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St. Anthony 2040 Comprehensive Plan Chapter 7: Sanitary Sewer 140 INFLOW AND INFILTRATION General Inflow is water, typically stormwater, which enters the sewer system through broken manhole covers, sewer cleanouts, sump pumps, foundation drains, and rain leaders. Infiltration is water, typically groundwater, which leaks into the sewer system through crack s in the sewer mains, laterals, joints, and manholes. Water from inflow and infiltration (I/I) can consume available capacity in the wastewater collection system and increase the flow into treatment facilities. In extreme cases, the added flow can cause bypasses or overflows of raw wastewater. This extra flow also requires a larger capacity in the city’s collection and treatment components, which results in increased capital, operation and maintenance, and replacement costs. As a sewer system ages and deteriorates, I/I can become an increasing burden on a City’s system. Therefore, it is imperative that I/I be reduced whenever it is cost effective to do so. The MCES establishes annual I/I goals for each community discharging wastewater into the Metropolitan Disposal System (MDS) based on historical wastewater flows, adjustments for community growth, and I/I mitigation peak hourly flow factors. The City of St. Anthony had serious inflow and infiltration before 1979. In the late 1990s and early 2000s, the City televised and rehabilitated the sanitary sewer lines and implemented an ordinance prohibiting the discharge of stormwater from drain tile into the sanitary sewer (enforced at time of sale). In the late 2000s, the Metropolitan Council required the City to inspect every house and business to enforce the disconnection of sump pumps and gravity foundation drains. These efforts have significantly reduced inflow and infiltration into St. Anthony’s sanitary sewer system.