| Popis: |
Historical disposal practices used by oil companies have caused the accumulation of contaminated sediments in their nearby lakes and ponds. These companies are now faced with the challenge of remediating the bodies of water that contain these contaminated sediments. The contaminants that remain in the sediment continue to pose a threat to human health and the environment. For example, high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are still present in the bottom sediments can have toxic effects on aquatic life. One form of remediation for this problem is In-Situ Capping (ISC), which is defined as a method whereby material is used as a covering or cap for placement over contaminated sediment located under a body of water. This work focuses on evaluating ISC as a remediation method for oil contaminated sediments. Bench-scale laboratory experiments were conducted on oil contaminated sediment samples to observe the effect of consolidation, contaminant migration, gas generation, and ground water migration on the caps ability to contain the contaminants. It was found that, overall, ISC could be used as an effective remediation method for the oil contaminated sediments tested. However, there was some migration of PAHs into the first few centimeters of the cap in all columns tested due to a combination of intermixing during cap placement, non-aqueous phase liquid migration, and retarded transport of certain PAHs. It was also observed that contaminant migration increased when gas bubbles, which simulated gas generated by the contaminated sediment, were injected into the column experiments over an approximately one month period. These results demonstrate that site-specific adjustments to ISC designs are necessary for the cap to most effectively contain contaminant migration in the field. |
