St. Louis' famed Gateway Arch shows its age

ST. LOUIS — As civic leaders reveled in the recent unveiling of grand plans to remake the Gateway Arch grounds, there was an ominous element not discussed.

Almost 45 years into its reign atop the St. Louis skyline, the 630-foot monument is suffering from growing rust and decay. And nobody knows how extensive the decay is.

Corrosion, some of it feared aggressive, and severe discoloration of the stainless-steel skin have long been present, according to engineering reports reviewed by the Post-Dispatch.

The documents and interviews with metallurgists indicate that the remedy could be as minor as an "expensive" surface cleaning or as elaborate as a full-blown restoration. One report, completed in 2006, called for a deeper study, for which the National Park Service says it only recently obtained funding.

"This is not yet a health and safety issue," said Frank Mares, the deputy superintendent of the Jefferson National Expansion Memorial, which oversees the Gateway Arch. "(The report) says learn more about what's going on. It's something that requires further study."

The problems are increasingly evident, with streaks and spots marking the upper reaches of the Arch's exterior.

None of the documents reviewed addressed concerns about safety in relation to corrosion, nor made estimates of what remedies might cost. One speculated it could take a "long time" before corrosion would "induce any integrity concern."

Officials said the structural issues were separate from — and would not compete for funding with — plans revealed Aug. 17 to rebuild the Arch site in time for its 50th anniversary celebration in 2015.

"It's apples and oranges," Mares said, suggesting he is confident there will be money to do what is necessary.

The 2006 report identified corroding bolt heads and staircases, a leaky interior sometimes shrouded with its own fog, rusting of interior carbon steel and a mysterious staining of the glimmering surface.

"The exterior skin has definitely degenerated since first constructed," it said. "However, it is not possible to accurately determine the rate of visual distress."

The deeper examination will analyze and test corrosion samples, to recommend steps for long-term preservation.

No repairs or changes have been made since the 2006 report, Mares said, with the follow-up study delayed for lack of funds. He said the first report cost about $150,000, and the second is expected to cost about $437,000.

A Post-Dispatch reporter was allowed to review the corrosion report for about 40 minutes earlier this month. But officials refused to make it available for a second look the next day, citing national security concerns and saying it should not have been provided the first time.

A formal Freedom of Information Act request for the material is pending, but did produce some other documents.

The first phase of the corrosion study was conducted by two architectural and engineering firms, Bahr Vermeer Haecker, of Nebraska, and Wiss, Janney, Elstner, of Illinois. Both declined to comment for this story.

Their report pinpointed several potential corrosion problems, with the culprit perhaps being water leakage. The report raised the question of whether the carbon-steel interior skeleton is rusting through failed welds and onto the stainless-steel outer surface.

"As the structure is subject to dynamic stress cycles, there is a possibility that welds have failed locally, generating points of water leakage into the interstitial space," the report says. "Corrosion products of carbon steel may then have stained the stainless-steel surface."

Water intrusion has long been an issue. "Condensation in the legs has been there since day one," Mares said.

Arch officials say they have set up a makeshift system of tubes and containers to try to collect water.