--> Abstract: Cleaning Up Sites Naturally Via Natural Attenuation as a Remedial Strategy, by S. M. Testa; #90958 (1995).

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Abstract: Cleaning Up Sites Naturally Via Natural Attenuation as a Remedial Strategy

Stephen M. Testa

It is well documented that soluble petroleum compounds such as BTEX tend to biodegrade in subsurface environments. Although biodegradable, petroleum compounds are the focus of cleanup efforts at tens of thousands of sites throughout the United States. Considerable national effort is being spent to accelerate the cleanup of compounds which eventually degrade. However, without excavation, engineered remedial efforts cannot completely remove residual petroleum hydrocarbons near the water table in the smear zone. At sites that have impacted aquifers of no beneficial use, natural attenuation (NA) with long-term monitoring should be given more emphasis as an effective bridge between active remediation and no further action. This alternative has often been ignored by regulators ecause of its tendency to be incorrectly categorized as a "No Further Action (NFA)" alternative. For NA to be used effectively, it is important to know its limitations and avoid its misuse. A review of parameters for evaluation and a discussion of the strategy to be used for applying NA is followed by two case studies. One of the case studies demonstrates that natural attenuation can be successfully demonstrated as a management strategy for diesel-range hydrocarbons in soil. Overall, the conditions supporting natural attenuation as a remedial alternative are: the release has stabilized, the site has been characterized and has an adequate long-term groundwater monitoring plan, recoverable LNAPL has been removed, remediation of source area has been accomplished to the extent practicable, a d documentation of ongoing natural attenuation has been obtained. The extent of data gathering for evidence for NA is site-specific, but should be incorporated into every site investigation from the onset.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California