Los Angeles, California

The Gateway Center underground parking facility requires the lowering of the ground-water table approximately twenty feet over eight acres during construction. The parking facility will provide space for the occupants of six future office buildings and Union Station, the hub of the Los Angeles metropolitan transit authority (MTA) in downtown Los Angeles.

Ground water at the site is affected by hydrogen sulfide produced by anaerobic subsurface conditions, and volatile organic compounds (VOC's), which migrated from off-site sources. Therefore extensive treatment is required before discharge to the Los Angeles River during the temporary dewatering process. The ground water, extracted from 25 perimeter wells, is pumped to the treatment plant, designed for a maximum flow of 850 gallons per minute.

The treatment process includes sulfide oxidation by hydrogen peroxide at high pH, followed by UV-H2O2 oxidation and/or activated carbon for VOC removal. The addition of peroxide and pH adjustment chemicals is fully automated and controlled, with the hydrogen peroxide addition being controlled using the prototype PEROX 20 control system (see PEROX 20 Article). This is the first commercial application of PEROX 20 in the world.

The water treatment plant was built in record time, with only two months from groundbreaking to startup.



Please note: A case study on the Gateway Project appears in Reference Library - Peroxide Applications : Hazardous Waste.

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