Introduction to Inflow & Infiltration

Manhole Frame & Chimney Inflow Points

Inflow spikes occur during, or within minutes, of a rainfall event and are a product of the inflow points. This typically overloads the system and disrupts the entire process at the treatment plant.  With fresh rainwater mixing with the sewage, the treatment plants fill beyond capacity.  Instead of forcing the overflow back to the residents houses, waste water utilities are forced to bypass the treatment process and send the excess sewer  flow into lakes, rivers and streams.

Infiltration is a constant and continual event because infiltration happens in the main lines that are generally below the water table.  Waste Water Utilities handle infiltration daily as a part of the normal flow.  Slip lining, relining the lines or installing new lines will stop the infiltration but is very costly and generally will not be very effective at preventing Sanitary Sewer Overflows.

The main areas of inflow occur through the Manhole Frame and Cover and the Chimney Section of the Manhole. To prevent rainfall from entering into these critical points, USSI uses ElastaSeal^®, a proprietary Aromatic Urethane Sealant for the Chimney Section and our custom fitted Inflow Defender™, "Inflow Dish", is installed.