Problem

How do I model an infiltration trench that does not discharge water? 

How do I model an infiltration trench where all the water is absorbed into the ground?

Solution

First,  layout a catchment and then associate the LID control to that because LID controls need to have a what we deem a "parent catchment", which is just a catchment that is associated with the LID control.

The blue box that is outlined above is where you will click on the ellipsis to open the low impact development controls manager where you will create your LID (infiltration trench) control. The LID control manager can also be accessed from the Components menu. This wiki should explain a little more about the LID controls:

http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/10324.low-impact-development-lid

The catchment needs to be setup to use the EPA SWMM runoff method. You also need to make sure that whatever loss method that you decide to use in the catchment matches with the loss method that you have set in your calculation options under the "SWMM Hydrology" section or vice versa.

In order to get the flow from your upstream manhole into your catchment you will need to add a hydrograph type inflow wet collection on your catchment. You can get this information by modeling up to the manhole point in your model and ending it at a free outfall. After doing this you would run your model and right click on that outfall then select data table. Finally, you would copy and paste the data table values into the inflow wet collection hydrograph. This will simulate the flow coming from that upstream manhole and pass it to the catchment and will be flow in addition to the runoff you are getting from your catchment.

The final part of your model will be a free outfall that you will connect to your catchment as the outflow element.  This infiltration trench will not have any outflow, but in order for the model run there needs an outfall and a downstream element from the catchment. This outfall will just be in place to satisfy the requirement of the software and should not receive any flow if your infiltration trench is set up correct.

Your final model would look something like this:

See Also

Low Impact Development (LID)