If you are a fan of the books written by David MacCaulay, such as Underground, take some time to look into, literally, the stormwater management project ongoing along John St. Right now at the corner of John and New is perfect to see the pipe construction and the size of the main pipe being laid. While there walk south on New where you can see the preparation for the 3 huge rain gardens that are going to be planted this week. Then go up to the side walk to look at the pervious concrete. All of this is in front of the Unit 4 administration building. Further east just off of John around Lynn, the pervious surfaces for a section of street and alleys is also being laid. Here is the city web site where one can follow the project progress  
http://ci.champaign.il.us/departments/public-works/residents/stormwater-management/boneyard-second-street-detention-project/john-street-watershed-project-videos/
http://ci.champaign.il.us/2011/09/09/john-street-drainage-improvements-project-pervious-pavement-installation/
Here is the John St Watershed steering committee web site
http://sites.google.com/site/champaignwatersheds/