This particular example file, Source1_Barriers.gsm, can be found in the Contaminant Transport Examples folder in your GoldSim directory (accessed by selecting File | Open Example... from the main menu).
Suppose that 100 drums were buried in shallow soil. The soil recharges a shallow aquifer. Each drum contains water (55 gallons) and two contaminants: 1 gram of nitrate and 1 gram of lead. Nitrate is very soluble, and hence is completely dissolved in the water within the drum. The lead, however, has a solubility of 0.1 mg/l. The drums are expected to fail at a uniform rate over 10 years. Once they fail, infiltrating water flows through each drum at a rate of 0.5 m3/yr. For simplicity, we can assume that neither species sorbs onto the surrounding soil once it is released. At what rate does the mass of the two species enter the aquifer?
To simulate this system in GoldSim, you would do the following:
1. Define two species (nitrate and lead);
2. Define the properties for the medium Water (in particular, the solubility of lead in Water);
3. Define a Source, and specify the number of packages, the inventory of each species in the Source, and the failure rate of the packages;
4. Define a Cell (representing the interior of a single drum). It will automatically be assigned as an Inventory Cell for the Source;
5. Define a Cell representing the aquifer (used here simply as a sink); and
6. Specify the simulation settings (i.e., duration and timestep), and run the model.
The output of this simulation, in the form of time histories of the mass flux of each species from the drums into the aquifer, is shown below:
Note that the nitrate species is released uniformly over 10 years as the drums fail and it is flushed into the aquifer (the rounded front and back of the curve are due to the finite amount of time it takes to flush a drum). The lead species, on the other hand, is controlled by a solubility constraint within each drum. That is, the release rate from a given failed drum is constant. The release rate from the Source increases linearly as more drums fail. After all the drums have failed, the release rate stays constant (and will continue to do so until all of the lead has dissolved).
Note: Because this example
includes a Source element, it requires the RT Module. If you are using the
CT Module, you will not be able to open the file.
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