Project will divert dry-weather water flows away from storm drains

Los Angeles, CA – NYSE, TSX:STN

As part of a comprehensive effort to improve the water quality in the Los Angeles River and Arroyo Seco, the City of Los Angeles Department of Public Works will soon break ground on the $13 million Low Flow Diversion (LFD) Project. The project, led by global design firm Stantec’s Pasadena office, in collaboration with Los Angeles Department of Public Works Bureau of Engineering (BOE) and Los Angeles Sanitation & Environment (LASAN), will provide new infrastructure to remove dry-weather flows from five sub-watersheds to the LA River and Arroyo Seco.

Both the LA River and the Arroyo Seco are negatively impacted by multiple pollutants contained in dry-weather flows. At times, high levels of bacteria in the two waterways rivals that of wastewater. Heavy metals and petroleum products are also washed into storm drains and waterways. Dry-weather flows are usually a combination of runoff from car washing, lawn sprinkling, and watering of plants/gardens.

Diverting the dry-weather flows from the storm drains into existing sanitary sewers and to the City’s Hyperion Water Reclamation Plant for treatment provides two benefits. The first is improvement to the water quality of the LA River and Arroyo Seco. The second provides additional water that, once treated, can bolster water security in the region.

“The City of Los Angeles wants to use Arroyo Seco and the LA River for more recreational purposes,” said Venu Kolli, Stantec senior principal and project manager. “It’s critical that the water quality is improved. Diverting this low-flow water is an excellent way to enhance the waterways and give the City additional resources through water reclamation. We are excited to see the community-enhancement project start construction.”

Nearly all the public-outreach meetings took place during the COVID-19 pandemic, which created unique challenges for stakeholder involvement. After one in-person meeting, all public meetings were switched to virtual meetings, including those with local council districts.

When completed, the project should divert about 1 million gallons per day from storm drains, while providing no negative impact on wet-weather flows from storms. Construction, which is led by Clarke Contracting Corporation for Los Angeles River LFD projects and Mike Pirch and Sons for Arroyo Seco LFD projects, is expected to be complete by November 2022.

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