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Study deals blow to planned replacement of Pope-Chaucer bridge

Original post made on Jun 8, 2023

An ambitious plan to replace the flood-prone Pope-Chaucer bridge between Palo Alto and Menlo Park is on the verge of faltering after the agency overseeing the project concluded that project would place downstream areas at risk.

Read the full story here Web Link posted Thursday, June 8, 2023, 7:49 PM

Comments (20)

Posted by Norman Beamer
a resident of Crescent Park
on Jun 8, 2023 at 8:29 pm

Norman Beamer is a registered user.

Sorry, but it’s time to fix the Chaucer bridge and say “tough luck” to the property owners who are downstream of the bridge and who might be vulnerable to increased flooding if the bridge is fixed. Look at it this way: if a big tree fell into the creek, and blocked the flow, that would “protect” everyone downstream, but flood the properties upstream. Would anyone seriously argue that therefore, the tree should not be promptly removed to restore the prior natural conditions? It’s the same with the bridge, which was improperly designed years ago and has created an unnatural blockage of the creek. The city was and is strictly liable for this improper design, under at least the principle of "inverse condemnation." As stated in Albers v. City of Los Angeles, 62 Cal. 2d 250, 263-264 (1965), "any actual physical injury to real property caused by [a public] improvement as deliberately designed and constructed is compensable ... whether foreseeable or not." There is no reason to believe that further flood events will not cause further damage as the direct result of the artificial constriction caused by the bridge, thus exposing the city to further liability. In contrast to the strict liability that the city is exposed to by leaving the bridge as is, the city would be shielded from any claims for damages "caused" by removal of the bridge. In Locklin v. City of Lafayette, 7 Cal. 4th 360 (1994), the California Supreme Court held that if a public agency makes flood control improvements to flow of a natural watercourse, and if those improvements are reasonable, the owners of downstream property "must continue to accept the burden of damage caused by the stream water." It is this point that pertains to the current arguments, to the effect that removal of the bridge will transfer flooding downstream. There can be no genuine dispute that it is reasonable to improve the Chaucer Ave. bridge to correct the mistaken design of 1948.


Posted by Native to the BAY
a resident of Old Palo Alto
on Jun 8, 2023 at 11:03 pm

Native to the BAY is a registered user.

Incredible! The flood of 1998 was when the city and the joint powers needed civil engineers the most. Yet on the doom of the Internet boom, software engineers exploded on the Peninsula and predominately grew a Silicon Chipped Valley. And so here we are at a riveted steel marker apex. A actual bridge for travel is ubiquitously serving as a damn! Are we so far removed from actual infrastructure breakdown and glued to Auto-Cad scenarios justifications to not replace a bridge because it’s structure acts as a flood plug downstream? It’s time for OES assessment. Apparently if it can’t be 3D printed or designed & installed by sexy robotics we are relying on the mid-20th bridge infrastructure as a twofer . Bridge&Dam. Who said it’s like the bridge over the River Kai ? If it looks like a bridge it’s not. It’s a dam. Might as well put up a sign “Welcome to Hollywood” .


Posted by Local Resident
a resident of Community Center
on Jun 9, 2023 at 10:39 am

Local Resident is a registered user.

Why not just clear out some of the in channel obstructions (e.g. trees: living and dead), rocks and dig a little deeper in areas that might overtop?


Posted by Optimist Pessimist Realist
a resident of East Palo Alto
on Jun 9, 2023 at 11:30 am

Optimist Pessimist Realist is a registered user.

IIRC Norman Beamer no longer lives in the area but his lack of concern for downstreamers remains intact.


Posted by M
a resident of Old Palo Alto
on Jun 9, 2023 at 11:38 am

M is a registered user.

Bridges are not designed to be dams. What happens if it gives way during a flood?


Posted by TuppenceT
a resident of Adobe-Meadow
on Jun 9, 2023 at 11:45 am

TuppenceT is a registered user.

Palo Alto should consider using the golf course to reduce the risks of flooding of East Palo Alto homes. This was an option that was rejected when the golf course surrendered 7 acres to the Flood Management project East of 101. Maybe time to reconsider, and provide flood plain capacity at the golf course during extreme rainfall events.


Posted by Anonymous
a resident of Duveneck/St. Francis
on Jun 9, 2023 at 12:12 pm

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A massive flood channel was installed years ago to cover East Palo Alto houses out by the bay.
It’s tume NOW to protect Palo Alto and Menlo Park.


Posted by tcr
a resident of Crescent Park
on Jun 9, 2023 at 1:28 pm

tcr is a registered user.

On June 10, 2014 the SCVWD Directors held a public hearing on a modification to the SFC flood protection project being developed jointly with the SFCJPA. The driving issue was funding — not enough money to implement a Preferred Project (PP), i.e., upgrades to the creek to contain at least a 100-year flow — 9,200 cfs from Middlefield bridge to the bay. The dilemma was should we wait an indeterminate time for federal, state, and local funding to be available to start the PP, or should we undertake a lesser Modified Project (MP) now, using available state and local funding? After much debate, SCVWD voted unanimously (Director LeZotte absent) to adopt the MP. SFCJPA Directors agreed.

The MP included (a) the PP upgrades in Reach 1 from the Hwy 101 bridge to the bay (done in 2019) and (b) in Reach 2 removing Newell and P-C bridge intrusions into the natural conformation and flow capacity of the creek, widening of 4-5 pinch points, and improving bank/floodwalls to contain around 7,200 cfs.

It is no surprise that the flow downstream of the P-C bridge would increase with its removal. Why Mr. Xu now cites this as the reason for abandoning the P-C bridge upgrade is hard to understand. Reach 2 widening and bank improvement work is focused mainly on minimizing the risk of flooding for everyone as much as possible. The MP unavoidably entails some flood risk from very high flows for all residents near the creek.

I strongly believe the Reach 2 work should proceed as planned and Mr. Xu's studies should update the model to account for current Reach 2 plans and any recently identified bank/channel problems. Then explore plans for better bank and channel treatments to maximize protection for properties bordering the creek and estimate the flow accommodated by the creek.

25 years after the 1998 flood, we can’t have more years of anguish over how to restore the natural capacity of the creek and protect residents from the ill-considered construction of the P-C bridge many years ago.


Posted by Jim Wiley
a resident of Menlo Park
on Jun 9, 2023 at 3:35 pm

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Valley Water is showing that if Pope-Chaucer was replaced, their updated modeling (based on the actual water levels observed and documented during the New Year’s Eve flood) shows that there would need to be 4 miles of 3-foot to 6-foot floodwalls from the Newell Street Bridge up to almost Pope Chaucer. 3 to 4 feet plus up to 2 feet additional on outside curves.

=======================================

Jack Xu, a Professional Engineer & Certified Flood Manager in the Valley Water Hydrology, Hydraulics and Geomorphology Unit, presented this conclusion in his June 8, 2023 presentation to the SFCJPA:

"Transfer of Flood Risk
Pope Chaucer cannot be replaced without a significant increase to the Reach 2 Project
• Floodwalls 3' - 4' for 2 miles on each side, from Newell Road up to almost Pope Chaucer"

=======================================

In Xu's June 5, 2023 technical memorandum, he added:

CREEK SUPERELEVATION
Creek superelevation is a phenomenon that occurs when water flows around a bend in a creek. The water on the outside of the bend moves faster than the water on the inside of the bend, which creates a higher water level on the outside. There are areas on the outside of bends that are shown to have flooded on NYE, but the revised models do not. Superelevation is not considered in the HEC-RAS model and must be accounted for separately. Using a simple methodology from the US Army Corps, an estimate for recommended additional freeboard due to superelevation at various locations ranges from 0.75’ to just under 2.0’


Posted by staying home
a resident of Crescent Park
on Jun 9, 2023 at 4:05 pm

staying home is a registered user.

how is this a surprise or shock to anyone associated with this effort? Hasn't this been identified previously in EVERY study on this issue? Each bridge on the creek has a designed maximum flow. Enabling more water to flow under a bridge upstream means the downstream bridges are the next in the line. This is a joke.


Posted by mp_resident
a resident of Menlo Park
on Jun 9, 2023 at 4:34 pm

mp_resident is a registered user.

Before the JPA throws the current plans in the trash, what I would ask is that they hire an unbiased hydrologic modeler to review the Valley Water report. Too much is riding on this to accept unquestioningly the conclusions of an agency that historically is more comfortable paving over creeks than maintaining them in their natural state. For example, is the fact (if true) that more debris was observed at the Pope-Chaucer bridge in 2023 versus 2012 due to the effect of four years of extreme drought? Weakened trees falling in the creek this year are not surprising, but using those conditions to represent all future conditions is not appropriate.


Posted by Bystander
a resident of Another Palo Alto neighborhood
on Jun 9, 2023 at 4:46 pm

Bystander is a registered user.

101 was closed overnight and the lanes all moved, and lots of work was done for months for work on this creek and then there was single lane on Bayshore near the Post Office for months to prevent flooding along with huge green levees in East Palo Alto. Why is this still a problem after all that work and all that money spent? I was under the impression that this work was so that the Chaucer bridge could be replaced. Was that misinformation and why were we told otherwise?


Posted by TuppenceT
a resident of Adobe-Meadow
on Jun 9, 2023 at 6:53 pm

TuppenceT is a registered user.

Will the analysis have to change again when Searsville Dam is modified to allow water flow through the dam and into the Channel? The flows MUST be modified when water flows through rather than over the dam?
The planners said they have to start near the Bay, and move up the channel with the flood management "improvements". So was that approach wrong for this particular stream?


Posted by MMM
a resident of Crescent Park
on Jun 9, 2023 at 8:30 pm

MMM is a registered user.

This is supremely disappointing news. Were all the previous engineering studies over the past 25 years erroneous? At a minimum the conclusions Jack Xu reached should be corroborated by another engineering firm before the PC bridge project is modified or cancelled; 25 years of work can’t be halted by a single analysis. Xu seemingly alludes to a benefit of keeping the current PC bridge in place because it acts as a dam that limits downstream water flows. I’d add that the bridge accomplishes this by flooding Crescent Park. We as a community need to take coordinated action to motivate the SFCJPA to reverse this decision or commit to another plan that can be accomplished in the same time frame. We can’t wait any longer, we can’t have more nights of sandbagging and worry during heavy rain.


Posted by Pat Landman
a resident of Old Palo Alto
on Jun 10, 2023 at 8:39 am

Pat Landman is a registered user.

As a very long time local remembering the mid ‘50’s floods, I have a simple suggestion. How about higher flood walls perhaps between Middlefield and Chaucer along with regular debris removals in that area as well?
Cheaper, easier, sooner, no?


Posted by tcr
a resident of Crescent Park
on Jun 10, 2023 at 3:56 pm

tcr is a registered user.

Re Pat Landman suggestion. Pat, raising the banks at Hale and Seneca, where the overflows occurred from the "lake" that built up behind the Pope-Chaucer bridge on Dec 31, would increase the maximum flow capacity only by ~200 cfs (to ~5,700 cfs ) before it would overflow the wall at Pope-Chaucer bridge itself (based on the latest rating curve for P-C). We're trying to accommodate somewhere ~7,200 cfs to reduce the flood risk seen in the 1998 flow of record, which is why we need to upgrade the P-C bridge.


Posted by Norman Beamer
a resident of Crescent Park
on Jun 10, 2023 at 4:14 pm

Norman Beamer is a registered user.

Dear downstream owners: you have NO RIGHT to complain about fixing the bridge. Restoring the creek to its natural state by fixing the bridge is necessary and appropriate no matter what the consequences of restoring the status quo ante.


Posted by StephenM
a resident of Duveneck/St. Francis
on Jun 10, 2023 at 10:55 pm

StephenM is a registered user.

I looked at the report describing the modeling effort - it was quite well done. In particular, the increases in Mannings n (the friction coefficient) used in the calibration effort seem very warranted given what the creek interior looks like. I am not sure as to what was used by Noble and the Corps in their modeling, but when our neighborhood group did our own modeling back in 2003, we increased n uniformly by 20% over the values that SCVWD was using at the time so as to best match the very limited observations available in early 2003. The new modeling does suggest that removing as much as possible of the vegetation in the channel (not on the banks), especially non-native plants and trees, would be helpful. I liked the fact that the report brought up the issue that bends in the creek can cause superelevation of the water surface on the outside of the bend - these need to be accounted for in design of any flood control measures. The bottom line is that I would be hard pressed to imagine anyone doing a model of similar or better fidelity that showed anything other than what was reported to the JPA this past week.

However, one aspect of the new modelling report that should be corrected is the map of where overflows occurred on 12/31 (figure 2) – the figure omits the overflow that occurred by the pump station at Hale and Palo Alto Ave. This omission is important because Hale St. is upstream of the bridge - how much of the water that came through on the Palo Alto side between there and Palm St. would be good to know, but it does appear from video and photos that the upstream overflow was significant. It would be good if someone could construct a map of where water flowed, e.g., along Center, Pitman etc., and if possible, flow depths.


Posted by Annette
a resident of College Terrace
on Jun 11, 2023 at 7:14 am

Annette is a registered user.

Between this decades old issue and the grade separation issue, I cannot help but think of Atlas Shrugged.


Posted by Xenia
a resident of Crescent Park
on Jun 16, 2023 at 8:49 am

Xenia is a registered user.

We have agreed to fix the creek from downstream to upstream to ensure that risk of flooding will not be transferred downstream. The modeling of the creek also needs to reflect planned work from downstream to upstream. The model presented on June 8 does not do that. The model needs to be redone and updated to reflect that improvements upstream will be done only after improvements downstream are completed, especially the removal of the huge cement wall inside the creek between Euclid and Manhattan on the East Palo Alto side just upstream of University Ave.

The goal of Reach 2 project has been and needs to be to accommodate flows of 7,200 to 7,500 cfs. That is the flow that can pass under Middlefield Bridge, and that is also the flood of record in 1998. Reach 2 project needs to include the replacement of Pope Chaucer Bridge that blocks the creek and overflows at 5,400 cfs. Those of us in the shadow of Pope Chaucer Bridge have been waiting patiently for 25 years; any further delay is unacceptable.

Prominently, there is a cement wall on the East Palo Alto side between Euclid and Manhattan that blocks the creek. It is immediately downstream from Oak Court and Euclid, where the creek overflowed on Dec 31. This is a huge structure INSIDE the creek! The wall is wide, it's the entire height of the creek bank, and it is a block long! There is even a staircase that leads into the creek bed! It is at a narrow point where the creek turns, immediately downstream from the overflow point. It takes up a huge amount of volume in the creek! There is a chunk of cement actually intruding into the creek and blocking water flow. I am enclosing a few photos below. I urge you to go and take a look at that cement monstrosity inside the creek -- you can see it from Woodland between Euclid and Manhattan.

This wall would be removed as part of the channel widening; and Jack Xu/SCCWD absolutely needs to redo the modeling with this wall removed.


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