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Thread: Excessive Stormwater in Sanitary Sewer System

  1. #1

    Join Date
    Jun 2013
    Posts
    5

    Excessive Stormwater in Sanitary Sewer System

    I have been working on calibrating a sanitary sewer model using some field data we collected last summer. I started the calibration process by using the EPA SSOAP tool to develop RTK values using my storm data. I then input that data into Infoworks CS and set some low baseline rainfall infiltration values (I set groundwater infiltration to 0.01 to turn it off). After running the model multiple time I have adjusted both the ground infiltration and RTK values to zero or almost zero and I am still getting substantially more flow into the system than my data shows actually happens. Are there other variables other than the Ground Infiltration and RTK sets (under the subcatchment group) that I should be adjusting? If not does anyone have any suggestions why I might be getting excessive flow into my system?

    I have include a sample site as well as the results below. To me the RTK values should move the curve to the right not all at the start of the storm.

    Basin 12
    Ground Infiltration
    0.500
    0.500
    0.010
    0.500
    99.000
    0.001
    40.000
    40.000
    392.000
    Absolute
    402.000
    Absolute
    RTK
    0.001
    2.000
    0.050
    0.001
    24.000
    36.000
    0.100
    48.000
    60.000

    Results
    Site 12.jpg

    Thanks,

    Josh

  2. #2
    Senior Member

    Innovyze Employee



    Join Date
    Feb 2013
    Posts
    146
    Hello HWEI,
    I would plot or graph just the RDII flow from that Subcatchment to see the response. It looks like you have a very small K1 value of 0.05 which may be making the response UH not smooth. It should not look like the hyetograph. If you still have questions please send us an email to support@innovyze.com Your contributing area may also be too large for the RDII response which accounts for the large flow even though the R1 value is small.

    Regards,
    Bob Dickinson

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