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This Directive clarifies EPA's policy with regard to the use of monitored natural attenuation for the remediation of contaminated soil and groundwater at sites regulated under all programs administered by EPA's Office of Solid Waste and Emergency Response (OSWER), including Superfund, RCRA Corrective Action, and Underground Storage Tanks.

The Directive is intended to promote consistency in how monitored natural attenuation remedies are proposed, evaluated, and approved. As a policy document, it does not provide technical guidance on evaluating Monitored Natural Attenuation remedies. This version of the Directive is being issued as Final and should be used immediately. It provides guidance to EPA staff, to the public, and to the regulated community on how EPA intends to exercise its discretion in implementing national policy on the use of Monitored Natural Attenuation. The document does not, however, substitute for EPA's statutes or regulations, nor is it a regulation itself and, thus, it does not impose legally-binding requirements on EPA, States, or the regulated community, and may not apply to a particular situation based upon the circumstances. EPA may change this guidance in the future, as appropriate.

NOTE: QA documents referred to in this publication may be outdated. Visit The EPA Quality System web site for the latest version of EPA's QA documents.

To order paper copies of this Directive, please call the U.S. Environmental Protection Agency's (EPA) RCRA, Superfund, OUST & EPCRA Hotline at (800) 424-9346 or DC Area Local (703) 412-9810 or TDD (800) 553-7672 or TDD DC Area Local (703) 412-3323 Monday through Friday between 9:00 a.m. and 6:00 p.m. EST. The Directive is available at three OSWER dockets:

  1. The UST Docket is open to the general public by appointment only between the hours of 9:00 a.m. and 4:00 p.m. EST Monday through Friday. No security clearance is necessary. Visitors may make photocopies of documents. The street address is: Office of Underground Storage Tanks Docket, 1235 Jefferson Davis Highway, Ground Level, Arlington, VA 22202. Telephone numbers are (703) 603-9230 and (703) 603-9234 (fax).
  2. The RCRA Docket is located in the RCRA Information Center (RIC). The RIC is open to the public from 9:00 a.m. to 4:00 p.m., Monday through Friday, however, it is recommended that visitors call ahead to make an appointment so that the material they wish to view is ready when they arrive. Patrons may call for assistance at (703) 603-9230, send a fax to (703) 603-9234, or send an E-mail to rcra-docket@epamail.epa.gov. Patrons may write to: RCRA Information Center (5305W), U.S. Environmental Protection Agency, 401 M Street, SW, Washington, DC 20460. The RIC is located at 1235 Jefferson Davis Highway, Ground Level, Arlington, VA 22202.
  3. The Superfund Docket is open to the general public by appointment only between the hours of 9:00 am to 4:00 pm Monday through Friday. No clearance is necessary and requestors of documents must make their own photocopies. There is no photocopying charge for documents less than 266 pages in length. The street address of the Superfund Docket/Document Information Center is 1235 Jefferson Davis Highway, Ground Level, Arlington, VA 22202. The telephone numbers are (703) 603-9232 and (703) 603-9240 (fax). The E-mail address is: superfund.docket@epamail.epa.gov.

Finally, copies of the Directive may be procured from the National Technical Information Service (NTIS). The EPA document Number is EPA-540-R-99-009, and the NTIS document Number is PB99 963 315. The phone number for NTIS is: (703) 487-4650. (For rush service call 1-800-NTIS.) NOTE: NTIS charges a fee for copies of documents and other materials.

FINAL VERSION (April 21, 1999)

This version replaces the Interim Draft (December 1, 1997)—it is distinguished from the earlier version by having a "P" at the end of the Directive number (i.e., 9200.4-17P). This Directive is 41 pages in length and consists of four parts: (1) cover sheet, (2) Directive Initiation Request (Form 1315-17), (3) transmittal memorandum--which contains a list of EPA Regional contacts (4 pages), and (4) directive text—which is 35 pages in length (counting the cover sheet, table of contents, and notice). Because word processing formats are printer dependent, and PDF* files are not, this file is the "genuine" article and this PDF file is the only electronic format in which the Directive is being distributed. This way, everyone who receives the document will have the same document, with the same words on each line of every page.

For more information about this Directive contact Hal White, U.S. EPA, Office of Underground Storage Tanks. More information is available on Monitored Natural Attenuation.

* About PDF Files: PDF is the abbreviation for "Portable Document Format". PDF files require a viewer, Adobe Acrobat, which is a FREE plug-in for your browser. You can go to Adobe via this link to download Acrobat. Exit EPA Disclaimer

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