An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »


Guidance: Issuing UAOs for RD/RA Evaluation and Guidance

Memorandum presents results of evalauation of the selection process EPA uses in issuing unilateral administrative orders (UAOs) to potentially responsible parties (PRPs) for remedial design/remedial action (RD/RA) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, commonly referred to as Superfund).  OSWER Directive No. 9833.2c. Issued 6/20/1991.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.