UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

SEPTEMBER 15, 1987

Mr. Stuart J. Gock

Environmental Coordinator

Printing Development, Inc.

2010 Indiana Street

Racine, WI 53405

Dear Mr. Gock:

The following information is being provided in response to your letter of April 6, 1987, 

regarding the definition of aqueous as used in the Corrosivity Characteristic, 40 CFR Part 261.22(a)(l).

As you are aware, the corrosivity characteristic does not specifically define what constitutes an 

aqueous waste. However, we have developed guidance in defining the term “aqueous.” In particu1ar, 

we consider a waste to be aqueous if it has a liquid phase containing more than 50 percent water.” 

(See attached letter from Dr. John Skinner, Director of the Office of Solid waste, on February 26, 

1985.) This position is currently in effect and you shou1d use the 50 percent water cut-off as a basis 

for evaluating whether or not to test your wastes for corrosivity.

I should point out that we are considering reviewing this position, as well as the need for a 

regulatory definition of aqueous waste. Therefore, you should be aware that a regulatory definition of 

aqueous may be proposed at some point in the future.

If you have any additional questions, please do not hesitate to contact me.

Sincerely,

Robert Scarberry, Acting Chief

Waste Characterization Branch

Attachment

FaxBack# 11292
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

SOLID WASTE AND EMERGENCY RESPONSE

FEBRUARY 26, 1985

Mr. Kevin J. Walter

Chief, Bureau of Technical Services

Division of Environmental Enforcement

Department of Environmental Conservation

State of New York

50 Wolf Road

Albany, New York 12233-0001

Dear Mr. Walter:

I am writing in response to your recent letter requesting clarification of the definition of the 

characteristic of ignitability for hazardous wastes.

Your understanding that the words “it is a liquid, other than an aqueous solution containing less 

than 24 percent alcohol by volume” were intended to exclude alcoholic beverages, such as wine, and 

non-liquid materials is correct. However, while the Agency’s intent was that this exemption apply to 

potable beverages only, because the term “alcohol” was used instead of “ethanol,” all aqueous wastes

which are ignitable only because they contain alcohols (here using the term alcohol to mean any chemical 

containing the hydroxyl [-OH] functional group) are excluded from regulation.

While the Agency completes the process of officially adopting a method for identifying “free 

liquids,” for use in the land disposal regulations, it is our current practice to employ Method

9095 (see “Test Methods for Evaluating Solid Waste, SW-846”) for such purposes. Any material 

passing through the paint filter is deemed to be a liquid.

With respect to what constitutes an “aqueous solution,” such a solution is one in which water is 

the primary component. This means that water constitutes at least 50 percent by weight of the sample. 

Although we have not officially approved any test methods for determining a waste’s water content, any 

competent laboratory should be able to make such a determination using standard techniques (e.g., Karl 

Fisher titration, GC).

We share your concern over the ambiguities in the current ignitability definition and have a 

program underway to correct the characteristic’s shortcomings. Specifically, changes are under 

development to replace the alcoholic solution exclusion with a generic exclusion for those wastes which, 

while possessing a flash point below 60°C, neither continue to burn nor, if they do burn, release enough 

energy to be cause a major fire. In addition, steps are being taken to expand the ignitability 

characteristic to include wastes which are physical solids. Both of these changes will involve proposal 

and promulgation of specific definitional test methods and thresholds. 
I hope this information clears up any questions you may have about the ignitability characteristic. 

If you have any further questions concerning any of the hazardous waste characteristics, please contact 

David Friedman, of my staff, at: 202-382-4770.

Sincerely yours,

John H. Skinner 

Director

Office of Solid Waste
General Chemical Corporation

Environmental Matters

P.O. Box 389

Parsippany, NJ 07054-0389

(201) 515-0900

June 22, 1987

Ms. Eileen Claussen, Director

Characterization and Assessment Division

WH562B

Environmental Protection Agency

401 M. Street SW

Washington, DC 20460

Dear Ms. Claussen:

In 40 CFR, Part 261.22(a)(l) of Subpart C, Characteristics of Hazardous Waste, one of the 

characteristics for determining if a waste is hazardous is defined as follows:

“(1) It is aqueous and has a pH less than or equal to 2 or greater than or equal to 12.5, _ _ _ _ 

_”

In attempting to determine the regulatory status regarding certain liquid waste streams we need to 

ascertain the EPA definition of the term “aqueous” in the above. This term is defined in the Glossary of 

Chemical Terms as a “solution or suspension in which the solvent is water.”

If this is the definition intended for use by EPA, then we would conclude that only those waste liquid 

solutions containing greater than 50% water and meeting the pH criteria would be characterized as 

hazardous wastes.

Your confirmation and comment on the above would be greatly appreciated. questions can be 

addressed to my attention at (201) 515-1841.

Sincerely yours,

GENERAL CHEMICAL CORPORATION

B.N. Fleischer 

Manager, Pollution Control
July 22, 1987

MEMORANDUM

SUBJECT: Definition of “aqueous” in RCRA regulations

FROM: Becky Cuthbertson

Information Specialist, RCRA/Superfund Hotline

TO: Jacqui Sales

Office of Solid Waste

Thank you for your presentation Monday on the California List land disposal restrictions. You 

had mentioned the lack of a regulatory definition of “aqueous”. A letter from John Skinner to Kevin J. 

Walter, dated February 26, 1985, defines “aqueous solution”, a term used in the ignitability

characteristic. A copy of this letter is attached for your information.

cc: Denise Sines
April 6, 1987

Mr. Matt Straus 

#WH562V

Waste Characterization Branch

USEPA 

401 M. Street SW

Washington, DC 20460

Dear Mr. Straus:

A problem with the definition of what “aqueous” means in the definition of the characteristic of 

corrosivity has again risen (See enclosed letter of February 26, 1987). Any assistance you might 

provide on this matter would be greatly appreciated.

Thank you again for your assistance in this matter. Please feel free to contact me if you have any further 

questions regarding this matter.

Sincerely,

PRINTING DEVELOPMENTS, INC.

Stuart J. Gock 

Environmental Coordinator

SJG/db

Enc.

cc: E. C. Sandvig

 J. G. Behrens