Underground Storage Tanks

Monitored natural attenuation (MNA) is a technique used to monitor or test the progress of natural attenuation processes that can degrade contaminants in soil and groundwater. It may be used with other remediation processes as a finishing option or as the only remediation process if the rate of contaminant degradation is fast enough to protect human health and the environment. Natural processes can then mitigate the remaining amount of pollution; regular monitoring of the soil and groundwater can verify those reductions.

MNA Policy

• OSWER Directive 9200.4-17P (PDF) (17 pp, 274K, About PDF) -- Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites -- April 21, 1999

MNA Technical Support Documents

• Performance Monitoring of MNA Remedies for VOCs in Ground Water EPA 600/R-04/027. April 2004.
• Site Characterization to Support Use of Monitored Natural Attenuation for Remediation of Inorganic Contaminants in Ground Water (PDF) (16 pp, 1.1MB, About PDF) EPA 600/R-08-114. November 2008.
• Natural Attenuation of the Lead Scavengers 1,2-Dibromoethane (EDB) and 1,2-Dichloroethane (1,2-DCA) at Motor Fuel Release Sites and Implications for Risk Management (PDF) (74 pp, 2.2MB, About PDF) EPA 600/R-08/107. September 2008.
• Monitored Natural Attenuation of MTBE as a Risk Management Option at Leaking Underground Storage Tank Sites EPA 600/R-04/179. January 2005.

Other Links

• Monitored Natural Attenuation (Ground Water and Ecosystems Restoration Research)

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