Water crib

Water cribs are offshore structures that collect water from close to the bottom of a lake to supply a pumping station onshore. The name "crib" is derived from the function of the structure—to surround and protect the intake shaft. Cities supplied with drinking water collected by water cribs include Chicago, Illinois; Cleveland, Ohio; and Buffalo, New York.

Cribs in Chicago, Illinois

The City of Chicago is supplied with drinking water from Lake Michigan. The first crib, the "Two-Mile Crib" was constructed as part of a scheme by Ellis S. Chesbrough in 1865. [" [http://www.chipublib.org/digital/sewers/history2.html Down The Drain: Raising Chicago.] " Chicago Public Library (URL accessed 14 October 2006).] [Alice Maggio. " [http://www.gapersblock.com/airbags/archives/the_lake_michigan_cribs/ The Lake Michigan Cribs] " Gapers Block, June 3, 2004.] Water was collected and transported through a tunnel 60 feet below the lake surface to the Chicago Avenue pumping station. [" [http://www.lhl.lib.mo.us/events_exhib/exhibit/exhibits/civil/lake_tunnel.shtml The Lake Tunnel in Chicago.] " Linda Hall Library of Science, Engineering & Technology (URL accessed 14 October 2006).] This was replaced by the Carter H. Harrison crib in 1900 (located at coord|41|54|59|N|87|34|23|W|type:landmark), which itself was intended to be replaced by the William E. Dever crib that was built alongside it in 1935. [" [http://www.chiefengineer.org/content/content_display.cfm/seqnumber_content/790.htm Chicago Water Tower.] " The Chief Engineer (URL accessed 14 October 2006).] However increased water demand meant that the Carter H. Harrison crib continued in service until 1997.

Other cribs include the Wilson Avenue crib (located at coord|41|57|58|N|87|35|28|W|type:landmark), the Four Mile Crib (coord|41|52|22|N|87|32|45|W|type:landmark), and the 68th Street crib (coord|41|47|10|N|87|31|54|W|type:landmark). The tunnels leading from the cribs are close to 200 feet beneath the lake and vary in shape from circular to ovular 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 then treated. From there it is pumped to all parts of the city as well as 118 suburbs.

Until the 1990s, [http://www.encyclopedia.chicagohistory.org/pages/300035.html Crib Tenders] lived on the cribs. Usually four man crews stayed aboard the cribs for a week at a time. Their duties included water testing, light maintenance, and dynamiting ice dams that formed against the cribs' walls. Crib facilities included rudimentary bathrooms, showers, and bunk rooms—and a fantastic view of the city and lake.

The massive amount of polluted water that flows into the lake from Chicago is beginning to affect the water quality—even four miles off shore.fact|date=May 2008 The City of Chicago has proposed a plan involving the construction of new cribs twelve or fifteen miles farther north.fact|date=May 2008

The Chicago cribs have also been designated a "security zone". [cite web | title = Security Zones; Captain of the Port Chicago Zone, Lake Michigan | url = http://cryptome.quintessenz.org/mirror/uscg-sz/uscg052202-chicago.txt | author = United States Coast Guard | date = 2002-05-22 | accessdate = 2008-01-17] In 2002 complete security systems were installed, including video, motion detectors, microwave link, and door sensors, all with direct links to Chicago Police monitoring stations. Any craft that enters the buoyed security zone is subject to boarding, ticketing and impounding.

Carter Harrison Crib Tunnel Collapse

In 1998 the tunnels leading from the Carter Harrison Crib to shore were de-watered for inspection, a process that was surrounded by controversy. Some experts feared that pumping the tunnels dry would result in a catastrophic collapse, while others guaranteed that collapse was not possible. The naysayers were proved right, and portions of the tunnel did in fact collapse. City lawyers soon filed suit against the engineers and contractors. The suit charged that the engineers, Alvord, Burdick & Howson, were negligent for advising the city that it was safe to drain the tunnels. It also charged that [http://luedtke-eng.com/ Luedtke Engineering Co.] , of Michigan, did the work in a way that caused the collapse. As a result of the collapse, the city spent $5.3 million to fill in a portion of the tunnel under Lake Shore Drive to prevent a possible additional collapse.

Carter-Harrison Crib Images

References

External links

* [http://www.glerl.noaa.gov/webcams/ NOAA Webcams, including crib mounted]
* [http://155.79.114.198/divacct/Fifth_Technical%5CFifth_Technical_intro.pdf Lake Michigan Water Diversion]
* [http://www.lindahall.org/events_exhib/exhibit/exhibits/civil/lake_tunnel.shtml Digging the Tunnel]
* [http://egov.cityofchicago.org/city/webportal/portalEntityHomeAction.do?entityName=Water&entityNameEnumValue=43 City of Chicago Water Department]
* [http://www.uscg.mil/hq/g-cp/history/WEBLIGHTHOUSES/carterharrison.jpgConstruction photo]
* [http://lighthouse.boatnerd.com/gallery/Erie/BuffaloIntakeCrib.htm Buffalo Crib Photos, Interior and Exterior]