Clear Water Inspections
What is clear water and why should it be monitored?
Clear water is ground, rain or storm water that ends up in the sanitary sewer. While the term “clear water” may not sound like such a bad thing, it is a major problem. Clear water belongs in storm sewers or on the surface of the ground, not in sanitary sewers. If excess clear water enters into the sanitary sewers, overwhelming the sewer, it may result in basement backups and sanitary sewer overflows.
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. In order to protect property owners from basement backups the City may discharge some of the flow to the environment during extremely high runoff events. During these high runoffs events, the clear water entering the sewer system can cause greater than a 10-fold increase in flow in the sewers.
How does excess clear water enter the sanitary sewers?
Clear water enters the sanitary sewers either through infiltration or inflow. 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. It can also enter through defective sewer pipes, pipe joints and manholes. These defects may be the result of structural failure, deterioration and aging.
Clear water may also enter sanitary sewers though inflow, which refers to the direct connection of downspouts, roof drains, foundation drains and sumps pumps to the sanitary sewer system. The City has completed many sanitary sewer rehabilitation projects to correct the infiltration problems within the sewer system’s mains and manholes. When inflow occurs, the problem needs to be handled at the source the inflow connections.
What can be done to help eliminate clear water entry?
In order to eliminate discharges to the environment, basement backups and/or very costly and otherwise unnecessary increases to the wastewater system, City of Viroqua is taking steps to eliminate clear water entries to its wastewater collection system.
The City has taken a variety of steps to identify inflow and infiltration to the system, such as televising, smoke testing and sanitary sewer replacements. However, there continues to be excessive amounts of clearwater in the system.
The City of Viroqua has deemed it necessary to conduct inspections of residential, commercial and industrial properties to identify possible sources of clear water entry into the sanitary sewer system. A Clearwater Inspection Checklist will be used to help guide a clear water inspection within and around the home in order to determine possible contribution of clear water to the sanitary sewer system.
What can you do to eliminate clear water entry?
The City urges residents to take voluntary measures to eliminate any clear water connections which discharge into the City’s sanitary sewer system from their property. Residents who are aware of, or have a suspicion of, any such connections may contact the City for advice on confirmation or correction of the connection. Voluntary action by residents will result in earlier correction of problems and, most of all; will reduce the wet weather load on our wastewater system and wastewater treatment facility.