On assignment: My underground pipe quest

Rare, but important, inspection of one of Denver Water’s largest pipes shows what it takes to maintain infrastructure.

May 14, 2018 | By: Jose Salas

As the new guy at Denver Water, I was recently asked to do an assignment. So without hesitation or an understanding of what I was about to embark upon, I raised my hand and blurted out, “Of course!”

The task: Cover the inspection of one of Denver Water’s biggest underground assets, a 108-inch-diameter pipe that brings untreated water from Strontia Springs Reservoir to Marston Treatment Plant, where it is ultimately cleaned to drinking water standards. (For you pipe geeks out there, the largest diameter pipe in our system is 144 inches wide.)

In my inexperienced mind, I pictured walking into an above-ground, 9-foot-wide pipe, snapping a few photos, asking some questions and going to lunch.

“Don’t worry,” they said. “It’ll be fun,” they said. Well, let me tell you what really happened.

It wasn’t until after several safety and planning meetings that I realized this would be an underground adventure. The day arrived and I was ready to face my newly discovered fears.

First, gear up:

Hard hat? Check. Boots? Check. Harness? Check. Gas monitor? Check. Scared out of my pants? Triple Check!

Marston 108-inch pipe
Nicole Babyak, water treatment plant supervisor, descends into a 108-inch-diameter water pipe for inspection on March 28, 2018 .

About 4,700 feet of this immense pipe were drained and emptied for two weeks so a team of engineers and maintenance crews could enter and perform a two-day inspection.

That’s when I realized not many people get to experience what I was about to do. Inspections of this caliber only happen every few years, and no one has been in this section since 2014.

Then it was time. The journey started with a tight squeeze into a manhole that descended into the pipe. Reality kicked in when my head lamp went out — thank goodness for the backup flashlight.

“We have been planning this particular inspection since late January 2018,” said Antonio Flori, corrosion engineer at Denver Water. “We will be looking for blisters, bubbles, rust and other potential defects to see how well the protective coating inside the pipe was performing in its 21st year of service.”

I looked on as the inspection crew checked the stability of the pipe, the need for any upgrades or maintenance and that the bypass valves were working properly.

Denver Water utilizes protective linings and coatings, like polyurethane, on metallic pipelines to protect them from corrosion. According to Flori, the pipe we were in was one of the first to have polyurethane interior lining, which was installed in 1996. The linings can be made of many different materials. The most common for Denver Water are cement mortar, epoxies and polyurethanes.

So, what was the inspection outcome?

“I am excited about how well the lining is performing as a corrosion protection system,” Flori said. “All signs point to a well-adhered lining that is preventing corrosion of the steel pipe.”

And for me? Well, I don’t recall this being in the job description and never in a million years did I think I’d be climbing into a massive underground pipe. Really, it was like being on the “it’s a small world” ride at Disneyland. Awesome to be there, but I couldn’t wait to get out.

Would I do it again? Probably, but I’ll have to wait a few years because this pipe isn’t scheduled to be inspected again until 2022.

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