Project Pull Interns Get a Closeup of the Presidio Water Treatment Plant

“The whole system was there to benefit the City while it isn’t even a part of the City,” said Project Pull Intern Joe Khorge.

The SFPUC’s Project Pull Interns in the Wastewater Enterprise recently toured a facility where few young people venture to. Led by Dan Patrick, Presidio Water Treatment Plant Supervisor, the interns got an inside look of the Presidio Water Treatment Plant during Patrick’s inspection visit.

​From left to right: Project Pull interns toured the Presidio Water Treatment Plant. Ryan Young, Conner Thomas, Ubaid Shaikh, Katrina Tang, Dan Patrick of Presidio Trust, Christianne Bailey, Lizbeth Maldonado and Joe Khorge​​.

During the tour, they learned that dischargers with a flow of 25,000 gallons per day or more require special permits from Wastewater Pretreatment Programs to ensure the discharge does not interfere with Publicly Owned Treatment Plant Operations. Sediment from the raw water is treated with alum to promote coagulation of fine particles which are settled out and discharged to the SFPUC sewer system. Additionally, fluoride is added to prevent tooth decay. As beneficial as fluoride is in dilute amounts, the concentrated Hydrofluosilicic acid is highly corrosive and its use is regulated.

The San Francisco Presidio’s current plant at Baker Beach was originally built in 1910 and the buildings are listed as contributing resources to the Presidio National Historic Landmark District. Source water from Lobos Creek has been distributed to the Presidio from the site since the 1850’s. The Presidio gets its water from two sources. Seventy to eighty percent is drawn from the Presidio’s Lobos Creek, the last free-flowing natural stream in San Francisco, while the remainder is purchased from the SFPUC.

As the summer and their internships come to an end, Khorge and his fellow interns reflected on what they learned during the tour and throughout the experience at the SFPUC.

Joe Khorge (center) and Ryan Young (left) during the tour.

“The tour of the Presidio Plant opened my eyes to the real-world application of engineering courses I am taking in school. I look forward to seeing where the cross section of chemical engineering and wastewater takes me,” said Christiane Bailey.

Katrina Tang emphasized how interesting she found the step by step processes of the plant operation, how all the moving parts work together. She also compared the much smaller Presidio system to the Hetch Hetchy water system that spans the width of the State.

Ubaid Shaikh shared about how different the Presidio plant was to North Point or Treasure Island, the smaller size and the differences between treating water and wastewater.​

Lizbeth Maldonado shared, “During my time at the SFPUC’s Collection System Division as well as in my past environmental engineering courses, I have learned a ton of interesting information about the wastewater treatment process and how the effluent is ultimately discharged. It was interesting to see the water treatment process at the Presidio Plant and how they provide the entire community with potable water.”

“Visiting the Presidio Water Treatment Plant was a great opportunity to finally see the real world applications of what I’ve been learning about Civil Engineering, and I hope to have more opportunities in the future to explore those applications more,” said Connor Thomas.

Ryan Young reflected that “It was an amazing experience to get this chance to explore the Preside Plant. I loved the environment, it’s close to the beach and has many natures around it. The Facility isn’t as big as I thought it would be, but it was worth the trip. It’s similar to the wastewater treatment plant at North Point, they go through a whole process before they can disburse it. Thanks to this tour, I know how they treat their water and how each machine operates. It was a pleasure to join this tour and explore new things.”

Board of Public Works, Water, Lobos Creek