Petroleum Hydrocarbon Monitored Natural Attenuation: Essential Framework for Remedial Managers

Abstract Monitored natural attenuation (MNA) is an attractive remedy for petroleum-contaminated sites. However, to use MNA as a partial or total site remedy, the remedial manager must first present unequivocal evidence that natural attenuation will occur at the site and will meet public and regulatory concerns. A considerable body of scientific evidence of natural attenuation exists, as does a small library of American Society for Testing and Materials and U.S. Environmental Protection Agency documentation on use of MNA. This article clearly and succinctly presents the background of MNA, guides the new remedial manager through the process, discusses the pros and cons of MNA alone and in combination with other low-cost remedies (primarily source removal), and outlines regulatory and public concerns and how to meet them. Key Words: intrinsic remediation, monitored natural attenuation, passive bioremediation.