Crater-in-progress near LAX is for underground stormwater treatment system

Excavation continues at the corner of Falmouth Avenue and
Westchester Parkway
Photo by Michael Kraxenberger

Many commuters along Westchester Parkway have been wondering: Why are workers digging a massive crater near LAX?

As it turns out, the excavation happening behind St. Bernard High School, near Falmouth Avenue, is to make way for a massive underground stormwater filtration system to treat runoff from LAX and surrounding areas — as much as 8.1 million gallons of it.

The Argo Sub-Basin Facility, primarily preventing runoff onto Dockweiler State Beach, is slated for completion in the fall of 2020.

Hardly any of it will be visible when work is done. Representatives from Los Angeles World Airports, the agency that governs LAX, held a community meeting in March that discussed what to put on top of the facility after its completion, with many attendees leaning towards recreational or open space.

Excavation began last year and is expected to resume in a few weeks until workers reach a depth of 27 feet, said Heather Johnson of the Los Angeles Bureau of Sanitation.

The project has already been recognized for its sustainability potential. In January the Institute for Sustainable Structures gave the future stormwater capture and treatment system its Envision Silver award for sustainable infrastructure.

“The Argo Drain Sub-Basin Facility will support the long-term needs and goals of the Westchester, Playa del Rey and Los Angeles International Airport communities by supporting the development of recreational and economic development opportunities in the area and helping to clean up Santa Monica Bay and surrounding beaches,” Institute of Sustainable Structures President and CEO John Stanton said.

The underground water storage tank — a full 250 feet in diameter — is being designed by OHL USA, a civil engineering firm. Though it’s being built on land controlled by LAX, the city’s Bureau of Sanitation is participating in the excavation and construction.

— Gary Walker