(a) Numeric cleanup levels. The subsections (b) - (h) of this section specify requirements that can define or modify numeric cleanup levels such as MSCs or require non-health based criteria to be addressed.
(b) Surface water. In determining the necessity for remediation at the facility, persons shall utilize Chapter 307 of this title (relating to Texas Surface Water Quality Standards) or, if those values are not available, Maximum Contaminant Levels (MCLs) promulgated under the Safe Drinking Water Act, or if MCLs are not available or appropriate, MSCs based upon human ingestion of the water. Any discharge or release into or adjacent to surface water, including storm water runoff, occurring during or after attainment of Risk Reduction Standard Number 2, shall be compliant with the Texas Surface Water Quality Standards of Chapter 307 of this title and may be subject to the permitting requirements of Chapter 305 of this title (relating to Consolidated Permits) or other authorization from the commission.
(c) Air. In determining the necessity for remediation at the facility, persons shall observe limitations established by the National Ambient Air Quality Standards (NAAQS) and the National Emission Standards for Hazardous Air Pollutants (NESHAPS) as found in the 40 Code of Federal Regulations (CFR) Parts 50 and 61, respectively, and other applicable federal standards and guidelines of the EPA. Also, limitations established by the commission under the Texas Clean Air Act, the state implementation plan or other federal requirements must be observed. Permit requirements, limitations established by standard exemptions, or other requirements of the commission relative to atmospheric emissions and/or air quality may also apply.
(d) Groundwater. The groundwater cleanup levels shall be determined by a consideration of the following.
  (1) For residential exposure, the concentration of a contaminant dissolved in groundwater must not exceed the MCL, if promulgated pursuant the Federal Safe Drinking Water Act, §141, otherwise the water MSC for ingestion determined pursuant to §335.556 of this title (relating to Determination of Cleanup Levels for Risk Reduction Standard Number 2). Phase-separated non-aqueous liquids released from the unit that is undergoing closure or remediation must be removed or decontaminated.
  (2) For nonresidential exposure, the concentration of a contaminant dissolved in groundwater must not exceed the MCL if promulgated pursuant to the Federal Safe Drinking Water Act, §141. If no MCL has been promulgated, the groundwater concentration shall not exceed the water MSC for ingestion determined pursuant to §335.556 of this title, which has been multiplied by a factor of 3.36 for carcinogens or 2.8 for systemic toxicants to account for lower ingestion rates associated with nonresidential worker exposure. Persons must be able to demonstrate that the quality of groundwater at the facility property boundary will be protective for residential exposure. Phase-separated non-aqueous liquids released from the unit that is undergoing closure or remediation must be removed or decontaminated to the extent practicable.
  (3) For residential and non-residential exposure, if the groundwater at the facility or area has a naturally occurring background total dissolved solids concentration greater than 10,000 milligrams per liter, the cleanup level for a contaminant dissolved in this groundwater determined pursuant to paragraph (1) or (2) of this subsection, as appropriate, may be adjusted by multiplying by 100. The resulting value becomes the maximum concentration for groundwater for residential and non-residential exposure, respectively.
  (4) The executive director may require the evaluation of additional exposure pathways or environmental receptors as part of the adjustment of paragraph (3) of this subsection.
(e) Soil. For all situations, concentrations of contaminants in soils must be protective of surface water, air, and groundwater as specified in subsections (b) - (d) of this section. No soil remaining in place shall exhibit the hazardous waste characteristics of ignitability, corrosivity, or reactivity as defined in 40 CFR Part 261, Subpart C. The sum of concentrations of the volatile organic compounds in vapor phase in soil shall not exceed 1,000 parts per million by weight or volume, as measured by EPA Test Method 8015 or calculated by using soil concentrations and Henry's Law constants.
(f) Residential soil requirements. In addition to the requirements of subsection (e) of this section, the concentration of a contaminant throughout the soil column (i.e., surface and subsurface soils) shall not exceed the lower of the soil MSC, based upon residential human ingestion of soil and inhalation of particulates and volatiles (as defined in the preceeding section), and the residential soil-to-groundwater cross-media protection concentration, a numeric value which is determined as follows:
  (1) a value which is 100 times the residential groundwater cleanup level determined by the procedures of subsection (d)(1) of this section. Examples of such values are listed in Appendix II; or
  (2) a concentration in soil that does not produce a leachate in excess of MCLs or MSCs for groundwater when subjected to the Synthetic Precipitation Leaching Procedure, Method 1312 of SW 846, Test Methods for Evaluating Solid Waste, United States Environmental Protection Agency. Other test methods that more accurately simulate conditions at the facility may be used in the demonstration in place of this method, subject to prior approval of the executive director.
(g) Nonresidential soil requirements. Nonresidential soils shall conform to the requirements of subsection (e) of this section. The concentration of a contaminant in near-surface soils (i.e., within two feet of the land surface) shall not exceed the lower of the nonresidential soil MSC defined in paragraph (1) of this subsection, based upon worker ingestion of soil and inhalation of particulates and volatiles, and the nonresidential soil-to-groundwater cross-media protection concentration deficned in paragraph (2) of this subsection. In no event shall compliance be achieved with the surface soil criteria by applying two feet of clean soil onto the surface of a facility or area without prior approval from the executive director. The concentration of a contaminant in subsurface soils (i.e., greater than two feet in depth from the land surface) shall not exceed the nonresidential soil-to-groundwater cross-media protection concentration.
  (1) Nonresidential soil MSC. The MSC is calculated using the equations and factors listed in subparagraphs (A) and (B) of this paragraph. The chemical-specific factors SFo , SF i , RfDo , RfDi , and VF are the same as for the soil MSCs of the preceding section. The derivation of all equations is presented in Appendix I.
    (A) Carcinogenic effects equation, in units of milligram per kilogram (mg/kg):
Attached Graphic
    (B) Systemic toxicant effects equation, in units of milligram per kilogram (mg/kg):
Attached Graphic
  (2) Non-residential soil-to-ground water cross-media protection concentration. Persons must demonstrate that a contaminant in soil does not pose the potential for a future release of leachate in excess of the groundwater concentration considered to be protective for nonresidential worker exposure. Persons may make this demonstration by showing that a contaminant occurs in soil at less than the concentration described in either subparagraph (A) or (B) of this paragraph:
    (A) a concentration which is 100 times the nonresidential groundwater cleanup level determined by the procedures of subsection(d)(2) or (3), as applicable, of this section.
    (B) a concentration in soil that does not produce a leachate in excess of the groundwater concentration of this paragraph when subjected to the Synthetic Precipitation Leaching Procedure, Method 1312 of SW 846, Test Methods for Evaluating Solid Waste, U. S. Environmental Protection Agency. Other test methods that more accurately simulate conditions at the facility may be used in the demonstration in place of this method, subject to prior approval by the executive director.
(h) Other criteria. For contaminants that do not exceed standards or criteria protective of human health and environmental receptors as determined by the procedures of this section but otherwise adversely impact environmental quality, or the public welfare and safety, or present objectionable characteristics (e.g., taste, odor, etc.), or make a natural resource unfit for use, other scientifically valid published criteria may be utilized such as but not limited to threshold limit values for air and secondary maximum contaminant levels for water.

Source Note: The provisions of this §335.559 adopted to be effective June 28, 1993, 18 TexReg 3814; amended to be effective November 15, 2001, 26 TexReg 9135