|The Wilson Avenue Water Crib & Lighthouse, Lake Michigan, Chicago. Looking West.|
The water cribs, aka "crib" in Chicago, supply the City of Chicago with drinking water from Lake Michigan. Water is collected and transported through a tunnel leading from the cribs to the filtration plant, which is close to 200 feet beneath the lake and varies in shape from circular to oval and in diameter from 10 to 20 feet. Lake water enters the cribs and flows through these tunnels to pumps at the Jardine Water Purification Plant (the world's largest) and the South Water Purification Plant, where the water is treated. From there, it is pumped to all parts of the city and 118 suburbs. There are six different cribs, the Two-Mile Crib, the Carter H. Harrison crib, the William E Dever crib, the Wilson Avenue crib, the Four-Mile crib, and the 68th street crib.
As the great city of Chicago grew, several additional water intake cribs and connecting tunnels to shore were built off the harbor. One of these structures was known as the Wilson Avenue intake crib due to its tulle system connecting to a new pumping station at the foot of Wilson Avenue. Work on crib began in 1915 with the sinking of a steel caisson with a ninety-foot diameter. Built using square-hewn granite blocks, the superstructure protected a forty-foot diameter inner well chamber. It housed the city employees who staffed the plant and tended the light erected at the center of its roof.
The Wilson Avenue Intake Crib supplied eight miles of water tunnels, which were hand-dug through the bedrock beneath Lake Michigan - a tremendous feat of engineering and back-breaking labor. This 1916 photograph shows the interior of one of these tunnels after completion.
When they were halfway through the Wilson Avenue intake crib construction in Chicago, the Engineers found that the caisson had settled, causing the superstructure to sit a few degrees from horizontal. Holes were bored beneath the low side of the caisson, and hydraulic cement was pumped into them, lifting the structure back to the correct orientation. This photograph, taken in 1916, shows one of the engineers on a platform erected in the center of the superstructure, using a theodolite to ensure the top surface of the granite walls had been brought back to horizontal.
Compiled by Dr. Neil Gale, Ph.D.