Photo by Sarah Mirk

CHRIS GOMEZ has spent the last two years 120 feet under Portland. He is part of a team driving a ferocious tunnel-boring machine the size of 26 TriMet buses far underneath the Eastside, constructing the largest sewer project in the city's history.

The tunnel-boring machine (which is named Rosie and, in a feat of PR creativity, has its own first-person Twitter feed, @RosieTheTBM) emerged from the soil at Swan Island in early December. Rosie last saw the sun two years ago when she was lowered into the earth across town near the Oregon Museum of Science and Industry.

In those two years, Gomez's team has piloted Rosie four miles underneath Portland, steering around the I-5 freeway pylons and cutting through soft silt "never touched by human hands," as one project supervisor poetically put it. A map in the project's office is marked with Post-it notes along the Eastside Pipe's path ominously reading "jet fuel line" and "historic house." All of this work (and $426 million) to keep our shit from flowing into the Willamette River. Once the Eastside Pipe is done Portland's sewers will no longer overflow; no more stormwater mingling with sewage and dumping out into the river during every big storm. Instead, all our dirty water will flow up, up, up the new pipe to a treatment station in North Portland.

"Do you want to go down and see the pipe?" Gomez asked me last week as we stood on the edge of Rosie's gaping entrance hole in industrial Southeast. I was feeling out of place at the construction site, standing in frozen mud with steel-toed boots slipped over my tights, a safety vest over my pink sweater, and goggles awkwardly shoved over my glasses. "Uh, sure," I replied.

Gomez nonchalantly strode onto a mesh metal platform extending over the 120-foot drop down to the pipe's entrance. He and a crew of 10-12 workers head into the pipe every day, working in three shifts around the clock. He says they don't lose track of time in the darkness and don't mind the small workspace in Rosie's cabin. They have snacks, a coffeepot, and a microwave. It's sort of like working in an office, says Gomez—that just happens to be far underground and fronted with giant whirling blades.

Gomez opens the elevator's thick metal doors with his hands. The metal floor inside is muddy. It feels rickety and adjusts under our weight when we step in. "Don't get scared on me," he says. Too late.

Down in the hole, the sky above is a clear slice of blue. Icicles hang over the entrance to the pipe, which is lined with 4,068 cement rings slotted together along its four-mile stretch. Each ring weighs 32 tons. Everything about this project feels massive, but Gomez isn't fazed—before this job, he worked 3,000-4,000 feet underground in an Arizona copper mine.

Bright bulbs hang from the length of the cement pipe, running far back into the darkness like industrial Christmas lights. Metal rails run along the bottom of the pipe, with two white rail cars waiting at the start where the icy, muddy soil turns to cement.

Now that the north side of the Eastside Pipe is finished, a barge will float Rosie back down to this site where she started two years ago. She'll be lowered down to where we are standing right now and start burrowing the south end of the tunnel, which is currently blocked off and spray painted with a pink warning, "SOUTH STOP." Another year from now, she'll emerge in Sellwood, the largest tunnel in Portland will be finished, and as for Gomez? He'll be looking for another hole to dig.