Infinitii I&I: Auto I&I Envelope

When Infinitii I&I analysis indicates that there is a problematic site, where the effects of a storm event exceed the normal parameters established for one of your collection systems, you will want to drill down and gain a full understanding of what's going on. This is where the Infinitii Auto I&I provides a deeper understanding of the data.

Accessing the Auto I&I Envelope

The Auto I&I Envelope is accessed by clicking the Details button next to a site on the main Infinitii I&I screen. You will be presented with a list of the sites associated with your project, click the site you want to examine.


Once you click a site, a new page opens showing the Auto I&I Envelope analysis. The I&I Envelope is a graphical method based on a summary of the rainfall events and sewer flow data from flow monitoring at the site. Plotting these results on a graph demonstrates the relationship between rainfall and rainfall-dependent I&I (RDII).

The Auto I&I Envelope Graph


The Envelope graph has the following sections:

  1. Analysis Overview: This section presents basic information about the data sources used to construct the graph.
    • Flow Channel: The friendly name of the FlowWorks channel providing the flow data used to create the graph.
    • Rain Site / Channel: The friendly name of the FlowWorks channel providing the rainfall data used to create the graph.
    • Rain Events Analyzed: The number of rain events used in the analysis to generate the graph. More rain events will generally produce a more accurate estimate.
    • IDF Chart: The name of the pre-generated IDF Chart used to determine the relative severity of the rainfall events shown in the graph.
  2. Correlation of IDF Flow: This section shows the mathematical results (linear fits and correlation) of the I&I Envelope analysis.
    • Best Fit: The linear fit between the rainfall and the average RDII flow during the rainfall events.
    • Best Fit to Max Flow: The linear fit between the rainfall and the maximum RDII flow during the rainfall events.
    • Correlation of Determination: The r2 value is the proportion of the RDII flow variability explained by the intensity of the rainfall events.
  3. Graph: The graph itself compares the RDII flow (y-axis, dependent variable) to the 24 hr rainfall total (x-axis, independent variable).
    • Each rainfall event is a separate data point on the graph, shown as a red square and numbered for identification.
    • The dotted line is the result of the Best Fit linear equation.
    • The solid line is the result of the Best Fit to Max Flow linear equation
    • . The x-axis has gradations to show the IDF chart values for the various rainfall events (2 years, 5 years, 10 years, 25 years, 50 years, and 100 years.)

The graph also has two buttons.


  • View Storm Events: Click this button to view details about specific storm events. Refer to the Auto I&I Storm Events documentation for more information.
  • Convert to Manual I&I: Click this button to import the Auto I&I data into a manual I&I Analysis project. This is useful if you want to do a more complex and detailed analysis of the data, for example analyzing only a specific subset of storm events. For more information on manual I&I, refer to the general Infiltration & Inflow Analysis documentation.
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