News

Officials warn of flooding from coming storms

Palo Alto residents face unknown conditions in predicted El Nino winter

If a 1998-level El Nino storm barrels into the Bay Area this winter, Palo Alto and East Palo Alto residents and city staff will be left literally holding the sand bag, officials said at a flood-information meeting on Nov. 19.

The National Weather Service is predicting an El Nino season that would rival 1997-1998, when San Francisquito Creek overflowed its banks and water damaged 1,700 properties, according to Len Materman, executive director of the San Francisquito Creek Joint Powers Authority (JPA).

City and other agency staff discussed everything from how to properly set up sand bags to how to obtain flood insurance with a crowd of nearly 100 people at Lucie Stern Community Center. But also on people's minds was the glacial pace of planned anti-flood work on the creek, which won't be completed in time for this year's stormy season.

If there is another major storm -- and especially if combined with a "king" tide in the San Francisco Bay -- "all bets are off," Materman said.

"Expect the worst. Don't assume it won't happen," he said.

Palo Alto has made some improvements to help prevent the kind of street and other flooding that last occurred on Dec. 23, 2012. The Public Works Department added closure gates to pipes to prevent backflow from storm drains, and a stormwater pump station downstream of U.S. Highway 101 should also keep water from backing up in storm drains in the Duveneck/St. Francis neighborhood, Senior Engineer Joe Teresi said.

The city has added raised berms where the creek overflowed in 2012. East Palo Alto officials, meanwhile, have repaired and raised a damaged levee on the east side of U.S. Highway 101 in the Gardens neighborhood and a section of the creek along Woodland Avenue. And the JPA began work on the San Francisquito Creek Bridge, which crosses under Highway 101 from West Bayshore Road.

But Materman and others cautioned that even with the best-laid preparations, no one knows what a walloping storm might bring, especially if combined with a king tide -- an ultra-high tide -- or a storm surge. A king tide is due on Nov. 25, followed by others in December and January, he said.

Impacts this winter could also be much greater than in 2012, which was a drought year. But "if this is not a drought year, then all bets are off. It's kind of sobering news," Materman said.

The city and the JPA have added new rain gauges upstream, along with gauges at Stanford University, that will now give a 1-hour-and-45-minute warning instead of 45 minutes for when a large volume of water will reach the Pope/Chaucer bridge, arguably the narrowest point along the creek, with the greatest potential for a blockage from debris.

The JPA also recently debuted a flood-warning web page, sfcjpa.org/floodwarning, which includes a map that shows areas of Palo Alto, East Palo Alto and Menlo Park at risk of being flooded or where flooding is imminent. Officials will attempt to update the information two hours ahead of any flooding, Materman said.

People can sign up to receive alerts by text message or email or can report a problem at the flood-warning page. The site's flood map should free up 911 dispatch, since users can look online and see if a problem they are observing is already being addressed.

Residents were also encouraged to visit cityofpaloalto.org/storms, which contains U.S. Army Corps of Engineers flood maps and links to the city's creek monitor, the JPA flood-warning site and road conditions, along with other important information.

City officials said they will maximize police, fire and utilities staffing during major storms. But Kenneth Dueker, director of the city's Office of Emergency Services, reminded the audience that there are many ways residents can help themselves.

"Create a family plan and safe routes to high ground and determine where you will stay. Talk to neighbors and identify those with special needs; build an emergency kit and obtain sand bags," he said.

Palo Alto Utilities recommends putting electronics up high in one's home so that equipment doesn't come in contact with water.

"If water enters your home, you may need to turn off electrical power and gas," Dueker added, noting that water can snuff out a pilot light, causing natural gas to fill a home.

Residents can also plan for their own evacuation. Unless people want to stay in a Red Cross shelter, they should identify friends or relatives with whom to stay, especially this year, he added.

"Two weeks before Super Bowl 50 you won't find hotels. If you want to go to Stockton or Modesto, maybe," he said.

The city's website cityofpaloalto.org/stormmap, will show closed roads, flooding, downed wires and other incidents, he said.

Some residents at the Nov. 18 meeting turned their attention to the San Francisquito Creek improvement project, with one person asking why the Pope/Chaucer Bridge, the main bottleneck in the whole creek/flood system, can't just be removed.

"You can't simply take out the bridge and not have effects downstream. We didn't feel like we were in a position to take it out and impact other communities downstream," Materman said.

The JPA is a regional government organization of five local agencies including Palo Alto, Menlo Park, and East Palo Alto, the County of San Mateo, and the Santa Clara Valley Water District, which formed 17 years ago to address the flooding problem, but it has been hampered by the slow pace of federal and state agencies, including 2 1/2 years of wrangling with the Regional Water Quality Control Board for permits on the project, he said.

City Manager James Keene told residents at a Nov. 12 town hall meeting that the JPA and the city have finally obtained a clearance from the Water Quality Control Board. But that board's approval is only one of seven required from state and federal regulatory agencies. Since those green lights did not come in time for this year's rainy season, residents and city officials will again face potential flooding and must themselves prepare for the worst, city and JPA officials said.

To-do list recommended by Dueker and other resources:

• Create a family plan

• Determine safe routes to high ground

• Determine where you will stay if you need to evacuate

• Talk to neighbors and identify those with special needs

• Build an emergency kit; obtain sand bags

If flooding is possible:

• Stay informed.

• Listen to KZSU radio, check Palo Alto Online at paloaltoonline.com; view the city's storm website, cityofpaloalto.org/storms, and check the JPA flood-warning site, sfcjpa.org/floodwarning.

• Put out sand bags, clean gutters, even those on the street

• Elevate electronics

• Make arrangements for where you will stay

• Load key items into your car, and perhaps park your car outside of the area

If flooding is expected:

• Monitor the radio

• If time, call and assist neighbors

• Don't wait to be told to evacuate. If things look unsafe, go beforehand

• If roads are blocked, don't drive across flooded areas

• If water enters your home, turn off gas and electricity

Resources:

cityofpaloalto.org/storms -- information and resources for Palo Alto regarding storms and flood tracking, including links to the city's Creek Monitor page

www.ci.east-palo-alto.ca.us/index.aspx?NID=509 -- information and resources for East Palo Alto regarding storms and flooding

sfcjpa.org/floodwarning -- warning map tracks potential flooding and flooding incidents

paloaltoonline.com -- online alerts, mapping, information and breaking news

KZSU Stanford, 90.1 FM, radio alerts and information

www.sccgov.org/sites/alertscc/Pages/home.aspx -- Santa Clara County AlertSCC emergency alert system allows sign ups for email and text alerts in disasters

• Blocked storm drains and/or landslides -- Palo Alto Public Works 650-496-6974; 650-329-2413 after hours

• Fallen trees: Palo Alto Public Works 650-496-5953; 650-329-2413 after hours

• Gas leaks, sewer spills: Palo Alto Communications 650-329-2579

• Power outages a electrical problems: Palo Alto Electric Operations 650-496-6914

• Road conditions: Palo Alto 650-329-2420 (during flood emergency only); Caltrans 800-427-7623

Source: City of Palo Alto

Comments

34 people like this
Posted by Midtown
a resident of Midtown
on Nov 24, 2015 at 10:53 am

15 years of lip flapping! You would think that the smartest folks on the planet could figure out how dig out a creek and blow up a bridge or two.


38 people like this
Posted by Crescent park dad
a resident of Crescent Park
on Nov 24, 2015 at 11:02 am

17 years and no improvement to the Chaucer st. bridge. great job team!
I'll continue to cruise the streets with my shovel and unplug the storm drains during big rains. Unbelievable!


14 people like this
Posted by Chris Zaharias
a resident of Crescent Park
on Nov 24, 2015 at 11:14 am

Chris Zaharias is a registered user.

2-hour YouTube video of a guy rafting down San Francisquito Creek from Highway 280 to Highway 101: Web Link

In the YouTube comments, there are time stamps listed for various landmarks so you can quickly get to what you'll recognize. I may just have to do this myself, feels like a Bucket List item...


7 people like this
Posted by Mr.Recycle
a resident of Duveneck/St. Francis
on Nov 24, 2015 at 11:20 am

If you want to keep electing people who care more about trout than flooding, then no surprise that the trout are doing fine, and the flooding problem still looms over the city. Even some trees obstructing the creek have not been allowed to be removed because they are "habitats". It is ridiculous, but people get the government they deserve.


2 people like this
Posted by Chris Zaharias
a resident of Crescent Park
on Nov 24, 2015 at 11:38 am

Chris Zaharias is a registered user.

[Post removed.]


33 people like this
Posted by Class Action
a resident of Crescent Park
on Nov 24, 2015 at 12:29 pm

If we get flooded out, is there a lawyer who would like to take a very large and angry class action suit against the agencies that were responsible for doing nothing for 17 years ?


43 people like this
Posted by IntelligenceSquared
a resident of Community Center
on Nov 24, 2015 at 12:33 pm

With a community that has this level of resources, it should be possible to preserve the trout and habitat while also alleviating flooding. But politicians get caught up in their own balls of wool so nothing gets done. And not soon.


33 people like this
Posted by Old Palo Alto
a resident of Old Palo Alto
on Nov 24, 2015 at 12:34 pm

It is very sad to hear the comment by Materman. "You can't simply take out the bridge and not have effects downstream. We didn't feel like we were in a position to take it out and impact other communities downstream," Materman said. This is very backward thinking, in that if you can reduce the number of homes flooded upstream, why not take the bridge out. Once the water goes over the banks at the Chaucer bridge it all goes to the down stream homes. The down stream home are still going to get flooded no mater if the water breaches at Chaucer or just below Chaucer. It is simple logic to fix upstream breaches and move down stream next. It should be all about reducing the number of homes that are flooded, until the big fix is in place


44 people like this
Posted by Hulkamania
a resident of Duveneck/St. Francis
on Nov 24, 2015 at 12:45 pm

Hulkamania is a registered user.

Seventeen years ago we were woken at 3:30 AM by flashing lights from fire engines parked in from of our house. It wasn't until daylight that we saw the devastation south of us on Saint Francis.

We ended up being a refugee center for our neighbors wading out from the south end of the street and Sierra Court. One kid who had Down's Syndrome almost drowned in his bed. No one from the City or Red Cross was anywhere to be seen.

I hope to Hell the City has their act to gather this year but I'm not betting on it.


18 people like this
Posted by Class Action
a resident of Crescent Park
on Nov 24, 2015 at 12:52 pm

Old Palo Alto ...
>> The down stream home are still going to get flooded no mater if
>> the water breaches at Chaucer or just below Chaucer.

Yes, when you look at the map it is as if they decided to detour flood
waters through areas of Palo Alto to make a slight relief in East Palo
Alto, which could have fixed its storm system to deal with a greater
flow, and needs to in any case.

What is the point in Palo Alto getting flooded too, for no reason?
Just to show solidarity with our our eastern neighbors?

There are so many factors doing into this that it was clear years
and years ago that something had to be done ... and yet nothing.

Does anyone recall the damage estimates from the last big flood
17 years ago? I don't recall but it was in the tens of millions. It is
only if the city, or county or whatever is responsible for those damages
that they are doing spend money to do something in order to
save money on compensation.

Is there a legal process for this?


8 people like this
Posted by Chris Zaharias
a resident of Crescent Park
on Nov 24, 2015 at 2:07 pm

Chris Zaharias is a registered user.

Does anyone know whether the probability of flooding can be lowered by removing as much of the debris currently in the creek as possible *ahead of the rains*? If so, this could be a great community project.


9 people like this
Posted by Brian
a resident of Evergreen Park
on Nov 24, 2015 at 2:09 pm

The reason for (as you put it) showing solidarity with our eastern neighbor is that if the water that would have flooded Palo Alto and East Palo Alto is allowed to pass through Palo Alto at a high rate, it will increase the flooding in East Palo Alto significantly, resulting in more homes being flooded and to a higher depth. It is fairly simple science. The larger the area that is flooded by a constant amount of water, the deeper it will be in the flooded area. So basically, you are asking that a regional problem (downstream flooding from a large watershed) that is being worked on by many different interested parties in the region, be focused primarily on just one of the parties. Tough for me to think that is the right course of action.


33 people like this
Posted by Midtown Resident
a resident of Midtown
on Nov 24, 2015 at 2:12 pm

We were at this meeting. Frankly it was VERY disappointing in that they showed a few slides to the "improvements" that were made and provided a lot of yapping on how to protect ourselves and minimal amounts of how the city actually has improved things in the last 15+ years.

The biggest takeaway and excuse was that the communities downstream can't handle the amount of water if improvements were made in Palo Alto. I have nothing against EPA but if their city moved as slowly as Palo Alto, we will never be able to make improvements if they had to make their improvements first. Palo Alto should stop beating around the bush, make the plans to make the improvements and prior to making the improvements and increasing the creek load, give the head's up to EPA and force them to stop beating around the bush.

As residents we should not suffer do to the lack of planning from our city muchless have our city's planning be affected by the lack of action from a neighboring city.


1 person likes this
Posted by Brian
a resident of Evergreen Park
on Nov 24, 2015 at 2:12 pm

Typo alert! My last post has an error.

@Class Action
The reason for (as you put it) showing solidarity with our eastern neighbor is that if the water that would have flooded Palo Alto and East Palo Alto is allowed to pass through Palo Alto at a high rate, it will increase the flooding in East Palo Alto significantly, resulting in more homes being flooded and to a higher depth. It is fairly simple science. The smaller the area that is flooded by a constant amount of water, the deeper it will be in the flooded area. So basically, you are asking that a regional problem (downstream flooding from a large watershed) that is being worked on by many different interested parties in the region, be focused primarily on just one of the parties. Tough for me to think that is the right course of action.


28 people like this
Posted by musical
a resident of Palo Verde
on Nov 24, 2015 at 2:35 pm

I saw high tide flood the walking path by the bench at the EcoCenter (old Sea Scout bldg) this morning, predicted +9.08 feet at 10:33a.m. Tomorrow promises to be higher, predicted +9.20 feet at 11:15. And Thursday +9.12 at 11:58. We will have similar on Christmas Eve at 10:55a.m. In simple terms the level is measured from average low tide. There's a tall measuring stick in the mud near the EcoCenter front door, but I don't know what zero point it's calibrated to. Water was at the stick's 6.5-foot mark. I plan to be out there again tomorrow.


2 people like this
Posted by Mr.Recycle
a resident of Duveneck/St. Francis
on Nov 24, 2015 at 4:36 pm

@Brian - By that logic debris shouldn't be cleared from the creek because removing it increases flow which could worsen downstream flooding.


11 people like this
Posted by Curmudgeon
a resident of Downtown North
on Nov 24, 2015 at 4:40 pm

"Does anyone know whether the probability of flooding can be lowered by removing as much of the debris currently in the creek as possible *ahead of the rains*? If so, this could be a great community project."

It depends on the definition of debris. Stuff like old mattresses, cardboard, loose branches, and the like can clog the Chaucer orfice, so should be removed. Rooted vegetation will reduce the water velocity and store water upstream, instead of letting it rush to Chaucer and pile up there.


20 people like this
Posted by Crescent Park
a resident of Crescent Park
on Nov 24, 2015 at 6:35 pm

And in a similar manner trees and other debris below the Chaucer Bridge will back up water there at the bridge. And by the Chaucer Bridge is the low point where water went over the banks first in 89.

So leaving debris in the channel is not good.


29 people like this
Posted by anonymous
a resident of Duveneck/St. Francis
on Nov 24, 2015 at 7:35 pm

So - the group tasked to work on the creek and severe flood risk: the Joint Powers Authority - that had the meetings over the years - has not in fact made many such improvements. How much of our Palo Altans' taxpayer money has 'flowed' to this group? I recall they had officials being paid significant sums. I wasn't here in that last flood, but I know some work was done on pumps under Channing -- why didn't they do a sufficient job to make it meaningful if (for some of us) the issue is backed up storm drains and slow/insufficient pumps?! I am nowhere near the creek and over 11 feet above sea level, but still warned to expect flooding! I don't think this is what we expect of our public servants.


28 people like this
Posted by resident 1
a resident of Adobe-Meadow
on Nov 24, 2015 at 9:02 pm

I remember when Adobe Creek was running at the top of the creek level and flooding homes next to it and businesses in East Meadow Circle. And at high tide water was coming up out of the manholes - it could not deal with the water coming downstream vs the water coming upstream from the high tide. This is on Louis Road and adjacent streets. It could not process the total amount of water. Everyone was up at all hours with lights checking what the status was.

I drove over to see what was going on with the SF Creek - people were out at all hours with lights - it was horrible to see the congestion of vegetation against the bridges and the water churning around it.

Adobe Creek was improved, widened, and is cleared periodically of vegetation. It has ducks in the summer so it is not without it's natural look - the ducks think it is great. And when a lot of water I have seen large fish moving upstream.

I know the residents want the San Francisquito Creek to be a natural creek but reality says the vegetation that is growing within the creek comes loose and creates a barrier which then creates flooding upstream as well as down stream - like a lot of beaver dams.

It is a sad commentary that the city does not relieve the potential damage that results from this - and in part is it because of the homeless people who have camps in there? I attended a meeting at the Department of Water a while back and a person was advocating that the creek remain "natural" during the summer as it is a homeless camp. they have a lobby for this????

I have gone over during the summer to check out if any thing was being done to clear broken limbs, bushes, overhanging trees - what the relationship of it all to the bridges. It appears that nothing has been done where the homeless people hang out. I think the homeless people at this point realize that they cannot stay in the creek - it is too cold and the water is coming. But there is still trash left there.

If the city wants to have a creek clean-up day then put it in the paper - I think a lot of people will come. But the vegetation needs to be dealt with by the professional city people. And they need to do it now - they should have done it during the summer.

One of the problems is that the creek is the border of San Mateo County and Santa Clara County so there are mixed messages as to what is suppose to happen here.




10 people like this
Posted by Mr.Recycle
a resident of Duveneck/St. Francis
on Nov 24, 2015 at 9:11 pm

@Curmudgeon - "Rooted vegetation will reduce the water velocity and store water upstream, instead of letting it rush to Chaucer and pile up there."

Rooted vegetation downstream of Chaucer slows the flow and increases the risk of overflow at Chaucer. Rooted vegetation upstream of Chaucer slows the flow and increase the risk of overflow at other points like Middlefield. If slowing the creek flow was a real solution, we could throw sandbags in the creek.


4 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 25, 2015 at 1:26 am

resident1
>> I know the residents want the San Francisquito Creek to be a natural creek
>> but reality says the vegetation that is growing within the creek comes loose
>> and creates a barrier which then creates flooding upstream as well as down
>> stream - like a lot of beaver dams.

I totally agree. My jaw nearly dropped when I heard they were considering this
drainage canal as some kind of natural creek ... it simply is not.

It is just common sense that anything that protrudes into a stream of water
will slow it down and cause turbulence. If these things get uprooted and go
downstream they can collect and get stuck together making a kind of dam
and blocking the flow.

I don't really care what the people living next to the creek want when it comes
to what is down inside the creek. That should not be an issue, and if it is, it
needs to be put out there along with its effects so everyone can take notice
and realize we are being flooded in some part to allow someone to have a view
or not to have a view of East Palo Alto on the other side of the creek.

17 years with virtually nothing done is intolerable ... I don't see why we in the
flood plane area don't have a demonstration or a riot in front of City Hall.
The cost and the bother of a flood is much greater than the cost of doing
something?

Buildup the sides of the creek. Rebuild the bridges. We know it has to
get done sooner or later. We could have gotten rid of the Newell St. Bridge
temporarily just for this season to see what the real effects would be and
if we could live without it ... and nothing. But when I go over it on occasion
and look down the creek I see bushes. trees, etc ... thought last time there
were less ... there are still big things in the creek.


3 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 25, 2015 at 1:33 am

One question for anyone who knows ...
No one wants flooding in East Palo Alto, and if they need help with
that we ought to be willing to help and work with them.

But what I got somewhere was that flooding in EPA was more due to
and a function of the tides and the low elevation of EPA itself. That
is that the flooding was not so much that the water was coming down
from the hills but that it swamped and rose the water in the bay.

So, would that mean that wherever the flooding water emptied
into the bay that this would contribute to EPA flooding, that is in
Palo Alto it seems to run along Greer and 101 and out to the bay
raising the water in the East Palo Alto area.

Is this a separate or the same problem, and is it helpful or thinkable
that hundreds in Palo Alto got flooded for no real purpose and that
any flooding in EPA would have been unavoidable anyway?

And, after 17 year ... why don't we have a clear answer to this?


28 people like this
Posted by bankruptcy
a resident of Another Palo Alto neighborhood
on Nov 25, 2015 at 8:16 am

If the City of Palo Alto ends up in bankruptcy due to its liability in flood
condtions,a possibility, then a reorganization should and must include decision-making relating to land use control which also has been contrary to the public interest,safety and welfare over the past 15 years and imposed costs yet to be even realized to deal with the negative impacts.
The failure here extends far beyond flood control.


4 people like this
Posted by resident 1
a resident of Adobe-Meadow
on Nov 25, 2015 at 8:46 am

We are talking about a creek from top to bottom - it starts at Searsville Lake with an over 100 year dam. Behind the dam is sludge - which will be very wet sludge. So at what point does wet sludge overpower a 100 year old dam? Throw in an earthquake with your wet sludge and you can make some bets on the outcome.

If you go up and hike on SU property you can see the branches and dead trees in the creek. Yes it is habitat but for who? Do any fish make it up there? I have seen those buildings up there dealing with flooding.

Start at the top and work down all of the impediments which cause the beaver dam effect. This is next to SU and the SU shopping center above El Camino. Then work down below El Camino.

The goal here is not to store water for what - a day? - the goal is to empty it into the bay so we do not have salt water encroachment moving upstream due to tidal effect. The pooling of water at the bottom is what the flooding is all about.

If side pools are desired then those should be consciously planned and constructed. There has to be more conscious thought applied here.


50 people like this
Posted by Forewarned is Supposed to be Forearmed
a resident of Another Palo Alto neighborhood
on Nov 25, 2015 at 10:37 am

Since February of 1998, the Weather Service and the USGS have warned cities with flood plains that 100-year floods are now occurring at 20-year frequencies, and even less!

The Weather Service has been warning all Pacific Coast Regions that this will be a severe El Nino--very severe in some areas, even a monster El Niño in Southern California. This warning has been repeated for several months now.

It seems that the Joint Powers Board, et al, are not taking these warnings very seriously--certainly not seriously enough. They seem to think they will not be held accountable for their lack of action. They need to think again!


4 people like this
Posted by An Engineer
a resident of Duveneck/St. Francis
on Nov 25, 2015 at 11:17 am

"Buildup the sides of the creek. Rebuild the bridges."

Easy to say. Why not think it through?

How high must the walls be? How do you bridge over them at, as a minimum, El Camino, Caltrain, Middlefield, University, and 101? Chainsaw El Palo Alto to make room for the wall?


2 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 25, 2015 at 1:42 pm

An Engineer said -
> Easy to say. Why not think it through?

You're the engineer, you tell us.

I know that at a certain point it doesn't matter because we have restrictions in place at Chaucer and Newell where the opening under the bridge is smaller than the cross-section of the creek at those places.

You mention El Palo Alto. I thought the original El Palo Alto was already gone? But the implied question is - do we keep a tree and live with people getting flooded out every 20 years or so? I think not, but I also do not know why we would need to remove the tree.

We don't even know what the problems are, what the options are ... and here we are now. 17 years later facing an imminent season of floods and the people who were paid to handle this have done virtually nothing?

Even an engineer is useless if you have not specs and don't know what the problem is?


25 people like this
Posted by Old Steve
a resident of St. Claire Gardens
on Nov 25, 2015 at 4:10 pm

Everybody here seems to be forgetting that Palo Alto has had two projects ready to go in the baylands that would help everybody, except the folks at Regional Water Quality Control Board can't get out of the way with respect to water quality issues in non-flood conditions. Don't sue the City, become less green and force the SFBRWQCB to be more practical. Since the various politicians can't agree, we should not be trying to "blame the engineers".

Similarly, Caltrans gets abused about the Bay Bridge, but the Mayors Brown (Willy & Jerry) are the ones who insisted on a "Signature" bridge.


6 people like this
Posted by An Engineer
a resident of Duveneck/St. Francis
on Nov 25, 2015 at 4:36 pm

"You're the engineer, you tell us."

Glad to: Ranting online has never stopped a flood.


3 people like this
Posted by Garden Gnome
a resident of Crescent Park
on Nov 25, 2015 at 5:15 pm

It's really quite simple.

Pass a law that forbids the water from spilling over.

(Joe Simitian...this one's on me.)


27 people like this
Posted by Stephen
a resident of Duveneck/St. Francis
on Nov 27, 2015 at 1:49 pm

Back in 2003 after a relatively high flow event in Dec 2002, several neighbors and I (a civil engineering professor at Stanford) did some modeling of the creek using the Army Corps of Engineers (COE) open channel flow code, HEC-RAS and channel data from the SCVWD. This was later done (albeit more professionally) by several consultants to the JPA. Given the ongoing discussion about the creek in light of a potential ENSO this year that may be even stronger than that of 1998, I think it might be informative to go over what emerged from this modeling, modeling which is likely to be as definitive about how the creek works as one can get given existing information/data.

(1) The bridges are problematic, especially the Pope-Chaucer bridge, each increasing water levels upstream. Interestingly, the Pope-Chaucer bridge that existed prior to the late '40s was certainly much more effective at passing flows with low head loss than is the one that is there now.

(2) Our modeling suggested that without the Pope-Chaucer bridge, there would have still been flooding in 1998, just in different places and at different rates than what occurred historically.

(3) The effect of the redirection of the stretch of the creek from the Bay to 101 is hard to define since the original path is comparable in length to the present path. Nonetheless, our suggestion for this reach was to consider raising the levee on the EPA side while intentionally keeping the levee low on the PA side so as to keep water levels as low as possible at the 101 bridge by flooding the golf course. This strategy is a common means of flood control – this past summer I visited a nature preserve on the Rhine in Germany that is based on the concept of a defined “floodway”.

(4) Tides have relatively little importance except downstream of 101.

(5) The existing (now being re-built) 101 bridge is also a major impediment to flow, and probably did not meet CalTrans’ own design standards for flow passage at the time the bridge was built. Unfortunately, the bridge rebuild will not be finished before the rains start this year.

(6) Even if the bridges were all to be replaced with ones that do not in any way affect flow passage beneath them, unfortunately, flood walls are likely to be needed along much of the stretch between 101 and Pope-Chaucer. The reason for this is that the creek cross-section is relatively small in this area, something that might be hard to change without securing some very expensive real estate, unless Woodland Avenue can be significantly narrowed. The height of those walls depends very much on what flow for which they are designed and on assumptions about friction in the existing channel. They also generally need to have 3 ft of extra height (freeboard) above what is needed to keep the Creek within its banks in order to meet FEMA requirements It must be appreciated that in designing those walls, there is a substantial degree of uncertainty about how the channel would behave in a flood and even as to what the flow rate might be, although that is a factor the 3ft freeboard is supposed to partially address. Lastly, adding to the challenge of making accurate predictions is the issue of blockage due to debris in the channel, e.g., the tree that we were told fell into the creek in 1998 near Oak Ct. in Menlo Park.

It is important to note that the issue of what flow is the basis for flood protection in the creek is in my view a political one that must balance some loss of aesthetic and environmental utility with a degree of flood protection. More flood protection means higher walls and hence a more loss of the feeling of the creek as an enclave of nature on the urbanized peninsula. This means protecting some homes and neighborhoods (ours) may mean reducing the attractiveness to others who value it in its natural state. Having seen close up the failure of the CalFed Bay/Delta program due in part to its attempts to promise too much to all of its stakeholders, I think this balancing of flood protection with the preservation of the natural environment of the creek might benefit from more public discussion. That said, I am encouraged by the direction that the JPA under Len Materman is taking in this regard.

Finally, while we all want a wet winter, as someone whose home is in the flood zone, I just hope it isn't too wet.....

Stephen Monismith

ps: The storm drain project that installed larger drains (but no pumps) under Channing and other streets as well as a pump station at East Bayshore would have nearly zero benefit during a flood except possibly to help drain flooded areas after the flood peak has passed. I understand that the primary justification for improving the storm drains was that water that sits on the streets after normal storms is a driving hazard and also shortens the life of the street pavements.


4 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 27, 2015 at 8:27 pm

Nice to see someone get down to brass tacks, so to speak Stephen.

> (6) Even if the bridges were all to be replaced with ones that do not in
> any way affect flow passage beneath them, unfortunately, flood
> walls are likely to be needed along much of the stretch between
> 101 and Pope-Chaucer.

I am not disputing that, but what is the basis for this statement?

> The reason for this is that the creek cross-section is relatively small
> in this area, something that might be hard to change without
> securing some very expensive real estate, unless Woodland Avenue
> can be significantly narrowed.

Maybe Woodland could be rerouted and the creek could be widened
into where the road currently is?

> The height of those walls depends very much on what flow for which
> they are designed and on assumptions about friction in the existing
> channel. They also generally need to have 3 ft of extra height (freeboard)
> above what is needed to keep the Creek within its banks in order to
> meet FEMA requirements It must be appreciated that in designing
> those walls,

Whatever it takes, we ought to build in as much extra capacity as possible
to keep from flooding and from having to do this again. I don't see flow
levels going down with all the development and draining from the hills
now where water would previously have been absorbed, now it makes
its way downhill.

>there is a substantial degree of uncertainty about how the channel
> would behave in a flood and even as to what the flow rate might be,
> although that is a factor the 3ft freeboard is supposed to partially
> address. Lastly, adding to the challenge of making accurate
> predictions is the issue of blockage due to debris in the channel,
> e.g., the tree that we were told fell into the creek in 1998 near
> Oak Ct. in Menlo Park.

The creek is not a park. When I was a teen we used to go down
there and play around ... even then I think it was against the law, but
there was not really much there. What about what we have over
past Oregon, is it Adobe Creek, the one that is all cement. That is
not an option we should ignore, just dig out as much space as we
think we will need with some space.

We have to stop fooling around.

It just seems to me there is no excuse that we should get flooding
here. We are not at the mouth of the Mississippi, or in a giant flood
plane, we have hills that need specific channels for water to flow
down, and we know where it comes from, don't we?

Is this basically a political problem, and if so, who are the stakeholders
and why are they preventing what needs to be done. Every time I think
about this it is astounding that almost 2 decades have gone by with
smaller floods/spiils and still nothing has happpened.

> It is important to note that the issue of what flow is the basis for flood
> protection in the creek is in my view a political one that must balance
> some loss of aesthetic and environmental utility with a degree of flood
> protection. More flood protection means higher walls and hence a more
> loss of the feeling of the creek as an enclave of nature on the
> urbanized peninsula.

It seems like it might be that we need to prioritize doing something
about flooding first, with the proviso that we commit to doing something
positive about not losing the aesthetics, but it might be that trees need
to come down or heavy equipment needs to get in there and excavate
for the greater good.

Please City, County and State ... get on the ball!


11 people like this
Posted by Hulkamania
a resident of Duveneck/St. Francis
on Nov 28, 2015 at 12:12 pm

Hulkamania is a registered user.

Posted by Plane Speaker

"Even an engineer is useless if you have not specs and don't know what the problem is?"

Forget the engineer. Find a finance guy who can get the money to hire engineers, etc. to get the work done.


12 people like this
Posted by Stephen
a resident of Duveneck/St. Francis
on Nov 28, 2015 at 1:02 pm

Plane Speaker's question: "I am not disputing that, but what is the basis for this statement?"

Answer: The modeling we did - even without bridges the water levels in the creek at 7200 cfs (the 1998 estimate) and 9500 cfs (the COE 100 year flood) were higher than the current bank elevations. In looking through my files from the time (12 years ago), I see that our calculations suggested wall heights of up to 7 ft would be required (just downstream of where the Chaucer Bridge is now) for 9500 cfs including FEMA's 3 ft factor of safety. As I recall, what was required for 7200 cfs was somewhat smaller (but not zero).


9 people like this
Posted by Slow Down
a resident of Community Center
on Nov 28, 2015 at 1:48 pm

Slow Down is a registered user.

@Stephen - perfect 100 year flood protection would be great, but I'd settle for ANY improvement, and removing Pope Chaucer, which only has a capacity of 4900 cfs would reduce the risk of flooding in many scenarios. The downstream capacity may not be 7200, but it is more than 4900.


2 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 28, 2015 at 2:21 pm

> I see that our calculations suggested wall heights of up to 7 ft would be
> required (just downstream of where the Chaucer Bridge is now) for 9500
> cfs including FEMA's 3 ft factor of safety. As I recall, what was required
> for 7200 cfs was somewhat smaller (but not zero).

Thanks for the number discussion, that is very interesting.

Stephen, to envision what this 9500 cfs, wouldn't one have to know the
velocity of the water flow, and then be able to put a volume on the "flux"
of water passing a certain area in a second, to then be able to calculate
the minimum area necessary to pass that water through?

So, for example, if the water flow was 10ft. per second that would mean
a opening of 950 sq. ft., a square 32' x 32'; or a big round
pipe with radius about 17 ft. for that much water to pass through it every
second, assuming other factors could be ignored.

Do we know how fast the water travels down the creek in a big storm?
If it varies, do we know how and what it is around the Chaucer St. bridge?

Is the flow of the water dependent at all on the level of the water in the
bay? Someone disregarded that factor, but at some point as the
water flows into the bay it must slow down the flow, is that right?
How far back does that go?


10 people like this
Posted by musical
a resident of Palo Verde
on Nov 28, 2015 at 2:50 pm

Welcome to fluid mechanics and estuarine hydrodynamics.


6 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 28, 2015 at 2:51 pm

"Slow Down" .... slow down

>> @Stephen - perfect 100 year flood protection would be great, but I'd settle for ANY improvement

You've seen what our system does ... ignore the problem, so I would suspect we get one chance at this so we better do it right.

--

Can barriers of 7 feet in height be made that are structurally sound ...

AND would squaring out the sides of the creek save some of that space up at the top if it could be done structurally soundly as well?

Having just seen a program on the ancient Romans and their civic works with the aquaducts at all ... I just find it amazing that today we cannot even build a situation that will prevent a flood? ;-)


7 people like this
Posted by Slow Down
a resident of Community Center
on Nov 28, 2015 at 3:05 pm

Slow Down is a registered user.

@Plane Speaker - 10 years ago, I'd might have agreed with "we only have one chance, better get it right," but after waiting 20 years for nothing, I think a better strategy is continuous small improvements. Remove the bridge, build up the height of the banks, even if it is 1 foot at a time.


11 people like this
Posted by stephen
a resident of Duveneck/St. Francis
on Nov 28, 2015 at 3:44 pm

Plane speaker:
(1) 9500 cfs is a lot of water - it is about what has been moving down the Sacramento this past summer. Converted to gallons per minute it would over 4 million gallons per minute. Design of an appropriate cross-section (so area for the flow to pass through) depends on what the surface of the channel is made of - i.e. concrete or gravel or gravel with vegetation which determines how much friction there is for a given flow velocity. It also depends on shape of the channel - most man-made channels (e.g. California Aquaduct) are trapezoidal since this minimizes the area needed for a given flow. These are the design variables that the engineers working for the JPA (or the Corps) would examine to come up with a design. For 9500 cfs our model gave a depth of about 25 ft at Chaucer where the width is about 50 ft, so the velocity would be a little under 10 feet per second.
(2) Tidal elevation at the Bay only has a small influence on water levels except in the Bay to 101 reach.
(3) 7 ft walls could be designed and built to do the job - I have seen pictures of walls that are much taller (try googling flood walls to see what they look like). I gather that constructing any walls in the space available around the Creek would involve some pretty significant disruption of Woodland Ave. and the houses on the PA side of the creek (and also some eminent domain actions). It would be pretty hard to make them look good or natural, although there are already a mixture of walls and engineered levees along the creek.


7 people like this
Posted by Peter Carpenter
a resident of Atherton
on Nov 28, 2015 at 5:25 pm

Peter Carpenter is a registered user.

It is strategic to plan what should be done over the next five years.

It is tactical to plan for what may well become essentialto do during the next five months - intentional breaches of creek walls and dikes and explosive removal of obstacles including bridges.

These tactical decisions will have huge economic and political consequences and those consequences need to be debated and evaluated in advance. There will be no time in the midst of a massive flood to sit down under a tree and have a philosophical debate.


11 people like this
Posted by Joe
a resident of Barron Park
on Nov 28, 2015 at 9:15 pm

Suppose the weather predictions are wrong??
Six days ago lots of rain was predicted and we got a puddle aNd then rain was predicted. For November 29 & 30 and now none.

This El Niño ,at not happen at all!


1 person likes this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 28, 2015 at 9:32 pm


That is really interesting ... so the 10 ft per second is not far off.

And so anything nominally less than 950 sq. ft. is going to obstruct the flow
of the creek, build up behind it, and then cause an overflow, assuming the
creek is running at full capacity.

In 1997 I recall driving home from seeing a movie at the Guild Theater and
thinking it would be fun to see what the creek was doing, having no idea there
was any flooding going on. We stopped over by the pedestrial bridge near
downtown that goes to Menlo Park and that creek looked like the Sacramento
river ... it was almost to the top and raging by like crazy.

At that time we lived off Greer and by the time we got home Greer was flooded
and we barely we able to drive home and get into the driveway. It was like
a lake.

I did not get the whole picture of how the flooding progressed, but I assume it
backed up behind Chaucer Bridge and flooded almost as far out as Channing.

Here is a picture of the Chaucer Bridge under a heavy load, but not flooding.
Web Link

I cannot really tell what the area of the opening is under the bridge, but I doubt
it is anywhere near 960 sq. ft. which means that at full load in the creek that
bridge is guaranteed to flood.

We have ways to get from any city to any other city so I just do not get why
this bridge, or even the Newell bridge stays standing just for the minor
convenience of traffic when the damages a flood will cause will so major.

Do you know if the City installed any of the bypass culverts they were talking
about that would route some of the water off the east under Hamilton?

What about taking the bridge or bridges out?

Are we really allowing going to allow flooding to save a little auto congestion?


10 people like this
Posted by Stephen
a resident of Duveneck/St. Francis
on Nov 29, 2015 at 10:44 am

The area through the Chaucer Bridge is somewhere between approximately 415 square feet (if there were no sediment in the bottom) and approximately 330 square feet (current condition with 3 ft of sediment in the bottom) - so a big constriction. It is the big change in area from the creek downstream of the bridge and the opening of the bridge that causes the "extra" back-up of water upstream of the bridge.

Bypass culverts would have to be large to be useful. A back of the envelope calculation shows that for a culvert that went between upstream of the Chaucer bridge and the 101B bridge, a distance a little over a mile and a half, would need to be 20ft in diameter and so would mean that whatever streets its route would involve would be a construction zone for quite awhile. For reference sake, the two 40ft diameter tunnels being contemplated for the Delta will cost of the order of $400 million per million even though they would be built in the middle of farmland, not a city. Thus, a bypass culvert is likely to be very expensive and its construction would be highly disruptive.


1 person likes this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 29, 2015 at 11:21 am

Would it be correct to say then that the first "choke point"
for water in the creek is the Chaucer bridge?

For example, say as an experiment, you could have a giant
faucet that would allow more and more water to flow down
into Palo Alto from above ... that as that faucet opened and
more and more water was to flow, that all things being equal
the first backup we would see would be behind the Chaucer
St. bridge?

If that was true, then if the Chaucer St. bridge was removed,
a greater flow would be possible until some other point,
presumably the Newell St. bridge would choke and back up?

Stephen, you said
>The area through the Chaucer Bridge is somewhere between
> approximately 415 square feet (if there were no sediment in
> the bottom) and approximately 330 square feet (current
> condition with 3 ft of sediment in the bottom) - so a big
> constriction. It is the big change in area from the creek
> downstream of the bridge and the opening of the bridge that
> causes the "extra" back-up of water upstream of the bridge.

Correct me if I am wrong, but I interpreted what you said earlier
to be that at a flow rate or 9600 cfs, the minimum aperature
necessary to constrain that flow would be about 960 sq. ft.

Or did I say that?

If the Chaucer St. bridge is less than half of that, it is a
major constriction even at a extended flow of half the
maximum rate until the creek starts to fill up behind the
bridge, at which point it will overflow.

That seems like a very bad situation to have a bridge that
limits the flow and will flood at half the maximum rater of
water flow that the creek could handle ... in fact, it makes me
wonder why we don't take it out right away?


10 people like this
Posted by Stephen
a resident of Duveneck/St. Francis
on Nov 29, 2015 at 12:11 pm

Plane speaker:
(1) To stay within its banks at Chaucer at 9500 cfs, a flow area of about 1000 square ft (so 960 is within this estimate) would be required. So no question that the bridge is a major impediment. If the creek could otherwise pass 9500 cfs, the bridge would back up the water 11 or 12 ft relative to the downstream water level.
(2) Until the replacement is finished, it turns out the 101 bridge is the "worst offender" in terms of flow resistance, i.e., has the lowest capacity before overflowing upstream. Noble Consultants did the same kind of modeling for the JPA and found that the 101 bridge had a capacity of 4400 cfs compared to Chaucer's 5200 cfs. Based on observed depths and USGS estimated flows from Dec 11/12 2014, I would say the the Chaucer Bridge capacity is more like 5500 to 5600 cfs.


17 people like this
Posted by Paly Grad
a resident of Leland Manor/Garland Drive
on Nov 29, 2015 at 12:31 pm

On December 23, 2012 the water level at the Chaucer Street bridge rose 8 feet in 4 hours reaching a height of 22.5 feet at 7:45 pm.


11 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 29, 2015 at 3:01 pm

Is there any way to store the water temporarily upstream, like in a reservoir.

Maybe I am totally offbase on this, but wasn't that what they used to do with
Stanford's Lake Lagunita, fill it with winter rain as a kind of bypass? What
about building or excavating deeper in order to detour the water so it does
not hit these bridges faster than the bridges can drain?

Are they doing anything like that?


16 people like this
Posted by Que Pasa
a resident of Another Palo Alto neighborhood
on Nov 29, 2015 at 3:25 pm

Apparently, Mexico is getting the El Niño rain we were supposed to get. There has been flooding from Sinaloa to Mexico City.

Up here, we may only get a mold El Niño, while SoCal gets a heavy one and Mexico gets the Monster El Niño previously predicted for this area.


6 people like this
Posted by Joe
a resident of Barron Park
on Nov 29, 2015 at 4:33 pm

@Que Pasa
Exactly what I wrote two days ago, this whole flood scare may not happen instead a few more years of drought. Where is the rain we were promised last week?


1 person likes this
Posted by Tara Madhav
a resident of Palo Alto High School
on Dec 1, 2015 at 8:39 pm

Hello all, here's another article on the coming El Nino that might be interesting for those of you doing active research (or who have direct experience with) on previous damage and ongoing preparations. Written by myself and fellow junior Gabriel Sanchez in Paly's student-run Verde Magazine, the article discusses preparations in Palo Alto and at Paly: Web Link.


Like this comment
Posted by Plane Speaker
a resident of Crescent Park
on Dec 1, 2015 at 11:24 pm

Thanks for the link to the article Tara ... I'm glad someone refreshed this
again. This creek flooding situation needs to be resolved. It sounds like
from previous discussion that one step forward would be to remove the
Chaucer St. Bridge, and rebuild it. Are we doing nothing because some
people are going to have worse traffic? Is that worth possible millions
of dollars of damages?

From the article you linked to ...

> Eventually, Singh and her husband would move to Los Altos, after years of
> worry about their house and a lawsuit against the City of Palo Alto for their
> negligence. While Singh and fellow residents who sued did not win, she
> says that the lawsuit was filed mainly to draw attention to her situation.

That was 1998, 17 years ago ... I wonder how a lawsuit would play today?

Unless people are talking about it here, I see nothing being done other than
talk about how complex and interrelated this is, but is has been 17 years
now. If there was not negligence 17 years ago, if we get flooding again I
don't see how negligence could be denied again.

High punitive damages would be in order in my opinion, this has dragged
on for way too long, and already there has been a few streets flooded
since.



1 person likes this
Posted by Stephen
a resident of Duveneck/St. Francis
on Dec 2, 2015 at 4:31 pm

Interesting that the litigants in the suit that was referred to in the Verde article were unsuccessful. Some of the folks who sued, notably John Hanna, did receive a settlement from the city - see Web Link

I wonder if the difference was due to where the Singhs' house was located compared to where the successful litigants live? The basis for the question is (again) the modeling we did - minus the Chaucer Bridge, the flooding would have taken place further downstream, thus missing some of the area affected in 1998. Thus, it is likely that some folks (maybe the Hannas but not the Singhs?) got flooded in 1998 because of the bridge.


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

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