Inflow and Infiltration (I&I)

Inflow and infiltration (I&I) refer to the entry of groundwater and rainfall-derived water into wastewater and stormwater collection systems through defects such as cracked pipes, deteriorated manholes, faulty connections, and other openings. This excess water can overload the capacity of wastewater treatment plants and collection systems.

Inflow refers to water that enters the sewer system from direct connections such as roof drains, yard and area drains, foundation drains, surface runoff, or street wash waters. Infiltration refers to groundwater that enters the sewer system from the surrounding soil through defective pipes, pipe joints, connections, or manhole walls. Infiltration is the focus of polyurethane grouting.

Managing I&I is important for preventing sewer overflows, reducing treatment costs, and minimizing energy consumption.

Understanding the Risks: What are Sanitary Sewer Overflows (SSOs)?

Sanitary sewer overflows (SSOs) are a prevalent concern, posing significant public health threats. EPA data indicates an alarming 23,000 to 75,000 SSO incidents annually in the U.S. These overflows, laden with raw sewage, are carriers of bacteria, viruses, and other harmful entities, potentially leading to conditions ranging from mild stomach discomforts to severe diseases like cholera and hepatitis.

The Financial Implications and Opportunities

Tackling these issues often requires a significant financial commitment. The EPA's Clean Water State Revolving Fund (CWSRF) has allocated hundreds of billions of dollars for diverse water infrastructure projects. Established in 1987, this initiative offers states the autonomy to address their unique water quality challenges.

A Cost-Efficient Approach to Mitigating Infiltration in Sanitary/Stormwater Systems

Here's an efficient plan employing flexible polyurethane grout that promises a robust return on investment:

1. Assessment: Start with inspecting lift stations and manholes.
2. Identification: Locate and prioritize significant leaks.
3. Targeted Repair: Utilize flexible polyurethane grout for precise point repairs.

A single crew can often mitigate leaks in two standard 8' deep manholes a day. This swift mitigation can lead to substantial savings. For instance, addressing leaks in just a single day can easily amount to around $30,000 in annual savings, based on local water treatment costs. In mere months, the cost of the repair is already recouped.

For municipal managers overseeing stormwater and wastewater systems, embracing flexible polyurethane grout for leak repair is a strategic move. It's not just about ensuring infrastructure longevity, but also safeguarding public health and achieving economic efficiency.

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