Project Overview

What the facility would include

• Battery modules housed in prefabricated enclosures (standard utility-scale BESS design)
• Thermal management / cooling systems (type depends on battery chemistry selected)
• Fire detection and suppression equipment
• Inverters, transformers, and substation
• Perimeter fencing and security gates
• 115kV generator tie-line to Mt. Si substation

Jupiter Power

Founded 2017, acquired by BlackRock (Diversified Infrastructure) in late 2022. About 8,000 MWh of battery storage operating or under construction, 12,000+ MW battery storage pipeline.

They’re also behind the Blackberry Grove project (100 MW) near Hillsboro, Oregon, the most contested land use case in Washington County history, opposed by the No Batteries In Backyards group.

In 2025, Jupiter Power signed a $500 million / 4.75 GWh supply agreement with Peak Energy for sodium-ion batteries, a chemistry that has shown no thermal runaway in abuse testing, with reduced toxic emissions and passive cooling. CTO Mike Geier called it a “potential game changer.” The company proposing lithium-ion for Snoqualmie Ridge is spending half a billion dollars on the technology that would fix the problems Snoqualmie Ridge is worried about.

PSE tolling agreement

PSE ran a voluntary All-Source RFP in July 2024 (UTC Docket UE-240532) for CETA-compliant resources and got 98 proposals. The Cascadia Ridge tolling agreement was signed August 22, 2025 and filed with the UTC on September 19, 2025. The financial terms are entirely confidential.

PSE needs storage to hit its CETA targets: up to 2.3 million annual MWh from clean resources by 2030, and up to 1,755 MW of summer peak capacity by 2029. The alternatives are overbuilding generation (expensive, and ratepayers pay for it) or keeping fossil fuel peakers online (which violates CETA).

PSE’s own siting study did not recommend this location

In 2020-2021, PSE hired Power Systems Consultants (PSC, Kirkland, WA) to conduct a qualitative and quantitative analysis of where to site energy storage across PSE’s transmission system. The study screened all ~382 PSE substations and identified the best candidates based on electrical capacity, substation configuration, surrounding land use, and environmental constraints. It was filed as Exhibit I in UTC Docket UE-210220 (PSE’s 2021 All-Source RFP). Full study (PDF).

Mt. Si substation was screened out on the merits. The substation had been operational since 2012, eight years before the study was conducted. It was not among the 36 candidates that passed initial screening, not among the 20 that received quantitative analysis, and not among the 15 final recommendations. The study required either 230 kV non-radial service or more than 4 lines of 115 kV non-radial service; Mt. Si is 115 kV only and did not qualify. The nearest Snoqualmie-area substation (“SNOQ SW”) was evaluated and rated high risk (red), meaning it was unsuitable for ESS interconnection. The Snoqualmie Falls station was called out by name as an example of a location that met electrical requirements “but clearly it is not a desirable location for additional development.”

The study’s siting criteria included a “Good Neighbor” test that flagged residential proximity as a problem:

• “Highly residential areas, constraints for possible transmission rights-of-ways to the PSE station, schools, hospitals, and other notable land uses indicate that that specific PSE station was less desirable as a practical location to interconnect an ESS.”
• “Early involvement of the public in the development process is a must and the public should be encouraged to provide constructive input and alternative projects/locations.”
• “The public knows their neighbourhood best and can suggest minimum impact alternatives.”
• “Land use should be reasonably consistent with its present use.”

The study identified 15 substations across western Washington that passed both qualitative and quantitative screening, with total maximum ESS capacities ranging from 9 to 86 MW. The recommended locations include White River (86 MW), Tono (85 MW), Alderton (76 MW), Midway (56 MW), and Sammamish (46 MW). None are in the Snoqualmie Valley.

Four years later, PSE signed a tolling agreement for a 130 MW facility at Mt. Si, a substation its own consultant screened out on the merits.

What Jupiter Power has not disclosed

As of April 2026, the following have not been publicly disclosed for the Cascadia Ridge project:

• Battery chemistry. Jupiter Power has narrowed the field to “lithium ion (LFP) or sodium ion” (April 1, 2026) but has not committed. The choice determines thermal runaway risk, toxic emission profile, cooling requirements, and noise. PSE’s tolling agreement is largely redacted, so the actual contract requirements are unknown. PSE has confirmed the agreement lists a specific battery brand and model number but includes “or similar technology” language.
• Atmospheric dispersion modeling. No study of toxic gas concentrations at nearby schools, along Snoqualmie Parkway, or in surrounding neighborhoods under valley inversion conditions.
• Fire suppression system type. Water, aerosol, hybrid? The Moss Landing fire began after a suppression system failed.
• Setback distances from property lines and the nearest residences on Snoqualmie Ridge.
• Deflagration venting design. The McMicken explosion in Arizona occurred when flammable gas accumulated in an unvented container.
• Emergency response plan. What mutual aid agreements exist with local fire departments? Has a tabletop exercise been conducted? Eastside Fire & Rescue has stated it “cannot confirm” preparedness.
• Decommissioning plan. How will batteries be removed and the site restored at end of life?
• Environmental monitoring plan. Will there be permanent air quality monitoring at the fenceline? Soil and water monitoring near Fisher Creek?
• Hydrogeologic assessment. No study of groundwater impacts despite dozens of private wells surrounding the site.

Jupiter Power’s project website and open house handout (16 pages, PDF) focused on general BESS safety statistics and code compliance. The presentation covered industry growth, generic safety layers, and community benefits (tax revenue, park land, construction jobs) but provided no site-specific details on chemistry, noise, setbacks, or environmental risk. The handout does not mention battery chemistry once.

Jupiter Power provides a project email address (cascadiaridge@jupiterpower.io). On April 1, 2026, Jupiter Power responded to questions submitted before and after the open house. The response addressed fire safety measures (monitoring, suppression, spacing, code compliance, fire agency coordination) and stated that battery chemistry “has not yet been selected” but is expected to be “lithium ion (LFP) or sodium ion.” This is the first time Jupiter Power has acknowledged sodium-ion as a possibility for this project in writing. Questions on setbacks, noise, the canceled permit, financial assurance, parcels, decommissioning, critical areas, and other site-specific details were deferred to “the final application materials.” Jupiter Power committed that “all project design, environmental diligence studies, and decommissioning plans will be made public during the SEPA checklist review.”

On April 6, 2026, Jupiter Power’s VP of Development Hans Detweiler and lead engineer Tom Walkinshaw met with a community researcher. Key disclosures from that call:

• Permit cancellation reason: King County required “issued-for-construction” drawings that Jupiter could not produce within the county’s timeline. They plan to file a clearing and grading permit instead, which will also initiate SEPA.
• Duration: Either four or six hours (undecided).
• Gen-tie parcel: Parcel 9030 (PSE-owned) provides the generation tie-line corridor to the substation. This parcel is subject to the PADA use restrictions between PSE and the City of Snoqualmie.
• Noise: Site-specific modeling shows 50 dBA or less at the property lines. The noise study will be included in the SEPA application package.
• Water supply: On-site water storage tanks plus a nearby fire hydrant, described as a “belt-and-suspenders” approach being finalized with Eastside Fire & Rescue.
• Chemistry: Jupiter cited sodium-ion as “not yet proven in utility-scale projects in the United States” as a factor in the decision, despite their own $500M sodium-ion supply agreement with Peak Energy.
• Ownership transfer: If the project changes hands, the project company (Cascadia Ridge Resiliency LLC) would be sold as an entity, keeping financial responsibility within the project company.

Regardless of which battery chemistry is selected, the site raises questions about toxic gas dispersion, emergency response, seismic risk, and groundwater that a SEPA checklist cannot credibly evaluate. That is why we are asking King County to require a full Environmental Impact Statement.

Community response

March 9, 2026. Residents spoke against the project at the Snoqualmie City Council meeting. Concerns included proximity to neighborhoods and parks, fire risk, noise, air and light pollution, and impacts on fish-bearing streams. Councilmember Dan Murphy: “Industrial battery storage doesn’t belong in the middle of a neighborhood.”

March 16, 2026. The City of Snoqualmie posted a statement saying it is “monitoring this proposal closely” and will “provide input at the points in the County’s review process where that input can be most effective.”

March 17, 2026. Jupiter Power held a community open house at The Club at Snoqualmie Ridge. The turnout exceeded the venue’s capacity. Traffic backed up into the parking lot, and the sign-in line was eventually bypassed. Jupiter Power used an open house format with individual information stations rather than a public forum. The crowd was large enough that the format broke down. Residents outside the venue held signs (“Who pays when it burns?”) and distributed flyers.

Jupiter Power’s presentation boards focused on generic BESS safety data (97% failure rate drop since 2018, NFPA 855 compliance) but did not address battery chemistry alternatives, the company’s own sodium-ion investments, or site-specific environmental risks (Fisher Creek, wetlands, floodplain, seismic hazard).

March 17, 2026. KOMO News covered the event, reporting that Jupiter Power is preparing a revised permit proposal. City officials told KOMO: “Residents care deeply about safety, environmental protection, and the character of our community. The city will provide input at key points.”

March 23, 2026. The Snoqualmie City Council cleared its regular agenda to take public comment on the proposed BESS facility (full meeting video). Approximately 35-40 residents spoke over two hours. The room exceeded fire code capacity, with overflow in the lobby. Mayor Pro Tem Johnson opened by saying no action was anticipated, that the council would listen, document concerns, and work through committee meetings toward next steps.

Speakers included a professional seismologist (Southern Whidbey Island Fault mapped through the valley, no seismic hazard assessment for any US BESS), a mechanical engineer specializing in failure analysis (UL 9540A certification limitations), a family physician (hospital lacks HazMat capability, hydrogen fluoride exposure risk), a financial advisor (5-20% property value decline from industrial proximity studies), and an environmental justice advocate (ESA-listed salmon, steelhead, and bull trout downstream in Fisher Creek and the Snoqualmie River).

Snoqualmie Neighbors for Responsible Energy Development (SNRED) delivered a coordinated multi-speaker presentation covering siting analysis, public health, environmental justice, economic impact, PSE franchise leverage, and process accountability. Their collective asks: a full Environmental Impact Statement (determination of significance from King County as SEPA lead), independent third-party environmental and emergency response review, a pause on permitting until risks are understood, a formal council resolution on siting standards, alternative site analysis, a council liaison for the community, and a PSE franchise review (the Mt. Si substation is in city limits and the franchise expires in 2028).

March 24, 2026. The Valley Record covered the community opposition, reporting on the March 17 open house and the city’s three news releases (March 11, 16, and 18). The article noted the city “is not seeking to block the project” but is “monitoring this proposal closely.” The article was republished in the Issaquah Reporter on March 26.

March 31, 2026. The City of Snoqualmie published a Public Summary of Community Input documenting the themes raised during public comment. The summary identified safety and emergency preparedness as “the most consistently raised concern” and documented resident requests for a full EIS, independent third-party review, consideration of alternative technologies, and evaluation of emergency response capability.

Snoqualmie’s Comprehensive Plan designates this site for “master-planned business park” and “innovative mixed use.” Not industrial battery storage. The Comp Plan puts utility and power generation uses near the city’s sewer treatment plant off Millpond Road, near SR 202.

April 6, 2026. Eastside Fire & Rescue Chief Will Aho provided a written statement that because critical details including battery chemistry, site design, fire protection systems, and available water supply “are not yet fully defined,” Eastside Fire & Rescue “cannot confirm that we are fully prepared today to mitigate an incident of this type and scale.” He called resident concerns about water supply, site access, evacuation, and final battery chemistry “valid and directly relevant to emergency response planning.” Full analysis.

April 8, 2026. A community researcher notified Mayor Mayhew and the City Council that parcel 3624079030 (a PSE-owned parcel confirmed by Jupiter Power as the project’s generation tie-line corridor) is explicitly listed in the Pre-Annexation Development Agreement (PADA) between PSE and the City of Snoqualmie. The PADA limits the PSE corridor parcels to PSE utility infrastructure. The city was asked to request a legal review of whether Jupiter Power’s gen-tie use of the parcel is consistent with PADA use restrictions.

April 9, 2026. A community researcher sent a letter to King County Department of Local Services (Director Leon Richardson) asking two procedural questions about SEPA: whether the clearing and grading permit will trigger SEPA review for the full BESS project, and when Condition 29 documentation enters the record. These answers determine whether environmental review covers fire risk, noise, and emissions, or just soil disturbance.

April 9, 2026. PSE filed suit against the Washington Utilities and Transportation Commission (PSE v. WUTC, Thurston County Superior Court) to prevent disclosure of the unredacted tolling agreement. Transparency analysis.