(a) Complete exclusions. In addition to the tanks exempted from regulation under §334.3 of this title (relating to Exemptions for Underground Storage Tanks (USTs) and UST Systems), the following USTs are completely excluded from regulation under this chapter:
  (1) any UST system containing a hazardous listed waste or identified under the federal Solid Waste Disposal Act, Subtitle C (42 United States Code (USC), §6921, et seq.), or containing a mixture of such hazardous waste and other regulated substances, where such system is already subject to regulation under the federal Solid Waste Disposal Act, Subtitle C;
  (2) any wastewater treatment tank (including an oil-water separator and any pretreatment facility), which is an integral part of a wastewater treatment facility which is either:
    (A) permitted under the federal Clean Water Act, either §307(b) or §402 (33 USC, §1251, et seq.); or
    (B) permitted pursuant to the Texas Water Code (TWC), Chapter 26;
  (3) sumps which have a capacity of less than 110 gallons;
  (4) emergency spill protection or emergency overflow containment tanks, including certain sumps and secondary containment systems, which are used solely for the temporary storage or containment of regulated substances resulting from a leak, spill, overfill, or other unplanned release, and where the regulated substances are routinely removed within 48 hours of the discovery of the release; provided that such tanks must be inspected for a release no less than once every month; or
  (5) UST systems which during their entire operational life have exclusively contained only regulated substances at such dilute concentrations that any release would not pose any significant threat to human health and safety or the environment.
(b) Partial exclusions. The following USTs are subject to all provisions of this chapter, except for Subchapter C of this chapter (relating to Technical Standards); Subchapter N of this chapter (relating to Operator Training); Chapter 30, Subchapter I of this title (relating to Underground Storage Tank On-Site Supervisor Licensing and Contractor Registration); Chapter 37, Subchapter I of this title (relating to Financial Assurance for Petroleum Underground Storage Tank Systems); and the certification requirements of §334.8 of this title (relating to Certification for Underground Storage Tanks (USTs) and UST Systems):
  (1) any wastewater treatment tank (including oil-water separators), where such tank is not an integral part of a wastewater treatment facility which is either:
    (A) permitted under the federal Clean Water Act, either §307(b) or §402 (33 USC, §1151, et seq.); or
    (B) permitted pursuant to the TWC, Chapter 26;
  (2) any UST systems containing radioactive material that are regulated under the Atomic Energy Act of 1954 (42 USC, §2011, et seq.);
  (3) any UST system that is part of an emergency generator system at nuclear power generation facilities licensed by the United States Nuclear Regulatory Commission and subject to United States Nuclear Regulatory Commission requirements regarding design and quality criteria, including but not limited to 10 Code of Federal Regulations Part 50.
(c) Other exclusion. In addition to the partial exemption for hydraulic lifts covered under §334.3(b) of this title, all other in-ground hydraulic lifts that use a compressed air/hydraulic fluid system and which hold 100 gallons or more of hydraulic oil are similarly excluded from regulation under this chapter, except that such lifts remain subject to the release reporting and corrective action requirements under Subchapter D of this chapter (relating to Release Reporting and Corrective Action).
(d) Upon request by the agency, the owner and operator of a tank claimed to be excluded under this section must provide appropriate documentation or other information in a timely manner to support that claim.

Source Note: The provisions of this §334.4 adopted to be effective September 29, 1989, 14 TexReg 4714; amended to be effective November 23, 2000, 25 TexReg 11442; amended to be effective May 31, 2018, 43 TexReg 3390