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The Pleasanton City Council unanimously gave staff the green light last week to move forward with a plan to construct two new groundwater wells, which is expected to cost the city a minimum of $23 million.
“The main thing is we want to provide clean and safe water to our residents, and that’s what we are trying to address here,” Councilmember Valerie Arkin said during the Oct. 17 meeting.
Staff told the dais during the council meeting that the construction of the two new wells, which is scheduled to take three to four years to complete, will help the city meet its long-term water needs and ensure safe, PFAS-free drinking water to Pleasanton residents.
“This provides the highest reliability at the lowest cost. The operational complexity is low,” said engineer Jenny Gain from city consultant Brown and Caldwell, an engineering and construction firm focused on water and environmental sectors. “Groundwater pumping is something that city staff are already doing, have done in the past, and it is within the city’s wheelhouse, whereas treatment is not.”
PFAS, also known as forever chemicals, have plagued the city’s groundwater basin since 2019 when city staff first learned of its existence in its city-owned wells 5, 6 and 8, which help meet the city’s city’s quota of producing 20% of the city’s drinking water supply. The rest of the city’s water comes from the Zone 7 Water Agency.
The council recently agreed to allow Well 5 and Well 6 to be turned on as deemed necessary during this summer’s peak water demands with the caveat that staff must test the wells every month — they are not currently on. Those wells have been found to have significantly less PFAS contamination than Well 8, which was the first well that the city found PFAS chemicals and continues to have the highest concentration of the chemicals.
That’s why the city has been hard at work in finding other solutions to address PFAS.
Originally, the council began by eyeing plans to construct a water treatment and rehabilitation facility, known as the PFAS Treatment and Wells Rehabilitation Project, to treat and rehabilitate the three wells in Pleasanton and to create a new centralized treatment facility for PFAS treatment, disinfection and fluoridation.
But on Sept. 6, 2022, the council paused that project in order to evaluate other options, mainly due to a $46 million price-tag on the treatment facility. That number had since gone up to roughly $60 million, according to staff.
Since then, a water ad hoc subcommittee was formed; the council established a new water supply alternatives study capital project and contracted with Brown and Caldwell in order to evaluate different potential options. The council accepted the final report of the water supply alternatives study on Oct. 17 with no additional comments
After several months of collecting and reviewing data from the city and from the Zone 7 groundwater model, staff narrowed a comprehensive list of 11 of water supply alternatives down to four preferred options and presented those options to the council on Sept. 19.
Those four options were the PFAS Treatment and Well Rehabilitation Project, bringing back the PFAS treatment facility and treating Wells 5, 6 and 8; treating only Well 8 for PFAS contamination; and purchasing 100% of Pleasanton’s water supply from Zone 7.
After reviewing the options, the council showed strong support for the option to build two new wells — Well 9 and Well 10 — outside of the PFAS plume, which has been spreading PFAS contaminants mostly in the East Pleasanton region. The two new wells would be located within the Bernal subbasin.
“It is something that will yield high-quality drinking water drawn in a manner unaffected by and not disturbing the PFAS plume,” Gain told the council.
According to Gain, staff is recommending that the city drill test wells ahead of the final designs for the two new wells, while Zone 7 performs its groundwater modeling to confirm the water quality and production capacity at the new locations. She said that pre-design work is expected to be completed by October 2024.
The goal, Gain said, is to have the two new wells constructed and operational by early 2028.
She said that by October 2024, the city needs to make the critical decision of moving forward with the two new wells plan or if it wants to pivot to a contingency plan, which would be treating only Well 8 for PFAS contamination.
“If you get to October of 2024, and we find that the test wells show that it’s infeasible or less favorable to move in the direction of two new city wells, the city can pivot to the reduced baseline alternative (treating Well 8) and still stay within that same schedule and actually maybe finished a few months earlier,” Gain said.
Arkin, however, clarified with staff that the Well 8 treatment option could have some additional personnel costs.
“The cost overall could possibly — possibly not for sure, but possibly — be less with the reduced baseline,” Arkin said. “But we have operations and maintenance costs that will be ongoing, that will be higher, and we would have personnel costs … that would also add to the cost.”
“Hopefully we don’t have to pivot to the other plant,” she added. “I think that gets us more into the treatment business, which I think we’re trying to avoid and there’s additional ongoing costs in perpetuity for that option so hopefully (the two new wells plan) works.”
Gain also said the city also work with Zone 7 to ensure the new wells align with the local groundwater basin management plan and minimize potential PFAS contamination, while also exploring the possibility of working with the water agency, which is also looking at constructing similar wells in that area of the sub-basin
“They’re also exploring installation of new wells in a similar area,” Gain said. “Staff will investigate possible opportunities for coordinated implementation, which could yield cost savings.”
Staff told the council that if the city does partner with Zone 7 in the future, both agencies could see a 15% to 20% reduction on overall costs.
That possibility of working with Zone 7 to build the two wells as a joint project that would be owned by both agencies was one of the main talking points for council members who said they think it would be the best option moving forward.
Staff said that as Zone 7 continues its process of determining the viability of the two locations for new wells, the city will have to agree on coming up with some type of agreement with the water agency to officially partner with them.
“I’m really hopeful that we have a joint cooperative approach that can solve problems for both of us,” Councilmember Jeff Nibert said during the meeting.
“I also just wanted to express my thanks to Zone 7 for the partnership that potentially we will have, to do this, but also their vote unanimously of their board to accelerate the groundwater basin study which we need,” Vice Mayor Jack Balch added.
The other main talking point was the costs for the two new wells, which staff said the design and construction work could be anywhere from about $23 million to up to $42 million. The actual costs will be brought to the council after the design work is completed, according to Gain.
“As we continue to progress with designing alternative three to new city wells, that level of certainty will become much more clear as we continue to figure out siteing and specific requirements,” Gain said.
The council already allocated $500,000 during the Oct. 17 meeting for administrative activities, developing agreements, monitoring and working with Zone 7 on its modeling efforts.
Staff said that if the city pivots to the Well 8 treatment plan next year, the sunk costs could be anywhere up to $1 million but would mostly come from the $500,000 that was allocated that night and any money spent on drilling the test wells next year.
That money for the preliminary design work will be moved from the city’s water enterprise fund balance to the water replacement capital improvement program.
If the city decides to pivot to the Well 8 treatment plan, staff are estimating the cost being anywhere from $29 million up to $34 million.
That’s why staff and the council reiterated that partnering with Zone 7 should be the path moving forward so that the city could save more money.
“I’m really hoping we will find a way to reduce some of these costs and not obviously pay for our two wells and their two wells and all of that,” Balch said. “I’d rather us find a path forward, especially for design and, and well drilling costs.”
Despite Gain saying that city staff will be working to secure grants and seeking federal funds, including loans to reduce the impact on ratepayers, regardless of the alternative that is selected, Balch said he will be looking forward to more studies to see how the city will be paying for these options.
“None of this will be easy and none of this is inexpensive,” Balch said. “So I look forward to a full and frank rate study, where we are very transparent with our public as to what needs to go in and how we will be looking to finance this.”
I just want to remind everyone that our cost could be 10 million less, but our city council decided to spend 10.4 million on upgrading an existing skatepark and upgrading century house. Just food for thought when you vote in 2024. Arkin and Brown supported both of those budget items.
What could be the source for the PFAS plume in east Pleasanton? The garbage landfill, the Airport, or something else???
It is not a simple test to determine the direction and distance the PFAS plume will travel in the aquifer, Pleasanton wells, and proposed future well pump locations. The level of PFAS may be acceptable with today’s standards west of the current plume location in east Pleasanton. In a few years, it may not be. Zone 7 is currently engaged with modeling the plume.
The PFAS predict tool is different from similar modeling software because it focuses on the unique mobility of PFAS in groundwater. The program has options to scale dispersion processes based on observed PFAS groundwater plumes. The model simulates advection, degradation, sorption, and source release options. It is compatible with industry-standard MODFLOW groundwater models for remediation, system design, risk evaluation-remediation system design source verification.
MDFLOW: A computer program that simulates the flow of groundwater through aquifers.
Risk Evaluation: The model predicts how the PFAS plume is likely to move through groundwater and allows evaluators to determine whether specific wells or groundwater receptors are likely to be at risk as the plume migrates.
Remediation system Design: System design can simulate pump-and-treat operations and predict how the plume will respond to the treatment.
Source verification: The model allows backward tracking of plumes to determine the likely
source (s) of contamination and enables apportionment of responsibility for plumes with multiple sources.
The hydrophobic nature of PFAS molecules makes them repel water. PFAS molecules have a chain of linked carbon and fluorine atoms. Thus, PFAS are attracted to carbon-which enhances plume migration. If the aquifer/bedrock in west Pleasanton is loaded with carbon, the plume will go there. It will flow in the direction of least resistance and attraction, covering a greater area.