Answering questions about the I-17 Regional Drainage System

ADOT announced in July the new Interstate 17 Regional Drainage System between Dunlap Avenue and Greenway Road in north Phoenix is fully operational in time for this summer’s monsoon. Construction started in summer 2020. Our Public Information Office checked in with Jimmy Naujokaitis, ADOT’s senior resident engineer on the challenging project, to get his perspective on the new system:

ADOT: Jimmy, what’s the biggest benefit of this new drainage system?

Jimmy Naujokaitis: It’s the removal of the existing pump stations and simplification of the drainage at the cross streets. Now that we don’t have to rely on mechanical means to remove storm water from the underpasses, the dependability of the drainage infrastructure has significantly increased, given that gravity will be the main driver of the system. While routine maintenance will always be necessary, not having to rely on these antiquated pump stations along this stretch of our freeway system is certainly a step in the right direction.

ADOT: Tell us a little more about the pump stations that were removed.

Jimmy Naujokaitis: Compared to the age of the rest of our infrastructure in the Valley, the pump stations range from “old” to “very old.” Since their original construction back in the 1960s, the Valley has changed significantly. With more concrete and asphalt surfaces in the area, more storm water finds its way to the underpasses at Peoria Avenue as well as Cactus, Thunderbird and Greenway roads in less time. That had increased the chances of these facilities being overwhelmed by storm runoff. Our engineers have designed the new system to better handle significant storm events. The new system is gravity controlled, which means the new pipelines were installed at angles that allow the stormwater to move without pumps.

ADOT: And the project team also constructed new detention basins on the east side of I-17 at Thunderbird Road?

Jimmy Naujokaitis: Yes, the basins were excavated as part of the new system. The basins located north and south of Thunderbird Road collect stormwater from the Greenway Road and Thunderbird Road underpasses, respectively. Once the basins fill to a certain point, the water will then begin to drain out into pipes that were tunneled underneath I-17, as part of this project, and into the new system’s mainline, which empties into the Arizona Canal Diversion Channel that is located to the north of Dunlap Avenue.

ADOT: How does it feel to have this new system in place?

Jimmy Naujokaitis: I think I can also speak for both our vacuum truck and pump station maintenance crews when I say we are glad the old pump stations are a thing of the past. Given the size of the pipes we needed to install, at the depths in which we needed to install them, and the tight quarters in which we had to work within, the project was quite the undertaking and didn’t disappoint in being a challenge. Thankfully, we already saw the fruits of our labor last monsoon (2022). We didn’t need to close the Peoria Avenue and Cactus Road underpasses, both of which were switched over to the new gravity-powered system last summer. While no system can guarantee that flooding at these underpasses will be eliminated, the new system has dramatically changed the outlook along this section of the I-17 corridor.

ADOT: Anything else you’d like to say regarding the project?

Jimmy Naujokaitis: On behalf of the Department, we’d genuinely like to thank all the business owners, residents, and other entities that cooperated with us throughout the duration of the project. Crews are still in the area to finish landscaping and other minor work, but the need for long-term closures is finally behind us, and we sincerely appreciate the patience exercised by the neighborhoods surrounding the project. We’d also like to thank our public partners at the city of Phoenix, APS, the Flood Control District of Maricopa County and the Maricopa Association of Governments, to name a few, for working with us throughout the course of the project.

For more information about ADOT projects, please visit azdot.gov/projects.