Milwaukee Sinking While Historic Foundations Rot
Michael Horne details the ongoing trouble in Milwaukee to save buildings and streets that are sinking due to the retreating size of the water table underneath the city.
“The problem begins with Milwaukee’s marshy base: it was built on marshland that bordered its three rivers. The entire Third Ward and nearly three-fourths of Downtown stands on a swamp. Although it was filled in with dirt and garbage and the like, underneath it, water still flowed.”
“Most of the substantial buildings in old Milwaukee (some erected as late as the 1940s) were constructed on foundations of wooden pilings pounded into the earth, often by Edward E. Gillen Co. The pilings would extend through the filled-in dirt into the ample water table about 10 feet beneath grade and then into the swampy soil found beneath that. The pilings were expected to remain submerged and be sound for centuries.”
But as the water table has retreated, the pilings of many buildings in Old Milwaukee have been exposed to the air and decay. According to Horne, “the technical term is ‘pile rot.’”
“The latest casualty is the 1904 structure at 734 N. 4th St., with an assessed value of nearly $1.7 million”
Some blame the Deep Tunnel (a 28.5-mile sewage and stormwater tunnel that runs 135-300 feet below the city) for the problem. “The Deep Tunnel is divided into three sections that extend from Downtown, giving this part of the city great exposure to its effect on the groundwater. The tunnel is so porous that huge amounts of water from the old marsh are seeping into it each day, lowering the water table and exposing the old buildings’ supportive timbers to pile rot,” writes Horne.
The Milwaukee Metropolitan Sewerage District argues that downtown Milwaukee has been overloaded with too many buildings, with uncapped, underground wells causing the problem.