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Applies To |
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Product(s): |
CivilStorm, SewerGEMS |
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Version: |
CONNECT Edition, V8i |
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Area: |
Layout and Data Input |
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Problem
What is the workflow to model treatment for pollutants in nodes and ponds using the Explicit (SWMM) solver in SewerGEMS and CivilStorm?
Solution
For this type of analysis, you would need to use EPA-SWMM features, so the solver needs to be set to Explicit (SWMM) in the calculation options.(Analysis>Calculation Options)
In the properties of the pond or node, find the section SWMM Extended Data. Find the property field Apply Treatment and set this to True. Then click in the Treatment Collection to open a new dialog. The Treatment Collection will include the pollutant and a treatment expression. For more information on the treatment expression and how this is formatted, see the Help documentation related to treatment. The EPA-SWMM user manual will have additional information as well.
A note on pond TSS removal
It's essentially impossible to have an accurate model of TSS (Total Suspended Solids) removal at a pond based on simple parameters such as detention time.
Consider the kinds of solids that are in pond influent; they can range from colloidal clay which will not be removed much at all to sandy erosion from a construction site that will tend to settle much better.
As for the treatment expression to model this, consider an equation such as the one mentioned here (SWMM Water Quality manual) or here, possibly adjusting it if you have data from ponds in the area with similar solids. High precision is not to be expected.
Reference: (forum discussion) TSS removal in a permanent retention (wet) pond
See Also
SWMM User Manual
SWMM water quality User Manual
Prediction of quality characteristics of sewers
Modeling septicity / hydrogen sulfide (H2S)
(Forum) TSS removal in a permanent retention (wet) pond