I/I and Why it’s Important to You


Adam StodolaMost people do not think about the pipes beneath the ground until they are not working properly. When the pipes burst or backup suddenly they consume people’s thoughts. What could cause the pipes to not work as designed?


Excess of Infiltration and Inflow (I/I).


During wet-weather events, groundwater and rainwater can enter a deteriorating sanitary sewer system and cause the backup. This is especially damaging when the rain falls on already saturated ground. Cities with already failing sewer pipes could face much bigger problems when the backup goes into resident’s basements. The City of Council Bluffs, IA, experienced such an event when two back-to-back storms exceeded the 100-year storm intervals causing backup. After the storms, six percent of the city’s homeowners filed claims followed by a class action lawsuit. This required the City to fix the issue. GBA was hired to evaluate the system and develop an improvement plan. After implementing the planned improvements there are nearly no backups and the City has a plan in place to monitor the system and stay ahead of the problems.


Council Bluffs is not alone. Other cities are experiencing the same problems because of deteriorating sewer pipes and requirements. GBA is currently helping to develop and implement plans for cities experiencing wet-weather problems, such as Leavenworth and Lansing, KS.


When developing a plan to get rid of excessive I/I, there are several ways to identify the problem. These include flow metering, rainfall monitoring, manhole inspections, smoke testing and CCTV review. Once these tests have been done, engineers create a report with the findings and then make recommendations on the best way to combat the excess of I/I and overflows.


GBA is working with clients to resolve the issue so residents can return to their daily routines and once again not worry about the pipes underneath the ground.