(a) The method of calculating the dry weight of each waste stream subject to assessment under §335.325 of this title (relating to Industrial Solid Waste and Hazardous Waste Management Fee Assessment) shall be determined initially and at any time the waste stream undergoes a significant change in water content using the appropriate method(s) as specified in this section. Determinations shall be made from a representative sample collected by grab or composite. Collection methods and sample preservation shall be by methods to minimize volatilization.
  (1) Wastes which contain suspended solids greater than or equal to 15% of the sample on a weight basis shall have the dry weight determination calculated using the method specified in Appendix I in §335.332 of this title (relating to Appendices I and II).
  (2) Aqueous based wastes which contain suspended solids less than 15% of the sample by weight basis and which contain a single liquid phase shall have the dry weight determination calculated using Standard Methods for the Examination of Water and Wastewater, 15th Edition, Method 209A, pages 92-93, or equivalent method in later editions.
  (3) Organic-based wastes which contain suspended solids less than 15% of the sample by weight and which contain a single liquid phase shall have the dry weight determination calculated using:
    (A) 1981 Annual Book of ASTM Standards, Part 30, Method E203, pages 803 - 812, or equivalent method in later editions; or
    (B) the method specified in Appendix II in §335.332 of this title.
  (4) Wastes which do not meet any of the criteria specified in paragraphs (1) - (3) of this subsection shall have the dry weight determination calculated using:
    (A) The 1981 Annual Book of ASTM Standards, Part 23, Method D96, pages 64 - 81, or equivalent method in later editions; or
    (B) the method specified in Appendix II in §335.332 of this title; or
    (C) The 1981 Annual Book of ASTM Standards, Part 23, Method D95, pages 59 - 63 or equivalent method in later editions. Method D96 determines the water and sediment content of the sample. The calculations shall be modified to determine only the water content.
  (5) The method for calculating the dry weight shall be that method specified in Appendix I in §335.332 of this title or an alternate method selected by the generator pursuant to §335.327 of this title (relating to Alternate Methods of Dry Weight Determination), if the waste cannot be analyzed by one of the other required methods of this section due to interfering constituents. Documentation identifying the method of analysis and describing the interference shall be maintained by the generator.
(b) Wastes containing free liquids which are designated for disposal in a landfill and must be solidified prior to disposal shall have the dry weight determination made on the waste, prior to the addition of the solidification agent.
(c) If the dry weight ratio of a hazardous waste as measured under this section exceeds 10%, an operator of a hazardous waste injection well may elect to determine the composition of the waste stream that is inorganic salts or brines and separately record the weight of such inorganic salts for the purpose of assessment of the fee under §335.325(q) of this title. The methods used to determine the weight of inorganic salts in a hazardous waste stream are subject to review and approval by the executive director. This subsection does not apply to:
  (1) any component of a waste stream that is a hazardous constituent or is a constituent for which the waste is designated as hazardous; or
  (2) any waste stream received by a commercial facility for a charge.
(d) For purposes of a fee assessed under §335.325 of this title, the dry weight of a waste disposed in an underground injection well, to which brine, inorganic salts, or other authorized agents are added to maintain density control to assure compliance with no-migration requirements of 40 Code of Federal Regulations 148 Subpart C, shall be determined prior to the addition of the agent. No solid waste, as defined by the Texas Health and Safety Code, §361.003(37), may be excluded from the determination of dry weight under this subsection.

Source Note: The provisions of this §335.326 adopted to be effective March 19, 1992, 17 TexReg 1737; amended to be effective August 24, 1992, 17 TexReg 5552; amended to be effective February 16, 1994, 19 TexReg 802; amended to be effective October 16, 1995, 20 TexReg 7993; amended to be effective November 15, 2001, 26 TexReg 9135