News

Palo Alto residents pumped up about groundwater 'waste'

New grassroots group calls for moratorium on basement projects that require dewatering

With California's drought stretching through its fourth year, the sight of water gushing out of Palo Alto's construction sites has drained the patience of Keith Bennett and his neighbors in the Crescent Park, Old Palo Alto and Community Center neighborhoods.

The water they're concerned about comes from the ground rather than the sky, and its flow is caused not by Mother Nature but by local property owners building basements in their homes. When the construction occurs in areas with shallow groundwater -- particularly in neighborhoods closer to the Bay or creek beds -- builders set up wells to pump out the water, sending it into the city's storm drains and, ultimately, the Bay.

Basement construction makes all the sense in the world for property owners because the city's zoning regulations don't include basements in calculating the density that is allowed for new homes. And with the city's property values soaring, building down is both a legal and logical option for increasing property values.

While a 2008 report from the Public Works Department stated that the city typically approves between five and 10 dewatering permits per year, in 2015 the number of such projects was 13, according to a new report.

In recent months, the gushing groundwater caught the attention of Bennett and many others, who argue that dewatering degrades the environment, causes land subsidence and wastes thousands of gallons of water at a time when residents are being encouraged to conserve.

Now, Bennett's new grassroots group, Save Palo Alto's Groundwater, is calling for the city to adopt an immediate moratorium on the practice. Over the past several months, he has been attending City Council meetings to bring attention to the topic.

Earlier this month, the group submitted a petition with about 200 signatures, asking the city to ban groundwater pumping until new laws are in place for preserving groundwater as an emergency water-supply resource during a drought; mitigating the impacts of pumping on the aquifer; and addressing the impacts of the activity.

"Water is too precious a resource to be wasted, and current city policies regarding dewatering do not take into account the possible need of this water to mitigate future droughts nor its beneficial effects of supporting our canopy, our properties and our infrastructure," the petition states.

The subject of groundwater pumping, like the water itself, has resurfaced periodically in Palo Alto during the past two decades. The city commissioned analyses on the topic in 2003 and 2004 and last held a public hearing on the issue in 2008, when the Planning and Transportation Commission discussed it. Then, as now, the hearing was prompted by complaints from citizens about the impacts of the practice on water supply, land subsistence and trees.

This year, with the drought firmly in place and basement construction on the rise, the chorus of complaints has been getting louder and louder.

Elizabeth Whitson, who lives on Webster Street, said the increase in the number of houses being replaced has been noticeable in the Old Palo Alto neighborhood, as has the groundwater pumping.

"At one particular house just down the street, they were pumping for about three months earlier this year," Whitson told the Weekly. "You just saw all this water getting tubed from this house to make up a basement and just going to the sewer and the Bay in the middle of the drought. All of us were wondering how the city allows this."

Bennett noticed something was awry in 2011, when a homeowner a few doors away was installing a basement and began a dewatering operation. After about three weeks, Bennett noticed that he could no longer open the front door to his Webster Street home, he told the Weekly. This persisted for a few months. Then the dewatering stopped. The door began to open again.

Unsure about the correlation, Bennett didn't pursue the subject until April of this year, when another nearby homeowner began a dewatering operation. This time, the patio door to his house wouldn't open, he said. By the middle of the summer, another door leading to the patio wouldn't close flush anymore and the brick on his front porch had settled about an inch, he said.

Bennett began talking to his neighbors. One reported that his house experienced cracks in 2008, when another groundwater pumping operation was taking place. Bennett began digging through the city's dewatering studies, reviewing the city's rules and conceptualizing exactly how much water is being pumped from the shallow aquifer. Relying on an estimate from the city's consulting engineers (which determined that each basement construction results in between 8 million and 10 million gallons of water getting pumped), he determined that the recent basement boom caused more than 100 million gallons of groundwater to be pumped from the shallow aquifer and sent to the storm drains and the Bay.

Now, Bennett hopes that city officials will start treating this water like the precious resource he and his neighbors believe it is.

He also wants to make sure that, until the city studies the issue further, no more permits will be issued for dewatering operations. Under existing laws, dewatering isn't permitted between October and April anyway but, as Bennett noted, contractors can take out permits any time for pumping in the spring. On Nov. 9, he presented the petition to the council. He also created the website, savepaloaltosgroundwater.org, to consolidate all the recent studies and to keep the community updated on the efforts to learn more about the impacts of basement construction.

"They're like great big dams in the soil, and they affect water flows," Bennett said. "And the city wants to say, 'No they don't.'"

With dozens of other residents making similar concerns throughout the spring, summer and fall, Public Works officials created an FAQ (frequently asked questions) page to address the topic, including explaining how dewatering works and the city's current permitting process for allowing the practice. And on Dec. 1, the City Council's Policy and Services Committee will dive deeper into the subject of groundwater and consider possible changes to the city's process for granting permits for basement construction that requires dewatering.

So far, however, Public Works staff have rejected residents' common assertion that the volume of groundwater being pumped from the city's shallow aquifer is sufficient to cause land subsistence or other lasting damage. The aquifer that contains the pumped-out groundwater sits above the much deeper and larger aquifer that acts as Palo Alto's emergency-water supply, said Assistant Public Works Director Phil Bobel, who asserted in numerous response letters to concerned residents that it would require more wells and longer periods of pumping to cause subsistence.

When resident Valoran Hanko warned that the groundwater pumping would change the elevation in the neighborhood, Bobel replied that the pumped-out water would simply be replaced with new groundwater.

In another letter, Bobel challenged the notion that the pumped-out water is being "wasted." Rather, he wrote to resident Georgia Relsman, the water ends up going to the creeks and the Bay -- the same place where it would end up if it remained in the aquifer.

"The pumping and the discharge of this shallow groundwater to the storm drains sends the ground water to the same place, our creeks and Bay, where it supports ecosystems and their wildlife."

Even so, Bobel wrote, the city is working with builders to "try to get as much of water used as practical."

"The main limitations are the very high cost of trucking the water and the lack of a piping system from the pumping sites," Bobel wrote.

At the same time, the city has been looking for new ways to use the water. In the summer of 2014, Public Works unveiled a "truck fill" station at a dewatering site. The water, while not potable, could then be used for efforts like irrigation and dust control, according to the city officials.

The city also now requires all contractors to have the pumping systems fitted with valves and connections to enable city crews to fill water trucks and other containers. The city now has six such pumping stations at 1405 Harker Ave., 1820 Bret Harte St., 804 Fielding Drive, 713 Southampton Drive, 3932 Grove Ave. and 2230 Louis Road.

While Public Works is not recommending any new restrictions on groundwater pumping, staff is recommending that the city's Basement Pumping Guidelines be broadened to "specifically require a determination of impacts of groundwatering pumping on adjacent buildings, infrastructure and trees and landscaping."

Under this proposal, applicants would determine the "approximate location of the temporary cone of depression caused by pumping," according to the Public Works report. Avoidance measures would be required if impacts are anticipated.

The department's list of additional proposed program improvements includes more public outreach to encourage fill-station use; increasing outreach about water flow to the city's storm drains, creeks and bay; and new specifications for fill stations to enable enough water pressure to accommodate multiple users. Staff also recommends exploring refinements for "use plans" submitted by contractors, with the aim of maximizing on-site water use.

The report also notes, however, that contractors have advised staff that imposing new requirements to use groundwater could "increase pumping duration and project cost." One contractor also said that users "could be injured at fill stations, leading to potential liability."

The measures, which the council committee will discuss, fall far short of the type of moratorium that residents like Bennett are recommending. At the Oct. 5 meeting of the City Council, Bennett argued for a new study of dewatering, noting that the city's last analysis was conducted more than a decade ago, when conditions were different.

"Only if such a study shows that the effects are negligible, and city policies are revised to ensure mitigation of the effects, should dewatering be permitted to continue," Bennett told the council.

Comments

21 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 27, 2015 at 9:03 am

There is no evidence presented for any of Bennett's fears. The paranoia around groundwater has reached a fevered pitch and is turning into a time-waster for the city and it's residents.


42 people like this
Posted by Jean
a resident of Duveneck/St. Francis
on Nov 27, 2015 at 9:34 am

Why in the heck are people in the community able to build basements? There is no need for them and ground water should not be wasted! Talk about greed!


47 people like this
Posted by Anneke
a resident of Professorville
on Nov 27, 2015 at 10:00 am

Our City wants to achieve Zero Waste, a noble goal for all of us to pursue.

That includes water as a precious resource.

I completely understand and respect Mr. Bennett's concerns.


59 people like this
Posted by Rick
a resident of Downtown North
on Nov 27, 2015 at 10:16 am

Building basements below the water table just does not make much sense. The huge volume of wasted water for an entirely selfish purpose is obvious. Why is the water not required to be reclaimed, rather than dumped in the street drain? I have to wonder how depressing the water table for months and months affects neighbors trees that suddenly find their existing root structure insufficient to cope with an artificial drought. Eventually, with additional water recharge, provided we get 'normal' rain fall in future years, the water table will rise, and in the contest of water vs basement, water always eventually wins.


105 people like this
Posted by DTN
a resident of Downtown North
on Nov 27, 2015 at 10:38 am

Timewasters- you must be building a basement or about to do so? We are all told we shouldn't water our plants at all or hardly, we should let all our work die and people are allowed to pump all that water down the drain? It sickens me to see it. I've often windered how in the world it is allowed. Bravo to those trying to do something about stopping it. To water a small downtown yard probably uses one minute's worth. They should have to pump that water into somewhere it will be used. Expensive? Apparently they can afford it. And if the neighbor's house settles and doors no longer open properly? They can pay for repairs too.


24 people like this
Posted by Slow Down
a resident of Community Center
on Nov 27, 2015 at 10:46 am

Slow Down is a registered user.

What about all the dirt wasted when a basement is excavated! tragic...


52 people like this
Posted by Green Gables
a resident of Duveneck/St. Francis
on Nov 27, 2015 at 10:57 am

Oh, Jean, sometimes the "basements" are apartments - only after the City signs off on the new construction. Sometimes it is used for the many other family members immigrating to the United State, i.e., two family home. I live in the flood zone but that did not deter a young family couple doors away from me to try for a basement in their new house, and the CITY was going to let that happen until many of the neighbors went to the planning department and complained. By the way the architect who designed the house has been in Palo Alto many, many years, and he would have known about flood zones and basements.


66 people like this
Posted by Miriam Palm
a resident of Old Palo Alto
on Nov 27, 2015 at 11:17 am

"the city's zoning regulations don't include basements in calculating the density that is allowed for new homes."

Why don't we change this regulation, if it is purely local?


10 people like this
Posted by Commonsense
a resident of Community Center
on Nov 27, 2015 at 11:24 am

The simple fact is that this water is not being wasted. It is simply taking a different route to the same destination. This group does not know what they are talking about and the claims about elevation drops and door not opening because of dewatering is just plain nonsense


30 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 27, 2015 at 11:27 am

Jean said
> Why in the heck are people in the community able to build basements?

The article said
> Basement construction makes all the sense in the world for property owners because the city's zoning regulations don't include basements in calculating the density that is allowed for new homes. And with the city's property values soaring, building down is both a legal and logical option for increasing property values.


One thing that has not been mentioned is the vibration and sound from pumps running all day and all night that can carry for blocks and be very annoying to many people.


11 people like this
Posted by Slow Down
a resident of Community Center
on Nov 27, 2015 at 11:57 am

Slow Down is a registered user.

@Commonsense - You are correct, water sitting 3 feet below my living room isn't usable in the first place, so moving from under my house to the bay isn't wasting it anymore than raking leaves off my lawn is wasting them. Furthermore, when I bought my property, I didn't just buy the air above the land, I bought the land, so even if you really think moving some dirt or water is 'waste', it is mine to waste.

And the drought is over, so time to start worrying about flooding, and stop worrying about ground water,


45 people like this
Posted by palo alto mom
a resident of Crescent Park
on Nov 27, 2015 at 12:33 pm

BTW - Did you know that multi-level basements are allowed - limited only by the $$ you are willing to spend!


91 people like this
Posted by Short Memories
a resident of Another Palo Alto neighborhood
on Nov 27, 2015 at 1:04 pm

During the floods of 1998, many older houses with newly constructed or enlarged basements had their new basements flooded. Worse, the built-in water pumps could not pump the water out as fast as it was coming in! During an El Niño year, the aquifers overfill.

When we lived in the east hills, which have underground springs, the water spouted out of the ground and destroyed basements and landscaping alike.

For decades, basements were illegal to build in new buildings because of earthquake worries ( in the 1906 earthquake, many houses collapsed into their basements, killing residents who had hidden in them for " protection").

Many people now want basements because it it square footage not included in the size of the house--therefore not taxable. However, this may soon change: two friends of ours who build custom homes in the area feel that now that so many people are using finished basements as living space-- once illegal--that it is only a matter of time before the tax assessor change the laws in order to tax finished basements. According to these two local builders, the county tax assessor's office is already fully aware of this problem, and in the past ( especially in the last two bubbles) has arbitrarily changes property tax laws.

And it is true that the ground water is undrinkable, but it is suitable for watering plants. Removal of it does cause ground level sinking. San Jose had this problem in spades: the entire city was sinking, so years ago they forbade ground water pumping for any reason, and the sinking stopped. The aquifers eventually refilled naturally over time.


6 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 27, 2015 at 1:15 pm

Most of the complaints about basements originate in envy:

'I don't like someone else having a basement, because I don't have one. If I don't need it they don't need it either...'

Then it proceeds down a path of bad data, speculation, misunderstanding of hydrology, local groundwater, etc as conspiracy-theory ideas replace sound thinking.

All of this ignores property rights of homeowners. Why do you care whether someone has a basement?

[Portion removed.]


38 people like this
Posted by Resident
a resident of Another Palo Alto neighborhood
on Nov 27, 2015 at 1:32 pm

I don't like the idea of all this removal of groundwater. We looked into having a basement but since we are in the flood zone, it really doesn't make sense.

The trouble with removing groundwater is the underground aquifers and the water table. Usually, messing around with these cause problems elsewhere with things like trees stretching their roots looking for water and ground subsidence. We haven't had major sink holes in Palo Alto yet, but I suspect they are in the offing.


74 people like this
Posted by Stephen
a resident of Duveneck/St. Francis
on Nov 27, 2015 at 1:33 pm

"Slowdown" makes the common mistake of assuming that the water being pumped comes from directly under the property where the pumping takes place. That is not the case - what happens is that the water table (the location of the water "surface" underground) is drawn down around the well. This drawdown causes water to flow towards the well from away from the well, replacing the water withdrawn by the pump. In the case of the basement excavation this means getting the water table drawn down to below the bottom of the excavation over the whole surface of the excavation, and so the region of depressed water table extends some distance away from the excavation. This distance depends on the pumping rate and the permeability of the aquifer. As a start, this is something the City public works folks could require to be calculated as part of the permitting process.

However, it is easy to show that the volume of water extracted must come also from adjacent properties. Palo Alto's public works estimates that a typical basement excavation requires 50 gallons/minute or so of pumping. That translates into about 10,000 cubic ft of water in a day, so for a 90 day project (what the city estimates to be typical) that means 900,000 cubic ft of water. If this is divided by a surface area of 10,000 square ft (a typical lot?), this means pumping to a depth of 90 ft, something far greater than the depth of the excavation. If the excavation were 10 ft deep, then 8/9ths of the water pumped would have come from underneath adjacent properties.

Bottom line: Requiring the owner to consider the effects of their proposed pumping on others' properties doesn't seem to be too much of an imposition....


2 people like this
Posted by Curmudgeon
a resident of Downtown North
on Nov 27, 2015 at 1:55 pm

"The simple fact is that this water is not being wasted. It is simply taking a different route to the same destination."

Same with the Hetch Hetchy water before they built those dams and pipes that route it to your spigots.

Show your conviction. Make a real statement. Open every spigot wide and leave it.


64 people like this
Posted by palosltan
a resident of Leland Manor/Garland Drive
on Nov 27, 2015 at 2:46 pm

The city needs to incorporate basement space into taxable property throughout the city of Palo Alto. And for the commentator who believes the water as the dirt under his house is his to waste, you are wrong buddy. We all live here in this city of Palo Alto and the water you waste is not only your water. At some point selfish self-interest has to cease. You do not live in a vacuum


7 people like this
Posted by Guess what
a resident of College Terrace
on Nov 27, 2015 at 2:48 pm

So what are they pumping out of the construction site on CA AVE? And what are the big red containers for? Who knows?


56 people like this
Posted by stealing from trees
a resident of Evergreen Park
on Nov 27, 2015 at 2:48 pm

Isn't this ground water being taken from the surrounding trees that we aren't allowed to water because of the drought. I remember reading somewhere recently that neighbors of these basement builders are complaining now of their trees dying because the water from the natural aquifer. I used to run by a house every morning in Old Palo Alto that was building a basment last spring and for 3 weeks straight it was pumping out ground water...like gushing.


75 people like this
Posted by worse yet...
a resident of Old Palo Alto
on Nov 27, 2015 at 2:56 pm

When Larry Page built his "compound" in Old Palo Alto, there was a huge pipe that ran from the back of his property and down Bryant to Cal Ave for TWO YEARS! This was at the onset of the drought. Aquifers gave not refilled due to the lack of rainfall since then.

I wonder how the heritage oaks on his property are doing now? Hopefully, they each have an abnormally long taproot to reach that low, low, low aquifer.


66 people like this
Posted by Douglas Moran
a resident of Barron Park
on Nov 27, 2015 at 3:13 pm

Douglas Moran is a registered user.

> Article: Bobel: "The pumping and the discharge of this shallow groundwater to the storm drains sends the ground water to the same place, our creeks and Bay, where it supports ecosystems and their wildlife." and echoed by several commenters.

Movement of water through aquifers is measured in feet per year; in storm drains in mile per hour.

And as several previous commenters have pointed out, there is a lot of vegetation between the de-watering site and the creeks that depend on the shallow aquifer for survival. When I started learning about native plants, I was surprised at the depth of their roots. For example, Purple Needle Grass (California's state grass, hold the quips) routinely has roots going down 20 feet. Anyone who has had acorns sprouting in their yard encounters taproots that are growing rapidly downward.

That the defenders of de-watering persist in disregarding this issue strongly implies that their statements are disingenuous and that their declamations are indefensible.


9 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 27, 2015 at 3:33 pm

If you are going to argue for a change in regulation, the burden of proof requires slightly more than just blockading falsehoods.

The preceding statements are outright wrong:

-basement pumping causes subsidence. No

- the aquifer is low. No

- trees are suffering because of groundwater. No

- trees get water from aquifer. No

- Hetch Hetchy drinking water, purified, pressurized and delivered reliably on demand from your tap is equivalent to groundwater. No

- building a basement in a flood zone is a community problem rather than an individual concern. No


Until there is credible proof put forth for these specious arguments, you are just wasting city time.

In fact, the city did studies on this subject at great cost to taxpayers, and found all these claims false. Stop wasting city money!!


3 people like this
Posted by Curmudgeon
a resident of Downtown North
on Nov 27, 2015 at 3:55 pm

"The preceding statements are outright wrong:"

Yup. (Second word is the key.)


25 people like this
Posted by musical
a resident of Palo Verde
on Nov 27, 2015 at 5:24 pm

Buried in the article was a mention of a Dec 1 meeting.

Policy and Services Committee
Tuesday, December 1, 2015
Special Meeting Council Chambers 6:00 PM

Agenda Item 1. Consider Tentative Staff Recommendations on Further Requirements for Basement Construction Dewatering Program for 2016

9-megabyte background document -- Web Link

Does anyone plan to show up?


44 people like this
Posted by Douglas Moran
a resident of Barron Park
on Nov 27, 2015 at 6:17 pm

Douglas Moran is a registered user.

According to unintentionally self-identified "Time Wasters": "The preceding statements are outright wrong:...- trees get water from aquifer. No"

Simple web search finds many contradictory statements from legitimate experts. For example, the US Forest Service page on Coast Live Oak (the predominate oak in this area): "Several deep main roots may tap groundwater if present within approximately 36 feet (11 m) of the soil surface" (Web Link). This web page was the FIRST result from Google(tm)'ing "coast live oak root depth"

When someone makes a claim contrary to such easily found facts, you need to question their whole agenda.


14 people like this
Posted by Homebuilding neighbor
a resident of Community Center
on Nov 27, 2015 at 7:00 pm

The article claims that there are currently dewatering operations at "1405 Harker Ave., 1820 Bret Harte St., 804 Fielding Drive, 713 Southampton Drive, 3932 Grove Ave. and 2230 Louis Road." This is outdated -- several of those operations ended months ago (I say as the owner of one of them). If you look at the city's dewatering policy (Web Link), you will see that dewatering is only allowed during the months of April through October, and so all dewatering operations should currently be shut down (unless an exemption to the policy was granted by the city).

One poster mentioned that the dewatering pumps make a lot of noise. In my (singular) experience the pumps used are 20' under ground, and standing immediately above the well it is difficult to hear if they are on -- I had to put my hand on a pipe to feel if water was flowing. The water flowing into the Baker tank and sewer drain does make some gurgling noise.

The city estimated that dewatering operations pump 50 gallons per minute. I expect this varies widely with the requirements of the project. In the case of my project once the peak capacity of the system was slightly below this, and once the water was drawn down (which took a couple of weeks) the pumping continued between 10-20 gallons per minute (I measured it). Sadly the water must be pumped until the concrete walls cure, waterproofing membrane is installed, and the dirt is backfilled into the hole.

The big red tank on site is called a "Baker tank". The city requires that only water is pumped into the sewer, and no dirt or sediment (this is to stop the sewers from getting plugged up). The tank allows any dirt or sand in the water to settle out before the water drains into the sewer system. It has the bonus effect of providing a reservoir in case anyone wants to quickly fill up a water truck with pumped water.

Why aren't there more trucks filling up at these tanks? Two reasons: (a) trucking water is incredibly expensive compared to just using pipes; and (b) the city has way more non-potable water available via the purple pipe system next to the bay (the output of the sewage treatment plant) at higher pressures -- so anyone who wants to fill a truck will just use that supply instead, and save time.

The building boom which is occurring right now has made it more difficult to hire basement concrete contractors. Also, the ones you can hire are having trouble finding qualified help -- this short-staffing means that they are taking longer to finish building basements than they do during slower years. This means that the total time from start of dewatering to completion is longer than anyone wants.


10 people like this
Posted by Curmudgeon
a resident of Downtown North
on Nov 27, 2015 at 7:09 pm

"Furthermore, when I bought my property, I didn't just buy the air above the land, I bought the land, so even if you really think moving some dirt or water is 'waste', it is mine to waste."

Likewise for your neighbors. So pump out only your groundwater and leave your neighbors' groundwater alone. Fair 'nuff?


7 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 27, 2015 at 7:46 pm

The single most useful data to make your case would be evidence that the groundwater is depleted. No one here can show that.

The rest is hot air.

Produce actual measurements. If you can...


31 people like this
Posted by Douglas Moran
a resident of Barron Park
on Nov 27, 2015 at 8:24 pm

Douglas Moran is a registered user.

For visualization,
the article states that the construction of one basement represents 8-10 million gallons of water pumped, which is 24.5-30.7 acre-feet, or 294-368.4 acre-inches (enough water to cover an acre to a depth of one inch).

Annual rainfall for Palo Alto is listed variously as 12-18 inches. For a 1-acre lot, this represents 16-31 years of rainfall for that lot (I leave it to you to adjust for other lot sizes)

Palo Alto is listed at 23.9 square miles, or 15,296 acres, but this appears to include Foothill Park, Arastradero Preserve and the Baylands. I estimate the developed portion of Palo Alto at 10-12 sq miles (12 sq miles = 7680 acres). Based on these figures, the de-watering of a single basement represents 0.04-0.05 inch of rain over all of developed Palo Alto. I leave it to the readers to do further cuts on the numbers.


27 people like this
Posted by daniel
a resident of Charleston Gardens
on Nov 27, 2015 at 8:34 pm

" ... would be evidence that the groundwater is depleted. No one here can show that."

Douglas Moran above produced a calculation that should be clear even for not the brightest. There are always trolls who will keep derailing the discussion by making snide comments because they do not have arguments.

Pump the water here and dump it in the bay. How does it not deplete the groundwater?


28 people like this
Posted by SavePaloAlto'sGroundwater
a resident of Leland Manor/Garland Drive
on Nov 27, 2015 at 10:10 pm

For those truly interested in understanding the issues check out the groundwater studies and reports for Palo Alto and adjacent areas posted on our website, Web Link.

Whether in favor or opposed to dewatering, please join us at the Policy and Services Committee Meeting held Tuesday, Dec. 1st, 6 pm at City Hall and make your voice heard.


28 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 27, 2015 at 10:22 pm

The Santa Clara Valley Water District monitors the water levels in several wells in Palo Alto. The groundwater levels have dropped in the last 2 - 3 years.

This data is available online
Web Link

Many reports are available at:
Web Link


1 person likes this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 27, 2015 at 10:51 pm

Do those reports that say groundwater dropping is specifically because of "dewatering" or are there other uses. And even if groundwater has dropped ... we are still talking about it being at the level of a basement. There's no basement in town that goes down significantly deep.

And ... how fast would the groundwater level recharge?

I really do not see what the issue is on the "dewatering." But, yes, it might be good if the water could be saved to use in irrigation for the city.

And, these pumps can be heard or felt far from where they are. One past project around my area was creating a vibration almost all day that sounded like a neighbors washing machine was going all the time. It was bewildering to try to figure out what it was because going outside you could not hear it. It was vibrating the ground in some way.


6 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 27, 2015 at 11:04 pm

Okay - the data shows annual variance around 2' and the drought brought groundwater down 2-3' since 2012

Hardly a crisis.

As for trees - it hardly seems a problem for tap roots to reach an extra 2'. (In fact most tree species get water from surface roots completely unaffected by groundwater)

As for total ground water impact, the drought has done far more than pumping.

In fact if you run the math on basement pumping throughout town, the annual impact of pumping is about 1/8" - 1/4". (One-eighth to one-quarter inch)

[Portion removed.]


3 people like this
Posted by AlexDeLarge
a resident of Midtown
on Nov 28, 2015 at 12:46 am

[Post removed.]


27 people like this
Posted by resident 1
a resident of Adobe-Meadow
on Nov 28, 2015 at 5:20 am

When we bought our first home in PA we had to buy flood insurance and were encouraged to buy earthquake insurance. We purchased maps and data from the California Division of Mines and Geology for the bay area.

What we received is detail maps of the types of soils and land formation broken down into specific areas. The combination of soils type and underlying rock formation determines the projected impact from an earthquake and where the faults are located. This is what was known at the time - dates on the maps 1961, 1975. It discusses the type of rocks and where they are located and types of soils in detail.

The bottom line here is that everyone is projecting a number of problems and potential problems that are not equal across the board. The problems of settling in some areas are real because the underlying land has a different
base from other locations on the peninsula. The higher you go in elevation the more stable the underlying ground. The more you move to the bay the more unstable the base due to the creation of flood control activities through time with various types of success relative to the filling of the bay. If people are reporting problems in one area those are real problems. You can't make a blanket statement across the board here as to what the impact of water table reduction is on the land parcel and surrounding land parcels.
If someone is planning on digging a basement they should probably get some type assessment of their parcel and the stability of the underlying land and soil / rock type.


33 people like this
Posted by new mindset
a resident of Another Palo Alto neighborhood
on Nov 28, 2015 at 6:22 am

One fact completely ignored by TimeWasters [portion removed] is
that the acquifer during drought such as we have been experiencing
requires recharging with imported water which is not an inexhaustible
resource. Secondly if trees are not being affected why are all the
Redwoods at Palo Alto Square dying?

The problem in PA for many years is that the mindset in City Hall has
been to support and promote development,at any cost, which as a corrolary included no restrictions on dewatering for basements which is needed to support Downtown office construction at the densities allowed. That is
how the staff has seen its role - to support the development community.
And the Council was right in lock-step, each side then reinforcing the
other as the City declined and degraded to the point where we are now.
The new Council needs to change the mindset. The destruction of our City
these last 15 years is appalling.


4 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 28, 2015 at 7:45 am

@new mindset - My point is that bad logic and sparse data is not an argument for changing regulation.

And it still isn't.

Groundwater pumping affects us by about 1/8 " - 1/4" over Palo Alto. In a year. That is just not a size able effect. Natural variation is 2' -3'. Show me how 1/4" matters. It doesn't.


Your comment underscores some more of the thinking that goes into the irrationality:

"that the acquifer during drought such as we have been experiencing requires recharging with imported water which is not an inexhaustible"

Is your concern basements? Or has it now shifted to drought? Do you want homeowners to cure the drought?

Look, your statement here is flawed - in its natural state, the valley went through droughts and floods. In more recent times irrigation of lawns recharges groundwater. We dump about 1/8" of water a day into the aquifer through watering. The drought maybe cut that in half. That is more water going into the ground in a week than basements pump out in a year.

So how is that a problem?


30 people like this
Posted by homeowner Greer
a resident of Midtown
on Nov 28, 2015 at 9:35 am

I support Mr. Bennett's cause. I'd like to know where to sign.

Water pumping into the sewer for weeks, even months. I've seen it.
Have councilpeople stood there and seen it?
It sickens one.

I'm not against basements. Nor envious.
To me this is simple $$$ and sense. If you want a basement so badly, you should be willing to pay off your neighbors for the water stress you cause to the underlying structure of their property and hardscape.

To assert that dewatering does not affect neighbors is just to ignore physics.
Try this thought experiment:
If neighbors surrounding a basement dewatering were to have the pumped water immediately redistributed to their yards, wouldn't the basement project take far longer?


28 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 28, 2015 at 9:45 am

@Homeowner Greer
Lots of information is available at
Web Link

If you'd like to be updated as new information is added, please subscribe to the blog and enter your e-mail address in the box on the lower right. You can unsubscribe at any time. We don't expect to send many e-mails.

An online petition is at:
Web Link



28 people like this
Posted by Incidentally
a resident of Another Palo Alto neighborhood
on Nov 28, 2015 at 10:21 am

BTW, no one owns the dirt, mineral rights, or water beneath their lot. You do own the airspace directly above your house, though.


5 people like this
Posted by Da Contractor
a resident of Another Palo Alto neighborhood
on Nov 28, 2015 at 10:42 am

The article points out the complete lack of understanding of the issues on the part of "Save Palo Alto's Groundwater" and supporters. If you are going to form committees, sign petitions, and accuse the City of not doing anything, you should at least try to learn more about the subject, and listen to the City's reasonable responses that they derive by talking to real experts. None of the concerns raised that I read have any validity at all. Several people mention subsidence. Comparing dewatering of basements to the subsidence that occurred in San Jose last century due to Ag Well overuse is ridiculous, and not even close to the same magnitude/type of dewatering. Dewatering is not impacting these groundwater resources. There is literally a tidal wave of billions of gallons of shallow aquifer groundwater coming down from the peninsula hills to the bay. Just because you can see it displaced to the storm drain, doesn't mean it's wasted. It's just taking a different route. This grass roots movement should really have a meeting and have a hydrologist explain to them how most of their fears/concerns are unfounded.


16 people like this
Posted by Curmudgeon
a resident of Downtown North
on Nov 28, 2015 at 1:04 pm

"BTW, no one owns the dirt, mineral rights, or water beneath their lot. You do own the airspace directly above your house, though."

Then nobody has an inherent right to pump out the water under their property, right?


"None of the concerns raised that I read have any validity at all. Several people mention subsidence."

So dewatering has caused no subsidence? Have you tried telling that to the neighbors whose foundations have cracked, whose doors don't close anymore? They'll doubtless be relieved to know it ain't really happening.


32 people like this
Posted by Douglas Moran
a resident of Barron Park
on Nov 28, 2015 at 2:28 pm

Douglas Moran is a registered user.

RE: "Da Contractor": "There is literally a tidal wave of billions of gallons of shallow aquifer groundwater coming down from the peninsula hills to the bay."

This used to be true for many areas, especially those south of Palo Alto. This was seen in the number of artisian wells -- wells that flowed without requiring pumping because of water pressure from higher up in the aquifer. The aquifer flows are so reduced that most of those wells are no more. Now, one of the major activities of the Santa Clara Valley Water District is recharging the shallow aquifers by managing releases of water from the reservoirs.

As the "Resident 1 of Adobe-Meadows" comments above, there are lots of different situations through the valley. In my Barron Park neighborhood, the shallow aquifer is blocked by folds from old earthquake faulting. There are two faults on my (long) block on Matadero Avenue (the Stanford Fault at Julie Ct and the Hanover Fault at Laguna Ave) and a major fault at the top of the hill (Pulgas Fault at Foothill Expy). As part of the study of the spread toxics in the ground water from Stanford Research Park, it was learned that in this neighborhood, the shallow aquifer doesn't flow long distances -- there are bands that are only 1-3000 feet wide. If interested in more details, see my article "Matadero Creek Geology" on page 7 the Fall 2012 issue of the Barron Park Association newsletter (PDF: Web Link).

That this was a surprise to the geologists suggests that there may be other unexpected situations in other areas of Palo Alto. Recognize that the situation in Barron Park is probably replicated under the Stanford Campus and if so, there is NOT an uninterrupted shallow aquifer between the hills and Palo Alto below El Camino.


17 people like this
Posted by Anneke
a resident of Professorville
on Nov 29, 2015 at 8:13 am

I have a simple idea:

Save the water from these projects in water trucks and offer it for a reasonable charge to people in Palo Alto who would like to deep water the trees on their property.

No water wasted, trees staying alive, and goodwill among neighbors restored.


19 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 29, 2015 at 10:18 am

RE: "Da Contractor": "There is literally a tidal wave of billions of gallons of shallow aquifer groundwater coming down from the peninsula hills to the bay."

You are partially correct. The Cities of Palo Alto and East Palo separately both conducted detailed studies to determine the amount of groundwater flowing in this area. The estimates are between 3,000 - 6,000 acre feet per year. 1 acre-foot is about 328,000 gallons, so There are between 1 and 2 billion gallons of water flowing through the aquifer in an average year. However, only about 30% of that amount comes from the hills, either subsurface or through San Francisquito Creek. The maximum estimate of water from the hills is 600 million gallons/ year.

It is estimated that about 130 million gallons, or >20% of the amount of water "from the hills" was pumped from the aquifer in Palo Alto to build basements in 2015. Some of this water would have flowed to the Bay, but the East Palo Alto study estimated that only 634 acre-feet would flow to the Bay annually from Palo Alto, East Palo Alto and Menlo Park combined; it's likely that pumping water for basement construction decreased the flow into the deeper aquifer used for potable water.

The reports are available at:
Web Link
Palo Alto Groundwater Supply Feasibility Study:
Web Link

Menlo Park & East Palo Alto Groundwater Feasibility:
Web Link

Do we have extra water to use for building basements?


4 people like this
Posted by Slow Down
a resident of Community Center
on Nov 29, 2015 at 1:02 pm

Slow Down is a registered user.

@ Incidentally - Cuius est solum, eius est usque ad coelum et ad inferos - whoever owns the soil, holds title all the way up to the heavens and down to the depths of hell.

Property owners, by law in California (civil code section 829), do own the soil.

Web Link


3 people like this
Posted by Reason
a resident of Community Center
on Nov 29, 2015 at 1:37 pm

Reason is a registered user.

@SavePaloAltoGroundwater points to two interesting studies on the groundwater yield - how much water can be extracted from the groundwater without negative consequences (saltwater intrusion, subsidence, etc.) The numbers vary quite a bit based on methodology, but appear to range from conservatively 500AFY to ~3000AFY.

The low number is based on conservative impacts from prior pumping, the second is based on water balance estimates of inflow and outflow. They indicate that a temporary drain of 1500AFY during a drought to supplement supplies would be easily recovered within 2 yrs.

So it would seem that during years when no groundwater is needed for supplementing HetchHetchy supplies, we could extract an additional 500AFY without any real cost to society, harm to groundwater, etc. This is water that is otherwise flowing to the bay.

They should pay for the water, per SCVWD rules - if you pump water, you pay for it. But it is pretty cheap.

A basement dewatering uses about 25AF - 30AF for the total project (many basements use none).

That would indicate that the groundwater could sustain an additional 20 basement dewatering projects and have little or no impact on groundwater.


And here's the cool part!

During a drought when we need the water for supplement, the city pumping will lower groundwater about 15'. Which means that basement dewatering will naturally stop. That's right - we don't need to dewater basements during periods when city is using the groundwater, as the groundwater will already be low enough that basements can be dug without dewatering!

So basically, it boils down to this: when the city needs water from groundwater, they pump as they need, dropping groundwater about 15' (from the study).

When the city does not need groundwater, basement dewatering can pump whatever they want - it is unlikely they will lower the groundwater by the same 15', as that becomes the point where their own pumps shut off (dry).

It actually works very cooperatively.

All that remains is an issue of fairness - the homeowners should pay for the water, just like all the other users of groundwater. That's about $21/AF x 25AF for the basement or about $500.00.

Seems fair.


16 people like this
Posted by save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 29, 2015 at 2:38 pm

@Reason
I agree with you that people who use the water should pay for it. Where did you find the $50 / AF price for water?
The wholesale rates for Santa Clara Valley Water District groundwater is about $650 / acre-foot. The going rate of SF Public Utilities Water (i.e. what Palo Alto pays SFPUC) is about $1,300 / AF.

The Carollo study for Palo Alto actually stated that a total of about 1,500 AF could probably be drawn over a period of 3 years. So, how much is available for emergency water supply in a year when there's a drought if basement dewatering removed 400 AF x 3 years = 1200 AF?
If the drought lasts longer than a year, reducing replenishment (which comes from rain + imported water, which may or may not be available), then would we not expect recovery to be delayed?

There are other significant users of the groundwater (including Atherton, East Palo Alto and possibly a new city well for Menlo Park). Therefore, over 1000 AF/ year is already being extracted for human use, in addition to basement dewatering.


20 people like this
Posted by It Ain't Over til it's Over
a resident of Another Palo Alto neighborhood
on Nov 29, 2015 at 3:52 pm

@TimeWasters: you stated that the drought was over in an earlier post.
Nothing could be more wrong!
This IS an El Niño year, but it has not, so far, come up this far north. The rain we have gotten so far has come from the Gulf of Alaska, not the South Pacific.
Mexico is getting the rain predicted for the Bay Area, and from South of Sinaloa to South Texas has had flooding for the last week. They are having a monster El Niño, Southern CA is having a heavy one, while up here we will probably have a mild one.
That is not enough to end a severe four-year drought.


5 people like this
Posted by Curmudgeon
a resident of Downtown North
on Nov 29, 2015 at 4:50 pm

"Property owners, by law in California (civil code section 829), do own the soil."

But only their own soil (and presumably the water in it), but not their neighbors. Therefore anybody dewatering their property must ensure they leave in place the water on their neighbors' properties.


1 person likes this
Posted by Reason
a resident of Community Center
on Nov 29, 2015 at 6:01 pm

Reason is a registered user.

I got the water rates from SCVWD. The cheapest rate is $21/AF.

Web Link



"So, how much is available for emergency water supply in a year when there's a drought if basement dewatering removed 400 AF x 3 years = 1200 AF? "

This is a good question - As I read the report, they felt that the city could pull 1500AF in an emergency, or 500AF/yr continuous (over and above current usage) - both were expected to reduce the groundwater level. If they pull 500AF/yr and reduce the groundwater 15' as Carollo estimated (conservatively), then I would guess no more basement dewatering would be needed. The water level would already be lower than the construction sites need.

So it doesn't look like the construction sites will compete with emergency water demands.

I have a question about where your numbers come from - each basement is supposed to take about 25-30AF for dewatered basements. The map at Web Link is pretty useful - this shows 13 sites. So I see this matches your estimate the water pulled from dewatering around 25AF x 13 = ~325 - 400AF/yr continuous.

BUT...

The Carollo study did not indicate how many basements were being dewatered when they pulled their data. It is safe to assume a few were in progress. So what we don't know is whether there is available water to pull an additional 13 basements, or 13 basements total.

One clear indicator - the basement pumping is happening right now, and the groundwater measured at the current wellheads is down about 2' due to the drought, and 2' seasonal. Hard to know how much the impact of basements is from this level, but it would seem that it is no more than a 2' impact. For removing 400AF/yr continuous.

So I suspect the Carollo study was quite conservative.

The real thing that I think is interesting is that the dewatering is self-limiting - they are not going to pump groundwater down 20' lower than current levels, as it is just not needed for construction. My understanding is that most of these sites pump local water levels down 5' - 10'. This does not appear to be close to the 15' drop that Carollo predicted city-wide from pumping emergency water.

So I think there is both plenty of emergency water, and if they start pumping emergency water, the basement dewatering automatically stops because the levels are low enough they don't need to pump.


Like this comment
Posted by Curmudgeon
a resident of Downtown North
on Nov 29, 2015 at 7:07 pm

"One clear indicator - the basement pumping is happening right now, and the groundwater measured at the current wellheads is down about 2' due to the drought, and 2' seasonal."

At what depth are these numbers measured?



5 people like this
Posted by MikeCrescentPark
a resident of Crescent Park
on Nov 29, 2015 at 8:12 pm

if this is the city's official stance then we have at the very least a solution for each of our homes' landscaping water needs. Dig a hole on your property and pump all the water you require.

The city employee statement that trucking the water pumped from these construction sites does not work economically seems suspect-Raindance commercially delivers recycled water by truck to many lawns in my neighborhood.


3 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Nov 29, 2015 at 8:21 pm

MikeCrescentPark, I used to know lots of houses that had wells in the area. I don't know ... is it still legal, or do you need a special permit?


3 people like this
Posted by Reason
a resident of Community Center
on Nov 29, 2015 at 8:34 pm

The well near Newell seems to have a good history of data, shows seasonal variation, and appears to take frequent measurements - seems the most reliable source in the area of the basement dewatering.

Web Link

They measure depth to ground water from the surface.


8 people like this
Posted by Paly Grad
a resident of Leland Manor/Garland Drive
on Nov 29, 2015 at 8:46 pm

A permit is required to dig a well in Santa Clara County. Permits are issued by the Santa Clara County Water District:

Web Link

These are the permit fees:

Web Link

These are the insurance requirements for the contractor who digs the well:

Web Link


9 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 29, 2015 at 9:34 pm

@Reason and @Curmudgeon,
The water level at the well at Rinconada Park was 8.7 feet below surface on Nov. 21, 2008, and 11.97 feet below grade on the Nov. 1 2015, a drop of about 3.2 feet, which is significant.

@Curmudgeon: These wells do not measure the depth of the shallow aquifer as they are solid pipe to depths deeper than the shallow aquifer. I don't the exact number, but it's probably measuring the water pressure at about 200' depth.

There will likely be a significant delay in pumping the shallow aquifer and the water head in the deeper aquifer levels in seeing the impacts of removing water from the shallow section of the aquifer that feeds the deeper aquifer, as can be seen from the lag between the seasonal peak water levels and the rainy season.


11 people like this
Posted by Stephen
a resident of Duveneck/St. Francis
on Nov 29, 2015 at 10:07 pm

@Save Palo Alto's Groundwater: Per SCVWD's website the depths shown are relative to ground surface and the elevations shown are referenced to NGVD 29, one of the several coordinate systems in use for mapping/GIS etc. Effectively the elevation referenced to NGVD29 is the height above sea level of the water surface. So for Newell Rd. the ground elevation is 20ft; as measured on this past Oct 1, the water table is almost 12 ft below ground level and has dropped several ft since 2011. I think this must be the shallow near-surface aquifer from which the local construction sites have been drawing.


9 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 29, 2015 at 10:26 pm

@Stephen,

I expected that the measurements were of the shallow aquifer as well, however Phil Bobel (Palo Alto Public Works)educated me that, as the pipe is solid down to the screened zone (where water can come in the pipe), the measurement is actually that of the water pressure (i.e. the head) at the bottom of the well. The soils between the top and the bottom of the well can support a significant pressure.

I agree that the water level has dropped about 4 feet since 2011. The 2003 Groundwater Supply Feasibility Study for the City of Palo Alto recommended not lowering the water table by 8' or less, except occasionally for emergency needs, special circumstances. Therefore, "generally usable" portion of the groundwater "reservoir" is about 1/2 empty now (4'/8'). It is down about 250 AF. It might be acceptable to lower the water table by 25' or so for a year, assuming recharge the following year.


9 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 29, 2015 at 10:33 pm

Typo in previous message;
Should read:
"...The 2003 Groundwater Supply Feasibility Study for the City of Palo Alto recommended not lowering the water table by more than 8', except for emergency needs, special circumstances..."


2 people like this
Posted by TimeWasters
a resident of Old Palo Alto
on Nov 30, 2015 at 1:52 am

@ItAintOver writes:
"@TimeWasters: you stated that the drought was over in an earlier post."


No. I said no such thing. This is a complete straw-man fabrication. This underscores my point about the irrationality and 'make-up-beliefs-as-you-go' seen in the anti-basement crowd.

Shees. At least argue a point I actually made.


2 people like this
Posted by marc665
a resident of Midtown
on Nov 30, 2015 at 9:34 am

marc665 is a registered user.

@MikeCrescentPark Re: Delivering pumped water. The question is whether you are willing to pay up to $0.25 per gallon for water delivered by tanker truck vs $0.01 per gallon that you pay for tap water.

A 2000 gallon water truck rents for $3,000.00 per month. Plus fuel, labor, insurance, taxes, etc. You are looking at a base cost of $12,000.00 to $15,000.00 per month (and this is a low end estimate). So that is $750.00 a day.

Two full truckloads delivered is around $0.19 per gallon. That is if you can find enough customers and can actually get an efficient route. More likely one truckload a day. And as soon as the rain returns your customers vanish.

So to anyone that says let's fill trucks and deliver water, go for it. Go sign up customers and then rent a truck and try it. Or better yet, go buy a truck for $125,000 and make a business out of it. See how long it takes you to go bankrupt.

/marc


9 people like this
Posted by Groundling
a resident of Midtown
on Nov 30, 2015 at 10:00 am

Easy fix for the City. Require basement square footage to be included in the allowable square footage calculation.

Ban construction of basements on lots shown to have water levels that require pumping for construction. Even if the pumped water is put in tankers and hauled away for landscape use, tanker trucks and pumps add to the construction noise, traffic and impact.

Huge basements are a cash cow for real estate developers. Basements requiring pumping are affecting neighbors' landscape trees and foundations. It is selfish. Check for the presence of water before you design a floating house! Really need that square footage? Buy land that has solid ground under it.


1 person likes this
Posted by Curmudgeon
a resident of Downtown North
on Nov 30, 2015 at 11:54 am

"They measure depth to ground water from the surface."

Aha! Now, did they tell you how far their well's water is below the surface? Feet, meters, inches, ... ?


2 people like this
Posted by marc665
a resident of Midtown
on Nov 30, 2015 at 12:16 pm

marc665 is a registered user.

@Grounding. Do you or anyone else have any documented case where the pumping caused any damage to nearby structures or trees? Not hearsay, not anecdotal, not what you think must happen, but actual documented case?

Keith Bennett claims his house shifted but he never lived directly next to a pumping site. He claims he "knows" it must what caused his door to stick. But this is all hearsay.

People claim there is settlement but all they site is hearsay. Anyone got actual proof? Or is all of this trying to prove a negative? People claiming the dewatering will cause damage and no matter how my studies say it won't they want another study.

/marc




7 people like this
Posted by Doof
a resident of Barron Park
on Nov 30, 2015 at 12:30 pm

And the drought is over


Whaaaaaa????


Like this comment
Posted by Show Me
a resident of Community Center
on Nov 30, 2015 at 5:20 pm

" People claiming the dewatering will cause damage and no matter how my studies say it won't they want another study."

Oh yeah? Please link us to those studies.


5 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Nov 30, 2015 at 5:46 pm

There are absolutely no studies, no data on the drop of the water table (the so-called zone of depression)caused by dewatering for basement construction. The "estimate" in the 2004 EIP report is not based on any quantitative analysis of the amount of water pumped, pumping rate, depth of pumps or the permeability or storage capacity of the soils.

So, what is the "evidence" that it's 10's of feet, not 100's of feet as estimated by a geohydrologist? And, it's well known that dewatering causes soils to compact, again in a very locally-specific matter.

We welcome suggestions on how to acquire meaningful and convincing data, either way.

Incidentally, the amount of water removed (400 acre-feet) in 4 - 6 months is equivalent to the pumping rates of Palo Alto's emergency water supply wells.

(See the 2003 Groundwater Supply Feasibility Study for Palo Alto):

Web Link


Like this comment
Posted by Walter Murray
a resident of Adobe-Meadow
on Nov 30, 2015 at 5:59 pm

If pumping water from more than 20 feet below ground is doing no harm is it ok for me to do that to water my garden? If not why not?


Like this comment
Posted by Slow Down
a resident of Community Center
on Nov 30, 2015 at 6:07 pm

Slow Down is a registered user.

@Walter Murray - it is ok, and you can do it. You need a permit, and to meter your water. You do raise the right question, if pumping water was harmful, why would the Santa Clara Water DIstrict sanction it? Answer: it is not harmful.


6 people like this
Posted by StopTheWastrels
a resident of Midtown
on Nov 30, 2015 at 6:14 pm

@TimeWasters - Irrespective of whether the water table goes down measurably or damage is caused to adjacent buildngs or not, the bottom line is that a huge amount of ground water that belongs to all of us is being wasted in a third year of drought.

I can't see any reason not to stop this egregious practice.


7 people like this
Posted by StopTheWastrels
a resident of Midtown
on Nov 30, 2015 at 6:14 pm

@TimeWasters - Irrespective of whether the water table goes down measurably or damage is caused to adjacent buildngs or not, the bottom line is that a huge amount of ground water that belongs to all of us is being wasted in a third year of drought.

I can't see any reason not to stop this egregious practice.


7 people like this
Posted by StopTheWastrels
a resident of Midtown
on Nov 30, 2015 at 6:22 pm

Please sign the petition to stop the draining of precious water

Web Link


5 people like this
Posted by Phil
a resident of Downtown North
on Nov 30, 2015 at 7:44 pm

"When resident Valoran Hanko warned that the groundwater pumping would change the elevation in the neighborhood, Bobel replied that the pumped-out water would simply be replaced with new groundwater.

In another letter, Bobel challenged the notion that the pumped-out water is being "wasted." Rather, he wrote to resident Georgia Relsman, the water ends up going to the creeks and the Bay — the same place where it would end up if it remained in the aquifer."

The article does not indicate whether or not the city has any data to back up these statements by Assistant Public Works Director Phil Bobel. I suspect that there is no data, and Bobel is making it as he goes. If the city has no actual data to back up, what I consider to be their baseless and frankly, ignorant claims, Bobel is demonstrating that the public works department, and Bobel specifically, is fundamentally unqualified to be making any policy with respect to legitimate ground water issues and concerns raised by residents.


1 person likes this
Posted by Todd
a resident of Another Palo Alto neighborhood
on Nov 30, 2015 at 9:03 pm

Another issue that is 1% legitimate concern about conservation 99% anger over people building houses that are "too big".


3 people like this
Posted by StopTheWastrels
a resident of Midtown
on Nov 30, 2015 at 9:41 pm

@Todd - please don't ascribe motivations - stick to the issues brought up. You cannot speak for other people.

What you say makes no sense either. Why would I, or anyone else care if a house is 'too big' underground.


3 people like this
Posted by marc665
a resident of Midtown
on Dec 1, 2015 at 7:40 am

marc665 is a registered user.

@Phil, On what basis do you believe that Valoran Hanko is correct and Phil Bobel is wrong? This whole discussion is based on nothing but people's opinion that they "know" they are correct and all the reports and officials are wrong.


12 people like this
Posted by Roger
a resident of College Terrace
on Dec 1, 2015 at 10:00 am

Sorry for the long post but I just compiled the comments I made on the Nextdoor site:

As a groundwater professional I have firsthand knowledge of groundwater levels in Palo Alto. In that area the depth to water is 6 to 8 feet below ground surface. But that is using a well. Water in the soil actually rises above the water table by capillary action and depending on the soil grain size the capillary rise can be many feet and be within reach of tree and bush roots. Therefore, the lowering of the water table from 7 feet below ground surface (bgs) to 15 or 20 feet bgs, as is done for these basement dewatering sites, would likely lower the capillary water level so that it is out of reach of the trees.

I am surprised there is not more concern about permanent differential settling of the houses adjacent to the basement pumping. With the water table drawn down for an extended period, months, the bay mud (clay) that is pervasive in the shallow soil of Palo Alto east of El Camino will dewater beyond its elastic range, resulting in permanent settling. This settling will be greater the closer one gets to the site of the pumping. For a house this means one side will settle more than the others (differential settling) causing cracks, sloped floors, and jammed doors. Since clay soils dewater slowly they may continue to dewater and settle after the pumping has ceased, because the pressures in the clay take a long time to equalize, and therefore the settling may not be noticed until well after the pumping has stopped.

Obviously, what I describe here is a general case scenario and each site is unique with the amount of settling occurring based on many factors. Nonetheless, I believe the potential for settling of neighboring houses should be studied and reported on by qualified soil engineers during the permit process to ensure all harm to neighbors is mitigated.
Marc is wrong on two counts. First, the water in the shallow aquifer is the water that replenishes the deep aquifer. Even in the area of current interest, where there is an aquitard blocking flow directly to the deep aquifer, the water in the shallow aquifer provides pressure that works its way upgradient to the unconfined recharge area of the deep aquifer. If you lower the water elevation of the shallow aquifer you increase the gradient and drain the water from the recharge area. I state all this to clear up the misconception that shallow and deep aquifers are not connected but I agree that the amount of water pumped for small basements is insignificant.

The second point that needs correction is that land subsidence only occurs in deep aquifers. Land subsidence occurs when the clayey soils are dewatered, regardless of their depth. If the 10 feet of clay below your house is dewatered by a neighbor’s pumping and that clay has not been dewatered since your house was built you may very likely experience some settling of your house by the current dewatering. And that settling won’t be uniformly distributed around your house since the pumping is causing a cone of depression of groundwater pressure which is not constant under your house.

And, for those of you considering installing a well to water your gardens, which do exist in Palo Alto, you should know that you will be charged for the water you pump, paid to the Santa Clara Valley Water District, and that you will need a permit for your well which will need to be installed by a licensed well driller. You should also know that the electricity to run your water pump adds up quickly. Unfortunately, construction dewatering, which includes basement construction dewatering, is exempt from the water pumping fee.


1 person likes this
Posted by marc665
a resident of Midtown
on Dec 1, 2015 at 11:46 am

marc665 is a registered user.

@Roger Do you have any first hand knowledge of any settling of any homes directly adjacent to any dewatering site?

Not hearsay, not this is what MIGHT happen, not that we should study it more, but actual first hand knowledge.

All I've ever see is people who claim that they live "near", not adjacent to some dewatering site and that they "know" the settling of their home must be caused by the dewatering because their doors never were stuck before.

This discussion goes on and on by people who claim the "know" the pumping is bad but have no evidence.

People can claim the potential for lots of things that don't happen in real life. The potential for something to happen does not mean it should be banned.

/marc


8 people like this
Posted by Roger
a resident of College Terrace
on Dec 1, 2015 at 1:16 pm

@ marc665, you seem to a person that must be shown absolute proof of a cause and effect before you act. Most issues we deal with in life are not either black or white and therefore some judgment and safety factors must be employed to reduce risk.

@marc665, I do not have firsthand knowledge of the settling of homes due to groundwater pumping for basement construction, but I do have firsthand knowledge of the settling of my home due to the natural drying of the clay beneath it. I also have over 20 years of experience studying the land subsidence (settling) that has occurred in Santa Clara Valley due to the over pumping of groundwater. Downtown San Jose land surface dropped 13 feet due directly to groundwater pumping. If you assume this pumping occurred between 300 and 500 feet below ground surface and then interpolate the potential subsidence for pumping for a 20 foot deep basement in 10 feet of clay you get about 3 inches of settlement. This 3 inches of settlement could occur with 50 years of pumping, but even with just 6 months of dewatering you should expect some settlement and even 0.5 inches is too much for a house.

It is difficult for those adjacent and near to this pumping to show they have been damaged by it since there are no before and after land surveys of their property.

Each site is somewhat unique with regard to its underlying soil characteristics, so broad generalizations should not be used in the permitting process. There are models that soil engineers and geologists can use to predict the effects of this pumping and homeowners that want basements in areas of high groundwater should be required to have subsidence/settlement modeling performed prior to construction to show that the settling being caused to neighboring homes would be below some tolerable level or a basement permit should not be issued.

The groundwater level during pumping should also be modeled and if it shows that the tree roots would be dewatered then the basement builder should be required to water the trees as well.




2 people like this
Posted by midtowner
a resident of Midtown
on Dec 1, 2015 at 7:17 pm


Irrespective of other concerns, if we can afford to dump several million gallons of fresh water *per basement*, into the bay, then we must not be in a drought.


3 people like this
Posted by Oldster
a resident of Old Palo Alto
on Dec 1, 2015 at 9:40 pm

Thanks Roger for some aquifer geology and history. Yep, San Jose sunk more than a dozen feet thanks to aquifer pumping for the orchards. And when parts of our aquifers are pumped dry, the soils with the pumped water comopress and won't fluff back up to be capable again of holding the all water they used to hold. Every basement dewatering process flattens a bit of an aquifer

40+ years of living in an old house in Palo Alto has taught me we have 2 soil seasons: wet and dry. Every year our front door gets sticky then gets loose. Ditto every other door, window, and gate on the property thanks to the surface clay soils.

We also have some nice Loma Prieta cracks in a brick walkway - a reminder every day of how the Earth moves at our nearby San Andreas fault zone. It's a shame that recklessly messing with aquifers does not leave such obvious surface traces until the damages are obvious enough to kindergarteners.


3 people like this
Posted by marc665
a resident of Midtown
on Dec 2, 2015 at 8:47 am

marc665 is a registered user.

@Roger, what you are doing is extrapolating some bit of knowledge in one area into another area where you have no direct knowledge or expertise.

As far as I can tell there are NO reports of any homes directly adjacent to a dewatering site reporting any damage to their homes.

There is one claim by Keith that his doors starting sticking sometime after the pumping down the street started (but not adjacent to his home) and they stopped sticking after the pumping stopped. This is one claim out of all the homes directly adjacent to dewatering sites.

So based on Keith's one claim you and others want all basement pumping stopped. Even if the pumping had some factor in Keith's doors sticking, as he says, everything returned back to normal after they stopped. No permanent impact.

Yes I want to proof of cause and effect. I don't what fear mongers going around making bogus claims of all sorts of things that "MIGHT" happen. And then want a report to prove a negative. If the report says no impact on adjacent homes, the the response is that another report is needed because you "know" there must be an effect.

So I would propose to continue to allow basements and dewatering as necessary and if and only if, homes directly adjacent to the dewatering sites begin to report damage to their property it should be investigated on a case by case basis. If there is damage, the damaged homeowner has a clear course of action in making a claim against the dewatering sites owner. Just the same as if one of their trees fell across property lines,

And it doesn't have to be costly, just document/photograph the adjacent homes for cracks, stuck doors, etc. And if/when something occurs, investigate.

/marc





4 people like this
Posted by Roger
a resident of College Terrace
on Dec 2, 2015 at 11:13 am

@marc665, I am sorry you are unable to grasp the transportability of scientific knowledge. If most people believed as you apparently do that everything must be proven at each new location we would still be living in caves. The ancient bay muds below San Jose are the same bay muds present below Palo Alto, I have first had knowledge of this via my well installation work. These muds (clays) respond identically to changes in water pressure. Since there is a significant probability that basement pumping will cause some subsidence the prudent course would be to require those wanting basements to show no harm to neighbors instead of putting the burden on the neighbors to show harm after the fact. Simple site specific modeling should be required prior to construction to estimate the risk. And before and after land survey data should be collected at neighboring properties, otherwise there is no way to validate a damage claim.


2 people like this
Posted by Roger
a resident of College Terrace
on Dec 2, 2015 at 11:30 am

Also, the neighboring trees should also be evaluated and monitored by an arborist before, during, and after the basement construction to ensure they remain healthy.


2 people like this
Posted by StopTheWastrels
a resident of Midtown
on Dec 2, 2015 at 5:56 pm

@Marc665 - And what's your opinion on the fact that we're wasting millions of gallons of water in a fourth year of drought that could be used to water trees and other foliage that is going dry.


1 person likes this
Posted by StopTheWastrels
a resident of Midtown
on Dec 2, 2015 at 6:01 pm

@Marc665 - and please don't say the water would've gone to the bay anyway. If that was the case, we could've dug some wells to alleviate the drought. Clearly groundwater is precious which is why we don't pump it up to water our lawns. Not sure why we would dump it into the bay.


1 person likes this
Posted by TimeWasters
a resident of Old Palo Alto
on Dec 2, 2015 at 9:24 pm

@Stop - yes, the water is just going to the bay anyhow. Deny it all you want. Yet it moves.


And yes, there is still a surplus of groundwater that could be pumped for watering trees. Nobody does it because I can only assume they don't value the trees, really. You can pump the water yourself. It is far more effective than arguing fact less opinions online.

Dig a well. Save a tree. Plenty off water 10' down.


1 person likes this
Posted by Slow Down
a resident of Community Center
on Dec 2, 2015 at 10:04 pm

Slow Down is a registered user.

@ StopTheWastrels - why would anyone bother to dig a well when you can just turn on your sprinklers and get cheap and easy water? California is in a drought, but there is no lack of water supply issue in Palo Alto, or the Bay Area.


3 people like this
Posted by Water Conserver
a resident of Old Palo Alto
on Dec 2, 2015 at 11:30 pm

We have a Green Building Code.
Pumping out groundwater when we are in a severe drought is not compatible with building anything "Green" or environmentally friendly".





Like this comment
Posted by Plane Speaker
a resident of Crescent Park
on Dec 3, 2015 at 1:44 am

>> Pumping out groundwater when we are in a severe drought is not compatible with building anything "Green" or environmentally friendly".

Tell that to the Dutch, Water Conserver.


Like this comment
Posted by Water Conserver
a resident of Old Palo Alto
on Dec 3, 2015 at 2:06 am

The Dutch aren't in severe drought.


2 people like this
Posted by Plane Speaker
a resident of Crescent Park
on Dec 3, 2015 at 2:22 am

Waterboard officials are carrying out emergency repairs on several hundred metres of dyke near Gouda which have become weakened by the drought. Despite heavy rain in the past few days, ‘more water has evaporated than has fallen,’ dyke chief Gerard Doornbos told broadcaster Nos. ‘Our dykes are very dry and that presents a risk, because they can crack.’

Read more at DutchNews.nl: Dutch dykes strengthened because of drought Web Link


6 people like this
Posted by Water Conserver
a resident of Old Palo Alto
on Dec 3, 2015 at 7:10 am

I'm just wondering how pumping out non-saline water can be allowed when we have a "Green Building Code" in Palo Alto, California. I thought the whole point of this relatively new Green Building Code was to build something environmentally conscious or with a low carbon or water "footprint". (I am not asking about the Netherlands - please).
Californians are re-landscaping with drought tolerant plants, and designing gray water systems now. How is a new home which is designed with a basement below the water table, allowed to pump out tens of millions of gallons of non-saline groundwater to do this under a Green Building Code?
I am just asking.
I don't really understand since non-saline water is our most valuable resource.



1 person likes this
Posted by MaryannH
a resident of Palo Verde
on Dec 10, 2016 at 9:44 am

Some thoughts:

Yes, the water in the aquifer will make its way to the bay eventually, but pumping it directly out of the ground into a storm sewer gives it an expressway. Once the water reaches the bay, it mixes into the salt water and is no longer useful until it eventually comes back down to the ground as rain (if it rains).

It takes trees and other plant material time to develop longer roots when the water table goes down. It's not clear to me that trees can react quickly enough to a mechanical water removal process and adapt in a timely fashion. Trees are a valuable resource for many reasons and should be protected.

There is not an infinite amount of water available to recharge the aquifer. It has to come from somewhere, and we are in a drought of some years' standing.

It seems that water being pumped from the ground, whether from a well or a basement under construction should be subject to the same charges from the Santa Clara Valley Water district. In both cases, the water is being removed to benefit humans and should be regulated in the same way. If this no longer makes it economically feasible to construct basements in this manner, then so be it. Then perhaps other methods of basement construction as outlined in other comments would be more attractive.



2 people like this
Posted by Prove it to ME
a resident of Midtown
on Dec 10, 2016 at 11:27 am

Roger said
"require those wanting basements to show no harm to neighbors instead of putting the burden on the neighbors to show harm after the fact. Simple site specific modeling should be required prior to construction to estimate the risk. And before and after land survey data should be collected at neighboring properties, ."

Marc uses the standard argument Prove it to Me to counter anything he doesn't like.
But he won't accept any proof. He will find something wrong. Standard obstructionist tactic.


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

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