In this walkthrough I will demonstrate how to use the tool to characterize the sensitivity of the improper disposal model to modeling assumptions and used oil composition parameters. This page assumes familiarity with the concepts introduced in the first walkthrough .

Getting Started

Ensure you are using the tool as an authorized user . Create a new scenario with the "Improper disposal (splitter)" fragment as the top-level fragment.

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Save the new scenario.

Evaluating Different Disposal Routes

Each disposal route is a distinct unit process in the model. Therefore, we can use the LCIA Comparison tool to compare their relative impacts.

1. Visit the LCIA Comparison page, and clear the default "Used Oil Management" comparison component.

1. Select "Process" from the component type selector, "Used oil, improperly disposed, to agricultural soil via dumping" from the process selector, "Model Base Case" from the scenario selector, and a descriptive name in the bar label.

1. Continue to add other improper disposal processes from the Model Base Case scenario.

So far, the results show that dumping to fresh water appears to be the worst option for ecotoxicity, human health-cancer, and eutrophication effects, while dumping to agricultural soil is the worst for human health-non-cancer.

1. Now add the same processes again, but under your newly-created variant scenario. For now, the processes from the model base case and the variant will have the same results.

2. Finally, add the overall Informal Management fragment from the model base case and variant scenarios. For now, the model base case and the variant will have the same results.

1. Now, make your changes to the variant scenario. First, visit the change the Zinc concentration from the default to a 10x-reduced value of 0.0001.

1. Now, if you return to LCIA Comparison, you will see the variant scenario already has much lower impacts in human-health non-cancer toxicity and in freshwater ecotoxicity. However, human-health cancer and eutrophication are not affected.

1. Now change the disposition assumptions. Visit the home screen and clone your variant scenario. Name the newly created variant "Informal Management II".

2. In the newly created scenario, visit Fragment Flows and edit the parameters of the "Storm Drain (splitter)" process. Change the "Dry Weather Diversion" parameter from 0.2 to 0.5 (since we are entering a prolonged drought, there may be more opportunities to employ dry weather diversion for storm drain flows). Be sure to "apply changes"!

1. Now, return to the LCIA Comparison view and add a new comparison case: the "Improper Disposal (splitter)" fragment under the newly created "Informal Management II" variant scenario. Go ahead and clear out the other processes to focus on what's important:

These new results show a slight decrease in Human health-cancer and eutrophication impacts from the reduced stormwater flow. They also show a greater avoided burden in acidification, smog, and criteria pollutants stemming from the increased incineration of waste sludge and the displacement of electricity. Finally, there is an increase in global warming potential and a slight increase in human health-non-cancer due to increased waste disposal operations.

1. These conclusions can be validated in the "Scenario LCIA Results" view, which shows contributions to the impact scores by stage.