Depth below invert is a space or certain depth of sump that function as rubbish/leaves or sediment trash to avoid blockage of outlet pipe.
In MiTS 3, there are 2 options for Depth Below Invert, Level and Fixed Depth.
Level is the depth below invert of any node. It is similar to the Depth Below Invert from MiTS 2 and MiTS 1. Set the Iterate to No if you want to input the Level value. You might want to analyse your project first before putting a depth below invert at any node if you let the software to iterate the Start and End IL of the drain for you. If not, then you can straight away put the depth below invert at any node.
Fixed Depth is the depth of the sump. You can fixed the depth of your sump using this Fixed Depth option. The sump depth at that particular node will use this value exactly, and if it is deeper than the node IL, there will be depth below invert (Level) at that node. Set the Iterate to Yes if you want to use this option.
These options can be found at Node & Storage >> Spread Input >> Depth Below Invert Settings
The difference can be viewed in the Longitudinal Section after Analysis as per the image below.
As per example above, the invert level is 31.704m. Since the fixed depth was 2.0m, therefore the lowest invert level for that sump is 30.30m (32.30 – 2.0). The depth below invert was 1.404m (31.704 – 30.300)
As per the example above, the invert level iterated is 30.06m. Since the depth below invert, Level was 0.5m, therefore the lowest invert level for that sump is 29.56m (30.06 – 0.5)
Click HERE to download the project as a reference.
