New rules target water pumping in Palo Alto | December 16, 2016 | Palo Alto Weekly | Palo Alto Online |

Palo Alto Weekly

News - December 16, 2016

New rules target water pumping in Palo Alto

Officials hope to encourage advanced construction techniques to reduce groundwater waste

by Gennady Sheyner

Palo Alto residents have deep concerns about what's happening above the city's shallow aquifer — namely, the millions of gallons of water that get pumped out of the ground every time someone in the area wants to build a basement.

On Wednesday night, a City Council committee waded into the complex issue of groundwater pumping by passing a slew of new requirements aimed at tightening the spigot and encouraging builders to adopt a less wasteful approach.

The rules from the council's Policy and Services Committee build on regulations the council approved last year. They will also likely serve as a preamble to even more stringent regulations in 2018.

Provided the full council adopts the committee's recommendations, starting in April, contractors engaged in what's known as "dewatering" will have to demonstrate their ability to fill a pumped water truck in 10 minutes, limit pumping in residential areas to 10 weeks, offer to water trees and plants on neighboring properties, conduct pumping tests to gauge how much water is getting discharged and provide bi-weekly reports to the city.

In addition, the committee agreed to look at more significant changes down the road, including ways to get people to adopt construction techniques that would significantly lessen the amount of the liquid that needs to be pumped out.

The effort to beef up regulations was inspired by a grassroots movement that sprung up in the Old Palo Alto neighborhood, where most of the basement projects have occurred, and gradually spread to the wider community. While basement pumping is far from new, as several committee members pointed out, the issue has recently risen to the surface thanks to the statewide drought, a growing number of dewatering projects and the fact that most of them are in close proximity to each other.

In 2015, there were 14 projects that required dewatering because they were located near Palo Alto's "shallow aquifer," according to Public Works staff. This year, there were eight, which pumped about 140 million gallons of water, enough to supply all of the city's water needs for more than 17.5 days (Palo Alto currently uses about 8 million gallons per day).

The slew of new rules adopted last year included requirements that applicants for permits supply a "statement of effects" of the groundwater pumping on nearby buildings and that they supply onsite filling stations to recapture the non-potable groundwater for such uses as irrigation and construction cleanup.

All of these rules will apply to the upcoming dewatering season, which will run from April 1 to Oct. 31.

The city has more sweeping ambitions for 2018 and beyond, however. On Tuesday night, the council committee agreed that the most effective strategy would be to provide incentives to developers to pump in a less wasteful manner.

The proposal was championed by local architect Dan Garber, who has spent the past year analyzing the dewatering problem together with Keith Bennett, founder of the citizens group Save Palo Alto's Groundwater.

Garber noted that most basement builders today use "broad-area dewatering strategies," which generally means building wells and then pumping the water out of the ground to enable excavation. Because of the nature of Palo Alto's soil, this often results in the surfacing of millions of gallons of water.

The alternative to this, he said, is to establish a cut-off wall to separate the basement area from the rest of the soil and only pump out the water inside the wall. Garber recommended that the city consider two sets of dewatering regulations: one for builders who use the broad-area approach and the another for those willing to go the localized route. The idea, he said, is to provide incentives for builders to use the latter approach.

The council committee agreed wholeheartedly and voted 2-1 to make the near-term changes and to explore incentives for encouraging cut-off walls that would take effect in 2018. Even Councilman Tom DuBois, who voted against the motion, only did so because he felt it didn't go far enough. DuBois said the city should explore a moratorium on basement pumping and a fee for each gallon discharged. His colleagues, Liz Kniss and Vice Mayor Greg Scharff, both felt this would be going too far, however.

Staff Writer Gennady Sheyner can be emailed at


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