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Bull Run Filtration Pilot Answers Key Questions About Treating Our Water

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The Bull Run Filtration Project will help keep Portland water clean, safe and delicious for generations to come.
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Scaling up to more robust operations is near impossible if you don’t have a strong foundation to build upon. After a year of trial and error the Bull Run Filtration Pilot team has found some successful recipes for filtering water in the Bull Run Watershed. It was a year filled with tinkering, teamwork, and tenacity. The year-long study provides the regulatory data the Oregon Health Authority needs to allow the project to move forward. Here are some of the key breakthroughs that laid the groundwork for the future filtration plant, which is set to be fully operation in 2027.

How does filtration treatment affect disinfection byproducts?

Water Quality engineer stands at desk with laptop and measuring device in one hand.
Anna Vosa getting results showing a dramatic drop in DBPs after running water through our filtration system.

Disinfection byproducts (DBPs) are potentially harmful materials created after chlorine reacts with certain types of organic material. The pilot team knew filtration would reduce DBP levels. Finding out exactly how much would require a series of simulated tests.

Anna Vosa with Water Quality says the team’s filtration methods “significantly reduced all DBPs regulated by the EPA to very low levels, easily meeting our project goals of cutting DBPs by more than 50 percent.”

What type of filters should we use?

Water Quality Engineer Mac Gifford describes choosing the right filtration rate like a driver on the highway setting their speed control, “too fast can lead to losing control, but too slow and you may never arrive to your destination.” By “test driving” the different filtration materials and rates the pilot team compared their effectiveness in real time. “The breakthrough we found was that anthracite and granular active carbon both work very well for our water.” While both are effective, anthracite is less expensive, so it was chosen to help control costs of the full-scale facility.

How did we learn to coagulate our water?

Coagulation neutralizes the charges of particles in raw water, bunching particles together which makes it easier to remove them during filtration. Chemical Engineer Mojtaba Azadiaghdam says the pilot team’s current coagulation and flocculation procedures “remove more than half of the organic matter that could otherwise react with chlorine and produce harmful disinfection byproducts.” Experimentation is ongoing, but once the right coagulant is selected it will give the design team guidance on how many chemical tanks and pumps are needed for the full-scale plant.

What is the value of ozone?

The team knew off the top ozone was a key ingredient to treating water in the filtration pilot, but how much to add and when to inject it wasn’t a simple equation to solve. “The ozone module is arguably the most complex and difficult to operate unit we have,” said Melanie Roy, Water Quality Assistant. The team worked tirelessly to troubleshoot and resolve equipment issues. The payoff was clear to see as ozonation made the filters more productive, reduced the DBPs in the water, and lessened the need for chlorine.

What did we learn with the spiking study?

Four people with masks stand around scientific table talking
Environmental Specialist Tom Krause goes over the daily agenda with the spiking team.

Right now, a major storm in the Bull Run Watershed could mean we’d draw exclusively from the Columbia South Shore Well Field. This is because a spike in turbidity from storm runoff may compromise water quality in the Bull Run. Filtration aims to improve that level of service. A spiking study was needed to simulate water conditions after a storm, which allowed the pilot team to find Anna Vosa getting results showing a dramatic drop in DBPs after running water through our filtration system. The results from a turbidity simulation that took water from 100 NTUs to just .1 NTUs.

What’s next?

The pilot team is now summarizing results of the pilot study to be submitted to gain regulatory approval from OHA. Once approved this information will be used in the design of the full-scale facility. Experimentation will continue and the pilot team will work on the best ways to manage disinfection and corrosion control. The Pilot will also be used to train treatment operators and develop staff expertise. Many thanks to the whole pilot team and other staff at PWB and the consultant team who worked so hard on this project.