(a) General. For closure/remediation in accordance with Risk Reduction Standard Number 3, persons shall propose media cleanup levels in accordance with the conditions set forth in subsections (b) - (j) of this section.     
      (b) Carcinogens. For known or suspected carcinogens, media cleanup levels shall be established at concentrations which represent an excess upperbound lifetime risk of between one in 10,000 and one in one million. The executive director will use one in one million as a goal in establishing such concentration limits. The cumulative excess risk to exposed populations (including sensitive subgroups) shall not be greater than one in 10,000.     
      (c) Systemic toxicants. For systemic toxicants, media cleanup levels shall represent concentrations to which the human population (including sensitive subgroups) could be exposed on a daily basis without appreciable risk of deleterious effect during a lifetime or part of a lifetime and where:      
        (1) the hazard quotient, which is the ratio of a single systemic toxicant exposure level for a specified time period to a reference dose for that systemic toxicant derived from the same time period, shall not exceed one; and       
        (2) the hazard index shall not exceed one. The hazard index is the sum of the hazard quotients for a single or multiple systemic toxicants which affect the same target organ or act by the same method of toxicity and act through a single or multiple media exposure pathways.       
      (d) Additional considerations. In establishing media cleanup levels pursuant to subsections (b) and (c) of this section, the executive director may consider and may direct persons who submit plans or reports in accordance with §335.553(b) of this title (relating to Required Information) to address the following:      
        (1) multiple contaminants in a medium;       
        (2) exposure to multiple contaminated media;       
        (3) reasonable expected future exposure conditions at the facility; and       
        (4) the technical limitations, effectiveness, practicability, or other relevant features of available remedies.       
      (e) Standard exposure factors. In determining media cleanup levels pursuant to subsections (b) and (c) of this section, persons shall use the standard exposure factors for residential use of the facility as set forward in Table 1 (located in §335.553 of this title) unless the person documents to the satisfaction of the executive director that:      
        (1) site-specific data warrant deviation from the standard exposure factors; or       
        (2) a land use other than residential is more appropriate based on:                  (A) historical, current, and probable future land use; and                   (B) effectiveness of institutional or legal controls placed on the future use of the land.         
      (f) Air. Media cleanup levels for air will be established to meet the lowest of the values determined by the requirements of paragraphs (1) - (3) of this subsection.      
        (1) Concentrations of contaminants in air that emanate from a facility, area of soil contamination, or plume of contaminated groundwater shall not exceed:                  (A) National Ambient Air Quality Standards (NAAQS), National Emission Standards for Hazardous Air Pollutants (NESHPAS) (as found in 40 Code of Federal Regulation Parts 50 and 61 respectively) and other applicable federal standards and guidelines of the Environmental Protection Agency; and                   (B) concentrations established by the commission under the Texas Clean Air Act, the state implementation plan, or other federal requirements. Permit requirements, limitations established by standard exemptions, or other requirements relative to atmospheric emissions and/or air quality may also apply.         
        (2) For residential exposure conditions, concentrations of contaminants in air that emanate from a facility, area of soil contamination, or plume of contaminated ground water shall not exceed concentrations that satisfy subsections (b) - (e) of this section at exposure points located both within the contaminated area and at the property boundary.       
        (3) For nonresidential exposure conditions, concentrations of contaminants in air that emanate from a facility, area of soil contamination, or plume of contaminated groundwater shall not exceed either OSHA permissible exposure limits, threshold limit values or other criteria applicable to an industrial exposure setting within the facility boundaries or concentrations that satisfy subsections (b) - (e) of this section at the property boundary.       
      (g) 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, values calculated pursuant to subsections (b) - (e) of this section based upon human ingestion of the water or other site-specific exposure pathway. Any discharge or release into or adjacent to surface water, including storm water runoff, occurring during or after attainment of Risk Reduction Standard Number 3, shall be compliant with 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.     
      (h) Groundwater. Media cleanup levels for groundwater that is a current or potential source of drinking water as defined in paragraph (1) of this subsection shall not exceed MCLs promulgated under the Safe Drinking Water Act or, if MCLs are not available, values calculated according to subsections (b) - (e) of this section based upon human ingestion of the water. Cleanup levels for groundwater may be subject to the modifications of paragraphs (2) - (4) of this subsection.      
        (1) Groundwater that has a background total dissolved solids (TDS) content less than or equal to 10,000 milligrams per liter (mg/L) and that occurs within a geologic zone that is sufficiently permeable to transmit water to a pumping well in usable quantities shall be considered a current or potential source of drinking water for the purpose of determining cleanup levels.       
        (2) The cleanup levels shall be achieved throughout the plume of contaminated groundwater, with the exception of the circumstances described in subparagraphs (A) - (C) of this paragraph:                  (A) when alternate concentration limits of §335.160(b) of this title (relating to Alternate Concentration Limits) have been approved in a permit issued by the commission for a hazardous waste management facility;                   (B) when the selected remedy calls for waste to be left in place and when appropriate control measures are installed or operated, the executive director may authorize the zone underlying the area encompassing the original source(s) of release to be excluded from this requirement;                   (C) when the person documents to the executive director's satisfaction pursuant to subsection (e) of this section that a future land use other than residential is appropriate for the facility or area and further demonstrates that institutional or legal controls will effectively prevent use of the contaminated groundwater, the extent of plume remediation may be determined in a manner consistent with §335.160(b) of this title.         
        (3) The executive director may determine that remediation of groundwater to the extent required in paragraphs (1) or (2) of this subsection is not necessary if the person demonstrates to the executive director's satisfaction that:                  (A) the contaminant is present in groundwater that is not a current or potential source of drinking water and the contaminated groundwater is not hydraulically connected with and is not likely to migrate to either surface water or to groundwater that is a current or potential source of drinking water; or                   (B) restoration of the groundwater to these levels is technically impracticable.         
        (4) If a determination is made pursuant to paragraph (3) of this subsection, the executive director may require any alternative measures or cleanup levels that are necessary to protect human health and the environment. At a minimum, for all cases described in this subsection, phase-separated non-aqueous liquids shall be removed from groundwater zones to the extent practicable.       
      (i) Soil. Concentrations of contaminants in soil shall not exceed the following values:      
        (1) the values calculated pursuant to subsections (b) - (d) of this section based upon human ingestion of the soils at all points where direct contact exposure to the soils may occur; and       
        (2) values which will allow the air, surface water, and groundwater cleanup levels specified in subsections (f) - (h) of this section, respectively, to be maintained over time taking into account the effects of engineering controls.                  (A) Such determinations shall be based on sound scientific principles including fate and transport evaluation of contaminant migration. Procedures and conclusions shall be documented to the satisfaction of the executive director.                   (B) The executive director may require the evaluation of additional migration pathways beyond those listed in this section if determined necessary. Such additional pathways may include but are not limited to, food chain contamination, impairment of soil for agricultural purposes, phytotoxicity, accumulations of contaminants in sediment of surface water bodies, or other impairments of natural resources, land, or water use.         
      (j) Other adjustments. Cleanup levels may be adjusted according to paragraphs (1) - (3) of this subsection.      
        (1) If the practical quantitation limit (PQL) or the background concentration (represented by results of analyses of samples taken from media that are not affected by waste management or industrial activities) for a contaminant is greater than the cleanup level determined by procedures of this section, then the greater of the PQL or background shall become the cleanup level.       
        (2) Other scientifically valid published criteria, such as, but not limited to threshold limit values for air and secondary maximum contaminant levels for water, shall be utilized as cleanup levels for contaminants for which the procedures of this section are not appropriate (e.g., mixtures or substances that do not have toxicological data) or that do not exceed standards or criteria protective of human health 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.       
        (3) More stringent cleanup levels may be established for a facility than are specified in this section if, by utilizing available guidance or scientific literature, the executive director determines that it is necessary to protect environmental receptors.       
     Source Note:        The provisions of this §335.563 adopted to be effective June 28, 1993, 18 TexReg 3814; amended to be effective November 15, 2001, 26 TexReg 9135