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Water treatment pilot plant construction begins in February

Archived News Release: January 27, 2023 - Water treatment pilot plant construction begins in February

During the past several months, the City of Ann Arbor has been working on a facility plan to rehabilitate the city's Water Treatment Plant (WTP). The city will be rehabilitating the softening technology some of which dates back to 1938. The WTP Facility Plan purpose is to evaluate the plant's operational, maintenance, and regulatory needs, both now and into the future. The city will continue to provide its reliable, award-winning water throughout this process. For more information, visit the project website.

To help the WTP planning team have full confidence in the recommended technology, the WTP facility plan includes a pilot plant. A pilot plant is a smaller-scale plant that tests water treatment technologies before it is implemented at full-scale. Pilot testing processes include frequent online analytics and in-lab testing to determine if the process is suitable for the ultimate, large-scale plant design as predicted. The source water for the pilot plant is the same that Ann Arbor uses in the full-scale water treatment plant. The pilot plant will be used to test removal of contaminants in our raw water source. Treated water from the pilot plant does not enter the city's drinking water distribution system as this is a test process only.

Why does this project need to use a pilot plant?
Pilot plant testing is important in determining if the selected technology will adequately address current and anticipated water treatment needs. Pilot testing will compare the results of different approaches to soften the water - namely single-stage softening process versus two-stage softening process used by the city at the existing full-scale water treatment plant. Softening removes calcium and magnesium hardness from water. Once pilot testing is complete, WTP staff will decide which technology will be used going forward. To copy or mimic treatment at the full-scale facility, additional treatment steps are included in the pilot plant after softening, including ozonation and filtration. This allows WTP staff to observe if or how the different softening processes affect downstream treatment provided at the plant.  

What will the pilot plant look like?
The pilot plant with be enclosed within a two-story building. The tank used for softening is called a clarifier and has a diameter of 11 feet, and a height of 11 feet. Piping will be built to deliver Huron River water and well water to the softening clarifier. Softened water will be piped to our existing pilot filters and then back to the new enclosure for ozonation.

Where will the pilot plant be located?
This plant is being built within the fence line of the existing water treatment site on Sunset Road.

When will the testing take place?
Pilot plant testing will continue for approximately one year. Construction will begin in February, with testing beginning in May.

What will go into the construction process?
Some construction noise is anticipated, and occasionally trucks will be coming and going from the WTP. The operation of the pilot plant itself will have minimal neighborhood effects. Once pilot testing has been completed, the city will investigate plans for rehabilitation of the full-scale plant. No specific dates have been determined.

Can I visit the pilot plant once the construction is complete?
Yes! The WTP hosts an open house in May each year for National Drinking Water Week. It is also possible to request a  Water Treatment Plant tour for groups of 5-15 people. Please visit the WTP website for more information.

Ann Arbor has 123,851 residents, spans 28.97 square miles and is frequently recognized as a foremost place to live, learn, work, thrive and visit. To keep up with City of Ann Arbor information, subscribe for email updates, and follow the city on Twitter and Facebook. The city's mission is to deliver exceptional services that sustain and enhance a vibrant, safe and diverse community.