May 2018 APWA Reporter


Santa Barbara County Public Works responds to devastating mudflow

By Helen Horwitz
Principal, HLH Communications, Albuquerque, New Mexico

Ashley Road, Santa Barbara County

Ashley Road in Santa Barbara County, near Lotusland. The left side shows the area through Google maps and the right side was taken around 10:00 a.m. the day of the debris flow. The tree on the right side provides a good point of reference.
More than 40 million people call California home, making it the most heavily populated of the 50 United States—and with good reason. The laid-back lifestyle, along with a variety of agreeable microclimates throughout the state, has long attracted people there to live and work.

But grave environmental dangers hide behind the many natural assets of California: Droughts are common, wildfires are a threat during the typically dry summer and fall months, and hot, dry Santa Ana and sundowner winds can produce gale-force conditions that make firefighting almost impossible. Moreover, the winter rainy season can bring torrential downpours.

Such difficult conditions pose an ongoing challenge for public works professionals throughout the state. So it was on Tuesday, January 9; or, as it’s now known throughout Santa Barbara County Public Works, the “One Nine Event.” 

In the early morning hours, heavy rains fell on the freshly burned mountainsides of the steep Santa Ynez Mountains high above Montecito, adjoining the City of Santa Barbara. Just a month earlier, the exclusive community of 9,500 had narrowly escaped the Thomas Fire, the largest wildfire in recorded state history, which had blackened and bared the mountains directly above the town. Now, with nothing left to absorb the downfall—nearly one inch in just 15 minutes, according to the National Weather Service—debris flows near the top triggered a massive mudflow. Creeks and streams overflowed their banks, tearing through many neighborhoods; more than 100 homes were destroyed, streets became grotesque rivers of mud and debris, and 23 people were killed. (Of this number, two remain missing and are presumed dead.)

This is the story of how Santa Barbara County Public Works responded to the disaster. In the aftermath, the tragedy has prompted new measures aimed at better protecting lives and property from future wildfires, subsequent rainstorms and their aftermath. Not every community is prone to mudflows, but virtually all public works departments must contend with local environmental dangers. Valuable lessons can be learned from the One Nine Event.

From Light Rain to Walls of Mud

“The rain that started falling late the night of January 8 was the first of the season,” recalls Scott McGolpin, P.E., Director of Public Works for Santa Barbara County. “At 3:15 a.m., it was falling lightly, but when the heavy downpour began an hour later, everything changed.”

The severe rains that night activated debris flows near the top of the rugged mountains nearly 4,000 feet above Montecito. This is because intense wildfires like the Thomas Fire don’t burn just what is above the ground; they physically change the soil itself. The Thomas Fire burned subsurface material including topsoil, leaves and twigs—a carbon-rich mixture that absorbs and holds water. After it burns away, what remains is a dense layer of noncombustible clay and rock that repels rainfall.

Racing down the mountain, the huge debris flows met with mudflows, more than streams and creeks could carry. Walls of mud, huge sandstone boulders and other debris surged downhill to destroy everything in their path.

“When the sun came up,” says McGolpin, “we faced a horrible scene like nothing I or my crews had ever seen.”

A Three-Phase Plan

Most of the 300-person department, including more than 80 on road and transportation crews, immediately began a three-phase plan.

“First, the transportation crews worked alongside Search and Rescue teams and the County Sheriff’s office,” explains McGolpin. “The crews literally had to dig their way in on the roads in the affected areas. During this phase, we established at least one lane of travel so the S&R crews could search for survivors.”

In the second phase, Search and Recovery, County road crews were joined by local contractor crews to open the full width of each affected right-of-way. This was essential because utility companies needed to be able to get in and reestablish service, as well as repair water mains.

Permanent Restoration, the third phase, is well underway. All roads and bridges affected by the mudflow are being repaired—and in some cases, rebuilt. Monumentation, the surveyor process for distinguishing property owner boundaries and public right-of-way, has also started reestablishing what the mudflow damaged or destroyed.

Disposing of the Debris

Soon after the Thomas Fire was extinguished in mid December 2017, County crews cleaned up a dozen watersheds affected by the fire along with 11 debris basins. On the steep hillsides, transportation and road crews had also begun clearing culverts and removing fallen trees and rocks—standard procedure before the winter rains arrive. But after the One Nine Event, the area was designated a Federal Disaster zone; the Federal Emergency Management Agency and the Army Corps of Engineers arrived to clear the debris basins and area of 400,000 cubic yards of debris, including from streams and creeks. The County cleared another 100,000 cubic yards.

Santa Monica Debris Basin
Santa Monica Debris Basin. The top photo was taken in October 2017 and the bottom photo was taken mid-February 2018.
 

All this was accomplished in just 60 days, at a cost of $130 million, according to McGolpin. “We’ll spend $120 million more for permanent restoration,” he says. “Everything must be put back in pre-storm condition.”

These days, Santa Barbara County Public Works is disposing of 500,000 cubic yards of sediment, rock and wood from three separate processing facilities.

“The Regional Water Quality Control Board tells us the sediment is a welcome addition to local beaches,” says McGolpin. “After seven years of drought, the beaches were eroded because little sediment had reached them. Now, we’re rebuilding our beaches as the ocean processes the sediment.” Woody debris was ground up and is being used in the County’s mulch program. Sandstone boulders were blasted into manageable sizes; they are being used to help build new walls and are available for landscaping, at no charge, to the community.

Despite these efforts, more than 70 percent of the remaining debris is from private property, and the County landfill has only seven or eight years of life left. McGolpin and other County officials are requesting state approval to waive certain environmental requirements to dispose of this private debris without affecting the remaining municipal solid waste life.

“We’ve also formed a group that includes the Sheriff, Fire Chief and National Weather Service to set evacuation orders based on weather forecasts,” says McGolpin. “If more than half an inch of rain an hour is predicted, this group will decide whether to order an evacuation. But state law prohibits removing anyone from their home who wants to remain.”

Since One Nine, one evacuation has been ordered; fortunately, it proved to be a false alarm.

“We call them flows because that’s what they are!”


Sunset Lower Debris Basin
Crew members remove large debris, including a vehicle and a trash can, from the Sunset Lower Debris Basin in the City of Burbank. One person is working from a dinghy next to the inlet tower. LACoPW owns and maintains 172 debris basins that protect downstream communities from debris flows. (Credit: Los Angeles County Public Works)
 
If there’s one fact that Loni Eazell wants everyone to know, it is this: The disaster that struck Montecito, California, on January 9 this year was a mud and debris FLOW—not a mudslide.

“For two important reasons, it’s incorrect to call a mudflow a mudslide,” she states. “First, a mudflow is what happens after heavy rain falls after a forest fire. Scorched soil can’t absorb the rain, so the water mixes with whatever soil is available to become free-flowing mud.

“A mudslide,” she continues, “is a large mass of wet earth that suddenly and quickly moves down the side of a mountain or a hill.”

But the second, and most critical, reason Eazell cites for using the correct word is that both insurance companies and the Federal Emergency Management Agency frequently deny financial compensation for mudslide damages because the geological conditions were usually known prior to the event.

According to veteran insurance consultant Marianne Bonner, both “landslide” and “mudflow” appear in many commercial property policies but are rarely defined. She points out that “mudflow” is explained in the Standard Flood Insurance Policy used in the National Flood Insurance Program (NFIP) as a river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water. The NFIP policy specifically excludes landslide, slope failure and other types of earth movement.

Bonner adds that the United States Geological Service considers “mudslide” an imprecise term. “Unfortunately,” she writes, “the news media uses it to refer to a variety of events—from actual landslides to floods laden with debris.”

Loni Eazell has been dealing with mudflows, mudslides and myriad other disasters for almost three decades. The Senior Disaster Services Analyst with the Los Angeles County Department of Public Works (LACoPW), she is marking her 29th anniversary with the organization, and her 28th in Emergency Management.

Her responsibilities include developing and implementing procedures that help to ensure LACoPW’s Emergency Management organization—ranging from dedicated dispatchers to the emergency managers for 24/7 response—have the best available information and tools to do their jobs. In Los Angeles County, which sprawls over 4,083 square miles and has more than 10 million residents, this is a tall order.

For Eazell, disaster planning includes a range of public hazards, including wildfires, floods, earthquakes, tsunamis and nuclear incidents. Given the drought that has plagued Southern California in recent years, wildfire prevention and remediation as well as mudflow mitigation efforts following the infrequent, but heavy, rainfall occupy much of her time.

“When we do get moisture in LA County, we like a slow, steady rainfall—say, 1/10 to 1/3 of an inch a day,” she observes. “This helps us to capture water and conserve it. Intense storms are not good for us.”

She says that since the heavy storms of this past January, crews haven’t stopped working to clean out the 172 debris basins which protect the county and are owned and maintained by LACoDPW. Forecasting future mudflows and providing this information to help both cities and individual homeowners avoid dangerous, destructive mudflows is another important function.

“Neither FEMA nor the federal government realize all the advance work we must do to prepare for storm season and avert disasters,” she says. “We’re fortunate that LA County can cover the expense, but smaller counties may not have the resources.”


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