1501 Page Mill Road Incident Update

Published on March 10, 2025

New details are available closing out the 1501 Page Mill Road hazardous materials response that occurred last October. Click on the accordion below. Additionally, a new dedicated webpage provides a central location to track hazardous materials responses and offers a sign-up to receive initial fire response email notifications.

March 10, 2025 UPDATE & FAQs

What was the cause of the 1501 Page Mill Road spill into the Matadero Creek and the confirmed amounts spilled?

The discharge originated from non-routine work inside the building when a computer cooling system was drained in preparation for work to be performed on the feed and return pipe of the system. The pipe was drained into a tank containment area drain that was tied to the storm drain system. Inaccurate engineering drawings (as-built plans) showed the drain was connected to the sanitary sewer line when in fact, it was tied to the storm drain line.

As noted in our update on October 25, the confirmed spill amounts are below.

 

Are there other environmental details known about the spill such as other testing results?

None that we have not already reported and shared on this same webpage.

Is there a map that shows the potential path of the spill into the drainage system?

The map below provides the storm drain system in the City’ s right of way. Tesla is mapping their private storm drain system per City requirement to prevent and mitigate future incidents and understand potential risks to Matadero Creek and the City’s storm drain system.

Is there a prevention plan in place with Tesla?

Yes. Tesla is required to have an emergency response plan. Also, as noted below, City staff and Tesla meet weekly to ensure prevention of future drainage or spills.

What fees and/or fines were imposed on Tesla for the October discharge?

The City issued a multi departmental notice of violation and citation for the October 17, 2024 unauthorized drainage. This violation notice outlines required fees and possible fines should Tesla not comply.

What other relevant information about prevention or the prior spill at Tesla that could be helpful to the public?

• The City has changed its hazardous material response notification protocols. Go here for the City’s Hazardous Materials Notifications page, sign-up to receive future notifications should there be a hazardous materials response by the Palo Alto Fire Department and review past spill information and details in one location.
• Prevention planning with Tesla continues and includes weekly inspections and bi- weekly meetings between the Fire, Planning, and Building Departments and Tesla staff.

NOVEMBER 4, 2024 UPDATE:

Thanks to the residents that attended the 1501 Page Mill Road neighborhood meeting on Friday, November 1. Several residents shared appreciation for the meeting and the summary below offers details shared at the meeting.

Following a short briefing, City Manager Ed Shikada, Chief Blackshire, Fire Marshal Jasso, and Chief Communications Officer Horrigan-Taylor answered community questions and took note of community concerns raised. 

While the spill itself was not a serious incident, it provides a valuable opportunity to review circumstances, explore changes to prevent reoccurrence and improve our response and communications to incidents in the future.

Brief overview of the incident:

• On Thursday, October 17, a suspicious liquid on Hanover Street was reported by 9-1-1 call. Tesla did not contact the City initially, though did report to California Office of Emergency Services.
• PAFD responded and determined by field testing observed by the Fire Department that the liquid was not hazardous and proceeded with containment and clean-up activities.
• Over the next several days, the area and level of activity required for the clean-up grew beyond initial expectations, leading to public notifications on Wednesday, October 23, with clean-up completed on Friday, October 25.

Meeting Summary:  The following is a summary of the issues raised organized by general topic, and responses provided by City staff.

Natural creek environment and storm drain system impacts, and the status of the investigation and remaining testing underway:

• Questions were raised regarding the area affected by the spill and composition of the liquid released.
• Tracking of the liquid through the City’s storm drain system is a part of the ongoing investigation, including confirming that the substance did not reach the natural part of Matadero Creek. Based on review to date, it appears that the substance went from Tesla’s private storm drain pipeline through to the concrete channel of the City’s storm drain.
• Remediation and clean-up included flushing of both Tesla’s pipeline that connects to the City’s storm drain system and the City’s storm drain system near Hanover Street.
• The next day following initial clean-up at the Page Mill Road property and Hanover storm drain areas, staff noted substance at or near the concrete channel of the creek system had pooled near Park Boulevard, resulting in much of the clean-up focus.
• The solution make-up of water and the substance specifically is: Bright Dyes FLT Yellow/Green Liquid, a non-hazardous coloring commonly used to aid in leak detection.  It has a bright yellow/green hue to aid in visual tracking and is highly water soluble. Meras 1020 is composed of Disodium Tetraborate pentahydrate (1-2%), and Sodium hydroxide (less than 1%). Staff concluded that 916 gallons of the solution was drained with 5.9 gallons of the solution being Meras 1020. This calculates out to 7.59 ounces of Sodium Hydroxide, a concentration of 0.00647% and 15.17 ounces of Disodium Tetraborate Pentahydrate, a concentration of 0.01294%. This level of concentration supports findings to date that the solution does not pose a risk to life or health.
• The investigation underway includes a final round of testing to determine any residual amount of the substance from the Tesla facility to confirm conclusion of the incident. This test is the standard for the toxicity of any materials that may have been left in the water. [11/4/24 UPDATE: The results of the fish bioassay testing confirmed that the water is non-hazardous for aquatic life.]

Tesla’s reporting and permitting, and clarity about City enforcement and prevention:  

• Physical changes at the Tesla facility have been implemented immediately following the drainage on Thursday, October 17 to prevent drainage from occurring again, with the drain involved plugged. Tesla does not have a permit for storage of the substance drained.
• Permitting requirements and issuance of any corrective actions as any regulatory actions are needed is pending. The investigation underway may conclude enforcement action is justified, as well as additional City/Tesla coordination and inspections to prevent spills in the future. Several City departments will work together to help bring Tesla into compliance, including Fire, Building, Planning and Public Works.
• There was a question about connection to a Creek/Steam Corridor Ordinance update underway.  That effort is focused on riparian corridor protections. To follow progress, gain regular updates by signing up for email updates, and learn more as an early 2025 community meeting details are released, go here.

Improved communications and setting protocols:  

• Understanding safety and environmental concerns, staff will increase public notifications for any significant incident involving potentially hazardous materials.
• Staff is establishing tiered communication protocols based on incident severity including reporting procedures, and communication methods/strategies.

OCTOBER 29, 2024 UPDATE

An in-person neighborhood meeting is planned for the neighborhood areas of North Ventura and Barron Park for Friday, November 1 at 5 p.m. City officials and Palo Alto Fire Department leadership will provide a briefing on the 1501 Page Mill Road incident and answer community questions. Gain Neighborhood Meeting Details

OCTOBER 25, 2024 UPDATE, 8:45 P.M.

This update shares more about the test results and status of operations. 

Test Results of Spill Substance 

Staff continue to review the initial sampling test results and PAFD has confirmed both the volume and concentration of the materials. In total, 916 gallons of the solution was drained with a 0.647% concentration of Meras 1020.  This continues to support findings to date that the solution does not pose a risk to life or health. 

Operational Details 

 At 2:00 p.m. today, in an unrelated incident, a fire hydrant was hit on El Camino Real near the Matadero Creek, resulting in a large volume of water flow into the creek. Fortunately, the spill cleanup was almost complete. With this level of dilution, staff has stopped any additional cleanup efforts. Naturally occurring green algae remains in the creek, which may generate some resident questions. This has been evaluated and poses no risk to life or health. A final round of testing is underway, and results are expected to take at least a week. 

OCTOBER 25, 2024 UPDATE, 2 P.M.

This update shares more about the test results, noticing, and ongoing work.

Cleanup work continues off Park Boulevard with work out in the residential areas from 8 a.m. to 8 p.m. with weekend work planned.

Test Results of Spill Substance

As noted in our update on October 24, the Palo Alto Fire Department (PAFD) received test results of initial sampling confirming the substance, at the levels of concentration observed, is not a risk to life or health. The results of sampling from the point of discharge of the spill indicate the liquid released is non-hazardous in nature, with additional documentation provided to PAFD indicating the spill consisted primarily of Bright Dyes FLT Yellow/Green Liquid, Meras 1020, and water. The exact quantities of the materials released are still being determined with an update provided when available.     

• Bright Dyes FLT Yellow/Green Liquid, is a non-hazardous coloring commonly used to aid in leak detection.  It has a bright yellow/green hue to aid in visual tracking and is highly water soluble.
• Meras 1020 is composed of Disodium Tetraborate pentahydrate (1-2%), and Sodium hydroxide (less than 1%).

Operational Details & Public Notifications

PAFD worked quickly with Tesla to contain and remediate the substance following the 9-1-1 call notification. That same evening, PAFD determined the substance was not a risk to life and health and the scene was transitioned from a hazardous materials emergency incident to a stable clean-up effort.

Weighing several factors including the rapid transition and progress of remediation and clean-up at all sites, and understanding that clean-up efforts would remain limited to industrial areas both at 1501 Page Mill Road and the concrete lined Matadero Creek channel near the Park Boulevard intersection, staff was focused on incident stabilization. Residential notifications occurred the day that clean-up activities affected the North Ventura neighborhood.

In hindsight and with appreciation for the input received since, staff recognizes that we should have made public notifications sooner.  We apologize for our delay in making notifications.

Next Update

An update will be provided upon completion of clean-up activities and secondary testing to validate the clean-up effort and conclusion of the incident. 

OCTOBER 24, 2024 UPDATE

In response to community questions about the hazardous material incident that occurred on Thursday, October 17, additional items on this matter are noted below. As a reminder, this continues to be an active investigation. 

TIMELINE/RESPONSE 

The hazardous materials incident was initially reported via 9-1-1 call on Thursday, October 17 around 5:00 p.m. PAFD responded to 1501 Page Mill Road noting a green liquid substance flowing into the street; initial field testing determined the substance was not a risk to life and health. Protocols for a hazardous material incident were followed including reporting details to the California Office of Emergency Services (includes notification to Valley Water, California Fish and Wildlife, etc.). Valley Water confirmed notification and has been in communication with PAFD Haz Mat Investigator. An initial estimate of 500 gallons of water and the spilled substance was reported. Containment, remediation, and clean up concluded at 1501 Page Mill Road on Friday.   

Continuous PAFD visual inspection of the creek at various storm drain/creek locations to monitor the situation and residual impacts were conducted and secondary locations were identified around the concrete lined channel of Matadero Creek near Boulware Park to the industrial area near Park Boulevard. Clean-up was initiated on Friday, October 18 and originally estimated to be complete by Monday, October 21.  

Early on Tuesday, October 22, increased clean-up efforts were required in the North Ventura neighborhood.  This was due to an unrelated natural watershed flow upstream that increased creek flow.  Resident notifications were provided on Wednesday, October 23 at approximately 5 p.m. Clean-up near this location continues. 

What was spilled and where?  

The hazardous materials response occurred at 1501 Page Mill Road. 

Tesla reported 12 gallons of the substance released into the storm drain. The substance continued through the concrete lined Matadero Creek channel to the area near Boulware Park, and was confined to a lower channel with no contact with the natural areas of the creek.  The quantity of release remains under investigation. Tesla indicated the substance is sodium hydroxide, a common additive to water in cooling systems. Staff sent samples for testing and results typically take one to two weeks. Initial testing results have been received today and are under staff review. Preliminary review substantiates initial field determination that the substance is not a risk to life and health. Secondary testing is planned after clean-up is complete to validate clean-up effort. 

What are the City’s next steps? 

In addition to cleanup, an investigation of the cause is under way.  Storage of sodium hydroxide requires a City permit, which Tesla had not obtained.  Staff will complete its investigation upon completion of this incident and appropriate regulatory actions will follow, including reimbursement for remediation and clean-up costs as well as potential fines. 

When is clean-up expected to conclude?  

At this time, clean-up of the secondary location in the concrete line channel near Park Boulevard is anticipated to conclude this weekend. Clean up from Lambert towards El Camino is complete though a pump is diverting watershed water towards Park Boulevard outside the clean-up area.  

INITIAL OCTOBER 23 UPDATE

Late last week, Palo Alto Fire Department responded to a hazardous materials incident at 1501 Page Mill Rd in Stanford Research Park, the former HP and current Tesla property. Initial hazardous material containment and clean-up is complete at the incident location, with testing of the substance underway. Importantly, it has been determined that the substance is not an immediate threat to life and health.

PAFD has identified areas east of the initial spill near Park Boulevard, Lambert Avenue and Ash Street, for remediation and additional clean-up, with anticipated work continuing into next week. While initial work was limited to industrial areas, PAFD was notified late Tuesday of work shifting closer to residential areas, with notifications occurring Wednesday. No 24-hour work will occur in residential areas, with authorized weekend work.

The investigation is ongoing and coordination with various agencies continues.