A Philadelphia Water Department crew unearthed a water main made of hollow tree trunks that lay buried and forgotten for 200 years.

The crew was replacing old cast-iron piping with a new ductile iron main on May 3 when the discovery was made.

Sections of 10-foot long pine drilled to create a 4- to 6-inch center were bound together with iron couplings. Adam Levine, a historical consultant for the water department, said records show the wooden piping with installed between 1811-1812.

The wooden piping served the city for 20 years until cast-iron pipe was installed in 1831.

The piping was connected to water tanks that stood on a hill a mile away. Philadelphia’s system used two steam engines to pump water from the Schuylkill River into wooden tanks at the Centre Square Water Works, which was designed by Benjamin Latrobe, who was also the architect for the U.S. Capitol Building.

Gravity delivered the water through the wooden piping network that eventually grew to 45 miles in length before metal piping became the norm.

More details here and here.

Source: Philly.com and Philadelphia Water Department.