ST. LOUIS (AP) -- The National Park Service has awarded a contract for a structural study of the Gateway Arch, a move officials say was under way prior to recent newspaper reports about corrosion problems in the 45-year-old monument to westward expansion.
Officials for the Park Service said Monday that the Northbrook, Ill.-based structural engineering firm Wiss, Janney, Elstner Associates will perform the study on the 630-foot-tall structure.
"The National Park Service considers it our highest priority to preserve our national treasure -- the Gateway Arch -- and to ensure the safety and enjoyment of our visitors," Tom Bradley, superintendent of Jefferson National Expansion Memorial, which includes the Arch and its grounds, said in a statement.
Bradley said the Park Service was taking "proactive steps" to address the Arch's long-term maintenance needs.
In a series of articles in recent weeks, the St. Louis Post-Dispatch has reported that the Arch was showing corrosion. The newspaper reported there were no short-term safety concerns, but repairs could be expensive.
Bradley said the new study was not in response to the Post-Dispatch articles, though he acknowledged they did raise public awareness about the problem.
The Arch, since its completion in 1965, has been St. Louis' defining image and one of the most distinctive symbols associated with any U.S. city. Inside, it includes a museum at the base and a tram that takes visitors to an overlook area at the top.
Earlier this month, the Park Service provided the Post-Dispatch with new photos of carbon steel inside the north leg of the Arch, showing orange and red rust that has been evident in other pictures for at least five years. A 2006 report cited by the Post-Dispatch said possible corrosion within the steel walls was bleeding through failed welds and staining the shimmering outside surface.
Bradley said officials aren't sure what's causing it.
"There is this staining going on that's kind of a mystery," he said. "It could be there's some air pollution or chemical reaction that's causing staining. We had something similar at the Statue of Liberty. Or it could be some sort of corrosion."
Frank Mares, the deputy superintendent of the Arch, said at the time that maintenance workers used mops and a makeshift system of wicks and barrels to collect water in the interior legs of the Arch.
Bradley said a recently completed "Historic Structure Report" found the Arch to be structurally safe.
"In fact, the Arch has been awarded the highest mark given in government structural assessment," Bradley said.
But the report also offered observations of staining and corrosion and recommended a more in-depth follow-up study. Wiss, Janney, Elstner will begun that study in November. The $150,000 study is expected to take about a year.
"Because the Arch did not come with an owner's manual, it is imperative that we seek the input of leading engineers and other experts to ensure that any potential problems are accurately identified, classified and repaired," Bradley said.
Bradley said Arch designer Eero Saarinen once said the monument was built to last 1,000 years.
"Who's to say, but we're in this for the long haul," Bradley said.
The Park Service said Wiss, Janney, Elstner has performed diagnosis of other complex structures that include Aloha Stadium in Honolulu, the Chicago Tribune Tower and the Nebraska state capitol.
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