Engineers to rappel down Arch to look at stains

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ST. LOUIS (KPLR) – An engineering team is set to rappel down the north leg of the Arch this week to look at stains on the surface of the Arch. The stains first started appearing in the Arch in the 1990s.

Crews will descend from a hatch atop the monument to collect samples about 425 feet from the ground.

The goal is to determine a cause and best treatment.

The sampling should be finished Friday.

The Arch will remain open during the inspection.