Inflow and Infiltration
Cedar Rapids has a problem with too much water entering the sanitary sewer system through inflow and infiltration. Inflow occurs when stormwater enters the sewer system through direct connections like sump pumps, foundation drains, storm sewer connections and openings in manhole lids. Infiltration occurs when groundwater enters the sewer system through defective joints or cracks in the sewer pipes. Inflow and infiltration can quickly overwhelm the capacity of the sanitary sewer system during extreme rain events, causing basement backups and sewer overflows. The excess flow also strains the capacity of our Water Pollution Control Facility.
The goal of this study is to gain an understanding of the prevalence and nature of inflow and infiltration problems in a specified area to use as a basis for developing a city-wide plan to reduce the problem.
The study employed a number of different methods.
Crews consisting of representatives from the City of Cedar Rapids and HDR Engineering visited homes in sections of the study area on Saturdays between 9:00 a.m. and 6:00 p.m. starting July 12 and continuing through August 2, 2014. Participation was completely voluntary. Residents received a notice on their door to let them know when crews would be in the area. The crews heard about any problems residents are having with the sewer system. If the home had a basement, crews examined the drains inside and around the home as well as the sump pump configuration.
Crews inspected manholes located in the public right of way throughout the study area to identify cracks or defects in the structures. This work was scheduled for the weeks of July 14 and 21 and occurred during the day.
Crews performed smoke testing to identify defects in the sewer system. This work began in late August. During this test, crews filled the sewer with a non-toxic, odorless smoke.
Televising Sewer Lines
Based on the findings of the smoke test, crews televised 2,000 feet of sewer mains and sewer service lines in late August and early September. This allowed the city to get a clear picture of the condition of the sewers in your area.
The information gathered during this pilot study will be used to develop a plan to reduce inflow and infiltration and the associated basement backups and sewer overflows throughout the 660+ miles of sanitary sewers in Cedar Rapids.
Ways Residents Can Help:
Disconnecting Sump Pumps
For More Information about the Pilot Study:
Cedar Rapids Project Engineer