Sanitary Sewer I&I

The designs of old stormwater management systems often relied on the existing sanitary sewer systems. This results in what is known as inflow and infiltration, often abbreviated as I&I. The Village's work through a CMOM seeks to identify, address, and correct these issues. The elimination of I&I in a better performance of our sanitary sewer system, and better management of our stormwater.
Fast Facts

  • The Village’s sanitary sewer system experiences significant amounts of ‘inflow & infiltration’ (referred to as I&I), or stormwater entering the sanitary sewer system, caused by connections between the sanitary sewer system and stormwater system. This used to be very common, when systems were designed without concern around overflows, backups or runoff.
  • The Village is operating under a framework known as a CMOM, which stands for Capacity, Management, Operation and Maintenance. This framework is outlined by the Ohio EPA, and requires action be taken to address I&I issues.
  • The first step of the CMOM is Planning, which requires extensive data collection to better understand the scale and scope of the issue. The Village received a $90,000, 0% interest loan from the State of Ohio for this Planning phase. With those funds from the loan, the Village had online mapping tools prepared showing the location of all water, sewer and storm sewer lines.
  • Additionally, the Village purchased 3 ‘flow meters’ or devices designed to measure the amount of flow in the sanitary sewer system, specifically after a heavy rain event. These meters report back flow rates and we compare that data with historical weather data to determine areas where I&I is most common, to identify areas of focus for future work.
  • The online mapping tools and the flow meters help identify areas where I&I takes place. 

Frequently Asked QuestionsWhat’s this project?
The Village’s original sanitary sewer system, when constructed, also collected stormwater runoff from properties in the area. The philosophy was simple – use stormwater to flush the sanitary system of clogs or debris using heavy rain events.

This approach worked when there were only a few homes in an area, but the more properties that connected to the sanitary system and the more demand that was placed on these systems, flooding and other issues occurred during more frequently.

The CMOM is an exercise that influences all parts of the Village’s sanitary sewer operation – including standard operating procedures, overflow management plans and other details.

The biggest piece of the project is the infrastructure work required to remove any remaining interconnections between the stormwater system and the sanitary sewer system.

How is this work being funded?
The Village has received a $90,000, 0% interest loan from the State of Ohio for the planning phase of the project. As of right now, the Village has utilized about half of these funds, with the remaining amounts to be used during the next part of the project, when cameras are run down the sanitary sewer lines to assess their condition.

The flow meters were purchased directly by the Village, using existing utility funds.

What is the status of the CMOM work?
Right now, the Village is in the Planning phase of the CMOM project. This is the first of three phases, followed by Design and Construction.

The Planning phase is the Village’s opportunity to collect as much useful data as possible to best understand the scale of the problem and where the problem is most prevalent.

Right now, the flow meters are installed in the sanitary sewer system, collecting flow rate of water entering our sanitary sewer after a rain event. If it remains constant, it is unlikely that stormwater is entering in that area. If the flow rate spikes, it is very likely that stormwater is entering the sewer system. The chart below shows the visual difference in the data.
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What data has been collected and what is it telling us?
The flow meters measure the flow rate (in cubic feet per second) of water through the sanitary system. Rain totals and flow rate data has been collected and analyzed for the period between May 19, 2022 and February 2, 2023. Rain totals were reported daily from the rain gauge at the Wastewater Treatment Plant.

These flow rates were correlated with rain totals for the same time period. Strong correlations in the data mean that it is more likely that stormwater is entering the sanitary sewer system in large volumes during rain events. Strong correlations were found in certain areas of the Village, indicated below in yellow. This includes the Historic District, the Village Square and the northwest corner of the Village. More data is being collected to find exact locations for I&I.
I&I map, yellow

What’s next?
Once specific locations are identified, the Village will contract with a company to ‘televise’ the Village’s sewer lines where I&I is believed to be taking place. This means a camera will be run through the sewer, identifying the condition of the lines, as well as looking for any connections where stormwater may be entering the sanitary lines.