Odor Control

Odor Control at USD's Treatment Plant

odor scrubbers 2 webOdor ScrubbersOn an average day, the District treats approximately 25 million gallons of wastewater for our customers in the Tri-Cities. Treatment involves separating solids from water, then stabilizing them through a natural biological process. The stabilized solids are dewatered in a high-speed centrifuge, then hauled away in covered trucks for beneficial reuse. The water is further treated, clarified and disinfected before release in the deep waters of San Francisco Bay.

Plant Operators monitor the process 24/7/365 to ensure that continuous compliance with rigorous EPA standards is maintained. USD's treatment plant has received recognition from the National Association of Clean Water Agencies for Outstanding Performance since its program began in 1993.

How USD Controls Odors

In 1986, the District installed state-of-the-art odor control facilities called "odor scrubbers." Additionally, all odor-producing treatment processes take place in covered buildings that are connected to odor scrubbers.

USD has taken additional steps to keep odors away from our surrounding neighbors. We built a 15-foot tall, 300-foot long wall along our eastern perimenter that is closest to residential neighorhoods. We also improved the performance of our odor scrubbers by increasing the height of 11 scrubber stacks and adding cones at their tops to increase air velocity. Both of these projects help to force odors higher into the atmosphere and away from nearby residences.

The District also topped 1,000 ft. of our boundary fence with an atomizing mist system to neutralize odors. This misting system is activated whenever weather conditions increase the possibility of odor dispersion from the treatment plant and the Bay.

USD constantly monitors the efficiency of our odor control systems, and we diligently maintain them to provide the best service possible to our neighbors and customers.

USD Takes Odor Complaints Seriously

View our Odor Brochure for information about USD's Treatment Plant and adjacent wetlands

View tide predictions for the USD Treatment Plant vicinity

Although most odors in the area come from the Bay during low tides, when the District receives an odor complaint from our neighbors we immediately investigate and report our findings back to the caller. All odor complaints received are investigated, recorded, tracked and reported to our Board of Directors at their bi-monthly meetings.

USD always checks the operation of our treatment processes and responds to the neighborhood location of the odor complaint to determine the cause.

If you believe an odor is coming from the USD plant, call us immediately at (510) 477-7500. We operate 24/7/365, and will respond right away.


For additional information about USD's odor control systems contact us at (510) 477-7500.

East Perimeter WallEastern Perimeter Wall       Dewatering Bldg scrubbersDewatering Building with Odor Scrubbers       Perimeter Misting SystemPerimeter Misting System


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5072 Benson Road

Union City, CA 94587-2508

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