm sewer, industrial, and construction NPDES permittees. The Jensen Hydrodynamic Separator (JDS) system is certified as a Full Capture System Trash Treatment Control Device by the California State Water Resources Control Board.

At the heart of the JDS lies its unique ability to screen and capture trash, debris, and pollutants from stormwater before it makes its way to streams, rivers, creeks, and oceans. Not only does the JDS excel in capturing large scale debris, but smaller pollutants as well. These include waste like oil, grease, sand, and grit. Captured elements remain in the JDS unit, while screened runoff is distributed to the rest of the storm drain system.

“The JDS setup in San Jose will result in the removal of litter from surrounding creeks, waterways, and ultimately the San Francisco Bay,” says Christopher Purdie, Sales Operations Manager at Jensen Precast, who served as an onsite representative during the installation.  “The dual JDS was required to achieve the city’s Stormwater Quality Flow Rate for this site.”

The JDS unit utilizes two 12’ diameter precast concrete manholes, with a flow splitting vault in between the two structures. The unit is part of San Jose’s Large Trash Capture Device Installation Phase XII, an initiative to install trash capture devices on the city’s storm drain system. The goal is to provide 100 percent trash load reduction by July 2025.

“This is the first Full Trash Capture project for the City of San Jose that Jensen Precast has been involved in,” Purdie explains. “This project has a total of five locations, and we have currently completed two.”

Along with the Quimby Road installation, Jensen Precast supported an installation on Alexian Drive in San Jose. Stormwater systems protect property and life from flood hazards. Current stormwater management prioritizes runoff as a valuable natural resource and provides new life through restoration, facilitating its potential for future reuse.

The installation of the Jensen Hydrodynamic Separator represents a step forward in stormwater management and achieving these goals, emphasizing the importance of collaborative efforts in safeguarding California’s precious water resources.

To download drawings of the JDS system, go here. To speak with a Jensen Precast engineer about hydrodynamic separators and stormwater solutions, call (775) 352-2700.

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