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Bracing ourselves for El Nino storms

How local communities are preparing for El Nino floods

El Nino, the periodic concentration of unusually warm water along the equator in the Pacific Ocean, may result in severe storms on the Peninsula this winter, and possibly flooding.

If the weather does turn nasty, emergency responders and residents in the vicinity of San Francisquito Creek will have information that was not available when the creek flooded in December 2012: advance warning of at least 90 minutes, and a color-coded map online showing areas at risk if the creek over-tops its banks.

Sophisticated rain gauges have been placed in the foothills to the west by the group that manages San Francisquito Creek watershed -- a joint-powers agency comprising representatives from the cities of Palo Alto, Menlo Park and East Palo Alto as well as San Mateo and Santa Clara counties.

The rain gauges are located on Windy Hill in Portola Valley and in Wunderlich Park in Woodside and Huddart Park in unincorporated San Mateo County, according to Len Materman, the executive director of the joint-powers agency.

Using data from those rain gauges and storm data from 2012 and 2014, the agency's online Flood Early Warning System map (at floodwarning.sfcjpa.org) shows the likelihood of flooding at four key locations: in Menlo Park, the Middlefield Road bridge just south of Willow Road and the bridge at Pope and Chaucer streets and, in East Palo Alto, a bridge near the intersection of University and Woodland avenues, and another where the creek crosses under U.S. 101 just north of the Embarcadero Road interchange.

"This (system) is new, it's very sophisticated and we're still doing tests," Mr. Maderman said. The map is updated every 15 minutes. Colored circles indicate the four bridges and represent expectations of what will happen at a particular bridge and the surrounding neighborhood about 90 to 120 minutes into the future.

The color codes:

■ A green circle indicates no danger from creek-based flooding.

■ A yellow circle indicates a flood watch -- that the water in the creek will be at 60 percent of the creek's carrying capacity soon.

■ A red circle indicates a flood is on the way -- that the water will exceed 100 percent of the creek's carrying capacity.

The creek management agency's website includes a form to sign up for alerts via text or email, a form to report problems and upload photos, and links to rainfall trends and data on rainfall collected from the new gauges.

The sophisticated rain gauges are a result of an extensive evaluation of equipment, Mr. Materman said. "I didn't want the residents or the fire department or the police department to have to look at data to determine where the threat would be," he said. "We wanted to give them the clearest possible communication."

One thing the gauges do not address is the unexpected. Debris in a creek bed can complicate the potential for flooding, Mr. Maderman said. A blocked storm drain anywhere "can be extremely problematic" in its effect on street flooding, he said.

And there is creek bank erosion. For Menlo Park residents living along San Francisquito Creek, while the flood danger west of El Camino Real is lower than further downstream, the rushing water can undermine a back yard or the side of a roadway.

On this issue, Fire Chief Harold Schapelhouman of the Menlo Park Fire Protection District recommended that residents with creek frontage consider having tarps installed over vulnerable ground to shield it from the direct impact of the water.

Acting locally

In Woodside, an ongoing effort since September has cleared debris from watercourses that are the town's responsibility, including ditches and storm drains, Town Manager Kevin Bryant said. Staff revisits them after rainy and windy days, he said.

Of particular concern are locations of dead trees and areas in which creeks and streams pass under roadways, Mr. Bryant said. Staff will be on-call "when it is likely we will have storm-related issues to deal with," he said. Sand and sand bags are available at Town Hall. The town uses NextDoor and an emergency notification system to keep residents informed, Mr. Bryant said.

In Portola Valley, the town stockpiled 10,000 fill-it-yourself sandbags and has ordered more sand after the first sand pile was much reduced, Public Works Director Howard Young said.

The storm drain system is checked regularly. The town will be standing by with heavy equipment during major storms and will be inspecting every street before and after a storm, Mr. Young said. "We have asked our citizens to assist during storms," he added.

Storm-related news will be broadcast online via PV Forum and over the air via the town's low-power AM radio station at 1680 kHz.

In Atherton, City Manager George Rodericks said in a report that staff have checked storm drains and walked the entire Atherton Channel to remove debris.

The city has restocked supplies of traffic-control gear, pothole mix, sand and sandbags, and will be ready with trucks, loaders, chainsaws, emergency generators and lighting, Mr. Rodericks said. Staff may be asked to work overtime during heavy weather, he said.

In Menlo Park, the city bought 10,000 fill-it-yourself sandbags and planned to buy 10,000 filled bags (at a cost of $40,000) more for its own use in flood-prone areas, according to a staff report. The city plans to issue a $75,000 "storm-response contract" for assistance in deploying sandbags near the creek, clearing debris from the creek, and stabilizing the creek bank.

The city may draw on a contract with a tree service, also for up to $75,000, to assist with removal, trimming, stump grinding and cleanup, the report said. The city has addressed and will continue to monitor storm drains and the city's portion of the Atherton Channel.

Managing storms

How ready is ready enough? In Woodside, Portola Valley, Menlo Park and Atherton, city and town staff have long had plans to open ad hoc emergency operations centers in a town or city hall in the event of a disaster. They'll function for a severe storm as well as for the aftermath of an earthquake.

Tabletop training for these local centers tends to include setting up a team to track mock incidents such as fallen trees, accidents and downed power lines. The drills often include radio communications and sometimes the participation of actual emergency responders.

In a serious multi-jurisdictional emergency involving the Menlo Park Fire Protection District, local authorities may create "multi-agency coordination" headquarters, according to Fire Chief Harold Schapelhouman. The fire district serves Menlo Park, Atherton, East Palo Alto and nearby unincorporated areas.

"Ideally, everybody should work together," the chief said. "If (a community) chooses to do (its) own thing, that creates problems. That's why we like the multi-agency coordination."

Vital questions can arise, the chief said. When are conditions bad enough in a community to warrant opening an emergency operations center? When are they bad enough to invoke multi-agency coordination? As for shelters, which ones should be opened and who should open them? When is an evacuation order called for?

With multi-agency coordination and everybody in one room, the players can make collective decisions, Mr. Schapelhouman said. "I'm actually pretty confident that we have people who know what their responsibilities will be," he said. "You may not know all that (a storm) is going to do, but you can presume that you know something."

For Chief Schapelhouman, the three top issues locally for first responders in the Menlo Park fire district during a storm are:

■ Objects falling into San Francisquito Creek and becoming dangerous. Volunteers from the creek oversight group removed "several tons of material" in the creek channel this fall, a staff report said.

■ Flood waters, where they will go and where sandbags should be deployed.

■ Life-threatening situations in East Palo Alto if a levee fails. Authorities in East Palo Alto, Palo Alto and Menlo Park have raised creek banks at places considered at risk of flooding, according to the staff report.

In wooded and relatively remote Woodside and Portola Valley and nearby unincorporated areas, all served by the Woodside Fire Protection District, a first line of defense for residents is the Citizens Emergency Response Preparedness Program, with 25 divisions meant to cover the entire fire district.

Go to cerpp.org for more information. Among the key features: nine weatherproof former cargo containers located throughout the district and stocked with emergency supplies.

Related story: Preparing for El Nino at home

Comments

Like this comment
Posted by Betty Schink
a resident of Menlo Park: Linfield Oaks
on Dec 20, 2015 at 3:18 pm

How does one access the Improved flood warning system map shown in your Dec. 16 Almanac?


Like this comment
Posted by Dave Boyce
Almanac staff writer
on Dec 21, 2015 at 9:52 am

Dave Boyce is a registered user.

To view the flood warning system map, go to floodwarning.sfcjpa.org

The prefix www. is not needed and will not work.


Sorry, but further commenting on this topic has been closed.

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