The integration of ICM SWMM into the ICM platform has brought with it the inclusion of the SWMM5 Buildup Washoff feature. This allows users to analyze the impact of tracer concentrations on a 1D network, specifically in determining the percentage contribution of real-time kinematic (RTK) urban hydrology or runoff to a wastewater treatment plant (WWTP). By incorporating the SWMM5 Washoff tool into the ICM InfoWorks network, users can more accurately assess the impact of various factors on the treatment and management of wastewater. This can be particularly useful for identifying potential issues or inefficiencies in the system and for developing strategies for improving the overall performance of the WWTP. #watermatters
The hydrology of combined sewer systems is highly complex. Runoff, dry weather flow, or rainfall-dependent infiltration and inflow can all contribute to the flow to a WWTP or an outfall (RDII from leaky sanitary sewers). All inflows are mixed in the 1D ICM pipes, and it is difficult to determine how much RDII flow gets to a WWTP or an outfall.
Suppose you utilize SWMM5 washoff in an ICM InfoWorks network. In that case, you can use tracer concentrations for DWF, Runoff, and RDII to calculate the percentage or fractional contribution from any source in the link flow.
How do you define the tracers?
It is a simple four-step process: (1) Use an InfoWorks Network, (2) Use the Water Quality and Sediment Parameters dialog, (3) Use the SWMM Buildup / Washoff Model, and (4) define rainfall and RDII concentrations. The output of ICM lists the concentration as kg/m3, so we enter the tracer as 100,000, so the link water quality percentage is 0 to 100. BOD will be the RDII tracer, and COD will be the tracer for runoff. The tracer for runoff is actually the rainfall concentration.
How do we tell if the RDII Tracer is working?
We will define a subcatchment with only RDII or an RTK UH. We run the model and see that the concentration of BOD or our RDII tracer, is 100 and the COD concentration is zero, as there is no runoff and no rainfall tracer contribution to the runoff water quality.
BOD is 100 as we have no Runoff and only RDII flow from the Subcatchment.
How do we tell if the Rainfall or Runoff Tracer is working?
We will define a subcatchment without an RDII or an RTK UH. We run the model and see that the concentration of BOD or our RDII tracer, is 0 and the COD concentration is 100, as there is runoff and a rainfall tracer contribution to the runoff water quality.
COD is 100 as we only have Runoff and no RDII flow.
What do we see if RDII and Runoff sources are mixed in the Link?
When the concentration in a link with upstream sources for runoff and RDII is examined, COD and BOD are not zero. BOD concentration is expressed as a percentage of RDII flow, while COD concentration is expressed as a percentage of runoff. Because the RDII peak is usually later than the runoff peak flow, the BOD concentration is after the COD peak.
If we look at the concentration in a link with upstream sources for Runoff and RDII then both COD and BOD are not zero
Use SQL to define the RDII UH or RTK UH Quickly.
There are nine used RTK UH parameters in our testing. You can also use the grid output to see the concentrations in a table at a particular time step for both the upstream and downstream ends of the link.