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The Beulah Park wastewater treatment system was built in the late 1990’s to replace failing septic systems.

It serves several dozen households on Vashon Island. The system is designed to treat a maximum of 14,520 gallons of wastewater a day. On average 5,274 gallons of wastewater are treated a day.

drain field signageBeulah Cove drain field

View more photos on our Flickr site  .

How it works

Wastewater is collected by a vacuum pump station, treated, disinfected, and then percolated through a drip field at the corner of Southwest 172nd Street and 136th Place Southwest.

  • Preliminary treatment: where trash is removed from the wastewater.
  • Biological treatment: next, the water goes to an oxidation ditch where hungry "bugs" eat up contaminants. The water then flows to a clarifier which acts like a giant bathtub and the solids fall to the bottom. The clean water is ready to move to disinfection.
  • Disinfection: (ultraviolet light) destroys most remaining pathogens, or disease-causing bacteria before the final effluent is released through an outfall pipe and diffuser into Puget Sound.
  • Solids removal: the solids are stored, settled, and loaded into tanker trucks and taken to the South Treatment Plant in Renton for solids handling. They are ultimately recycled in various beneficial ways.

Take care of your system!

  1. Flush only human waste and toilet paper. The treatment system treats human waste with sensitive biological processes. The system can be negatively disrupted by materials you put down your drain. Never put grease, coffee grounds, caustic chemicals, facial, or cleaning wipes into your drain.
  2. Use water wisely, conserving when you can.
  3. Limit garbage disposal use. A garbage disposal can lead to a significant increase in solid matter build-up, they are not recommended for use in your system.
  4. Take care of the drain field (download print version ).
    • Don't dig, drive stakes, or plant anything on the drain field.
    • Pick up after your pets.
    • Help keep invasive plants of the drain field. Grass is the best cover for the drain field. The roots of trees, shrubs, and invasive weeds can clog the drain field.
    • Report anything unusual. Odors, ponding, or exposed pipes may signify a problem. Report problems 24-hours a day at 206-263-1760.
  5. Report problems. If you notice decreased performance, smells, or have other concerns about the function of the sewage system call:
    • For treatment plant or drain field problems call King County at 206-263-1760.
    • For vacuum collection system problems call the Vashon Water and Sewer District at  (206) 463-9219.

Learn more about the Beulah Park plat wastewater treatment system .

Contact us

24 hour emergency and odor reporting:   206-263-1760
Administration:  206-463-7318

9615 S.W. 171st St.
Vashon, WA 98070

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