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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #20-0030

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: ORBITAL ATK

Individual Name: Robert Weston

Location State: UT Country: US

View the Interpretation Document

Response text:

March 29, 2021

Mr. Robert Weston
PO Box 98
Magna, UT  84044

Reference No. 20-0030

Dear Mr. Weston:

This letter is in response to your April 8, 2020, and May 4, 2020, emails requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to waste water collected from washing down feed chutes that supplied fuel to test rocket motors. You state that the waste water contains 75–95 percent “UN1442, Ammonium perchlorate, 5.1 (oxidizer), Packing Group (PG) II”; 5–25 percent water; and 0–1 percent trace amounts of "UN0226, Cyclotetramethylenetetranitramine, wetted, 1.1D (explosive)," also known as "HMX (high melting explosive), wetted."

We have paraphrased and answered your questions as follows:

Q1. You ask whether you may transport these drums using the associated safety data sheet (SDS) and description for the "UN1442, Ammonium perchlorate."

A1. In accordance with § 173.22 of the HMR, it is the shipper's responsibility to properly classify a hazardous material and assign it a proper shipping name from the Hazardous Materials Table (HMT; § 172.101). This Office does not generally perform that function. However, while the previous material may have met the description for "UN1442, Ammonium perchlorate," the characteristics of the waste water mixture may differ significantly from the ammonium perchlorate ingredient. In addition, all compositions containing any amount of explosive material, including compositions of diluted (desensitized) explosives or explosives combined or contaminated with other materials, meet the definition of a new explosive and must be classified and approved by PHMSA. Therefore, given the trace amounts of HMX present in the waste water, it must be examined in accordance with § 173.56.

Q2. You ask whether you may use “generator knowledge” in this scenario along with the SDS to classify the waste water for disposal.

A2. The answer is no. Please see Answer 1. The characteristics of the waste water mixture may differ significantly from those of the ammonium perchlorate that are reflected on the SDS. Additionally, the waste water also contains a secondary explosive; therefore, the shipper must classify the material in accordance with the HMR (see § 173.56(a)(2)).

Q3. You ask whether the material meets the definition of a "new explosive" as defined in § 173.56, or whether you may ship these drums of waste water that contain trace amounts of "UN0226, Cyclotetramethylenetetranitramine, wetted, 1.1D (explosive)" using the original SDS for ammonium perchlorate.

A3. The material meets the definition of a "new explosive," so you may not use the original SDS as the basis for determining classification. A "new explosive" means an explosive produced by a person who: (1) Has not previously produced that explosive; or (2) Has previously produced that explosive but has made a change in the formulation, design or process so as to alter any of the properties of the explosive. The term "formulation" as used in the definition of a "new explosive" applies to the entire mixture and not just the explosive components. See § 173.56(a). Compared to the original ammonium perchlorate, the waste mixture has been altered during the process you described and contains a secondary explosive ingredient (HMX); therefore, the new mixture must be classified and approved in accordance with the HMR.

I hope this information is helpful. Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

173.22, 173.56, 173.56(a), 173.56(a)(2)

Regulation Sections

Section Subject
173.22 Shipper's responsibility
173.56 New explosives-definition and procedures for classification and approval