In the fall of 1999 and the spring of 2000 Grand Blanc Township experienced two wet weather events that caused considerable flooding, sanitary sewer backups and overflows. The damage caused by these two events included flooded basements for many residents. The primary cause of the sanitary sewer backups and overflows was clean water entering the sanitary sewer system from leaks in pipes, leaks in manholes, and from sump pumps and footing drains that were connected to the sanitary sewer.
Following the 1999-2000 wet weather events, Grand Blanc Township embarked on an aggressive Inflow and Infiltration (I & I) removal program to try to reduce the possibility of flooded basements and sanitary sewer overflows. In 2000 the township purchased a specialized vehicle that televises sanitary sewers to determine if there are any defects and instituted a program to have every residential sanitary sewer in the township televised every five years. Any defects in the sanitary sewers are then repaired, keeping the clean water out of the system. Since 2000 the township has televised every residential sanitary sewer in the township, some twice, and repaired the defects that were found. To date the township has spent over $3,500,000 in the repair of these sewers.
In November of 2006 the township received a $1,079, 200.00 S2 Grant from the State of Michigan for the purpose of studying the I & I problem in the township. As part of the study 36 flow meters were installed in February of 2007 to monitor I & I throughout the township sanitary sewer system. As meter data was collected and evaluated, meters were moved to areas with higher I & I in an effort to localize the data. These metering locations are shown on the Sanitary Sewer Flow Meter Map. Despite the efforts outlined in the previous paragraph, flow monitoring continues to show excessive I & I in many areas causing system surcharging, flooded basements, and sanitary sewer overflows. The sources of this I & I can be attributed primarily to illicit sump pump and footing drain connections.