What if a superstorm strikes Sacramento? Flooding danger puts the capital at risk of a disaster worse than Sandy
11/18/2012 12:00 AM
12/06/2013 5:13 PM
Superstorm Sandy made one thing clear to millions in the New York metro area: Despite modern transportation and communication systems, and extensive water and electricity services, nature is still in control.
The same is true in Sacramento.
California's capital city is unlikely to experience a devastating hurricane, and it doesn't rely on subway systems to keep its economy moving the way New York does.
But, aside from New Orleans, Sacramento has the greatest flood risk of any major urban area in America. A levee breach in Sacramento could cause many deaths and cripple the economy for 1.4 million people in the metro area who depend to some degree on the city of Sacramento staying dry.
How such a disaster would unfold depends on many variables. Where will the levee break occur? What time of year? On a weekday or a weekend? Which river?
None of these variables can be controlled, and in some ways, a Sacramento flood could be much worse than a New York hurricane.
Rick Martinez, chief of emergency services for the city and county of Sacramento, noted that experts can plot a hurricane's speed, intensity, destination and arrival time with fairly high accuracy. A levee break can be difficult to predict with precision.
If it happens, residents of some neighborhoods could have as little as 20 minutes to flee before the water gets 1 foot deep. At that point, self-evacuation is more difficult because driving a car becomes impossible.
"That window is really narrow and there are a whole host of things that could occur that would slow us down," Martinez said. "It's going to be very difficult to get everyone out. There's just no way to say it nicely."
Another key difference is that most Sacramento residents actually live below the water level flowing by in the rivers, especially when rivers swell in a storm. This means recovering from a levee break could take a very long time, because it could take weeks or months just to pump out the water from a flood.
Billions of dollars in levee and dam improvements are under way in the area, supported by local, state and federal tax dollars. But emergency officials are quick to acknowledge that a levee break can still occur.
As a result, residents need to be ready, Martinez said, and know how vital services would be affected. The Bee spoke with a number of experts to shed light on this fearful "what if" scenario.
If officials have enough information to know levees are threatened, their goal is to evacuate threatened areas before a levee break occurs, Martinez said. This would be driven by data on water level and flow volume provided by in-river monitors, and by storm predictions.
We've come close before. On Feb. 16, 1986, the American River swelled to less than 6 inches from the levee top, threatening to spill over and erode the levee in the process.
Martinez said evacuations would apply only to areas where water is expected to flow. Other areas would be urged not to evacuate, to preserve escape routes for those who really do have to leave.
But when the order goes out, he said, it's important for people to heed it. Anyone who stays behind is likely to create trouble for themselves and rescue crews later.
"People need to take responsibility for their actions when they've been advised that it's time to leave," Martinez said. "When it gets bad, you're not going to be able to reach 911 or call regional transit and say, 'Hey, can you send a bus by here.' "
Several neighborhoods – the Pocket, Land Park, River Park and Natomas – are considered "rescue areas" in a levee break because floodwaters would reach 1 foot deep in two hours or less. As the flood continued, some of these areas would see water rise high enough to submerge a two-story house. Residents who can't get out fast enough would have to be rescued.
Anyone left behind in a flood will not have electricity. If a levee break is projected, the Sacramento Municipal Utility District would turn off power in affected areas beforehand to protect vital equipment that would be damaged if it remained energized during a flood.
"We tend to wait almost to the last second for such interruptions," said Vicken Kasarjian, director of grid planning and operations at SMUD. "If you don't do that, we may end up damaging our own infrastructure to the point that it cannot come back from such a situation."
In downtown, SMUD has some transformers installed in underground vaults, where they are vulnerable to flooding. In the event of a levee break, even aboveground transformers and substations would be flooded. Most of this equipment could simply be cleaned off and turned back on after the water subsides.
It is important not to damage transformers, Kasarjian said, because the United States no longer manufactures these. They would have to be built to order in Asia, which can take up to 18 months.
"When you go to this kind of an extreme case, the best thing we can do is be prepared to serve the load again as soon as possible," he said.
Drinking water, sewage
The city operates two drinking water treatment plants, one on the American River and one on the Sacramento.
The plants are served by backup generators sufficient to meet citywide water demand in winter. The generators sit above the 100-year floodplain, said Jessica Hess, spokeswoman for the city Utilities Department. The city plans to move them above the 200-year floodplain, the target for urban flood safety enshrined in state law.
It is likely both treatment plants would survive a flood unless a levee broke very close to either plant, Hess said.
However, pressure changes underground caused by flooding could rupture water distribution pipes, she said, cutting off supply to parts of the city and potentially contaminating the supply for others. In addition, above-ground drinking water storage tanks could be damaged by flooding.
The city also operates dozens of electric pumps that move raw sewage through pipes underground to the regional sewage treatment plant near Elk Grove. Because the city is flat, sewage won't flow by gravity alone. It is likely some of these pumps would be damaged in a flood and cease to function afterward, Hess said.
Large parts of Sacramento can flood internally during heavy rain even if levees hold. The only thing preventing that is a network of 105 electric stormwater pumps that move water out of the city and into the rivers.
In 1996, some pumps quit and a few neighborhoods in south Sacramento experienced significant flooding. Few pump stations had backup generators then.
Afterward, the city spent more than $5 million installing generators at 25 pump stations. The remaining 80 stations were equipped with "plug-and-play" hookups so a portable generator could simply be plugged into a socket to run the pumps.
Sacramento also depends on a network of 15 floodgates to keep the city dry when rivers rise. These seal off roadway openings in levees that allow traffic to flow in dry times.
The floodgates are closed only when rivers rise and begin to threaten low-lying areas. The gates are crucial to protect the city, but when closed they also limit evacuation routes.
The gates are manually operated and somewhat medieval in appearance. They take several hours to shut and require city workers to either close giant steel doors or place heavy boards into steel slots. Both types are then sealed with sandbags and plastic sheeting. These materials are stored with some gates, but in other cases must be transported from storage yards.
City transportation crews hold drills each fall to stay skilled at operating the gates as swiftly as possible.
Sacramento's light-rail system is intended to play a "major role" in evacuating people if a flood is expected, according to the city evacuation plan, prepared in 2008. A single four-car train can carry about 600 people, said Mark Lonergan, operations chief at Sacramento Regional Transit.
The light-rail system itself is vulnerable to small amounts of flooding. Trains can function only up to a water depth of 6 inches. The system also depends on "traction power substations" located about every mile along the track. These are also vulnerable to water deeper than 6 inches.
"They would not survive a flood," Lonergan said. "I don't know what would be required to put them back in service after a flood. I don't know if allowing them to dry out would work, or if we would have to do some component replacements inside. I suspect it's the latter."
Buses would also be important for evacuations. Until recently, buses were entirely dependent on one natural gas refueling station at RT's maintenance center at 29th and N streets in midtown – a location vulnerable to flooding.
By the end of this month, RT expects to complete a second refueling station at McClellan Field – outside the flood zone.
Five major hospitals in the city of Sacramento fall within the 200-year floodplain. They have roughly 2,000 beds – about two-thirds of the available hospital beds in Sacramento County.
Of those, Sutter Medical Center in midtown is most vulnerable. In a number of levee-break scenarios modeled by the city, the hospital would be surrounded by floodwaters 4 to 6 feet deep.
Hospitals cannot function without two things: electricity and fresh water. Both are vulnerable in a flood. There are currently no state or federal requirements to floodproof these services at hospitals.
A proposed change in the state building code, which would take effect Jan. 1, 2014, requires new or substantially remodeled hospitals to place backup generators above the predicted flood elevation. Existing hospitals will not be required to comply.
The draft code also requires hospitals to store at least 5,000 gallons of water on site. Again, the rule would apply only to hospitals built after Jan. 1, 2014. Existing hospitals would not be required to comply until 2030.
Sutter Medical Center, located alongside the Capital City Freeway in midtown, is in the midst of a major remodeling and expansion. This was triggered largely by a state deadline requiring hospitals to be strengthened against earthquakes.
Ironically, earthquake risk is relatively low in Sacramento, and that law says nothing specific about flood risk.
For instance, Sutter's backup generators – as at many hospitals – are located underground. They reside in a vault built to resist water intrusion. But it is not floodproof, said Carl Scheuerman, director of facilities planning and development at Sutter Health. The generators are not being moved as part of the remodeling.
"Like anything underground – like the subways in New York City – we could expect that, over time, water would seep in there," Scheuerman said.
Sutter officials say their strategy is to evacuate the hospital before flooding occurred. Patients would be moved to other area hospitals, which work together on regular disaster drills – including one last week – to train for such patient transfers.
"We do recognize that flooding is a hazard for us," said Loni Howard, the hospital's emergency preparedness coordinator. "We would err on the side of safety and evacuate those patients out early."
Cellphones have become a primary means of communication for the public and emergency responders. But cellphone systems are not floodproof, and building codes in most communities do not impose such a requirement.
Like other systems dependent on electricity, cellphone service would likely go out during a flood, at least initially.
"Massive flooding like Sandy brought is almost impossible to engineer for," said Robert Jystad, vice president of the California Wireless Association and an attorney who represents cellular companies. "However, the industry has taken measures to minimize the impact flooding will have on the networks."
This includes battery backup systems to sustain cellular service for four to eight hours, Jystad said, depending on call volume. Some also have generator backup. And when possible, transmission equipment is installed on the upper floors of buildings, above a potential flood.
Because the city is enclosed by two rivers, limited evacuation routes would be available. At the website stormready.org, Sacramento city and county have developed maps that show flood depths and available evacuation routes in hypothetical levee-break scenarios. It would pay to know those routes.
Martinez said families should develop evacuation plans to account for different flood scenarios. This applies to families who may not live in the city of Sacramento but may have members who commute downtown for work. On weekdays, commuters add about 110,000 people to the city population.
Though emergency officials have developed elaborate response plans, city residents would have to fend for themselves to a large degree. Some may be forced to shelter in place for several days with standing water around their home or workplace.
The website sacramentoready.org includes lots of information about how to prepare for a flood, what to pack or set aside in advance, and how to make a family disaster plan.
Hurricane Sandy reinforced the importance of these preparation steps. One tool it showed to be important is a means to recharge a cellphone in a power outage, be it from a solar panel, a backup power source, a car charger, or all of the above.
Other important tools include an old-fashioned battery powered radio and a paper map of the community, which could be helpful in an evacuation. Such simple tools have vanished from many homes in the digital age.
Join the Discussion
The Sacramento Bee is pleased to provide this opportunity to share information, experiences and observations about what's in the news. Some of the comments may be reprinted elsewhere on the site or in the newspaper. We encourage lively, open debate on the issues of the day, and ask that you refrain from profanity, hate speech, personal comments and remarks that are off point. Thank you for taking the time to offer your thoughts.