Charting a Course Toward DPR

Indirect potable reuse has been practiced in Arizona for some time but recently direct potable reuse (DPR) has gotten a lot of attention. Brown & Caldwell’s Katie Vanyo explains why focus has shifted and how one city is preparing for change.

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Indirect potable reuse has been practiced in Arizona for some time but recently direct potable reuse (DPR) has gotten a lot of attention. Katie Vanyo, an environmental engineer with Brown and Caldwell, tells WaterWorld why focus has shifted and how one city is preparing for change.

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WATERWORLD: Arizona’s attitude toward DPR has shifted recently. Can you explain why?

KATIE VANYO: As of January 1, 2018, the Arizona Department of Environmental Quality (ADEQ) lifted the ban on direct potable reuse. There were a couple of drivers behind that, of course. As we progress into the future, finding those sustainable water supplies [will be important] but also the technology is there, it’s proven. Now we just need the regulation behind it.

WW: Brown and Caldwell has been working with the city of Flagstaff on a feasibility study. Tell us a little bit about that and why it was done?

KV: The city of Flagstaff, Arizona, is currently evaluating its future water supplies. They have a couple of options on the table, one being a groundwater source about 40 miles east of town. And direct potable reuse is also on the table. What they’re planning to do is look at all of these different alternatives and compare them on an apples-to-apples basis to really find out what’s best for the city.

WW: What kinds of treatment technologies did you evaluate in your study?

KV: We looked at two different alternative treatment trains. One was an RO-based treatment train with full advanced treatment, traditionally called FAT. But particularly with that RO-based treatment, you have that concentrate stream that you have to deal with and that’s very costly, especially for inland communities in Arizona. So, we also looked at an ozone biologically activated filtration-based treatment train and actually compared those on a cost basis as well as on a land-use basis.

WW: The study also had a public outreach component to it. What did that entail?

KV: First off, I’d like to say that Flagstaff is doing great with its public outreach. They’ve been doing it for a while now. But our study did include a [public outreach] component. Our [objective] was to interview key stakeholders in the community, a large diverse group of people, to really get a feel for, one, are they aware of future water supply planning; two, what are their general feelings on reuse; and three, are there any concerns. The general feel from the public was very positive. They’re very comfortable with reuse. They expressed concerns with pharmaceuticals and they did express some preference towards indirect potable reuse but what I love about this community is that they expressed a desire to receive more information and more education to really understand what’s going on.

WW: What’s the current status of Flagstaff’s water reuse plans?

KV: The city of Flagstaff is working on a pilot for DPR and waiting for the study to be finished to compare this to another water supply alternative. If they do go with DPR, they’re taking all the right steps to get there. WW

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