Monday, November 4, 2013

This is cool! Before D.C. was settled in 1789, Tiber Creek began where a bunch of streams flowing south came together at Truxton Circle. It followed 1st Street NE to Union Station, then Louisiana Avenue NW down to the center of the National Mall in front of the Capitol. It flowed west to about 7th Street, jogged north until it hit Constitution Avenue NW, and then flowed west to 14th Street NW. At that point, it hit the Potomac River.

None of the National Mall below Constitution Avenue and west of the Washington Monument grounds existed until 1881. It was all water -- not swamp, as comedians would suggest, but water.

Congress knew that the city of Washington needed hotels, restaurants, retail shops, and then like to cater to members of Congress as well as the federal workforce. A vibrant economy of light industry and trade (both import and export) was needed to sustain this city. At the time, canals were the most efficient means of transport. The Chesapeake & Ohio (C&O) Canal was already under construction from Georgetown, D.C., to the Ohio River. Congress decided that the lower part of the Tiber would serve nicely as part of the new "Washington City Canal" that would help bring barges deep into the heart of the District of Columbia. So they straightened and deepened the Tiber, and made it into a canal.

Just as it was finished, the train was invented. Overnight, canals became useless! The Washington City Canal now became an open sewer.

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Let's switch gears for a minute, and talk about flooding.

It was quite common for the District of Columbia to suffer flooding each spring due to snowmelt, rain, and ice dams on the Potomac. A major flood hit the city in 1881. It was so bad, it lapped the foundations of the White House and Pennsylvania Avenue was under three feet of water.

Congress finally got enough of this flooding, so in 1881 they ordered the Potomac dredged to bedrock. They felt that a deeper channel would contain the floodwaters. But what to do with the silt and muck dredged up? It was decided that a gigantic levee -- a massive mound of earth -- be built along the shoreline. There was so much fill material that they extended the shoreline south and west to help create a floodplain that would help disperse these dangerous floodwaters. Today, this is the National Mall. There was so much material that the Army Corps of Engineers also built an island -- East Potomac Park -- as well.

At the same time, the city was building its first sewer system. Someone got the bright idea to cover over the Washington City Canal and use it as part of the system since it was already a sewer anyway. The water pressure from Tiber Creek would help flush waste out into the Potomac. Famous local builder Adolf Cluss was hired to the job. He was known as "the Red Architect" for his love of red brick and his affinity for the works of Karl Marx. And so the canal was enclosed in a masonry tunnel. The sewers were connected to it, and the natural flow of the Tiber pushed the sewage into the Potomac. Gates at the Potomac shoreline were installed to prevent tidal forces from causing back-ups in the sewer.

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The ground along the Tiber is still so saturated with water that it's difficult to dig there. The water pressure won't let jackhammers or backhoes pierce the soil! When they built the Sherman Memorial on the grounds of the White House around 1900, groundwater so destabilized the soil that they had to push pilings an extra 35 feet into the soil. When the Department of Commerce was constructed in 1929, more than 18,000 pilings had to be set to stabilize the soil. Water pressure from the submerged Tiber Creek made it too difficult to drive them, so a deep-sea diver in full suit and helmet descended into the underground creek and drilled a hole 20 feet into the earth. A hose was inserted into the hole, and water pumped from the earth until the water table dropped and the driving of the piles could be accomplished.

Even today, eight buildings -- including the Commerce Department and the FBI -- collectively pump 1.7 millions gallons of groundwater per day from their basements because of submerged Tiber Creek. The east wing of the Smithsonian's National Museum of Natural History is pulling away from the main building because Tiber Creek is beneath it.

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