Inflow and Infiltration


What is Inflow and Infiltration?

Inflow and Infiltration (I&I) is the excess flow of clear water (rain or groundwater) into the City's sanitary sewer system.
  • Inflow is when clear water from illegal connections of sump pumps, downspouts, and foundation drains is channeled directly into sanitary sewer pipes.
  • Infiltration is when clear water that gradually enters the sewer pipes through cracks and openings in sewer service lines and joints, and public sewer mains and deteriorated maintenance holes. 
Because the sanitary sewer system was not designed to handle excess clear water, it becomes overloaded during these times of high groundwater or heavy rainfall and can cause basement flooding or bypassing of raw wastewater to local streams and lakes. These overloads also make the cost of treating wastewater much more expensive to all members of the community.

What's the Problem?

Wastewater from Mounds View travels through the City's sanitary sewer to the Metropolitan Wastewater Treatment Plant, which is operated by the Metropolitan Council Environment Service Division (MCES). MCES treats wastewater for communities in the seven-county metropolitan area. The MCES requires the City of Mounds View to reduce peak flows to the system. To minimize the possibility of MCES surcharges, the City and MCES are making improvements to the public sanitary sewer system. In addition, the City requires private sanitary sewer services to be maintained and has developed an I/I Inspection Program or H2OPP.

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