Texas Department of Public Safety — Hazardous Materials Safety Interpretation

Page 11200 New Jersey Avenue, SE Washington, DC 20590 U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration December 8, 2025 Dustin Henderson CVE-Corporal IV Radiation/Nuclear Threat Detection Unit Texas Department of Public Safety 1600 West Loop 306 San Angelo, TX 76904 Reference No. 25-0084 Dear Mr. Henderson: This letter is in response to your June 23, 2025 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to bulk containers commonly known in industry as “frac tanks.” Specifically, you ask for clarification regarding the use of frac tanks for the transportation of “NA1993, Diesel fuel, 3, Packing Group (PG) III.” We have paraphrased and answered your questions as follows: Q1. Does a frac tank meet the definition of a portable tank in accordance with § 171.8? A1. No. Frac tanks do not meet the definition of a portable tank and the term “frac tank” is not defined in § 171.8. In addition, the pictures provided in the initial request do not display the characteristics (e.g., skids, mountings, etc.) to identify these packagings as portable tanks; however, they may qualify as non-DOT specification cargo tank motor vehicles. Q2. If a frac tank meets the definition of a portable tank, is “NA1993, Diesel fuel, 3, PG III” authorized for transport in a frac tank in accordance with § 173.241(c)? A2. Frac tanks do not meet the definition of a portable tank; however, “NA1993, Diesel fuel, 3, PG III” may be transported in a non-DOT specification cargo tank motor vehicle suitable for the transport of liquids. It is the offeror’s responsibility to determine the flash point of the hazardous material1, package compliance, and all requirements of the HMR are met prior to the shipment being offered for transportation. 1 § 172.102(c)(3), Special Provision B1.#

Page 2Q3. Can “NA1993, Diesel fuel, 3, PG III” be transported in a frac tank as residue? A3. Yes. An empty packaging containing only the residue of a hazardous material shall be offered for transportation and transported in the same manner as when it previously contained a greater quantity of that hazardous material.2 Q4. Can “NA1993, Diesel fuel, 3, PG III” be transported in a frac tank, while the frac tank is located on a trailer? A4. Yes. The HMR does not prohibit frac tanks from being transported on trailers. However, it is the offeror’s responsibility to ensure the hazardous material is properly classified, and the package is offered for transportation in accordance with the HMR. Q5. Would a frac tank qualify as a “tank” for purposes of a commercial driver’s license (CDL) and require the driver to obtain an endorsement? A5. The endorsement requirements for a CDL are under the purview of the Federal Motor Carrier Safety Administration (FMCSA)—see 49 CFR Part 383. FMCSA is the lead Federal government agency responsible for regulating and providing safety oversight of commercial motor vehicles. You may wish to contact the FMCSA regarding clarification of any applicable CDL endorsement requirements. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, Dirk DerKinderen Chief, Standards and Development Branch Standards and Rulemaking Division 2 § 173.29.#

Page 3Horne, T. 25-0084 From: INFOCNTR (PHMSA) To: Baker, Yul (PHMSA) Cc: Hazmat Interps Subject: FW: Letter of Interpretation Request Date: Tuesday, June 24, 2025 12:19:31 Attachments: image001.png image004.png Hi Yul, Please see the below interpretation request. Let us know if you need anything, -Breanna From: Henderson, Dustin <Dustin.Henderson@dps.texas.gov> Sent: Monday, June 23, 2025 8:47 PM To: INFOCNTR (PHMSA) <INFOCNTR.INFOCNTR@dot.gov> Subject: Letter of Interpretation Request CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. May I get a formal letter of interpretation on the following: A frac tank is a large piece of mobile equipment used to store bulk liquids. These tanks get their name from their popularity in the oil & gas industry. They commonly store fluids and diesel fuel on site during oilfield operations. They range in capacity from 8,400 to 210,000 gallons, therefore meeting the bulk package definition. They are typically manufactured with a single or tandem axle and are not designed to transport liquids. Since they are not “intended primarily for the carriage of liquids or gases,” they do not meet the definition of a cargo tank. Still, they are often transported with diesel or diesel residue. I’ve attached two photos for reference. 1. 2. 3. 4. 5. Does a frac tank meet the definition of portable tank in 171.8? If it meets the portable tank definition, is NA1993, Diesel Fuel, 3, PGIII authorized for transport in a frac tank under 173.241(c)? Can NA1993, Diesel Fuel, 3, PGIII be transported in a frac tank as residue? Can NA1993, Diesel Fuel, 3, PGIII be transported in a frac tank, while the frac tank is located on a trailer? Would the frac tank qualify as a tank and therefore the driver be required a tank endorsement?#

Page 41993 AGON DI#

Page 5Dustin Henderson, CVE-Corporal IV Radiation/Nuclear Threat Detection Unit 1600 West Loop 306 San Angelo, Texas 76904 432-553-4188-cell#