An 18-month, $30.7 million project to replace the 80-year-old Lincoln Memorial Reflecting Pool in Washington, which began in November, is well under way.
Last week, workers started sinking timber pilings - 2,133, to be exact - that will support the new pool. The old pool, which dates to the 1920s, was not built on pilings.
Two rigs work side by side, astride their lumber platforms in the middle of the pool. Pile drivers lift and aim four-ton hammers, which pound 50-foot timbers deep into the reflecting pool, bashing the dust from the smooth yellow pines until the wood hits bedrock and the ground starts to shake. One timber piling every 12 feet, 9 inches. Almost a hundred a day. Five hundred a week, with more than 1,300 to go.
The ground is a 40-foot deep layer of marshy river clay and some dredged material atop the bedrock, said Dennis Quinn, a project specialist with the National Park Service. A metal "shoe" is nailed on to the tip of the piling to help it penetrate.
Sometimes the pilings snap, and two more must be sunk on either side of the broken one. "We have to get it to bedrock ... but you can't hit it too much ... (or) it will break in the ground," said Dennis Brown of Corman Construction, a project engineer. It's like hammering "a toothpick through mud and hitting it on concrete," he said.
The reflecting pool is roughly 160 feet wide and 2,100 feet long and is one of the most iconic sites in the nation. It dates from shortly after 1922, when the Lincoln Memorial was dedicated before a crowd that included Lincoln's only surviving son, Robert, who was then 78.
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To see video of work on the Lincoln Memorial Reflecting Pool, please go to links.tampabay.com.