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The Pleasanton City Council recently received an update on the first phase of the so-called “Regional Groundwater Facilities Improvement Project”, which determined that the two best locations to construct and operate new groundwater wells in the city are the Pleasanton Tennis and Community Park, and Hansen Park.
The two new wells would be located outside of a PFAS plume and would contribute to the city’s water supply, which has taken a significant hit after the city had to shut down its wells and buy 100% of its water supply from the Zone 7 Water Agency because of the presence of PFAS, also known as forever chemicals.
City-operated groundwater wells contribute up to 3,500 acre-feet per year of water — approximately 20 to 25% — of Pleasanton’s total municipal supply needs.
“I do hope this turns into a win-win,” Pleasanton Mayor Jack Balch said during the Feb. 3 meeting. “I know Zone 7, as well as us, want to diversify our water supply. That’s something we’ve been pretty focused on as we’ve been 100% reliant on the state water project so how we utilize our 3,500 acre-feet is obviously something top of mind to us.”
Now that the first phase of the project — the feasibility study — is complete, Pleasanton city staff will spend the next couple of months analyzing the findings and return in either March or April with recommendations on whether or not the city should move forward with constructing and operating the wells on its own, or with the help of Zone 7.
“I’m looking forward to seeing what our options are and how we can make that work for our community to best serve our community,” Councilmember Craig Eicher said during the council meeting. “Whether it’s joining forces with Zone 7 or diverting from the agency, he is looking for the best option to activate the city’s groundwater that will serve the residents best interests.”
The city first discovered the synthetic chemicals in its groundwater Well 8 back in 2019. After shutting it down, the city discovered similar chemicals in Wells 5 and 6, which were later shut down in 2022 and then allowed for use only if necessary during peak demand.
During that same year, the council approved the initiation of a water supply alternative study and the following year, supported one of the alternatives: the development of new groundwater wells outside of the PFAS plume.
The overall goal of the project is to construct new wells within the Bernal subbasin which, according to experts, is expected to be outside the existing PFAS plume.
Since June 2024, Zone 7 and the city have been jointly working on conducting the first phase of the wells project. This work involved installing test wells at the three sites the agencies deemed viable locations: Del Prado Park, Pleasanton Tennis and Community Park, and Hansen Park.
“The objective of this study was to determine the feasibility of Zone 7 and the city jointly constructing and operating a new groundwater facility in the Bernal subbasin,” Pleasanton utilities planning manager Todd Yamello said.
Yamello, along with public works director Siew-Chin Yeong, went over the findings of the feasibility study and explained how, after running through all the data and criteria, the most viable locations to construct and operate new groundwater wells would be Pleasanton Tennis and Community Park, and Hansen Park.
The two also went over the costs of building these well facilities, which Yamello said would be single-story buildings located at the parks, and how even though the initial estimate is around $42.3 million, that number could be subject to change.
“As the project advances through each level of design, that estimate gets more detailed and that level of accuracy gets smaller,” Yamello said.
He also noted that the total project cost does not include the additional infrastructure costs that the city would need to pay for and construct aside from the well facilities in order to accommodate for the additional water flow to the water treatment facilities, where the groundwater would be treated.
One of the main topics that came up during the meeting was whether or not Zone 7’s feasibility study discussed the possibility of PFAS entering the Bernal subbasin following the construction of these two groundwater wells. However, Zone 7 staff told the council that the agency conducted models that showed how, even if there were three wells operating in that part of the city, it is very unlikely that PFAS would contaminate that area of the basin.
“To be very conservative, we ran the model with running these three wells 24/7, which is very conservative, for 20 years – and we did not see, at that point, PFAS coming to the facilities,” Zone 7 General Manager Valerie Pryor said during the meeting.
As part of the city’s next steps, staff will work on weighing out the pros and cons of continuing with the overall regional groundwater project alongside Zone 7, which would mean some cost sharing between the two agencies for the project development, or if it should go about moving forward without the help of the water agency.
If owned and operated by the two agencies, the city will have to spend more money on making improvements to its water system infrastructure, but if it owned the wells solely, those improvements wouldn’t be necessary, staff said.
However, the council majority seemed to support the idea of saving money by joining forces with Zone 7.
“I do hope this achieves the cost savings that we’ve talked about,” Balch said. “When Zone 7 saves money, we save money and so that matters to our ratepayers, as we just went through a difficult rate-setting process … We would like to have stability in the rates for the community.”
