The Village of Mount Prospect is required by the United States Environmental Protection Agency and the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) to eliminate clear water from entering sanitary sewers.
Clear water is ground, rain or storm water that ends up in the sanitary sewer. It's hard to think of clear water as bad, and that's part of the problem. Clear water belongs in storm sewers or on the surface of the ground, but not in sanitary sewers. Too much clear water is getting into the sanitary sewers and overwhelming the sewer, causing basement backups and sanitary overflows.
The Village has a Clear Water Inspection Program, commonly referred to as the Building Inspection Program, in place to identify areas where clear water may by entering the sanitary sewer system and to encourage homeowner compliance with Village code in fixing improper connections. The Public Works Department requires all properties to have a clear water elimination inspection.
During a major storm, clear water entering sanitary sewers can overload the system causing sewage to backup into homes. Backups can cause significant damage, cause odors and are very difficult and expensive to clean. They often result in loss of property and expensive repairs. Backup problems can be caused or worsened by clear water entering the sewer system. When these issues are addressed, fewer backups occur.
What Happens When Excess Clear Water Enters the Sanitary Sewers?
Sanitary sewers are designed to convey a certain amount of water. When the sewers are overcome with clear water they become surcharged (flowing at a level greater than the "normal" level). Basement backups occur when significant amount of clear water infiltrates the sanitary sewer.
How does excess clear water enter the sanitary sewers?
Clear water enters the sanitary sewers either through infiltration or inflow. Infiltration/inflow is clean water that enters the sanitary sewer by means other than street inlets. Infiltration/inflow can occur from cracks and separation in the sanitary sewer main or private services laterals, area drains, window wells, downspouts and sump pumps that discharge directly to the sanitary sewer.