News

Palo Alto prepares to plumb the mysteries of groundwater

Spurred by citizen complaints, city prepares to revise rules, pursue studies to better understand impacts of 'dewatering'

The millions of gallons of water that have been pumped out of Palo Alto sites this year and sent toward the city's storm drains have historically been viewed as a byproduct of basement construction, rather than a valuable resource going to waste.

But with the drought now in its fourth year and residents increasingly raising flags about groundwater pumping, or "dewatering," the city is taking a fresh look at the practice and preparing to institute new construction requirements, as well as pursue new studies in an attempt to plumb the mysteries of this hidden water source.

In its first discussion of a topic that has rattled the residents of Old Palo Alto, Crescent Park, Community Center and other neighborhoods where the practice of dewatering occurs, the City Council's Policy and Services Committee tentatively endorsed on Tuesday a list of short-term reforms proposed by staff to address the issue and added a list of other, more ambitious, initiatives relating to basement construction and dewatering.

These include requiring contractors to analyze and mitigate the impacts of dewatering; exploring new fees to capture the value of the discharged water; finding new uses for the water being pumped out; and pursuing a long-term study focusing on best practices for groundwater.

Dewatering has become a bigger issue this year in Palo Alto, with more residents buying up properties, tearing down houses and building bigger ones, often with large basements. Whereas a decade ago, the city issued between five and 10 dewatering permits per year, this year the number was 14. In 13 of these cases, the homeowner was building a second story in addition to the new basement, according to Public Works staff.

Signifying the rising level of concern, close to 50 residents attended the hearing for what was mostly a technical discussion about the complex topic. More than a dozen, including those affiliated with the new group Save Palo Alto's Groundwater, addressed the council to request a moratorium on dewatering permits and more studies about the impact of basement construction on the city's water supply, nearby homes and trees. Many argued that allowing the water from construction sites to flow freely into the storm drains (and, ultimately, into the Bay) sends the wrong message about the value of the water.

"It is important to remember that this groundwater serves as an emergency water system for Palo Alto," said Rita Vrhel, a member of the citizens group. "Even though it's not potable at this time, it could be treated and in a period of continued drought, it could be a significant resource to us all."

Former Mayor Peter Drekmeier told the committee that under the present system, the water being pumped from basements is "seen as a problem versus a resource."

Keith Bennett, a resident of Old Palo Alto who spearheaded the formation of Save Palo Alto's Groundwater, also argued that water should not be treated as a mere byproduct of construction.

"Whether potable or not potable, this water is clearly usable for irrigation," Bennett said. "It should be managed as a valuable resource."

Skip Shapiro drew applause from the audience after suggesting that the committee consider zoning laws that would simply restrict basement construction in areas where groundwater needs to be pumped.

"If (someone is) building basements in residential areas where dewatering is required, perhaps that's not an appropriate place to add basements," Shapiro said.

The council had commissioned studies on the topic in the past, though Public Works staff acknowledged Tuesday that the numbers in these reports aren't particularly reliable. The Santa Clara County Water District doesn't have all the desired data either, said Phil Bobel, assistant director of Public Works.

The water district "would be the first to admit that our northern county groundwater situation is not well studied enough to answer the kinds of questions you'd like answered," Bobel told the committee.

Committee Chair Pat Burt, who also sits on a water district committee charged with looking at the subject, noted that the water district has recently allocated $3 million in funding for water-conservation efforts, money that could be spent on further exploring groundwater and possible uses for it.

Burt also suggested that the city consider zoning changes related to basement construction, though this would be a longer-term initiative that is unlikely to be completed by next spring, when dewatering projects could resume (the city's existing policy prohibits dewatering between October and April).

In the short term, Public Works staff will confer with hydrogeological experts and other stakeholders, refine the city's proposed reforms and return to the committee early next year to discuss any potential rule changes.

Among the most significant changes, Bobel said, would be requiring a contractor to do a study on the localized "microimpacts" of dewatering, including impacts of water pumping on nearby houses and trees.

"This would be a major new feature," Bobel said. "The contractor would have to engage a third-party expert to evaluate the impacts and effects on neighboring properties and to avoid those impacts."

Staff also proposed firming up the city's rules on filling stations at dewatering stations, which would allow residents, landscapers and others to fill up trucks and buckets with the pumped-out groundwater. While these stations are already required, they would now be required to have adequate water pressure to accommodate multiple concurrent users.

Another proposal that will be further explored in the coming months is one requiring contractors to provide water hauling services once per week to deliver the water to area parks or other areas where it can be used.

The committee generally endorsed most of these recommendations, though members also proposed a host of new initiatives for staff to pursue in the longer time frame, possibly in collaboration with neighboring cities and the county's water agency.

Councilman Cory Wolbach said his biggest concern is water security, making sure Palo Alto's aquifers continue to be adequately supplied. He supported going ahead with the long-term study, which would explore the water levels in both the deep and shallow aquifers (the deep aquifer, which is much larger than the shallow one, includes the city's emergency-water supply), estimate the amount of water that flows between the two aquifers and how it fits into the bigger picture of the area's water ecosystem.

"We don't want a knee-jerk reaction. We want to be data-driven," Wolbach said. "Before we decide what to do, let's think about what goals we're trying to achieve. What are the problems we are trying to solve?"

Committee members also suggested that whatever rules the city adopts should be flexible to account for dry and wet years. Councilman Tom DuBois suggested that there be some "context sensitivity in terms of what we require."

"If we're in year three of the drought, maybe requirements are different then after a couple of rainy seasons," he said.

Comments

10 people like this
Posted by Wondering
a resident of Another Palo Alto neighborhood
on Dec 2, 2015 at 10:47 am

Why does the city not count basements in the square footage of the house?


8 people like this
Posted by Alan Zulch
a resident of Professorville
on Dec 2, 2015 at 10:48 am

Our house, which has been very stable for many decades of its 60 years, has only started to settle in the last five or so years, with wall and slab cracks, window and door problems, etc. Is this because of dewatering in the neighborhood? Drought? A combination?


16 people like this
Posted by Karen Ewart
a resident of Community Center
on Dec 2, 2015 at 10:54 am

I first started complaining about this in April. 72,000 gallon of water a day (the equivalent of 14.5 5000 gallon tankers) premium fresh ground water being washed into the day turning into salinated water.

Over the span of 4 months that is over 8 million of gallons of water wasted FROM JUST ONE SITE. Dead trees, houses shifting and other countless problems are created by this extremely selfish one percenter need for a basement in a place where not many have them.

Multiply that by 5 job sites that were active in the beginning of September and you can see the magnitude of the problem just beginning.

When I called the attention of the city to the problem I was ignored. It's only when KTVU picked up the story when something was done. It's appalling what so few can cost so many.

I'm sure everyone saw the news story with the San Jose mayor drinking reconstituted waste water. Wouldn't he have preferred drinking reconstituted grey water? Think about it.


7 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Dec 2, 2015 at 11:20 am

Much ado about nothing, or very nearly nothing. This is a research program, not a priority.

Want to be concerned about water ... do something about the possible creek flooding in this El Nino year - and PRONTO!


4 people like this
Posted by the_punnisher
a resident of Mountain View
on Dec 2, 2015 at 11:24 am

the_punnisher is a registered user.

Having dealt with groundwater problems in the past, I can see what has been done to mitigate the " damp basement " problem.

Many houses have a small collection area and a water lift pump that discharges into the wastewater system. Proper design of the basement allows these drainage systems to work. This has NOT been a problem when a basement is properly designed.
My friend certified wells and septic systems for new constructions and paid close attention to the laws in the State of Wisconsin.
Rural groundwater considerations are met by laws considering both potable ( household ) and non-potable ( agricultural ) wells.
There is a high water table in the SFBA because of the development of all the land at the same ( or close to the same ) elevation to the Bay. The land masses " filter " the Bay water underneath a shallow well system. A deep well system taps an aquifer system. That resource can " run dry " if overpumping exceeds the rate that aquifer recharges itself.

Just design these basements like others in the Midwest areas. This is not any new problem, just new to the SFBA.




2 people like this
Posted by enough!
a resident of Charleston Gardens
on Dec 2, 2015 at 11:43 am

Here's the KTVU story: Web Link


8 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Dec 2, 2015 at 11:46 am

> Having dealt with groundwater problems in the past, I can see what has been
> done to mitigate the " damp basement " problem.

So you mean when the basement already exists? If there is seepage into an
already existing basement, they are are designed to collect in one area and
get pumped out.

I thought the "dewatering" problem was about the construction phase of a
house, wherein, you dig a hole and it begins to collect water because there
is so much water in the soil that it collects like a spring in the future basement.

I am all for people being able to do what they want, within reason with their
own properties ... because God knows we pay enough to live here. So, in the
construction phase of a house this seems necessary if one wants a basement.

The fact that there is so much water so close to the surface seems to say to
me that this is not a problem, but I do agree if it can be used for something
all the better.

Someone quoted 72,000 gallons a day from one dewatering operation ... did
I hear that right ... because it translates into a cube of water 21 feet on a side.
That number is ridiculously high. But that is about the volume of a large
swimming pool. When you use gallons for any measurement of water it
always seems like.

So, how about let's get some real baseline numbers here ... but in the meantime
realize that this has been going on for years if not decades and the groundwater
is still high enough to be seeping into people's basements. That means it is
being replenished, and replenished rapidly.

First, I don't have a basement, nor am I building one or planning to, but I don't
see what the issue is here. We are in a drought and someone thought water and
saw water from the ground being pumped. Then they started mentioning here
in Palo Alto Online, with lots of exaggerated claims and fears, and voila, now the
City is spending time on this without knowing if it is a real problem?

Are there really no more important things to do in our city ... I mentioned one above.
If I am wrong please let me know, so I can get on the same page with everyone,
tell me what I am missing.

Is there a place there the pumps might collect this water and dump it so it can
be used, or trucked to where it can be used. I recall someone said they were
making money off trucking water for landscaping around ... maybe they need to
step forward and offer to coordinate with the pumpers?

Also, what is in this water. At one time Palo Alto had a problem with some
parking garages that had water with solvent in it leaking into it, and maybe
offgassing ... it was a long time ago that I read this. There were solvent
spills and I think from underground gasoline tanks as well thoughtout history.
This is all quite close to the surface ... so who says this water flushing action
is not natural and even good?

Please, let's get some facts, and let's let the City concentrate on things that
are important ... AND URGENT, like flooding, the bridges, the creeks, etc. That
could be a real problem and right away.


11 people like this
Posted by mutti allen
a resident of Adobe-Meadow
on Dec 2, 2015 at 11:48 am

Our home was built in south PA in 1947 on a dirt road when there were no city services -- it was unincorporated county land. So, we have a well. We're one block east of Mitchell Park! Now a house a block south of us has been pumping and pumping. For the first time EVER our well began to go dry this summer. It would pump fine for 5-10 minutes, and then just dribble. It is only 33 feet deep -- so not the deep underground aquifer. Yes, some of the groundwater that is 8 feet down flows to the Bay, but it also percolates down to our well, and feeds the roots of the trees and shrubs in the whole neighborhood.

When we put in a new tree or shrub we can tell when it gets about 6 feet tall and the roots go down about that much, because all of a sudden it starts to grow like crazy. That shallow 'stream' is what keeps the trees and bushes of Palo Alto doing so well, even in drought times.

A house on East Meadow, between Middlefield and Ross, dug a big basement about 15 years ago. Now they are having all kinds of leakage problems. The "boat" they built to hold back the water is cracking. The adobe soil swells and shrinks every year, depending on amounts of rain. Even a concrete basement can't fight that.


16 people like this
Posted by AllenE
a resident of Old Palo Alto
on Dec 2, 2015 at 11:51 am

AllenE is a registered user.

I bought my house in 1972. When I was looking the realtor told me that you can't have a basement in Palo Alto because of the groundwater. The problem was that if you did have a basement it was either wet, or the house would pop out of the ground like a boat in a small pond. Now we have better weatherproofing and pumps so that people can have basements. Progress? The solution is simple as suggested above, just add basement square footage to the maximum allowable or even count it double. Don't count it as zero. That is stupid and encourages basements where they should not be.


17 people like this
Posted by enough!
a resident of Charleston Gardens
on Dec 2, 2015 at 12:21 pm

It's NOT much ado about "nothing." Have you seen the dead trees on the streets where the water is being drained? Of course it's not just the dewatering, but it's the drought combined with the dewatering that's causing more issues. The water doesn't just come from the property being drained, but from that of it's neighbors too causing dead ground cover, trees, bushes and changes to the foundations themselves. The water going into the storm drain is NOT salinated, and therefore could be reused for many purposes.

When we moved to Palo Alto in 1974, we were shocked that homes here didn't have basements. Coming from back east, that was quite an adjustment. But you know what? We adjusted and learned to live without. I think others need to learn the same lesson. Basements are simply not necessary in this drought prone state.


12 people like this
Posted by Curmudgeon
a resident of Downtown North
on Dec 2, 2015 at 12:45 pm

"The water doesn't just come from the property being drained, but from that of it's neighbors too..."

That is why the law should prohibit pumping water from beneath adjacent properties unless their owners give explicit permission. Theft is theft. It is up to the prospective pumpers to figure out how to implement the details and to demonstrate their effectiveness.


10 people like this
Posted by Rita
a resident of Crescent Park
on Dec 2, 2015 at 1:45 pm

This is a great discussion of a complex problem.

Don't be angry be involved.

The Policy and Services Committee members listened last night and appeared committed to making changes.Staff was asked to follow up on numerous questions and will provide some answers most likely at the 12/15 P&SC meeting. I invite all to attend, speak and be heard.

Also please go to savepaloaltosgroundwater.org and see how you can become involved.

Sign our petition, read the posted articles on the complexity of this topic and the value of our groundwater, which is indeed Palo Alto's emergency water supply.

Help Palo Alto become a leader in groundwater sustainability and set the standard moving forward.

If you think not having enough water to irrigate is bad, consider what would happen if there was limited drinking water for any reason.

I would hate to think that the estimated 126 millions gallons pumped directly into the storm drain during the construction of 14 residential basements helped deplete our emergency drinking water supply and we remained silent.




4 people like this
Posted by ChrisC
a resident of Community Center
on Dec 2, 2015 at 3:33 pm

"Why does the city not count basements in the square footage of the house?"

To answer this, you need to look at why the regulation exists -- it is to prevent people from building houses that are visually too large, and out of character for the neighborhood -- which could negatively affect their property values. It effectively sets a numerical limit on how big a house can look from the street.

Since basements are not visible from the street, this regulation doesn't affect them.

If you were to impose a square footage regulation that includes basements, you'd first have to establish what the new rationalization for the regulation is, and establish that it was legal.

===

Some wild and crazy ideas: if the problem being addressed is the water shortage, then why not try to find other (better) uses for the shallow aquifer? As far as I know, it is not currently legal for me to dig a 15' deep well in my backyard and use the water I find for irrigation. Instead, I am required to use city water for that, or water I can truck from construction sites. Why not legalize that?

If everyone in Palo Alto watered their lawns from private wells instead of the city water, think of all the drinkable water that would be saved! Also, construction sites would not have to dewater as often -- as the water table would already be pre-lowered by folks watering their lawns. In wet years the irrigation water would be plentiful, and in dry years folks would naturally lose access to irrigation water as the water table lowers. So this is self-regulating.

Potential issues with this: you'd probably have to have some way of testing the water for contamination (salt, or other pollution). You'd have to have some way of discouraging folks from using this water for drinking. Anyone accidentally plumbing their well into the same system as the city water would be a problem for all. This does not address concerns about settling caused by groundwater pumping (someone would still have to establish if this is a real or perceived problem in this area).


8 people like this
Posted by Slow Down
a resident of Community Center
on Dec 2, 2015 at 3:45 pm

Slow Down is a registered user.

@enough & @Karen Ewart Which specific dead trees are you talking about next to which specific pumping sites. We live pretty close to a couple, and there are no dead trees. I ride past several pumping site in Old Palo Alto, and no dead trees near the dewatering.


2 people like this
Posted by musical
a resident of Palo Verde
on Dec 2, 2015 at 4:07 pm

Is there any Palo Alto contour map of the ground water depth we are talking about?
Just curious where basements would be less controversial, and how deep.


2 people like this
Posted by ChrisC
a resident of Community Center
on Dec 2, 2015 at 4:28 pm

@musical -- not that I know of. The ground water depth varies dramatically year over year, and location by location (as I understand it the depth can vary even between adjacent lots). On my street it seems it is usually 10-14' deep.

Typically an engineering test well is drilled before excavation is started, and that is used to establish whether they expect dewatering to be required. But even that can be a gamble -- in the case of my basement project the test wells showed that no dewatering would be required, so we designed a home with a basement. After all plans were approved and excavation started, they hit water at a depth of 12' -- requiring construction to stop and a dewatering system to be installed to lower the water level to 14' before the project could continue.


2 people like this
Posted by maps
a resident of Midtown
on Dec 2, 2015 at 4:38 pm

@musical, see the last map, "Palo Alto Shallow Groundwater Map" on this page: Web Link


5 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Dec 2, 2015 at 5:18 pm

On the link from maps above the following pop-up displayed ...
--
Map Details
Title
Free Water Filling Stations
Description
Update 11/2/15: With the exception of 713 Southampton and 2832 Grove, all filling stations are now closed for the wet season. As new projects start up in next spring starting in April, check back here to see if a station will be available in your neighborhood! Thank you to the contractors who made these stations possible and all who made use of the water.

Visit any of these locations to fill up water for free! Just look for a wooden cabinet located behind the city sidewalk and find the attached garden hose valve. Open the hose valve to use the water. Remember, the water is not suitable for drinking.

Questions? Contact:
Mike Nafziger
Senior Engineer - Public Works Engineering Services
mike.nafziger@cityofpaloalto.org
650 617 3103
DONE

--

It appears as if this water is not going to waste.

There are lots of claims here, like tons of fresh drinking water going to
waste, trees dying, houses all but collapsing, or floating away ... come
on! Lots of people seem jealous their neighbors have basements.

In the Crescent Park area and others I've known people that had houses
with basements going way back. And basements are not counted probably
because they are not living space except for families with too many kids
where someone would rather live in a basement than share with their brother
or sister. They can also get flooded, like if the City doesn't get moving
on doing something about the bridges and the creeks.

Some of this conversation is really going off the rails.


2 people like this
Posted by musical
a resident of Palo Verde
on Dec 2, 2015 at 5:31 pm

Doh! I was there but didn't look down far enough. Thanks, @maps, exactly what I wanted. (Note to others, it's a 20-megabyte pdf.) Helps explain why Oregon underpass needs more pumping than Embarcadero or University. And why San Antonio is an overpass. @ChrisC, illuminating story about your basement project.

Was the water table a reason the Mings site won't be a hotel with underground parking?


6 people like this
Posted by Rita
a resident of Crescent Park
on Dec 2, 2015 at 6:06 pm

At the Policy and Services Meeting last night a professional "water distributor" indicated that in his experience of going to the dewatering sites and hooking up to obtain water; only 2 of the 14 sites had connections that were to Code and allowed filing in a reasonable amount of time.

12 of the sites did not meet Code; this made it difficult for him and for the neighbors to obtain the pumped ground water for any beneficial use.

His comments will be transcribed and are part of the City record from the 12/1 P&SC meeting for those who wish to check.

It was estimated that last year only 1-2 % of the 126 million gallons of groundwater pumped during the construction of the 14 residential basements was used for a beneficial purpose.

The rest went down the storm drain, day and night, 7 days a week for 3-6 months.

This 126 million gallons of pumped groundwater = 40 gallons of water a day for every 29,543 household in Palo Alto for 10 days.

That means members of each of these 29,543households would need to haul 320 #'s of water a day as a gallon of water is 8 #'s.

Then repeat for 100 days carrying or transporting by whatever means possible a total of 32,000 pounds of water to "capture/recycle" this pumped groundwater.

If hauling buckets from the shower is problematic this is impossible.

It was agreed that it is not the neighbors responsibility to beneficially use this pumped groundwater. Rather the Contractors will be asked to suggest and implement methods to use this groundwater.

savepaloaltosgroundwater.org has a plethora of information from USGS, respected organizations, Engineering firms and neighboring Cities. It is available to all who want to learn more about the Water Cycle, aquifers and water management.






6 people like this
Posted by Rita
a resident of Crescent Park
on Dec 2, 2015 at 6:14 pm

My last post contained 2 errors which I wish to correct..

The 126 million gallons of ground water pumped during the construction of 14 residential basements in 2015 is equal to 40 gallons of pumped groundwater a day for each Palo Alto household for 100 days, not 10 days.

Sorry for the error.


2 people like this
Posted by WaterWaste
a resident of Old Palo Alto
on Dec 2, 2015 at 9:39 pm

I'm really mad about the water flushed out of the water treatment plant! This is almost 20million gallons per day that could water our trees!

The treatment plant sends more water to the bay in 2weeks than all the basements in a year!!

Why isn't the city doing anything to save this valuable resource???


4 people like this
Posted by Rita
a resident of Crescent Park
on Dec 2, 2015 at 9:50 pm

You could obtain an answer to your question by attending a City Council meeting and speaking during the Public Comments period.

You would have 3 minutes to state your concerns or ask your question. The City Manager or Assistant City Manager is present at CC meetings and most likely would take your contact information and respond timely.

You could also call or email the City Manager with your question and obtain a response. I have found Staff to be very responsive.


2 people like this
Posted by Slow Down
a resident of Community Center
on Dec 2, 2015 at 10:02 pm

Slow Down is a registered user.

@WaterWaste - because water from the treatment plant and water pumped from basements actually isn't that valuable. If it was valuable, people would already be collecting and selling it. Treated water in particular has residual chemicals that limit the ability to use for irrigation. We need 3-4 more years of drought to drive the value of water up high enough to make it worthwhile.


5 people like this
Posted by reality of Palo Alto
a resident of Another Palo Alto neighborhood
on Dec 3, 2015 at 5:58 am

The staff and Council over these past 15 years has
seen its role to support and subsidize through bonuses, loopholes, exceptions, overzoning, under-regulation the development community without regard to any short-term and long-term impacts on the City, its quality of life,character,parking,
traffic,aesthetics,environment, etc. That is the reality of Palo Alto, a beautiful and unique
City which had the most to lose in this situation
of failed government and that is what happened.
As for dewatering,the oversized Downtown office projects require dewatering as a contingency for basement construction in the event water is present which is not known until drilling takes place on the cleared site so restricting dewatering as a policy decision even during drought was off the table including residential basements despite the obvious and known subsidence risks to adjacent properties and landscaping in addition to broader ground water effects in times of severe drought. The City went so far as to try to engineer around FEMA restrictions in the flood zone if possible in its pro-development agenda.


7 people like this
Posted by Midtown
a resident of Midtown
on Dec 3, 2015 at 11:10 am

Just include the basement in the square footage calculation. Basements will vanish as fast as three car garages.


5 people like this
Posted by Crescent Park Dad
a resident of Crescent Park
on Dec 3, 2015 at 1:20 pm

I have owned houses with and without basements in our neighborhood. Due to the flood zone restrictions - no new basements or basement expansions are allowed by FEMA and CPA. The future of basements is essentially moot for our neighborhood as I don't see the flood zone issues getting resolved in my lifetime. That being said...

Banning basements or changing the sqft calculations to include basements is akin to using a cruise missile to kill a fly. Address the issue/concern - come up with a solution for the perceived problem (would like to see scientific data instead of anecdotal claims by various parties). Further, including basements as part of living space calculations is not a standard practice in an overwhelming portion of the US. Guaranteed private property lawsuit if attempted (can anyone say, "Buena Vista?"), so let's not go there.

Here's a simple solution (albeit expensive for the commercial or residential developers or property owners). Require all pumped water to be recycled back into the aquifer. Which probably means pumping the water into a trailered tank and hauling that tank to some water distribution site up in the hills....let it run down the streams or re-percolate into the ground.

@ "reality": Please provide proof of claim that CPA has tried to circumvent FEMA regulations on commercial and/or residential basement requirements/restrictions. I have no doubt that developers or homeowners have tried to circumvent the rules - but I don't see the city trying that at all. As someone who had to repair a basement after the 1998 flood, I am keenly acquainted with all of the flood zone regulations. The commercial exceptions for basements (generally speaking, allowing garages and storage space) have long been on the books --- way before the 1998 flood and/or the expansion of the FEMA declared flood zones in the mid-1990's. Further, the FEMA prohibition against new or expanded residential basements in flood zones has not been challenged by PA - ever. And CPA holds a tough line on remodeled/expanded property sqft calculations when it comes to determining whether an existing basement must be filled in. Same goes for all houses (basement or not) that have first floors built below the BFE.

The other claim I'm having issue with is de-watering and tree health. The city arborist has already stated that the greater majority of PA trees have roots that rarely go past 5' depths. The water table is farther down than that. This includes the protected class of trees (Oaks and Redwoods). There are plenty of trees in our neighborhood (flood zone declaration prohibits basement construction...no new basements or de-watering for almost 20 years) that are stressed from the drought. I find it difficult to agree with the claims that de-watering is the culprit for tree stress when we have plenty of trees in our area that have issues without new basements going in. Further, there's no way (or at least has been presented to-date) to delineate the cause/effect of de-watering vs. drought effects.


4 people like this
Posted by the_punnisher
a resident of Mountain View
on Dec 3, 2015 at 4:28 pm

the_punnisher is a registered user.

Most of your water issues involve the shallow water table. You just have to have a shallow water barrier if you want a basement! Just adding a pump DOES steal water from other neighbors and adds new problems to what were building compromises.

A case in point: A developer bribed a zoning administrator to built a plat of houses on an open site that had lots of visibility. He built over 15 new houses. The people who bought those houses soon complained about basement walls collapsing. This on NEW houses?
The reason ( and why that land originally was zoned unbuilaible )was that the soil on that hill was BENTONITE ( AKA KITTY LITTER! ). That became a major scandal and the builder had to buy back those houses.

What needs to happen is for a Geologist and Hydrologist be involved when wanting to build a basement. PERIOD. Their reports make sure there is no impact in the community when digging a basement. If these reports are negative, no basement can be built. Yes the Palo Alto Zoning people need to say yes or no when a contractor is pulling a building permit.
That is how construction is done everywhere else in the US. BTDTGTTS

That is why you cannot build a basement in the SFBA. Common sense dictated NO BASEMENTS. $50k worth of vapor barriers ( that WILL eventually leak ) ?

GET REAL, PEOPLE!


2 people like this
Posted by Slow Down
a resident of Community Center
on Dec 3, 2015 at 5:07 pm

Slow Down is a registered user.

If you want to get real, understand that having a hydrologist and geologist involved every time a basement gets built is NOT construction is done in most of the US.


4 people like this
Posted by Rita
a resident of Crescent Park
on Dec 3, 2015 at 8:01 pm


Or require all basements be constructed without dewatering.

There are other construction techniques available; but they are considerably more expensive.

Perhaps the extra expense would give some home owners pause.

The effect of large and deep basements on aquifer flow in periods of excessive rainfall,etc then must be determined. Do these basements put neighbors at risk of increased flooding as the rainwater is unable to soak into the ground (occupied by the basement) and so instead must drain around the basement?

Lots of questions. Time for some real answers based on the cumulative impacts of large basements, many times concentrated in a small geographical area.

Basement square footage not being included in the FAR was described as a decision made in the 1980's. I believe Staff was directed to investigate this issue and report back to the P&S Committee, perhaps as early as their next meeting.


2 people like this
Posted by Red
a resident of Community Center
on Dec 3, 2015 at 8:39 pm

Wait a minute, hasn't the assistant public works director been casually dismissing resident concerns and complaints about the absurd amount of water being pumped for basements as inconsequential, irrelevant and of no concern? Now the city basically admits that they really have no idea how ground water works? Any consequences for knowingly throwing piles of BS at concerned residents?

Public works fail, and doubts that anything meaningful will result.


1 person likes this
Posted by WaterWaste
a resident of Old Palo Alto
on Dec 3, 2015 at 9:13 pm

I don't get the subsidence complaints. How does a neighbors land dry out if they have irrigation running? Even during drought many people still irrigate. Anyone next to basement projects can use the water to irrigate.

How do properties dry out?

The bigger problem is the drought and trees need water. The waste water plant is just dumping millions of gallons per day. A few trees near 13 basements is nothing compared to all the trees throughout town that are suffering.


5 people like this
Posted by reality of Palo Alto
a resident of Another Palo Alto neighborhood
on Dec 4, 2015 at 5:22 am

@Crescent Park Dad
The City conditionally approved a basement excavation plan which was then rejected by FEMA. It's not a "claim". I get it - what you provide are facts, and what those who contradict you provide based on their own knowledge and experience and observations are "claims".

As far as your second "claim", you say that "the city arborist has already stated that the greater majority of PA trees have roots that rarely go past 5 foot depths". That's like saying the greater majority of drivers don't speed and
rarely bust through crosswalks so there is no
need to hire more police for traffic control-
don't worry about it.







Like this comment
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Dec 15, 2016 at 7:24 pm

Thank you to all who wrote letters, showed up and spoke up for reducing groundwater waste for construction purposes at the Policy and Services Committee on Dec.14th. Thanks to your support and advocacy, together we changed the game!
It’s clear that the Policy and Services Committee and City Staff now understand that wasting water is the issue, and that it’s not acceptable politically. Or morally. Or for any city that thinks of itself as sustainable. They also know that alternative construction methods are available and practical.
See our blog Web Link for more.

One of the highlights of the many presentations to the Policy and Services Committee was the 2-minute animated video made by Cate A, an 8-year old in 3rd grade. The message is powerful – please share with your friends.
Web Link


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