(a) Hazardous waste determination. A person who generates a solid waste, as defined in §335.1 of this title (relating to Definitions), must make an accurate determination as to whether that waste is a hazardous waste in order to ensure wastes are properly managed according to applicable Resource Conservation and Recovery Act (RCRA) and Texas Administrative Code regulations. The hazardous waste determination for each solid waste must be made at the point of waste generation, before any dilution, mixing, or other alteration of the waste occurs, and at any time in the course of its management that it has, or may have, changed its properties as a result of exposure to the environment or other factors that may change the properties of the waste such that the RCRA classification of the waste may change. A hazardous waste determination is made using the following steps:      
        (1) A person must determine whether the material is excluded or exempted from regulation as a solid waste or as hazardous waste under the definition of solid waste in §335.1 of this title or identified in 40 Code of Federal Regulations (CFR) Part 261, Subpart A as amended in the                 Federal Register                through December 9, 2019 (84 FR 67202), or Subpart E as amended in the                 Federal Register                through August 6, 2018 (83 FR 38262).       
        (2) If the waste is not excluded from regulation as a solid waste, the person must then use knowledge of the waste to determine whether the waste is a hazardous waste because it meets any of the listing descriptions, or is mixed with or derived from a waste that meets any of the listing descriptions identified in 40 CFR Part 261, Subpart D, as amended in the                 Federal Register                through February 22, 2019 (84 FR 5816). Acceptable knowledge that may be used in making an accurate determination as to whether the waste is listed may include waste origin, composition, the process producing the waste, feedstock, and other reliable and relevant information.       
        (3) The person must also determine whether the waste exhibits one or more hazardous characteristics as identified in 40 CFR Part 261, Subpart C, as amended in the                 Federal Register                through March 18, 2010 (75 FR 12989) by following the procedures in subparagraph (A) or (B) of this paragraph or a combination of both.                  (A) The person must apply knowledge of the hazard characteristic of the waste in light of the materials or the processes used to generate the waste. Acceptable knowledge may include process knowledge (e.g., information about chemical feedstocks and other inputs to the production process); knowledge of products, by-products, and intermediates produced by the manufacturing process; chemical or physical characterization of wastes; information on the chemical and physical properties of the chemicals used or produced by the process or otherwise contained in the waste; testing that illustrates the properties of the waste; or other reliable and relevant information about the properties of the waste or its constituents. A test other than a test method set forth in 40 CFR Part 261, Subpart C or an equivalent test method approved by the United States Environmental Protection Agency (EPA) Administrator under 40 CFR §260.21, or by the executive director under §335.509 of this title (relating to Waste Analysis), may be used as part of a person's knowledge to determine whether a solid waste exhibits a characteristic of hazardous waste. However, such tests do not, by themselves, provide definitive results. Persons testing their waste must obtain a representative sample, as defined in §335.1 of this title, of the waste for the testing,                   (B) When available knowledge is inadequate to make an accurate determination, the person must test the waste according to the applicable methods set forth in 40 CFR Part 261, Subpart C or according to an equivalent method approved by the EPA Administrator under 40 CFR §260.21, or approved by the executive director under §335.509 of this title, and in accordance with the following:                      (i) Persons testing their waste must obtain a representative sample, as defined in §335.1 of this title, of the waste for the testing.                       (ii) Where a test method is specified in 40 CFR Part 261, Subpart C, the results of the regulatory test, when properly performed, are definitive for determining the regulatory status of the waste.           
      (b) Recordkeeping for small or large quantity generators. A large quantity generator and a small quantity generator shall maintain records supporting its hazardous waste determinations in accordance with 40 CFR §262.11(f) as adopted under §335.53 of this title (relating to General Standards Applicable to Generators of Hazardous Waste).     
      (c) Recordkeeping for hazardous waste and Class 1 waste generators. Generators shall make and maintain records of a hazardous waste determination in accordance with §335.513 of this title (relating to Documentation Required), and 40 CFR §262.11(f) as adopted under §335.53 of this title.     
     Source Note:        The provisions of this §335.504 adopted to be effective November 27, 1992, 17 TexReg 8010; amended to be effective November 23, 1993, 18 TexReg 8218; amended to be effective March 6, 1996, 21 TexReg 2400; amended to be effective November 15, 2001, 26 TexReg 9135; amended to be effective August 16, 2007, 32 TexReg 5010; amended to be effective October 29, 2009, 34 TexReg 7321; amended to be effective February 21, 2013, 38 TexReg 978; amended to be effective January 8, 2015, 40 TexReg 77; amended to be effective June 16, 2016, 41 TexReg 4259; amended to be effective June 11, 2020, 45 TexReg 3780; amendedto be effective February 3, 2022, 47 TexReg 318