In the right light, the smooth concrete buildings of the Kennedy Center’s new Reach complex resemble gleaming white icebergs. And, as with icebergs, there’s a lot going on below the surface. You wouldn’t know it by looking at it, but before a single performance or practice space could be built, a massive piece of sewer infrastructure — a concrete-lined shaft as big as two grain silos stacked atop one another — was constructed underneath the Reach.

Just as the Reach will contribute to the cultural health of the city, so this shaft will contribute to the actual health of the Potomac and the Chesapeake. It’s designed to keep poop from flowing into the river.

A sewer pipe has emerged into the river just west of the Kennedy Center since before there was a Kennedy Center. It’s called Combined Sewer Overflow Outfall No. 21 and is part of an antiquated system that, during storms, causes rainwater to mix with sewage. The foul brew is then discharged into the Potomac. As part of its $2.7 billion Clean Rivers Project, DC Water has been methodically working to separate those two things, with pipes for storm water and pipes for sewage.

Addressing CSO 21 has been on the books for years. DC Water was planning to dig the shaft about five years from now. But when the Kennedy Center announced it was planning to build the Reach, the utility basically said: Okay, but it’s probably a good idea if we build our thing before you build your thing. That way, we won’t have to sink a sewage shaft next to your ballet dancers.

The concrete-lined shaft — 23 feet in diameter and 100 feet deep — is just east of the Reach’s River Pavilion, underneath a grove of ginkgo trees. Eventually, the bottom of the shaft will be connected to a tunnel that will take sewage to the treatment plant at Blue Plains, from whence it will emerge “looking almost like Colorado mountain spring water,” said Carlton Ray, director of DC Water’s Clean Rivers Project.

Also constructed under the Reach as part of the project: a ventilation control facility. Air will be pulled through the tunnel and passed through granular carbon filters. “We want to make sure we don’t have any kind of odors ever generated from the facility,” Ray said.

The two projects were very different. DC Water’s sturdy sewer pipes cost $34 million. The swooping Reach cost $250 million. But they have something in common. Both are made primarily of the same material: concrete.

“Obviously we’re much more meat and potatoes,” Ray said. “We’re the concrete that you would see on a bridge, versus the beautiful work that’s done on the Reach. That’s magnificent concrete.”

Hey, don’t sell yourself short, Carlton.

The Kennedy Center’s senior vice president of operations, Ellery J. Brown, said the shaft may be utilitarian, but the two projects — the concrete Reach above the concrete sewer — perform “a nice little handshake.”

Your name here

The Reach — designed by architect Steven Holl — is pretty cool. I haven’t seen a performance there yet, but architecture is like a performance and just admiring it can stir the soul.

There was one unusual thing I noticed on my visit: the marble interior wall that’s covered with the names of benefactors. Donors are typically thanked by having their names chiseled in stone. But these names are made from adhesive letters that have been stuck on the wall.

Is that a new way of doing things?

No, said the Kennedy Center. The adhesive letters are temporary.

Donations were still coming in as of August. “Using temporary decals allowed us to recognize as many of our leadership donors as possible at the Sept. 7 opening,” wrote a spokesperson in an email.

The official engraving is slated to begin in January.

Smoke on the water

Cathy Strickler of Fredericksburg, Va., attended some of the Reach’s opening festivities with her husband, Charlie. Experiencing live performances outside on a warm summer evening — the jets landing at National — reminded her of another alfresco experience: being in the audience at the Water Gate.

Those are the steps west of the Lincoln Memorial where people would sit while an orchestra performed on a barge. The concerts lasted from 1935 to 1965. The steps gave their name to a building complex that, in turn, gave its name to a political scandal.

“This new venue certainly recreates the ambiance that I remember so fondly,” wrote Cathy.

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.