United States Air Force Guidelines for Successfully Supporting Intrinsic Remediation with an Example from Hill Air Force Base.

Based on work performed at numerous hydrocarbon-contaminated sites across the United States, a methodology and protocol for scientifically supporting and documenting intrinsic remediation was developed. Intrinsic remediation is a risk management strategy that uses natural attenuation to control exposure to hazards associated with contaminants in the subsurface. Intrinsic remediation is achieved when naturally occurring degradation mechanisms work to bring about the in situ destruction of contaminants. Mechanisms of natural attenuation can be classified as destructive and nondestructive. Destructive processes include biodegradation, abiotic oxidation, and hydrolysis. Biodegradation (both aerobic and anaerobic) is generally the most important natural attenuation mechanism. Nondestructive attenuation mechanisms include sorption, dilution, and volatilization. The first part of this paper presents a brief overview of the technical protocol for data collection and analysis, ground water modeling, and exposure assessment in support of the intrinsic remediation with long-term monitoring remedial option for restoration of fuel-hydrocarbon-contaminated ground water. This protocol is currently under development by the Air Force Center for Environmental Excellence (AFCEE) - Technology Transfer Division (Wiedemeier et al., l994a) and is being prepared through the joint effort of AFCEE, the Bioremediation Research Team at the United States Environmental Protection Agency (USEPA) Robert S. Kerr Environmental Research Laboratory (RSKRL) in Ada, Oklahoma, and Engineering-Science, Inc. (ES) to facilitate implementation of intrinsic remediation at fuel-hydrocarbon-contaminated sites. Specifically, this protocol is designed to evaluate the fate of dissolved-phase fuel hydrocarbons having regulatory maximum contaminant levels (MCLs).