New wastewater pipe to sea passes milestone
Los Angeles may not have an underground subway system, but engineers are getting ready for an equally herculean task of tunneling a 22-foot-wide pipeline from the county’s main sewage treatment plant in Carson to the waters off the Palos Verdes Peninsula.
Nothing like it has taken place for the past 50 years, and nothing like it will take place again for at least that long, say project designers.
Known as the Clearwater Program, the project achieved a milestone last week when the administrative board for the Sanitation Districts of Los Angeles County approved an Environmental Impact Statement and set the stage for the beginning of design work over the next three years.
“It is really exciting,” said supervising engineer Steve Highter, who’s been on the project since its inception six years ago.
The 6-mile tunnel will replace two aged pipelines, one built in 1937 and the other in 1958 that travel below Western Avenue, under the Palos Verdes Peninsula and emerge about 100 yards off the coast at the White Point Nature Preserve. Another two miles of pipeline extend along the seafloor, which will not be replaced, before it expels the treated wastewater into the ocean.
Unlike the older pipelines, which were dug by hand, dynamite and small excavators, a tunnel-boring machine the size of a Zamboni will slowly burrow the new tunnel anywhere from 140 to 450 feet below the surface over the course of six years beginning no earlier than 2015.
“These tunnel-boring machines have been in use for several years now. The beauty is they’re underground,” Highter said. “People won’t even know they are there.”
Over the past several years, the sanitation district has conducted more than 500 public outreach meetings. Planners also managed to do something relatively unheard of in public works projects: They brought the price tag down from around $1.5 billion to its current $550 million estimate mainly because it was determined the existing ocean outfall pipes are in good shape and don’t need replacing.
The Joint Wastewater Treatment Plant in Carson where the pipeline originates is the nation’s largest sewage treatment facility of its kind
servicing the needs of 300 million people treating 300 million gallons of wastewater on a daily basis. For anyone in LA County other than people living within the City of Los Angeles, this is the end of the line for anything flushed down the toilet and washed down the drain.
Up until passage of the Clean Water Act in 1972, the outfall pipes were a leading cause of pollution, passing industrial chemicals such as PCBs and DDT into the ocean, which earned the coastal area its distinction as a federal Superfund Site.
Montrose Chemical Plant paid a hefty fine for its part in flushing DDT into the sewer system, while the wastewater treatment plant also paid a $4 million fine because it conveyed the chemical. At the time, marine mammals all the way up the food chain, including eagles, were being affected by the chemical.
Today, the district employs about a dozen scientists who monitor ocean quality around the outfall pipes on a daily basis. Biologists peer daily into microscopes while another team collects samples by scuba diving beneath the surface and through an unmanned submarine.
Tom Parker, who heads the ocean monitoring group, said conditions are continually improving with almost no noticeable effects these days.
“Over the decades with this treatment plant performance, it’s done nothing but improve,” Parker said. “We have a community of animals that live in the mud that’s the way they would be even if there wasn’t a treatment plant here.”
Today’s treatment plant treats wastewater to secondary standards, reusing nearly every bi-product from the process including burning the methane gas for energy that goes back to power the treatment plant. At the very end of the process, the solid waste is converted into fertilizer that’s sold by Kellogg Garden at Home Depot and distributed throughout the state for agricultural use.
When the new tunnel project finally gets underway, crews will dig a shaft about 140 feet deep and between 40 and 60 feet in diameter near the treatment plant. From there the boring device will be lowered and aimed toward the ocean. For the next six years, until roughly 2021, the machine will slowly grind away at the earth burrowing through subterranean levels, through water tables and the Palos Verdes fault line.
As the boring machine makes its way slowly up Western Avenue and beneath the Peninsula, engineers say local residents won’t feel a thing. The only impact will be roughly one additional truck leaving the waste treatment plant per hour.
All the dirt’s that removed and the cement segments that make up the pipeline will travel by rail car within the tunnel so that the only truck traffic will be back and forth from the plant in Carson. At Royal Palm Beach trucks used to pour concrete and retrieve the boring device will be about all that’s affected above the surface.
“Most people understood this was the best option, but you can’t ever get everyone to agree on one thing,” Highter said.
In Rancho Palos Verdes, some area residents were concerned about the placement of the exit shaft used to retrieve the boring device once the tunnel shaft is completed. The least costly and most convenient location is at Royal Palms Beach just west of White Point. While the impact is promised to be minimal, some local residents such as Mark Wells, who’s followed the project closely, would have rather seen them put the exit shaft on Terminal Island in San Pedro
“In general it’s a necessary piece of progress to create a new outfall system. The current pipes are jam-packed and they’re full and more people are coming into the area,” said Wells, who writes numerous blogs about city affairs. “My opinion is the least amount of impact on the population and the best source of cheap transportation of the debris is on Terminal Island.”
But that would have ballooned the project cost and could have been risky, Highter said.
“There were groups out there who liked two other options because they went to the port of LA, but they would also include having to tunnel beneath the ocean,” Highter said. “If it turned out that our outfalls were not in great condition we would have to build new outfalls. But it’s hard to justify a project in which you would spend $1.4 billion instead of $550 million, which is still a lot of money. And we were being told by experts that it was very risky to construct it.”
For David Haug, a senior engineer, being a part of the current tunnel project represents a unique place in history. Haug’s grandfather worked on the 12-foot tunnel, which finished construction in 1958. Haug remembers hearing stories about the sweat and toil from the hundreds of workers that largely carved the tunnel out by hand.
“Back then projects were measured in terms of lives,” said Haug, who never heard any stories of workers being killed in the tunnel. “In today’s standards we don’t use that anymore because we obviously have much safer conditions with this machine.” ER