I was feeling giggly about going down the Lake Montebello sinkhole.

As one of my coworkers put it, I’ve experienced some “daredevil antics.” I got bitten by a horse while reporting. I jumped in the Inner Harbor.

“Now, you’re descending into a sinkhole?” he asked. “What health care plan are you on?”

Here’s what he likely imagined: I was going to walk to an active construction site — think heavy machinery, dusty air and loads of dirt. Caution tape and signs. And, of course, the infamous hole, swallowing soil into a dark cavern, with little space to breathe.

At least, that’s what I had in mind. The reality was, in some ways, underwhelming — which is probably a good thing.

Instead, I walked down into an excavation site with Tim Wolfe, the chief engineer for the Department of Public Works, and Cherod Hicks, the lead engineer on the project.

Wolfe and Hicks gave me a refresher on the sinkhole. City engineers decided to inspect the storm drain after a summer storm in 2020 caused a flooding at 35th Street and Hillen Road, severe enough that buses were halfway underwater.

There was no evidence on the surface that there had been any failures. But after further inspection, they found a 70-foot section of the drain had sunk about 15 feet. I could see the brick arch, which had been hand-mined about 140 years ago, collapsed on top of the exposed drain.

Hicks, the engineer on the project, can see the sinkhole from his bedroom window. We walked towards the exposed drain and he told me this area of the park used to be part of a disc golf course. They had dumped loads of soil where people used to work out on teal and purple outdoor exercise equipment.

When they first finished inspection of the site in the summer of 2022, they still could not see where parts of the drain first collapsed. By November of that year, though, the sinkhole — once the size of a basketball — opened up wide enough to expose the depression from the top. Fixing it became a priority, Wolfe said.

They constructed a bypass in December so the city could keep supplying water to East Baltimore and parts of Baltimore County residents — between 40 million and 70 million gallons of water flow through the main when it’s working properly. The engineers initially thought they could repair the sinkhole by spring 2023. But issues with the soil delayed them.

Hicks and his colleagues had been working on undisturbed soil, Hicks said while walking down into the ditch. That soil, which was hand-mined over a century ago, required a stabilization process that took almost a year.

“So initially, this looks like this is sedimentary rock,” Hicks said. He knelt and picked up what looked like a shiny, warm grey rock. It quickly disintegrated. “But once it’s exposed to oxygen, it actually behaves like a sand.”

I looked at the cement wall that was holding the soil, unnerved and slightly dizzy.

Hicks said there are structural nails between 40 to 60 feet long that help stabilize the soil. They injected the nails into the earth, grouted them tight and sprayed them with concrete. And then, in front of it, was the drain, surrounded by what Wolfe called “rock strata.”

He said those were what engineers call “rotten rocks,” decomposed and unstable. Wolf pointed out a piece of wood from 140 years ago. Back then, it had been part of a wooden frame to support the structure temporarily while they laid the bricks.

To the engineers, it was a glimpse into the past. Hicks called the craftsmanship — the six layers of brick, the arch formation — phenomenal.

“They had to literally build that from the inside out,” he said. The timber on top, which was used as the bulkhead to protect the workers when they were hand-mining, is over 100 years old. The drain, installed in 1876, was one of the oldest storm drains in the country.

Hicks then told me to look again at the wall and notice how the material was different in the first 15 feet and the next 35 feet.

When the engineers were installing the first nails, piezometers — devices used to measure pore pressures on the soil — identified some movement. They found there were cracks 3 to 4 feet long and the shoulder had moved about 3 or 4 inches. If they continued to work, the area would completely collapse. So, they paused the project in June 2023 to run geotechnical analyses and revise the plan.

The nails from the original plan were 40 feet long, so they decided to increase them to 60 feet. They have to do that in small layers of 2-foot increments, and each nail took about an hour to put in. There were other delays, including the inclement weather. They can’t work if it’s forecast to rain in the city or Baltimore County.

They finished the wall in May of this year. They were also draining the lake by 2 to 3 feet to help keep the soil stable.

Now, they can finish installing a 108-inch pipe and connect it with the drain to close it in. They are also going to put concrete behind a steel plate to stabilize it and tie it all in. Then, they’ll start backfilling the site. They can’t dump it all in at once, but do what they call a controlled fill, 8 to 12 inches at a time. They hope to be done by late fall, allowing residents to walk the full loop around the lake by the end of the year.