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Different Methods of Managing a VOC Release into Groundwater

You are the environmental manager of the site and there has been a release of VOC's and metals onto the ground surface and have migrated into the subsurface sediments and groundwater. The underlying aquifer is very close to the surface, only about 2 feet< and the groundwater generally flows toward the lake. From benchmarks, the elevation of the site is 20 feet above sea level and the lake is about 7 feet above sea level. This distance to the lake from the release is about 400 feet.

The subsurface sediments are: lacustrine (lake deposits) to a depth of 7 feet from the surface with a permeability of 10-3. Underlying the lake deposits is 10 feet of glacial till with a permeability of 10-2. Underlying the till is a thick layer of shale with a permeability of 10-9 which acts as a impermeable barrier.

Develop a management plan to address this problem.
What kind of questions might you ask in-order to identify a possible technology?
Is there any other information you can identify and provide that would be useful in solving this problem?

Solution Preview

Generally the first step in remediation of a contaminated site is to model the contamination plume. The size and shape of the plume will vary depending on the type of material through which it moves, and the type of chemical involved. There is critical information missing from this problem, namely the amount of the chemical spilled. If it was a very small amount, it may be absorbed by the surface sediment and reach the groundwater. However, since the groundwater is near the surface, it is likely that the amount is sufficient to have caused contamination. It would also be useful to know if it is the wet or dry season. This will help determine the current rate of groundwater recharge. The overlying foliage is important. Roots can work to bioremediate VOCs. This is a form of natural bioremediation. Enhanced bioremediation would include activities such as adding nitrogen to the soil. Organic compounds undergo degradation dependent on factors such as pH. Thus the pH of the groundwater should be measured.

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Solution Summary

Different methods of managing a VOC release into groundwater.