July 2025 Vol. 80 No. 7
Rehab Technology
Double-stacking manhole liners to rehab, stop corrosion in Midland, TX
Corinna Hunt, Contributing Editor
It is said that life imitates art, and in every epic story, there is a hero, a villain, a victim and a guide. In this story, the villain is corrosion caused by hydrogen sulfide gas, victimizing the manholes in Midland, Texas; the guide, perhaps, is Madewell Products Corporation and its products being used to rehabilitate the manholes.
And according to Don Rigby, Madewell’s director of marketing and education, this story’s hero is the city’s local utility contractor: Red Deer Construction.
“They’re the hero in my mind,” Rigby said. “David Chandler, Trey Chandler – this project is happening in their backyard, so it’s a very crucial and critical job for them. And they are doing everything just right.”
David Chandler Jr., the owner of Red Deer Construction, described the praise as humbling.
“I didn’t do anything special,” he said. “I just did business the way you’re supposed to do business.”
The story
Several years ago, the city of Midland began noticing larger inflows into its wastewater plant during heavy rain events. Some infiltration and inflow (I&I) is normal, but this was in excess of that.
“At that time, we were actually doing a $132-million public-private partnership at our water reclamation facility,” said Carl Craigo, Midland’s utilities director. “Looking at putting that much capital into that plant, we decided it was time to figure out why it seemed like the I&I was moving up and up and up.”
To learn more, the city began sending out crews along the draws – water sources that are not actively flowing, because Midland doesn’t have any of those – during heavy rainfall, and what they found was that many concrete manholes were starting to collapse. One that Craigo witnessed was so bad that water was visible on one side of the draw but not on the other, meaning the manhole was taking in that entire flow.
“They were getting to the point where rebar was starting to show inside the manhole, meaning H2S gas was eating that concrete,” Craigo said.
The city of Midland is ground zero for the Permian Basin, where oil deposits make the ground more caustic than any other part of Texas. Not only that, but Midland’s wastewater treatment collection system was built on a casual grade.
“When you have the caustic soils and a gravity sewer that’s not really built on a fast plane, then you have a recipe for H2S gases and corrosion,” said Rigby. “Corrosion is wicked. It eats through mortar and destroys a concrete structure – like a manhole.”
Midland officials plan to structurally rehabilitate about 250 concrete manholes and the same number of brick manholes over a four-year period, using about $2 million each year to do as many as possible.
“We’re concentrating on these manholes that are in our draws, because those seem to be, by far, the worst manholes in the system,” Craigo said.
In this second year, workers will probably end up doing 80-85 manholes, and they completed about the same number last year, he reported.
Right choice
Based on the size of this project and the number of manholes involved, it was decided that geopolymer was the most economical solution.
“Our standard microsilica restoration mortar is ML-72, which has a lot of Portland cement in it, which is pretty common and inexpensive,” Rigby said. “But that is what erodes from the corrosion. Geopolymer does not have a lot of Portland cement in it, which makes it more resistant to corrosion.”
It is a fact that corrosion will occur specifically where previous corrosion was already present. For that reason, surface preparation is incredibly important: 84 percent of any restoration failure can be attributed to a lack of good preparation, Rigby stressed.
“Inadequate preparation is the source of failure,” he observed. “Red Deer didn’t want that; they said, ‘I think I know what we can do,’ and we tried something we’d never done before.”
Red Deer Construction did an excellent job of prepping each manhole from the bench to the chimney, using injection grouting to stop active leaks, and in some cases rebuilding some bench work using Madewell’s ML-72FS fast-set product.
“(Red Deer) said as long as only half of the rebar is showing, they can rehab that manhole, and we didn’t have to replace it entirely,” Craigo said.
Then, crews installed a composite liner using Mainstay GeoSpin, a high-strength, low-permeability geopolymer repair mortar with “excellent corrosion resistance properties,” according to the product information sheet. Right away, they topped it with Mainstay DS-5 100 percent Solids Epoxy, which is “designed for use in corrosive environments with a pH of 0.5 or lower.”
Double stack
The geopolymer base coat has a thickness of about 1 inch, and the epoxy resin on top is 125-150 mils thick. Using the geopolymer as the base coat is what made this work unique, special and different.
“We had never, ever done geopolymer and epoxy in a single curing process,” Rigby said. “Sure enough, it worked great.”
The single curing process is necessary because if the mortar cures before the epoxy is applied, it can cause outgassing, which creates air bubbles through which corrosion can reenter. Keeping corrosion at bay and separated from the mortar behind is “the one-two punch.” The single curing process allows for the adhesion necessary for the liner – and the rehabilitated manhole – to last 50 years.
“The composite liner just works unbelievably,” Rigby said. “The base coat of cement and then the epoxy on top of it – that is an impermeable coating. No corrosion is going to enter.”
The hydrogen sulfide gases were so high that without the epoxy layer, the geopolymer – even though it is resistant to corrosion – still would have eventually failed, as has been demonstrated in other parts of the country.
So, Chandler thought, “Well, what are our options? How can we go forward and still give the customer the product that they’re needing?”
Red Deer applied the epoxy layer on top of the geopolymer for no additional cost for materials or labor.
“I looked at the cost of adding the epoxy, and it did consume more of the budget than was anticipated originally without the epoxy, but I could still make it work, and by doing so, I gave the city what they were looking for,” Chandler said. “We’ve discovered a system that will take care of the need, and then we can continue, for years, doing this.”
What Red Deer did was concern itself not with profit, but with doing the right thing. “Doing the right thing is never the wrong thing,” said Rigby.
Other contractors should operate similarly, he pointed out.
“You’ve got to do what’s right for the project,” Rigby said. “The spirit of cooperation is really important, and when push comes to shove, if you want to satisfy a customer … you’d better do some things above and beyond, and that’s what they did.”
As a family-owned company local to Midland, Red Deer Construction is one of Craigo’s main utility contractors, and it’s been great to work with, he said.
Relationship
Red Deer values its relationship with the city, and that was a big driver in finding a solution.
“This is my city,” Chandler said. “Taking care of where I live is important. The city has grown to know that if they call us, we’re going to show up, we’re going to get the job done, and we’re here after the job is done.”
Though it is only the second year of the four-year project, Midland officials have already noted an improvement.
“We haven’t had a lot of rain in the last two years, but we have noticed that in a heavy storm, we would normally peak out our meter at our water reclamation facility, and that hasn’t happened, meaning we’ve actually seen a lower I&I intake into our sewer system,” Craigo said. “If that I&I kept increasing, we would have had to increase the flow capacity of the plant because we were treating so much stormwater, but we’re seeing that come back down to levels that our current plant can handle.”
Midland is also already seeing a financial benefit. Being able to rehabilitate, rather than replace, those 85 manholes last year saved $4.2 million.
“A city should always look for solutions that aren’t just ripping out and replacing because that takes a lot more time, and this product saved us time and money,” Craigo stressed.
Having proved that this system is successful, Chandler hopes now to bring this solution to other places in need of it in the long term.
“We’re happy with it, and we’re trying to go forward and grow the program with this city and others,” Chandler said.
MORE INFORMATION:
Madewell, (765) 810-3497, madewell.net
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