USE OF FOOTING DRAIN DISCONNECTION TO CORRECT BASEMENT BACKUPS IN ANN ARBOR, MICHIGAN

Collection system capacity issues that caused sanitary sewer overflows (SSO) and basement backups led the city of Ann Arbor, Michigan, to address the root cause of the problem--connected foundation footing drains. An evaluation of the magnitude of flows entering the sanitary collection system concluded that 70 percent to 90 percent of the wet weather flows introduced in residential areas were from connected foundation footing drains that convey drainage from around most homes constructed before the early 1980s into the collection system. While foundation footing drains were long suspected of being the primary cause of Ann Arbor's basement backups, directly addressing this source of Inflow/Infiltration (I/I) has not often been used to correct overflow problems in collection systems due to the difficulty and associated risks of funding work on private property.To address this issue, the city of Ann Arbor worked with a special task force that included significant participation from affected homeowners. The process also included periodic workshops with the homeowners in flooded areas to provide information and a better understanding of the viability of different solutions. Ultimately, many of these homeowners supported an approach that would fix the excessive I/I problem and provide protection of their homes from flows backing up into their basement. This approach, disconnecting the footing drains from almost 20,000 homes, will likely be phased over a 20-year period. The implementation is 1 year into the program.