Where’s the protection for residents’ homes?

This evening, Oct. 23rd at City Hall, 250 Hamilton Ave., City Council will discuss and likely certify the Final Environmental Impact Report (FEIR) for our City’s Comprehensive Plan. This topic is scheduled for 7:45 pm but may start earlier or later depending on length of discussion of earlier topics.

The FEIR is a very lengthy document that covers many important topics such as housing, noise, transportation, etc. If any of those topics are very important to you, we encourage you to read and comment on the relevant sections of the FEIR.

We took a quick peek at the Hydrology section (FEIR Vol. 1, page 3-14, Adobe page 76) and while protection for groundwater is included, we are dismayed at the following paragraph.  Note: Cross-outs mean that the original language is dropped. 

“Mitigation Measure HYD-2: To reduce potential impacts associated with construction dewatering the proposed [Comprehensive] Plan shall include policies that address achieve the following topics:

  • Impacts Avoidance of the impacts of basement construction for single-family homes on adjacent properties, public resources, and the natural environment and safety.”

Notice that avoidance of dewatering impacts on “adjacent properties and public resources” is eliminated!

Yes, we want groundwater to be considered a resource and the FEIR addresses that. But last week we visited a homeowner whose property only three months ago was fine and now has extensive, and probably expensive, damage (see photo below). He is researching his options so we are withholding his name and address.

Public infrastructure and basement owners, old and new, are not immune from damage either. People with old utility basements and newer basement construction alike tell us of replacing basement drywall and insulation during or shortly after nearby dewatering due to water damage.  Some owners just repair and sell.  This is a matter of public record since City permits are required for this work.  It is important to note that not everyone near a dewatering site will be impacted.  There are many factors involved including types of soils, location (on an old stream bed?), construction type, etc.

We know your time is valuable and we will be asking you to attend the City Council meeting on dewatering that will probably be scheduled in November. However, if protection of all private and public property from dewatering impacts is important to you please attend this evening’s City Council meeting or write to City Council at city.council@cityofpaloalto.org and let them know.

We all expect increased inconveniences from nearby construction:  noise, traffic, parking, etc.  Homeowners shouldn’t be expected to pay thousands, and in some cases, tens of thousands of dollars for impacts from dewatering.  Even if your house is not impacted, we all pay for damaged infrastructure including broken water mains, sewers lines, etc.

Posted in Blog | Leave a comment

Promising Solution or Potential Problem?

As we near the end of Palo Alto’s dewatering season, October 31st, we face a dilemma. Do we support the use of cut-off walls for underground construction where the water table is high or not?  We’d like you suggestions and comments.  Save Palo Alto’s Groundwater is hosting a table at this Sunday’s, October 1st, Midtown Ice Cream Social, Hoover Park, 1 – 4 pm. Either in the comments section below or at the Ice Cream Social we would like to know what you would like the City to do about construction dewatering.

The City’s Public Works Department released the chart below that shows the results of three finished 2017 City of Palo Alto dewatering projects. Item number 3 shows a project that used cut-off walls. Not only did this project pump out less than 2% of the amount  of groundwater pumped by the other projects that used conventional dewatering methods, it was able to percolate back all this groundwater so that this process didn’t waste any groundwater! This project also had less impact on neighboring properties, the canopy and infrastructure because of the smaller groundwater drawdown.

Terrific, isn’t it? What’s not to like? One of our concerns about all underground construction is its impact on flooding. Underground construction means the removal of soil – soil that we depend on to retain and slowly release storm water on its way to the Bay. Not only is the removed soil unavailable for storm water management but, also, all those underground basements and garages can act like sticks in a stream. If beavers could speak they would tell us that with a few sticks we can build a dam – a dam to the underground flow of storm water during heavy rains.  With the loss of this soil and underground construction acting as dams, the City will have to build ever more expensive  infrastructure to handle heavy rains and reduce flooding.

But if we are building basements and underground garages already anyway, what’s wrong with using cut-off walls?  To be effective, cut-off walls need to be built down to a non-water bearing layer (clay layer).  In our area this depth is roughly twice the basement’s depth. This means we essentially double the amount of soil unavailable to absorb storm water and block water flow through much of the lot   Do we understand the impacts of basements or cutoff walls on flood risks?  We think not.

Thank you for your interest and your support.

Posted in Blog | 6 Comments

Too many regulations?

The stories and photos coming from Texas (and likely soon from Florida) are sobering and, some, heartbreaking – they are a reminder of what can happen and what did happen in a much smaller way in Palo Alto  during the February 1998 winter storm.

Although unprecedented amounts of water fell on the Houston area, experts say [1], [2] that among other measures, having and implementing zoning regulations could have minimize the impact of the storm.

A neighbor mentioned that she is opposed to regulating dewatering for basement construction because “we already have too many regulations”.  While too many regulations might feel like being “nickeled and dimed”, what if those regulations actually improve our lives and our safety?

In the case of dewatering for underground construction, regulations that limit or eliminate the waste of shallow groundwater can protect this resource for use in future droughts. Additionally, instead of pumping this shallow groundwater and shunting it to the Bay, a sustainable amount of this groundwater could be used for current non-potable needs such as irrigation. This would decrease our use of ever more scarce and expensive potable water.

Beyond dewatering and with the floods in Houston in mind, we know that soils regulate the flow of stormwater (plus sequester carbon dioxide, a greenhouse gas). With ever more underground construction, we are removing this soil and it will no longer be available to retain stormwater and release it slowly over time. Thus, we increase the chances of flooding in our neighborhoods. As the failure of the Oroville dam demonstrates, flood protection infrastructure can be overwhelmed, despite the assurances of planners. And, when overwhelmed, the damage can be extreme.

With expected sea level rise the groundwater level will concurrently rise. As with underground construction, there will be less soil available to retain stormwater and release it slowly over time. This means that areas not currently in the FEMA flood zone are more likely to have flooding in the near future. Should we be building basements and underground garages in these areas? According to the USGS, underground construction in which the groundwater level is currently at 13 feet or less is at risk of flooding within its lifetime. For these reasons, shouldn’t we be regulating underground construction to ensure it’s in the right place and impacts are minimized?

Times and circumstances change.   We should eschew regulations that are no longer applicable and enact regulations that reduce risks to public safety and protect our properties, infrastructure and natural resources such as shallow groundwater and soil. These resources are vital to our safety and well-being and that of future generations. We believe we all have a responsibility to see that these resources are not squandered and that private development doesn’t increase public risks.

 

 

Posted in Blog | 4 Comments

City Council will vet Marriott Plans on June 12, 6 pm, City Hall

No one has failed to notice there’s a building boom in Palo Alto. And there are several projects with two levels of underground construction already started or in the pipeline. So what is unique or different about the Marriott hotels proposed for San Antonio Road and why should we be concerned?

Marriott proposes to open two hotels with a two level garage on a 1.9-acre site at 744-750 San Antonio Road (between Leghorn and Middlefield). The Courtyard by Marriott and AC by Marriott Hotels would total 294 rooms and each would be five stories high. The neighborhood is primarily residential and one-story businesses such as Summerwinds Nursery. The proposed underground parking garages fill the property and allow little room for trees, shrubs or landscaping.

Save Palo Alto’s Groundwater is specifically concerned about the plan to build two levels of underground garage – a total of 82,660 ft² – in an area where the groundwater level is 7 – 11 feet below ground surface, according to their geotechnical report. Last year a single-level residential basement of 3, 500 ft² with a similar groundwater level pumped out more than 30 million gallons during construction. This area is more than twenty times larger, and part of the underground construction is twice as deep. Maybe they’ll be extra careful when pumping and not discharge 600+ million gallons of groundwater but it’s still going to be a lot of water. At the same time over a million cubic feet of soil will be removed to accommodate the two-level garage. The Final Environmental Impact Report (FEIR) does not quantitatively analyze the impacts on groundwater at all, but rather summarily dismisses such concerns as “no significant impact.”

We believe that this project requires much more careful vetting of its underground construction plans than it has received thus far. The amount of soil and groundwater to be removed under the proposed construction is significantly large enough to impact our aquifer, infrastructure, neighboring properties and the amount of soil available for future storm water mitigation.

City Council will discuss and decide whether to approve the Final Environmental Impact Report for 744-748 San Antonio Road on Monday, June 12, 6 pm at City Hall, 250 Hamilton Ave. We plan to be there and voice our concerns. Please join us and the neighbors from Greenhouse One and Greenhouse Two and let City Council know your opinion about this project. If you can’t attend, you can contact the City Council at city.council@cityofpaloalto.org.

Posted in Blog | 1 Comment

City 2017 Dewatering Map Now Online

The City has updated the online map of dewatering sites.  You can easily find the location of Palo Alto’s 2017 dewatering sites by clicking the Maps link on the right-hand side of this page.  As of May 31st, yellow marks indicate pending, green indicates pumping, red indicates completed.

Palo Alto Dewatering Site Map, 5/31/0217

Note that dewatering impacts can extend 200 – 400 feet (about 1 city block) from the dewatering site.  See the graph on our Feb. 5, 2017 blog, “Building basements without wasting water”.  Neighbors have mentioned cracked walls, cracked windows and cracked walkways, doors that stick, trees that died a few months after dewatering ended, etc.  If you notice any such impacts on your property, please let us know by entering a reply/comment at the bottom of this page, or send us an e-mail at info@savepaloaltosgroundwater.org.

Also, we consider dewatering to be “localized drought” for the neighboring properties. This article in the Mercury News  and this article in the Business Insider explain drought mitigation for properties.  Caveat emptor!

 

Posted in Blog | 1 Comment