By Tom Blodgett
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Nine years ago, the driver of a lone truck on Greenfield Road in the wee hours of a weekday morning unexpectedly found a spot where the road was no longer road.

An engineering failure of the wastewater line had caused a large sinkhole in the street. The driver was fortunate: He only suffered minor injuries. The road was closed for weeks.

But that incident presented Gilbert Public Works officials with their nightmare scenario, one that may be hard to fathom for every-day residents but all too real of a possibility to the town: a catastrophic sinkhole in the Loop 202-San Tan Freeway.

Rapidly growing Gilbert is grappling with the mounting challenges posed by its aging sewer infrastructure.

Recent inspections have revealed critical weaknesses that, if left unaddressed, could lead to severe community disruptions, including sinkholes and sewage overflows.

One such inspection in October was in a line under the 202 near Williams Field Road – the SanTan Village mall area. The line was filled with holes from which raw sewage could leak as the ductile iron pipe had corroded and failed. The only saving grace was that the line was further encased in steel because of its adjacency to the freeway.

A sinkhole opening in the 202, particularly if it opened up during rush hour, would be far more consequential than one on Greenfield Road opening in the middle of the night, potentially costing several motorists their lives.

That inspection put an exclamation point on a need as the Gilbert Town Council is now considering a five-year, $230-million capital improvement plan to address these needs through the town, while also weighing how to minimize the financial impact on residents.

How Gilbert’s sewer system works

Gilbert has two main types of sewer lines to manage wastewater: gravity sewers and force mains.  

Gravity sewers rely on the natural force of gravity to transport wastewater from homes and businesses to treatment plants. These lines must be installed at a slope to maintain flow, which becomes increasingly expensive and impractical as the depth required grows. 

While gravity lines are able to take waste away from homes and businesses in Gilbert, the relatively flat terrain means eventually it will have to go to "lift station" where a force main will bring it up again for its journey to one of Gilbert's wastewater treatment plants. Then it can be put back into storage at a recharge station like the Riparian Preserve.

Source: Town of Gilbert/Independent Newsmedia

In flat regions like Gilbert, the use of force mains and lift stations becomes necessary.  

Lift stations pump wastewater from lower elevations to higher ones, allowing it to continue flowing by gravity. Force mains are the pressurized pipes connected to these pumps, moving wastewater efficiently over long distances.  

However, these systems are far more complex and costly to maintain than gravity sewers. Eric Braun, Gilbert’s assistant public works director, estimated that a lift station may cost the town 100 times more than a gravity line, given that gravity is free. 

Unveiling the issues 

The problem with the sewer line beneath the 202 Freeway, found during a routine inspection, is not an isolated incident.  

Emergency inspections of other freeway crossings revealed additional lines in equally critical condition.  

Braun likened the discovery to finding a failing water heater in an aging home.  

“Corrosion is not necessarily linear in fashion,” he said. “It can start out very slow and then kind of accelerate. And I think that’s a part of what we’re finding is that maybe a lot of our infrastructure is in that kind of exponential age where different components are degrading at a little bit faster pace than they did initially.” 

Public Works Director Jessica Marlow emphasized the importance of such inspections. 

“When it fails, it fails spectacularly,” she said.  

She compared the sewer system to the unseen yet essential wiring and plumbing in a home, vital to maintaining the town’s quality of life. 

The current predicament stems, in part, from past decisions aimed at keeping rates low, Braun said. Routine inspections, which should ideally occur every six years in the town’s timetable, were delayed, allowing issues to worsen undetected.  

Furthermore, Gilbert’s sewer infrastructure, much of which was constructed during the town’s rapid expansion, is now reaching the end of its expected lifespan. 

A particularly concerning issue is the use of ductile iron pipes, which Braun said were once considered industry-standard for pressurized sewer lines.  

Ductile iron pipe has corroded in town much faster than its anticipated life span. (Courtesy Town of Gilbert)

Courtesy Town of Gilbert

These “50 year” pipes were designed with an interior lining to resist corrosion. However, improper installation often damaged this lining, exposing the pipes to corrosive sewer gases. The result has been greatly accelerated degradation, requiring immediate replacement.  

Emergency measures and long-term plans 

In response to these findings, Gilbert’s wastewater team has accelerated inspections and emergency repairs.  

Under the 202 Freeway, for example, the first relining project was scheduled to begin by Jan. 20, with subsequent repairs planned through March.  

The town’s proactive approach includes bypass systems to temporarily redirect wastewater during repairs, an expensive but necessary measure to prevent service interruptions, Braun said. 

Braun highlighted the team’s efficiency during emergencies, recalling a 2021 incident at the Islands Lift Station.  

A sewer bypass line had to be quickly built when a lift station in the Islands neighborhood failed in 2021. (Courtesy Town of Gilbert)

Courtesy Town of Gilbert

Within 24 hours of a rupture, a bypass system — spanning more than 4,000 feet — was operational, averting a community-wide crisis. 

“If there is ever a time when you’ll learn whether or not your staff is professional and knows what they’re doing, you’ll find out in an emergency,” he said. 

Funding the Fixes 

The proposed $230 million capital improvement plan addresses the most urgent needs over the next five years. Yet even with this significant investment, Braun said $134 million in additional projects will remain deferred, potentially requiring further rate increases in the future. 

Town officials are exploring two primary funding options. One involves using bonds to cover a portion of the costs, spreading repayment over 20 years but potentially requiring further rate increases. The second option — a cash-only approach — would impose steeper initial rate hikes of $29 per month but ensure sustainable funding for future infrastructure needs. 

Braun explained the trade-offs. 

“The all-cash option ... would set us up with ongoing funding after the five years to continue to invest in the capital plans,” he said, thus allowing the town to start addressing the other $134 million in projects. 

Conversely, the bond option could result in smaller initial rate hikes but also in higher long-term costs due to interest payments, affecting both ratepayers and taxpayers.

Failure to act now could have catastrophic consequences, Marlow said. She warned that delaying necessary maintenance and repairs only increases the likelihood of more frequent and costly failures.

“These emergencies are way more costly even in the short term than had we just kept up with our inspection and replacements as planned,” she said. 

The community’s feedback will play a crucial role in determining the path forward. Public outreach efforts include virtual and in-person open houses later this month, where residents can learn more about the proposed rate increases and their impact. 

One thing the council most certainly will not do is ignore the issue. 

“This is not something we have a choice about,” Councilmember Jim Torgeson said. “Your sewers start collapsing, everything in your town is done.” 

Gilbert Town Councilmember Jim Torgeson voted against a notice to raise wastewater rates but acknowledges the sewers must be addressed. (Screen capture from YouTube)

Screen capture from YouTube

However, Torgeson did say it was important to prioritize the repairs. 

“Once the critical things — like let’s say Williams Field and the 202 — once those are taken care of, then it’s got to be reassessed. Where’s the priority, where’s the urgent need on each one of these?” 

Gilbert’s sewer system may not be a topic residents think about daily, but its reliability underpins the town’s way of life, officials said.  

“Water often gets the glory (because) we can’t live in the desert without water, but our wastewater manager, Ken Snow likes to say, without sewer service, we’re all just camping,” Braun said. “We can’t live in cities without sewer service, otherwise we’re all going to have an outhouse in the backyard or we’re going to have a septic. And so the wastewater system really is one of the key foundational components of our way of life.” 

We would like to invite our readers to submit their civil comments, pro or con, on this issue. Email AZOpinions@iniusa.org. Tom Blodgett can be reached by email at tblodgett@iniusa.org or follow him @sp_blodgett on X. 

Tom Blodgett
Senior News Editor | Gilbert

tblodgett@iniusa.org

Meet Tom
Tom Blodgett joined Independent Newsmedia, Inc., USA, in 2022, when the company acquired Community Impact Newspaper's Phoenix-area properties. Raised in Arizona, he has spent more than 35 years in journalism in the state.

Community: He has served as an instructional professional in the Walter Cronkite School of Journalism and Mass Communication since 2005, and is editorial adviser to The State Press, the university's independent student media outlet. He also is director of operations for an 18U girls fastpitch softball team from Gilbert.

Education: Arizona State University with a BS in Journalism. 

Random Fact: He lived in Belgium during his freshman year of high school.  

Hobbies: Tweeting enthusiastically about ASU softball (season-ticket holder) and grumpily about other local sports (pessimistic fan).