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Tunnel boring machine lowered at Clearwater Project in Los Angeles

The ambitious $630-project in Los Angeles, CA to replace two aging underground wastewater pipes launched on June 21 as the tunnel boring machine was lowered to the begin boring the 7-mile project.

The San Gabriel Valley Tribune reported that the details have been continually refined since planning began in 2006. The Clearwater Project was approved in 2012 by the Los Angeles County Sanitation Districts and was described by engineers involved in the work as sophisticated, intricate and precise.

The boring of the project will begin in July or August and will take about four years to complete. Factoring in a two-year project at the end to build a smaller shaft at Royal Palms Beach in San Pedro that will connect to the existing outfalls to the ocean, the entire project won’t be finished until 2027, according to current projections.

The aim of the project is to replace two aging wastewater pipes — installed in 1937 and 1958 — with one 18-foot wide pipe sufficient for today’s much larger water flow.

The new tunnel the mammoth machine digs will be between 50 and 460 feet below the surface, depending on the overlying topography. At the beach, the tunnel will be 30 feet below the surface.

“It will take three and a half to four years of tunneling from Carson to Royal Palms Beach,” said Clearwater spokesman Glenn Acosta. “Just before that, the work on the beach will start to build a smaller shaft” to connect to the existing outfalls. Three of the four existing ocean outfalls are in good working order. The work at the beach, planned for 2024-25, should take about two years with the beach and parking remaining open, Acosta said.

The need for the project was first documented as planning began. Currently, 73 of Los Angeles County’s 88 cities rely on the existing antiquated pipelines to take more than 260 million gallons of treated wastewater from the plant to the ocean.

The sanitation department, Acosta said, has been “the largest provider of recycled water in the U.S. Since 1962 more than a trillion gallons of water” have been recycled with 11 waste water treatment plants across the county.

In what is turning into an enduring era of drought, recycling of water has become a pressing issue.

But the water transported through the pipes being replaced — due to the many industrial sites that are its source in the southern region — is too salty to be recycled or used, he said. To remove all the salt and other impurities from that particular water requires an advanced water purification system that is still in the design phase.


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