New rules on the way for groundwater pumping

Palo Alto prepares to add restrictions on 'dewatering' for basement construction

Palo Alto resident Keith Bennett estimates that you can quench the thirst of Palo Alto's entire daytime population for a year with all the water that was pumped out of eight residential properties last year to construct basements.

For Bennett and his growing grassroots group, that's a problem that the city isn't tackling with enough gusto. Next week, as the City Council prepares to consider new regulations for "dewatering" -- the practice of pumping out groundwater -- he and others members of Save Palo Alto's Groundwater plan to lead the call for action.

The group, which sprung up in 2015, can already claim some success. Two years ago, the council began requiring that dewatering sites provide "fill" stations, which allow water otherwise headed for the storm drains to be recaptured and used for other means, including irrigation and construction cleanup. And in early 2016, the city strengthened the fill-station requirement, mandating that these stations have enough water pressure to accommodate multiple users drawing from them at once. The council also began requiring builders to submit studies showing how their projects affect nearby trees, landscaping and buildings.

On March 7, the council is preparing to go even further. One proposed change would require stations to be capable of filling a truck in 10 minutes, which must be demonstrated before any dewatering can proceed, and to be designed such that the storage tank would always be at least one-half full.

Another requirement would limit pumping to 10 weeks (in addition to the two-week "startup period," during which time the builder would have to demonstrate compliance with water-quality standards). A builder would also be prohibited from digging out more than 3 feet below the basement floor during the startup period. Once the basement slab is poured, the depth would have to be 1 foot. Further, the property owner would have to offer to water trees and plants on adjacent properties if requested; to report all measurements on a bi-weekly basis; and to submit a geotechnical study based on pumping tests at wells on the site.

While these rules would take effect in this spring (pumping is only allowed between April and October), the council is also eyeing more substantial steps in 2018. The city may start requiring builders to rely on "cutoff walls" for basement construction -- a technique that limits pumping to a more contained area and that generally is more expensive.

The new regulations have already received the endorsement of the council's Policy and Services Committee, which approved them in December after hearing from dozens of residents, many wearing "Save Palo Alto's Groundwater" buttons. Bennett posited at the meeting that it's not unreasonable to asks developers to pay a little more to avoid wasting a public resource.

"Our aquifer is a precious shared resource, which Palo Alto has the responsibility to protect," Bennett said. "A significant amount of the community's groundwater is pumped and dumped. This is neither acceptable to the community nor sustainable."

Bennett has plenty of allies in his battle to preserve groundwater. Esther Nigenda, also a member of the grassroots group, recently penned a letter to the council listing the various reasons why her group opposes dewatering. The practice, she wrote, is environmentally unsound and is equivalent to a "localized drought," with impacts to properties hundreds of feet away. She also argued that less than 1 percent of the pumped water comes from the property being dewatered; the rest comes from neighboring properties.

"Residents want to know why they should conserve water (on their properties) when they see water gushing down their (storm) drains," Nigenda wrote.

While her group has in the past called for dramatic measures, including a moratorium on groundwater pumping and a per-gallon fee for pumped water, Palo Alto officials have opted for a more gradual approach. This generally involves tweaking existing rules, adding relatively modest regulations, monitoring impacts and making revisions based on experiences.

Last year, according to Public Works staff, the city's eight projects pumped out 140 million gallons (the city as a whole uses about 8 million gallons per day). In several cases, the applicants submitted geotechnical studies that predicted lower flow rates than occurred. This prompted the new requirement that the measurements be based on actual wells, rather than projections. The proposed rules also addressed a concern from some residents that the fill stations have inadequate flow rates.

A bigger change may be on the way in 2018, when the city may abolish the existing groundwater-pumping methods (known as "broad area dewatering") and require "localized" techniques that require less pumping. Last year, Bennett began working with local architect Daniel Garber to discuss the benefits and added costs of localized construction, which separates the basement from the rest of the area with a cutoff wall and only pumps from within the wall.

Garber himself plans to do projects this year that will use a localized-dewatering technique known as "secant shoring." The process calls for boring holes to create an underground wall without excavating the soil. The wall is formed by mixing the earth with a weak cement or clay, according to Garber.

In December, Garber argued that one way to incentivize the localized approach to dewatering is by waiving the requirement for the type of enhanced geotechnical study that those who do broad-based pumping would have to conduct. The enhanced study, Garber said, costs more than twice as much as a standard geotechnical study, which all applicants would still be required to conduct.

Last week, Garber submitted a letter outlining several other advantages of the secant-wall strategy. According to Garber, it takes about half the time to build the wall than to pursue the broad-area dewatering; and unlike the broad-area method, it can be done any time during the year.

"The homeowner isn't restricted to just the non-rainy season to build because the City's storm drain system isn't burdened by the large amounts of water that results from a project that utilizes broad-area dewatering methods," Garber wrote. "Thus, localized dewatering strategies add flexibility to a homeowner's construction schedule, adds only a very small percent to the overall cost of any new house and importantly avoids removing millions of gallons of water from our underground aquifer."


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8 people like this
Posted by Curmudgeon
a resident of Downtown North
on Feb 28, 2017 at 5:08 pm

"...require “localized” techniques that require less pumping."

In other words, build a cofferdam around the footprint that extends to below the water table. That can be very expensive, but hey, if you can't afford it, just dig your hole in a dry area and avoid all those post-construction hydroheadaches too.

1 person likes this
Posted by ChrisC
a resident of Community Center
on Feb 28, 2017 at 6:50 pm

If you can't dig any holes more than 3' below the basement floor then installing plumbing becomes more challenging. I wonder if ejection pumps can for in that space. (Ours is certainly deeper.)

21 people like this
Posted by What?!
a resident of College Terrace
on Feb 28, 2017 at 7:20 pm

"Another requirement would limit pumping to 10 weeks (in addition to the two-week "startup period," during which time the builder would have to demonstrate compliance with water-quality standards)."
10-12 weeks of continuous pumping sounds like it'd cause a heck of a lot of wasted water and impact to the surrounding homes. And this is an improvement?!

4 people like this
Posted by ExageratedConcerns
a resident of Crescent Park
on Feb 28, 2017 at 8:07 pm

[Post removed due to factual inaccuracies.]

27 people like this
Posted by Eric
a resident of Downtown North
on Feb 28, 2017 at 8:49 pm

What a colossal waste of water, there is no other way to describe what this dewatering process is. Selfish, and wasteful. In good time, the water should return, and your ego basements could turn into moldy mushroom farms.

I am glad that the city is finally taking action to mitigate how dewatering impacts neighbors. This is a huge improvement over statements from the city employee, who had 0 credentials as an expert at anything, who not so long ago, and quoted in this paper, dismissing dewatering as nothing to be concerned about.

34 people like this
Posted by Hulkamania
a resident of Duveneck/St. Francis
on Mar 1, 2017 at 5:15 pm

This is all very complicated with fill stations, cutoff walls, water the neighbors trees, time limits and new techniques. Wouldn't it be easier to stop allowing basements to be built?

23 people like this
Posted by Follow SJ
a resident of Old Palo Alto
on Mar 1, 2017 at 6:23 pm

If you think groundwater pumping is insignificant, ask anyone who has been living in San Jose for a few years.

The city was sinking due to the draining of aquifers. Roads and buildings, especially homes, were damaged.

The SJ City Council made the decision to forbid groundwater pumping and the building of basements, residential or otherwise.

Since that decision only a few years ago, San Jose has regained most of the water in its aquifers and thus has stopped the sinking-- actually regaining some of the elevation it had lost.

Mtn View has begun to tax basements: the deeper the basement, the more square footage it holds, the bigger the tax.

New basement building has virtually stopped in Mtn View!

1 person likes this
Posted by Resident
a resident of South of Midtown
on Mar 1, 2017 at 7:00 pm

Drilling is excavation. An eighteen inch diameter hole, that is drilled sixteen feet in the ground produces about 2 cubic yards of dirt or more.According to this type of drilling,many holes will need to be dug. Sometimes the water table may be very deep. If one cannot excavate below three feet of basement floor which is about 14 feet total. I wondering how this will work. For example, the water table on Bryant and El Dorado is about 11 feet, this was during drought years, this year I have no doubt that it will be higher. Just wondering how all this will work?

12 people like this
Posted by Rita Vrhel
a resident of Crescent Park
on Mar 1, 2017 at 8:45 pm

Thank you for again spotlighting the dewatering issue. This is a not a small issue as over 140 million gallons of community groundwater was pumped and dumped in 2016 during the construction of 8 residential basements.

Yes, it's probably better not to build basements in areas of high water but that is a different decision. Probably won't happen. But the groundwater can be percolated back into the soil on the property.

The goal of "no dumping of any extracted groundwater into the storm drain by 2018" is do-able. Period. Easy for the City to monitor; no fines nor curtailment of property owner's rights. No dumping could also reduce neighbor's complaints of property damage - cracked windows and foundations caused by dewatering. A ban would likely cause innovative thinking and problem solving.

Not mentioned in this article is the property owners/developers "free" use of the storm drain when the groundwater is dumped.

Many problems; the REAL solution is not dumping the extracted groundwater into the storm drain. The property owner must be required to use 100% of the extracted groundwater rather than the current dismal 1%.

Please send your comments to the city council at Or better still come to the March 7th meeting. Thank you.

11 people like this
Posted by Hydraulic Engineer
a resident of Greenmeadow
on Mar 2, 2017 at 8:24 am

This is the dumbest use of city resources ever.

[Portion removed.]

There is no engineering or agricultural evidence that temporary localised dewatering has any durable effect on the water table, local trees, or global warming.

In 30 years of shallow foundation construction (meaning less that 14 feet deep) we have never seen any adverse structural, hydraulic, or horticultural damage caused by correctly designed and executed dewatering.

I challenge ANYONE to identify (with something close to facts) a case where correctly performed shallow foundation construction has permanently damaged the water table, caused structural damage to adjacent properties, or killed trees.

This is a red herring for those who really do not want large homes with basements constructed in there neighbourhood.

I get it.

I did not like the 2 bedroom mid-century modern house across the street replaced with a Spanish revival pavilion with 5 bedrooms, 6 baths, and a one car garage either. When we challenged the CPA Planner over the pending approval, she stated that the house conformed to every PA requirement.

This is the real problem.

3 people like this
Posted by Me 2
a resident of Old Palo Alto
on Mar 2, 2017 at 8:26 am

[Post removed.]

2 people like this
Posted by my_water_too
a resident of Duveneck/St. Francis
on Mar 2, 2017 at 10:30 am

From Web Link

In most areas of California, overlying land owners may extract percolating ground water and put it to beneficial use without approval from the State Board or a court. California does not have a permit process for regulation of ground water use. In several basins, however, groundwater use is subject to regulation in accordance with court decrees adjudicating the ground water rights within the basins.

The California Supreme Court decided in the 1903 case Katz v. Walkinshaw that the “reasonable use” provision that governs other types of water rights also applies to ground water. Prior to this time, the English system of unregulated ground water pumping had dominated but proved to be inappropriate to California’s semiarid climate. The Supreme Court case established the concept of overlying rights, in which the rights of others with land overlying the aquifer must be taken into account. Later court decisions established that ground water may be appropriated for use outside the basin, although appropriator’s rights are subordinate to those with overlying rights.

This part is especially important IMO:
"..the rights of others with land overlying the aquifer must be taken into account. Later court decisions established that ground water may be appropriated for use outside the basin, although appropriator’s rights are subordinate to those with overlying rights."

So, if my neighbor is pumping out water (and wasting it), they are infringing over my rights to the same water??!

7 people like this
Posted by SP
a resident of East Palo Alto
on Mar 2, 2017 at 10:40 am

"The city was sinking due to the draining of aquifers."

Shallow groundwater pumping has no impact on local aquifers, which are close to 1000 ft. down. Also, the local aquifer has shown very little impact by the drought.

"Residents want to know why they should conserve water (on their properties) when they see water gushing down their (storm) drains".

The answer is that water coming out of your sink and that fills your irrigation system comes from 167 miles away and is limited. This local groundwater is a nuisance when building, and is abundant. Neighbors freaking out about inconsequential groundwater and looking to put restrictive regulations on something that really impacts nobody are also a nuisance.

7 people like this
Posted by Simple
a resident of Barron Park
on Mar 2, 2017 at 11:00 am

Let's not overcomplicate with needless science. The point is 'don't waste water...ever.'

18 people like this
Posted by allen
a resident of Old Palo Alto
on Mar 2, 2017 at 12:14 pm

Just include the basement in the floor area ration and maybe people will quit destroying every existing house in Palo Alto to make partially buried mega homes.

6 people like this
Posted by Me 2
a resident of Old Palo Alto
on Mar 2, 2017 at 12:17 pm

Put some of this on Doug Moran's blog post comment thread, but even on the "save our groundwater" website, there is a report from a firm that actually has credentials in this area:

"Because the deflection is temporary and very localized, and because groundwater levels at the sites recover rapidly once pumping has ceased, there appears to be no discernible long-term effect on the surface aquifer"

"Although the amount of water pumped from an excavation may appear substantial as it flows along a street to a storm drain inlet, it is small compared to the amount of groundwater directly beneath the Santa Clara Plain."

"Because dewatering for basement construction occurs only in the uppermost portion of the surface aquifer, there would be no effect on the deep aquifer."

There you go. Saving our groundwater is based on #fakescience. It's amazing how people with little or no knowledge can propagate this kind of nonsense in Palo Alto. For a self-proclaimed educated community, I'm really disappointed. It's like we live in Berkeley or something like that.

3 people like this
Posted by Me 2
a resident of Old Palo Alto
on Mar 2, 2017 at 12:32 pm

(in case you want to read the report yourself, since I'm guessing the Save Our Groundwater group will take it off their website)

Web Link

[Portion removed.]

9 people like this
Posted by We can do better
a resident of Midtown
on Mar 2, 2017 at 12:51 pm

Simplest solution is listed above - stop the FAR exception for basements and charge a dewatering fee based on actual metered outflows. Since there's no agreement in the science, why wouldn't we at least use logic as it relates to development? Exceptions to FAR are a relic of a bygone era, get rid of them. And if someone is just hell-bent on going underground in an area clearly not suited for that, then charge them for the privilege.

Doesn't have to be a complicated or half-measure solution. Or are we too scared to offend any developers at all?

Cmon CC, do the right thing.

6 people like this
Posted by allen
a resident of Old Palo Alto
on Mar 2, 2017 at 1:00 pm

To me the basement thing is not about water, it is about the character of our community. The FAR exemption means that every home in Palo Alto that does not have a basement is a tear down. It is destroying the reason we all want to live here.

7 people like this
Posted by Save Palo Alto's Groundwater
a resident of Leland Manor/Garland Drive
on Mar 2, 2017 at 2:07 pm

@Me 2

No, we will not remove the 2004 EIP report. A number of us are scientists (physicists, chemists) and we have read it as well as all the other more recents reports and articles on our website. Historically, there have been some misconceptions about the shallow groundwater, including that there is no connection between the shallow and deeper aquifer (see the 2016 San Mateo Groundwater Workshop powerpoint link that shows otherwise, also on our website). Read our White Paper for a rebuttal of the 2004 EIP report. The 2004 EIP report has some deficiencies including no data and no references to other studies or peer-reviewed articles. But, it is part of the historical record and it is nothing we would try to hide or pretend doesn't exist.

[Portion removed.]

2 people like this
Posted by Me 2
a resident of Old Palo Alto
on Mar 2, 2017 at 2:45 pm

"A number of us are scientists (physicists, chemists) and we have read it as well as all the other more recents reports and articles on our website. "

What would physicists and chemists have to do with geology? That's like asking a neurologist about hemorrhoids. Sure, there's some overlap in training, but not really the experts we should be relying on.

[Portion removed.]

14 people like this
Posted by Cracks in Foundation and Walls
a resident of Midtown
on Mar 2, 2017 at 3:20 pm

Cracks in Foundation and Walls is a registered user.

For anyone who doubts the affect of dewatering on neighboring properties, I have new and recent LARGE cracks in my foundation and walls due to the giant basement that was dug at 2724 Cowper St. To add insult to injury, the dewatering hose was run past two houses, directly in front of my house, to a nearby storm drain causing us inconvenience (muck, closed sidewalks, no available parking in front of my own home) for several months. Of course people building new homes have property rights, but so do neighbors when their properties are affected. These basements are not dug in a silo and ground water doesn't respect property lines. Dewatering can affect all neighboring properties. At this point, we have no recourse. The damage to our home is done.

7 people like this
Posted by resident
a resident of College Terrace
on Mar 2, 2017 at 3:35 pm

why in this city we must do everything convoluted way when simplest solution staring us in the face. Tax the basements.

Like this comment
Posted by Curmudgeon
a resident of Downtown North
on Mar 2, 2017 at 5:08 pm

"What would physicists and chemists have to do with geology? That's like asking a neurologist about hemorrhoids."

Well, I'll ask a neurologist about that before I'll ask a physicist, and I'll ask a physicist about groundwater before I'll ask a neurologist. [Portion removed.]

5 people like this
Posted by worried
a resident of Duveneck/St. Francis
on Mar 2, 2017 at 5:08 pm

After hearing news media on the subject of de-watering near the leaning/sinking Millennium Towers in San Francisco, I am worried since my property and home are close to a house that had water gushing at a high rate down a pipe to the storm drain for many weeks....cracks may be an issue...garage at Millennium Towers has cracks...seems odd to permit de-watering in a recognized flood zone where we wren told basements were not permitted to be built.
Guess we'll find out...our valuable property is being experimented on by someone else.

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