United States Environmental Protection Agency

April 19, 1993

Mr. Raymond D. Hiley
Goodwin, Procter & Hoar
Counsellors at Law
Exchange Place
Boston, Massachusetts 02109-2881

Dear Mr. Hiley:

     Thank you for your letter of March 24, 1993 concerning the determination of the corrosivity characteristic. The Paint Filter Liquids Test (Method 9095 in SW-846) was developed to determine free liquids in a waste. It was never intended for use in determining if a waste contains any bound or absorbed liquid or if
such liquid is aqueous.

     The Office of Solid Waste is looking at the issue of what constitutes a liquid for characteristic testing. We will shortly be proposing revisions to the Third Edition of "Test Methods for Evaluating Solid Waste" (SW-846) in the Federal Register. In this proposal, we hope to clarify the meaning of liquid for characteristic testing. After this rule is proposed in the Federal Register, we would happy to sent you a copy of the notice.

     The guidance on the use of Method 9095 provided in the February 16, 1990 letter to Mr. Robert D. Wyatt would still be our best advice to you until rules have been promulgated defining the meaning of "liquid" and "aqueous" for characteristic testing.

     As you have correctly stated, under the present regulations an aqueous phase must be present in the sample in order to determine the corrosivity characteristic by pH measurement. This is because it is technically impossible to determine pH in liquids where water is not present.

     I hope that this information will be of use to your analytical program. If you have any questions, please feel free to call Ollie Fordham of our Methods Section at (202) 260-4778.

Sylvia K. Lowrance
Office of Solid Waste