2018 Dewatering regulations on the City Council Consent Calendar, Monday, Dec. 11, 7 pm

Proposed 2018 dewatering regulations for below ground construction are on City Council’s consent calendar for Monday, Dec. 11th, 7 pm, City Council Chambers, 250 Hamilton.  City Council accepts written and oral comments from the public on any item on the consent calendar.  It does not, however,  discuss items on the consent calendar.  It will therefore vote on, but not discuss, revisions to the dewatering ordinance this coming Monday.

In 2017 cut-off walls for three residential basements were successfully used with zero to minimal amounts of groundwater placed in the City’s storm drains.  While these work very well to reduce the waste of groundwater, Save Palo Alto’s Groundwater does not request that cut-off walls be mandated for all below ground construction that requires dewatering.  Cut-off walls have disadvantages, including use of potable water during construction, construction impacts, increased amount of soil unavailable for stormwater retention and possible interference of the cut-off walls with groundwater flows, these last two leading to increased risk of flooding.

Staff’s proposed 2018 dewatering regulations add the following requirements that address some impacts of construction dewatering to the current ordinance : a) Construction work must be continuous during the dewatering period, b) A pre-building survey and report on structures on adjacent parcels must be submitted, c) After an 8-week dewatering period trucking of water to irrigation sites increases from 1 to 5 days/week.

We have heard from various neighbors, builders and other stakeholders that the proposed Dewatering Ordinance needs improvement in several areas:

  • According to the Oct. 23, 2017 Public Meeting Groundwater Assessment Use slides, the estimate of the “safe yield” of groundwater for Palo Alto is 2,500 acre ft. /year.   This “safe yield” is the total amount of groundwater that may be pumped for any purpose per year, including groundwater for emergency situations, and should be incorporated in any Ordinance and Plan that allows groundwater pumping.
  • Require large commercial and residential sites to install cut-off walls to dramatically reduce required pumping. Specifically address the coming Marriot hotels on San Antonio Road that could conceivably pump up to 2,900 acre-feet of groundwater with broad area dewatering.
  • Require sites in or near contaminated ground water plumes to install cut-off walls (to reduce the spreading of the contaminant plume).
  • Improve the use of broad area dewatering by specifying “Best Practices” when designing pumping systems (such as a limit on flow rate of 60 gpm).
  • Include clear metrics and avoid case-by-case requirements and exemptions in the regulations.
  • Require data in the hydrogeology report that helps design a dewatering system with lower flow rates.
  • Address pumping and impacts to groundwater flows for railroad trenches and tunnels.
  • Consider the cumulative impact of all below ground construction and dewatering.

The following is an excerpt from Staff’s response to some of our concerns:  “In response to the issues raised by Save Palo Alto’s Groundwater, Staff believes that the appropriate course of action is to adopt the proposed Ordinance enhancements now, and consider the other suggested changes after the New Year. We concur that more work on this topic is needed, especially with respect to large commercial sites. But it is critical to get the proposed changes in place now for residential sites, to provide certainty for designers, and to avoid more “grandfathering “ of residential sites as has occurred in the past. Most of the new sites will be residential, not commercial, as in past years.”

We are requesting Council to a) approve the ordinance revisions on the consent calendar and b) as proposed by Staff, direct Staff to follow-up with additional amendments to the Dewatering Ordinance in Q1 2018.

Whether you are a homeowner whose property has been impacted by dewatering, an environmentalist who believes we should protect our groundwater, an emergency services volunteer who believes we’ll need groundwater for future droughts, a homeowner/builder who believes regulations are too onerous, etc. we invite you to attend the City Council meeting on Dec.11th at 7 pm and make your voice heard.

Thank you for your interest and your support.

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Fracking in Santa Clara County

Did you know fracking for oil and gas production is permitted in Santa Clara County?

The Sierra Club invites us to write to the Santa Clara County Board of Supervisors, BoardOperations@cob.sscgov.org, requesting a ban on fracking in Santa Clara County. Although there are 15 gas producing wells in Santa Clara County, there is no fracking yet.  However, the potential for fracking exists and neighboring counties of Monterey, San Benito and Santa Cruz and the city of Los Angeles have already banned fracking.

In addition to the potential contamination of ground and surface water, Wikipedia lists methane emissions, air pollution, migration of gases and hydraulic fracturing chemicals and radionuclides to the surface, the potential mishandling of solid wastedrill cuttings, increased seismicity and associated effects on human and ecosystem health as other possible impacts from fracking.  After reading this powerful article it is clear that we cannot risk contaminating our groundwater, impacting peoples’ health and becoming another Washington County, Pennsylvania.

Please join us and the Sierra Club in asking the Santa Clara Board of Supervisors to ban fracking in Santa Clara County.  You might also write to the Santa Clara Valley Water District, the groundwater steward for the Santa Clara Water Basin.  Most effective may be to email the director for your district (e.g. gkremen@valleywater.org and copy the full board for the record, board@valleywater.org.

This Thanksgiving we give thanks for your interest and support in protecting our groundwater.

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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.

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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.

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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.



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