Rachel Rae Rachel Rae

The Drama Beneath Your Feet

Bacteria are converting concrete sewer lines into chalk while cities go about their day above. AGRU America's Ernie Hines on the fix that's been around for decades. Infrasound podcast from reVerb Communications.

Civil engineer Ernie Hines walked us through the slow-moving disaster happening inside concrete infrastructure everywhere. The fix has been around for decades. The problem is nobody talks about it until something collapses.

Infrasound Podcast | reVerb Communications

In January 2024, a pickup truck drove over a stretch of road in Iowa and fell through. Beneath it, an 86-inch trunk sewer line feeding a wastewater treatment plant had corroded to the point where it couldn't support the weight of an F-150.

The pipe was bare concrete. No protective liner. Bacteria had been converting hydrogen sulphide gas into sulfuric acid on its interior walls for years, softening the concrete until it crumbled. The truck just happened to be the thing that made it visible.

That story came up midway through our conversation with Ernie Hines, a civil engineer and technical product manager for concrete protective liners and geosynthetics at AGRU America. Hines flew to Calgary to speak at a CPL Academy session. We caught him for an episode of Infrasound. What followed was a surprisingly gripping tour of everything that's going wrong beneath the surface of every city you've ever lived in.

Concrete Has Two Kinds

There's a saying Hines shared that stays with you: there are two kinds of concrete. Concrete that has cracked and concrete that hasn't cracked yet.

Concrete is a calcium-based material. That makes it a base. Acids eat it. Moisture penetrates it. Reinforcing steel inside it corrodes and causes spalling, where chunks of surface break away. And in wastewater environments, a process called microbial induced corrosion (MIC) turns the structure's own chemistry against it.

Here's how MIC works. Decomposing waste generates hydrogen sulfide gas. That gas rises above the water line inside a pipe or structure and condenses on the concrete surface. Bacteria colonize that surface, building a slime layer. Over time, the bacteria convert the hydrogen sulfide into sulfuric acid. The acid softens the concrete. Turns it to chalk. The structure begins crumbling from the inside.

In high-risk environments, this can render a concrete structure useless in as few as five to ten years. Engineers know where it's most likely to happen: drop manholes, pumping stations, digesters at wastewater treatment plants. Anywhere hydrogen sulfide concentrations are high. The at-risk structures are identifiable. The question is whether anyone acts before a truck falls through.

A 30th Birthday in a Pumping Station

The solution Hines brought with him, literally, to our recording session is a concrete protective liner. A sheet of high-density polyethylene, typically two to five millimetres thick, anchored directly into the concrete with embedded studs. The plastic does what concrete can't: resist chemicals, block moisture, withstand abrasion.

CPL technology has been around for about 75 years. AGRU has been manufacturing it for roughly 40. It's been used in Canada for 30.

That 30-year mark came up in a story Hines told about a pumping station in Florida. The municipality had been cycling through spray-applied and roller-applied coatings for years. In 1995, they installed a concrete protective liner. In 2025, an AGRU engineer went down, pressure-washed it, inspected it. The city representative's assessment: every other structure in the system had problems. The ones with CPL never did.

The engineer made a birthday card on the back of a piece of liner. Brought a chocolate cake. Left it outside the pumping station. Nobody ate the cake.

The Geosynthetics Research Institute estimates that a buried geomembrane made from the same resin as CPL has a half-life of over 440 years at certain temperatures. In a wastewater environment, Hines puts the practical service life at 50 to 100 years.

The Problem Nobody Campaigns On

Glenn asked Hines to recall the last time hydrogen sulphide was a municipal election topic. The room went quiet.

This is the fundamental challenge with subsurface infrastructure. It's invisible until it fails. Voters don't demand action on things they can't see. Elected officials balance budgets against lifespan, and the math often favours the short term. Hines put it bluntly: "Sometimes we get the impression they're like, 'Well, it only has to last 10 years because I retire.'"

The American Society of Civil Engineers gives US wastewater infrastructure a D+ rating. In Calgary, the 2024 water feeder main break that triggered weeks of restrictions wasn't an isolated event. The city experiences up to 170 smaller failures per year. The work is largely reactive.

The cost difference is staggering. Repairing a few feet of failed pipe costs a minimum of ten times the per-unit price of new construction. Mobilization, excavation, disruption. Every emergency repair is an argument for having done the job right the first time. And "right the first time" is the entire value proposition of concrete protective liners: spend marginally more upfront, get decades of service life, avoid the emergency dig.

The Plastic Stigma

Hines works for a company that manufactures thermoplastic products. He knows what people think when they hear the word plastic. They think of the Great Pacific Garbage Patch. Microplastics. Single-use water bottles.

What they don't think about is the polyethylene membrane between a hazardous waste landfill and the groundwater. Or the liner inside a subway tunnel beneath Los Angeles, installed to prevent methane from accumulating and causing an explosion. (That concern stems from a 1985 incident at a Ross Dress for Less store in LA, where naturally occurring methane caused a flash that injured over 20 people and shut down an entire retail district.)

The LA Metro is currently expanding its subway system ahead of the 2028 Olympics. AGRU is lining those tunnels with hydrocarbon-resistant HDPE membranes.

Modern landfills, too, are lined engineered systems. Hines bristles at the word "dump." Today's facilities use multiple layers of geosynthetics, textured geomembranes with interface friction to prevent slope failure, and drainage systems that capture leachate before it reaches groundwater. The industry learned hard lessons from the Kettleman Hills hazardous waste facility failure in the late 1990s, when layers of geocynthetics slipped against each other and part of the landfill simply moved. That event reshaped how the entire sector designs containment.

Almost everything AGRU does connects back to water. Protecting groundwater from contamination. Transmitting potable water through fused polyethylene pipe with zero acceptable leakage (the same standard applied to natural gas lines). Lining canals in the western US to prevent irrigation water from being lost to infiltration and evaporation. The average American water system loses 14% of its treated water between the plant and the customer. Most of that loss is pipe joints that have separated or were never properly sealed.

Why It Matters to People Who Never Think About Pipes

Hines said something near the end of the episode that deserves to sit with anyone who works in public infrastructure communication. Civil engineers, he argued, have saved more lives than the entire medical profession. Sanitary systems. Water treatment. Safe bridges and tunnels. The infrastructure that keeps disease, contamination and structural failure out of daily life.

Hollywood hasn't figured that out yet. There's no civil engineering drama on Netflix. Engineers, Hines said, "are not the most interesting people. At least unless they're talking to one another."

We'd push back on that. The story of a bacteria colony slowly converting a concrete structure into chalk while a city goes about its day above is genuinely dramatic. The story of an anchor stud design being refined millimetre by millimetre to resist hydrostatic back pressure is the kind of iterative problem-solving that keeps cities standing. The story of a pumping station getting a birthday cake after 30 years of uninterrupted service is, in its own way, moving.

The infrastructure beneath our feet doesn't ask to be noticed. It asks to keep working. The people who make that possible deserve a longer conversation than they usually get. This episode was ours.

Referenced in this episode:

Infrasound is produced by reVerb Communications. We tell the stories behind the infrastructure that shapes how communities live, move and grow.

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Rachel Rae Rachel Rae

Do You Like Being Here?

Sustainable urban integration on Edmonton's Valley Line LRT started as a set of design guidelines. Fourteen years later it's a lesson in how infrastructure earns trust. Infrasound podcast from reVerb Communications.

The simplest question in urban design is the one nobody thinks to ask. A conversation with DIALOG about sustainable urban integration on Edmonton's Valley Line.

Infrasound Podcast | reVerb Communications

Nineteen minutes into our conversation with Georg Josi and Larissa Ulcar from DIALOG, we asked how you measure the success of sustainable urban integration on a public infrastructure project. The answer had nothing to do with design theory.

"Do you like being here?"

That's it. That's the metric. Not whether the architecture is award-worthy. Not whether the sustainability rating checks out. Whether a person standing on a platform or walking along a corridor feels like they want to be there. Whether they'd linger. Whether they'd come back.

It's a disarmingly simple standard for something that took 14 years to develop, codify and fight for across one of the most complex infrastructure projects Edmonton has ever built.

The Problem SUI Was Built to Solve

If you've ridden Edmonton's Capital Line, you know what utilitarian transit feels like. The northeast leg runs alongside what is essentially a rail yard. The shared-use path beside it is straight and bare. You get from A to B. That's the transaction.

The Valley Line LRT, Edmonton's first low-floor urban line, presented a different proposition. The stops are closer together. The train runs through established neighbourhoods. People aren't commuting from a park-and-ride to a downtown office tower. They're hopping off at Bonnie Doon to grab groceries, stopping at the Muttart to meet a friend, living the line rather than taking it.

That shift in use required a shift in design thinking. And the design thinking that existed at the start of the Valley Line project kept getting lost.

This is the pattern Josi described: every major linear infrastructure project starts with a grand vision. Planners and urban designers set the tone. Then the project moves into engineering. Then procurement. Then construction. At each handoff, the vision erodes. Cost pressures flatten it. Schedule constraints trim it. By the time someone is pouring concrete, the original intent is a memory.

Sustainable urban integration, or SUI, was created to prevent that erosion. DIALOG developed it into a set of guidelines that run parallel to the technical specs, giving the design vision the same contractual weight as the structural requirements. If it's in the contract, the contractor has to build it. If it's an aspiration, it gets value-engineered out.

Making It Contractual Changed Everything

The most practical insight from the episode is how SUI survived contact with reality.

DIALOG's team wrote visual requirements into the Valley Line contracts. Renderings of what stations were supposed to look like became deliverables the contractor was held to. "We said, okay, now build it. Make it look like this." And when they compared the renders to what was actually built, the result was close.

That level of fidelity between design intent and finished product is rare on large infrastructure. It happened because the SUI principles were baked into procurement documents, repeated during construction team onboarding, and enforced by designated SUI leads on the owner's side, the design side and the construction side.

The engineers who were initially skeptical, the ones who asked "what is this fluffy SUI stuff?" became some of the strongest advocates. Josi put it simply: engineers are smart. You explain it to them, they see it, and they start living it.

The Details Nobody Notices (and That's the Point)

Ulcar walked us through examples that most riders will never consciously register. The curved cantilever arms on the overhead catenary poles. The sack-rub concrete finish on station platforms that smooths out imperfections. The hook-shaped railing detail where tracks split at a centre-loading platform on the Davies elevated guideway, designed to replace what would have been a blunt wall.

These are choices that cost a bit more time and a bit more thought. They don't show up in ribbon-cutting photos. They show up in whether someone standing on a platform at 7:30 on a January morning feels like the place was built with them in mind.

The refuge areas at the base of platform ramps are a good example. You step off, you walk down the sloped walkway, you wait for the light. There are bollards. Delineation. It's flat. You feel safe. You don't think about why you feel safe. You just do. Josi's take: "That's big for you, that you're not even thinking about it."

The goal of good urban integration is to disappear. If you notice it, something went wrong. If you feel welcome and can't quite articulate why, the work is doing its job.

Four Values, One Measure

SUI operates on four principles. Pedestrians first: every design decision scaled to human experience. Integrated: the infrastructure belongs in its neighbourhood, responds to its character zones, adapts to the communities along the corridor. Flexible and adaptable: some of these structures have 100-year design service lives. And sustainable, in the full sense of the word. Environmental, economic, social, cultural. The Envision rating system, designed specifically for linear infrastructure, is the framework DIALOG wants to see Edmonton adopt more broadly.

But the measure of success remains the same question Josi posed at the 19-minute mark. A question that has nothing to do with design credentials. A question any rider on any platform can answer for themselves.

Do you like being here?

Where It Came From (and Where It Could Go)

DIALOG drew early inspiration from Seattle's Link Light Rail, particularly the stretch along Martin Luther King Jr. Boulevard where the at-grade line sits comfortably inside the neighbourhood. The pier design on Seattle's elevated sections, with a recess down the middle that conceals rainwater leaders and makes the structure feel less massive, was directly adapted for the Valley Line's elevated guideways. Every pier on Edmonton's line carries that detail.

European systems were also a reference point. French cities like Toulouse, where trams run through downtown so smoothly they almost disappear, represent the end state SUI is working toward. A system so well integrated it stops being a system and becomes part of daily life.

Josi's hope for the next 50 years is straightforward. SUI spreads beyond the Valley Line. Beyond Edmonton. It becomes standard practice to the point where the guidelines aren't needed anymore because the thinking is already embedded in how people design linear infrastructure. It stops being a specialty and starts being the baseline.

The incremental cost of SUI on a project is real. Josi didn't pretend otherwise. It's also, in his words, "minuscule compared to the benefits." A city that feels worth living in attracts the people and the business that sustain it. The investment pays for itself in a tax base, in commercial activity, in the simple fact that someone chose to stay.

Referenced in this episode:

  • DIALOG — integrated design firm (architecture, engineering, planning, landscape architecture) and developer of the SUI framework for the Valley Line

  • City of Edmonton — project owner for the Valley Line LRT

  • Valley Line LRT — Edmonton's low-floor urban light rail transit line

  • Valley Line West — the western extension currently under construction

  • Walterdale Bridge — referenced as an example of SUI principles applied to a single structure

  • Envision Rating System — sustainability framework for civil infrastructure, developed by the Institute for Sustainable Infrastructure

  • Seattle Link Light Rail — cited as a design inspiration, particularly the MLK Boulevard at-grade section and elevated guideway pier details

  • Edmonton Arts Council — collaborated with DIALOG on integrated public art throughout the Valley Line stations

Infrasound is produced by reVerb Communications. We tell the stories behind the infrastructure that shapes how communities live, move and grow.

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Rachel Rae Rachel Rae

The Rat Hole, the Roadway, the Relationships and the Rebuilding

A conversation about Edmonton's rat hole demolition turned into a lesson about what happens when you treat communication as seriously as concrete. Infrasound podcast from reVerb Communications.

A conversation with bridge engineer Guy Boston about Edmonton's rat hole demolition is really a story about what happens when the people building things treat communication as seriously as concrete.

Infrasound Podcast | reVerb Communications

There's a moment in our latest Infrasound episode where bridge engineer Guy Boston describes walking out of a stakeholder meeting. Forty to fifty business owners packed into a car dealership boardroom on 104th Avenue. They'd been there an hour before Boston and his project manager Hugh Donovan arrived. The room was already at a boil. The City of Edmonton had come to explain a road closure. The crowd had come to fight.

Boston turned to Donovan and said, loud enough for the room: "We're leaving. We don't have to take this abuse."

Then he did something that tells you everything about how he thinks. He waited in the parking lot.

Two business owners followed them out. They apologized. They offered to reconvene properly. Two days later, a different venue, different tone, same group. The loudest voice from the first meeting sat in the corner. The rest of the room told him to listen.

That second meeting led to the value engineering exercise that compressed a full-summer road closure into a four-to-six-week sprint. The project won the American Public Works Association's Project of the Year. The engineering was excellent. And the engineering was shaped by what stakeholders said they needed.

The Project That Disappeared (Exactly as Planned)

The rat hole was a 109th Street tunnel built in 1928 to pass under CN Rail's downtown yard. It was dark, low and narrow. It earned its name from an unnamed city councillor who called it "a big dark rat hole," and the name stuck for 73 years. When the rail yards left downtown, the city filled it in. Two lanes became four. A bottleneck became an intersection.

If you drive through that spot today, there's nothing to see. A few lanes of asphalt. Students waiting for a bus. The Mechewana Pedestrian Bridge overhead. Boston's grandkids have no frame of reference for it. "There used to be a hole here." So what?

That's what success looks like in infrastructure. The finished product disappears into daily life. Nobody notices a road that works. The work worth examining is everything that happened before the road opened, the decisions and conversations and compromises that determined whether the project would land well or land badly.

Engagement That Moved the Engineering

Boston is an engineer who describes himself as a salesman. His peers told him he should turn in his iron ring. He took that as a compliment.

What he understood early in his career is that public opinion starts shaping project outcomes the moment a closure sign goes up. The businesses on 104th Avenue were convenience stops. Drive-by traffic was their entire model. Close the road and the revenue goes with it.

The original construction plan was technically sound. Shut down in March, open in October. Standard approach. The stakeholders, though, were focused on one thing: surviving the summer. The value engineering exercise that followed came directly from that input. It was scoped around their concern, reducing the timeline on the 104th Avenue corridor specifically.

The solution, hydraulic shears mounted on excavators that could cut through a foot and a half of reinforced concrete, sounds absurd. Boston described it as "the Bugs Bunny approach." The project partners, Standard General, Morrison Hershfield (now part of Stantec) and Wayward Construction, delivered the critical intersection ahead of schedule. The APWA recognized the project. The businesses survived.

All of it traces back to the parking lot conversation.

Setting a Boundary to Open a Door

It's worth sitting with Boston's decision to leave that first meeting.

There's a default posture in public sector engagement that says you absorb whatever comes at you. You're there to serve the public. You take the heat. Boston's own project manager told him as much: "We're here for the stakeholder meeting. You're going to have to take it."

Boston overruled him. And it worked because it changed the dynamic in a room that had no interest in dialogue. The two business owners who chased them into the parking lot were the most reasonable voices in the group. They needed the performative anger to clear the room before they could step forward.

This is a pattern worth recognizing. In any stakeholder group, the people you most need to hear from are often the quietest. They won't compete with whoever showed up to grandstand. Creating the conditions for those voices to emerge is part of the job. The traffic modelling matters. So does the room you build for people to talk in.

Austerity Forced Creativity

Boston placed the rat hole project in an interesting economic context. Edmonton was deep in austerity. The provincial government was cutting. The city was following. Projects were utilitarian. Get the job done. Don't spend a dollar you don't have to.

That constraint shaped the engagement. There was no budget for a charm offensive. There was no political appetite for overruns. The value engineering exercise had to deliver a faster timeline within the existing envelope. And it did, because the people closest to the problem were in the room when the decisions got made.

Boston drew a line from that era of austerity to what Edmonton eventually became. The rail yards cleared. MacEwan University went in. The Valley Line LRT followed. A suspension pedestrian bridge at Fort Edmonton Park was the first structure Boston can recall that carried any design ambition. Then the new Walterdale Bridge. Then the LRT bridge. Each one a statement about what kind of city Edmonton intended to be.

"The first fancy bridge that came here, I think, was an awakening," Boston said. "It's like we can be something better than a utilitarian northern city."

The rat hole cleared the ground for that transformation. And the engagement work that made the demolition possible set a precedent the city has been building on since.

What We Took Away

Guy Boston retired from the City of Edmonton having worked on over a hundred infrastructure projects. The rat hole is the one he wore a hat for.

The National Film Board of Canada shot the time-lapse. The concrete keystones stamped "1927" are still embedded in the ground at the site. The project hat lists every partner. And Boston still remembers the exact moment he and Donovan stood on the finished intersection, looked at each other and hugged.

He also remembers receiving the APWA award on September 10, 2001, and choosing the cheaper train to New York the next morning. A decision that, for reasons nobody could have anticipated, saved his life.

Infrastructure stories do this. They start with concrete and end somewhere profoundly human. The rat hole episode of Infrasound is about a tunnel. The lesson is about what happens when you treat communication as a line item with real budget and real accountability. When you let stakeholders shape the engineering solution. When you walk out of a bad room so a better one can form.

The physical thing you build matters. The trust you build while doing it is what determines whether the community is with you when it's time to build the next one.

Referenced in this episode:

Infrasound is produced byreVerb Communications. We tell the stories behind the infrastructure that shapes how communities live, move and grow.

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