Beech Tree News Network

The Lincoln Memorial Reflecting Pool is one of the most recognizable landmarks in Washington, D.C.  Strikingly, the 2,028-foot-long water basin on the National Mall almost succumbed to the marshlands on which it was built.  The pool, which was built in the early 1920’s between the Washington Monument and the Lincoln Memorial, is massive.  Approximately the length of 12 Olympic-sized swimming pools and the width of two, the reflecting pool ranges from 18 to 30 inches deep and holds around 6,750,000 gallons of water.  

Nearly 90 years after its construction, the pool had sunk about a foot into the wet, marshy ground.  In 2010, a massive project kicked off to fix the sinking and save this mammoth monument’s place in history.  Why did the Reflecting Pool sink?

The Lincoln Memorial Reflecting Pool, built as a compliment to the Lincoln Memorial, was completed in 1923, shortly after the monument’s dedication in 1922.  However, the pool was installed on marshland that had not been drained and supplemented with dredged material from the Potomac River.  Constructed without an underlying support structure, the pool sat directly on this soft ground.

Over time, the heavy structure began to slowly sink and leak.  In the 1980’s, concrete was poured into the bottom of the pool to try to fix some of the damage, but by 1986, the pool’s structural system was falling, The Washington Post reported.  Eventually, the pool was losing around 500,000 gallons of water per week due to cracks, leaks and evaporation.  Drastic repairs were needed to restore its structural integrity.

How was the reflecting pool fixed? Between November 2010 and August 2012, crews drained the reflecting pool and worked to restore the water feature, elevating it back out of the marshland and decreasing the depth by about 6 inches.  Nearly all of the original structure was torn out, with just some of the old tile and asphalt bottom left behind.  Over 2,100 timber pilings were pounded into the ground every 2 feet, 9 inches apart to provide support and keep the new pool from sinking.

Beyond fixing the major issue of sinking, the $34-million renovation provided an opportunity to enhance the pool in other ways.  It originally lacked a circulation system, causing the pool to be drained and refilled twice a year toclean it.  So, a circulation and filtration system was added.  Elsewhere, a new tinted bottom was meant to improve the reflectivity of the water.  Although no longer at risk of sinking, the repairs weren’t perfect.  Algae bloomed in the reflecting pool just weeks after it was refilled with water post-construction.  Officials at the time stated this was due to ozone calibration in the pool’s new filtration system.  Now, once a year, the National Park Service scrubs the pool to clear it of trash and goose poop.  (www.history.com)