Inflow and Infiltration Study

The City of Orillia is working with a water management consultant, Civica Infrastructure Inc., to conduct an Inflow and Infiltration Study to identify and reduce sources of inflow and infiltration entering the sanitary sewers in the City of Orillia. As part of this, the City will be implementing a flow monitoring program to identify areas within the City that have high inflow and infiltration, and using field testing to identify specific sources.

Inflow and infiltration occurs when rain, melted snow or groundwater gets into the sanitary sewer system. This can happen when downspouts or sump pumps are directly connected to the sanitary sewer, or when surface water or groundwater seeps into gaps, cracks or holes present in the sanitary sewer pipe network. See Figure 1 below that depicts common sources of inflow and infiltration.

Inflow and infiltration can:

• Reduce the capacity of the sanitary sewer system, restricting space for existing residents and future growth
• Make sewage treatment less efficient as the sewage is diluted by water
• Increase the cost of wastewater treatment due to a higher volume of flow
• Increase the likelihood of sewage backups into basements
• Increase the chance of overflows/bypasses (wastewater spills to the environment)

As part of this study, the City of Orillia and Civica Infrastructure Inc. will be completing the following activities:

• flow monitoring in sanitary sewers
• maintenance hole inspections

Based on the flow monitoring results, further testing may be required, including:

• fog testing
• dye testing

If fog or dye testing are required, notices will be distributed to residents and businesses in testing areas.