Topic Thread

  • 1.  Fire ants in bioretention basin

    Posted 11-17-2021 07:53 AM

    Hi everyone,

    I'd like to ask if anyone has experience with fire ants in bioretention cells and how to control it?

    We are monitoring water quality and hydraulic performance of multiple bioretention cells and one of them is infested with fire ants. We've been applying hot water to their mounds, and they are slowly migrating but still persistent.
    I'd appreciate any recommendations on effective methods for eliminating fire ants with the least impact (no chemicals), since we are monitoring the water quality of the outflow. Also what could be their impact on overall performance of the bioretention cell? Is the hydraulic conductivity of the cell significantly impacted by their tunnels leading to changes in the performance of the cell?

    Thanks,

    Abtin Shahrokh Hamedani

    PhD Candidate, University of Texas at San Antonio



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    Abtin Shahrokh Hamedani Ph.D., A.M.ASCE
    San Antonio TX
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  • 2.  RE: Fire ants in bioretention basin

    Posted 11-20-2021 05:14 PM
    The periodic flooding doesn't drown them out?

    Close the bottom orifice for a couple storms?

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    Ann Wingert P.E., M.ASCE
    Project Engineer
    Stroudsburg PA
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  • 3.  RE: Fire ants in bioretention basin

    Posted 11-22-2021 02:26 PM
    Beneficial nematodes.




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    Robert Thomas EIT, A.M.ASCE
    Qualified Member of the Engine Department (QMED)
    Waxahachie TX
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  • 4.  RE: Fire ants in bioretention basin

    Posted 11-29-2021 12:13 PM
    Thanks for your recommendation, I'll certainly look into it.

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    Abtin Shahrokh Hamedani Ph.D., A.M.ASCE
    San Antonio TX
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  • 5.  RE: Fire ants in bioretention basin

    Posted 11-29-2021 12:13 PM
    Thanks for your response. Unfortunately the fire ants don't drown easily. They create a raft and can float on water for days.
    https://www.amdro.com/learn/fire-ants/hurricanes-floods-and-floating-fire-ants

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    Abtin Shahrokh Hamedani Ph.D., A.M.ASCE
    San Antonio TX
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  • 6.  RE: Fire ants in bioretention basin

    Posted 11-30-2021 09:47 AM
    Hi Abtin,

    While we use chemicals to control fire ants (we live near Houston), many of our neighbors have reported good success using dish soap. This may also help to get rid of the rafts by destroying the surface tension I am sure they rely on to float.

    Roger.

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    Roger Kitchin P.E., M.ASCE
    Richmond TX
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  • 7.  RE: Fire ants in bioretention basin

    Posted 13 days ago

    Hi Roger,

    thanks for your recommendation, I'll give it a try for sure.

    Thank you and happy 2022!



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    Abtin Shahrokh Hamedani Ph.D., A.M.ASCE
    San Antonio TX
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  • 8.  RE: Fire ants in bioretention basin

    Posted 12-06-2021 07:56 AM
    Abtin,
    Can't you meter the flow rate on the outfall to evaluate the impact? What type of filter media is used? Do you know the soil/filter ingredients? You can also try steam injectors which still uses hot water, but I guess hot water may kill the plants if used too many times. 

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    Hadi Beigi M.ASCE
    Civil Senior Designer
    Houston TX
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  • 9.  RE: Fire ants in bioretention basin

    Posted 13 days ago

    Hi Hadi,

    Thanks for your response. We have been monitoring the outflow for 2 years and multiple factors can cause changes in the outflow including aging, plants cycles, clogging and ... so we can not be sure of the sole impact of fire ants in this cell. The filter media is sandy loam with mulch on top.

    Thanks for your suggestion, steam injectors could work, we'll give it a try.



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    Abtin Shahrokh Hamedani Ph.D., A.M.ASCE
    San Antonio TX
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  • 10.  RE: Fire ants in bioretention basin

    Posted 4 days ago
    Have you tried Diatomaceous earth?  It is commonly used for crawling insects and should not harm your water quality.

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    Hall Charles EIT, A.M.ASCE
    civil eit / designer
    Renton WA
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