Wanted: Lots of Fill Dirt

It is the biggest sinkhole veteran Los Angeles city engineers have ever seen.

Ground under Tujunga Avenue opened up two weeks ago, after rain runoff barreled down from the foothills and turned the busy Sun Valley street into a river, undermining the pavement.

A sewer pipe was crushed, a power line was severed and the chasm swallowed large chunks of roadway. The hole initially measured about 40 feet in diameter. But it kept growing, eventually eating away 200 feet of road. A public works supervisor, who was trying to halt the damage, died when he either fell in or the ground beneath him collapsed into the gaping expanse.

Today, the opening is a stark reminder of the rainstorms’ destructiveness, bisecting the road like a 30-foot-deep fault line. About 25,000 cubic yards of soil have washed out -- the equivalent volume of about 500 backyard swimming pools.

City officials are still trying to determine how to fix it.

They say the stretch of Tujunga Avenue will remain closed until the fall. Work to fill the hole isn’t expected to begin until June, when the rainy season ends.

“It was a major loss of a roadway, and it can’t be fixed overnight,” said deputy city engineer Tim Haug. “As far as a washout I’ve been involved with, this is biggest I’ve seen.”

Over the last week, workers have poured concrete along the sides of hole, hoping to stop it from growing. So far, they have been successful. But the real test will come when the next heavy rainstorm hits, though officials are confident it will hold.

The long process for reopening to road is bad news for local merchants.

A-1 Metals recycling center has been struggling for three weeks to get back the nearly 150 customers who have been deterred by the roadblocks. For a while, the company had trouble getting its mail.

“Our loyal customers find a way around,” said office supervisor Karen Escobar. “If it wasn’t for them, we’d be out [of business] right now.”

Flooding has long plagued Sun Valley, a working-class industrial district on the northeastern edge of the San Fernando Valley. When it rains, water comes down from the Verdugo Mountains and onto streets such as Tujunga Avenue, which is a former riverbed.

Los Angeles city and county officials have been talking for years about ways to improve flood-control systems in Sun Valley, where streets often flood during heavy storms.

Tujunga Avenue, for example, lacks an underground pipe system or curbside channels that could catch rainwater and carry it swiftly to the Los Angeles River, Haug said.

Instead, the street serves as a water basin for runoff. It gave way Feb. 19 when floodwater from days of severe rain cut a groove underneath the asphalt, officials said.

Turbulence allowed the water to quickly eat away at the gravel and sand, undermining levels of concrete that eventually caved in. That opened up a hole about 40 feet long and followed the street northward. As water continued to fall into the crater, the size of the hole kept growing.

“It was like Niagara Falls eroding its way upstream,” Haug said.

The rapid current quickly moved into an adjacent concrete company’s parking lot. That breached a slope that was supporting Tujunga Avenue and created a gully of storm runoff on the east side of the street and drained into a landfill.

The next day, workers from the concrete company provided city crews with 250 cubic yards of concrete mix to help slow the sinkhole’s growth, said Kevin Josing, director of operations for Over & Over Ready Mix Inc.

“It didn’t even begin to help, it was just continuous,” he said.

As rains continued that week, the situation worsened. The force of the water, rushing at speeds estimated at 15 mph, continued to consume the gravel underneath the roadway, widening the hole, city officials said. A car in the concrete company’s parking lot and a city worker’s vehicle fell into the hole as the water kept moving.

Workers raced to remove a power pole and a streetlight before the hole swallowed them up.

Public works supervisor Rory Shaw, 47, who was working on the site, was killed Feb. 20 when he fell into the sinkhole. Los Angeles City Councilman Tony Cardenas said Shaw had greeted him when he arrived that night to inspect the damage. Shaw had been assessing the hole near its edge when the accident occurred.

Cardenas was being briefed by Bureau of Public Works Commissioner Yolanda Fuentes across the street when they saw Shaw slip into the rushing water flowing into the hole.

The water engulfed him, Cardenas said. Shaw clung to a water pump on a truck parked near the hole’s edge as workers kept reaching out their hands to try to grab him. But they could not reach him, and Shaw lost his grip on the pump.

“It was a like a scene from a movie: the wind, the rain, the pumps,” Cardenas said. “The water was rushing at that moment and unfortunately no one realized how dangerous it was.”

When the rain stopped, crews removed truckloads of large pieces of concrete as well as the city truck and the other car from the pit.

Slurry was placed along the walls of the hole and bottom of the trench. To slow the swift-moving current, 100 concrete boulders were placed in the bottom of the hole, Haug said.

“It’s designed to slow the water down so that it’s not tearing the heck out of everything,” Haug said.

Soil compacted by bulldozers will fill the hole, the roadway will be repaved, the sidewalk rebuilt and the power pole replaced, Haug said.

Cardenas said the city isn’t sure how much it will cost to fix Tujunga Avenue.

But making significant improvements to Sun Valley’s flood infrastructure would cost more than $100 million, he said. Although several plans have been drawn up, a lack of funding has stalled the effort.

Once an area of sand and gravel pits, Sun Valley now consists of modest homes, landfills and recycling centers. Some residents believe the sinkhole underscores how much the community needs a major flood-control improvement project.

“It’s been a pain in the neck for years,” said Fabio Parra, a resident for 10 years. “It’s very dangerous here when it rains.”

“It’s just ridiculous,” added Escobar, the office supervisor at A-1 Metals. “What makes you mad is that they neglected this street. It’s not that we didn’t call and complain, it’s just that they didn’t care.”