| (C) installed to cover all surrounding earth likely to be in contact with the wastes or leachate. (3) The applicant or licensee may be exempted from the requirements of paragraph (1) of this subsection if the agency finds, based on a demonstration by the applicant or licensee, that alternate design and operating practices, including the closure plan, together with site characteristics will prevent the migration of any hazardous constituents into groundwater or surface water at any future time. In deciding whether to grant an exemption, the agency will consider: (A) the nature and quantity of the wastes; (B) the proposed alternate design and operation; (C) the hydrogeologic setting of the facility, including the attenuative capacity and thickness of the liners and soils present between the impoundment and groundwater or surface water; and (D) all other factors that would influence the quality and mobility of the leachate produced and the potential for it to migrate to groundwater or surface water. (4) A surface impoundment must be designed, constructed, maintained, and operated to prevent overtopping resulting from normal or abnormal operations, overfilling, wind and wave actions, rainfall, or run-off; from malfunctions of level controllers, alarms, and other equipment; and from human error. (5) When dikes are used to form the surface impoundment, the dikes must be designed, constructed, and maintained with sufficient structural integrity to prevent massive failure of the dikes. In ensuring structural integrity, it must not be presumed that the liner system will function without leakage during the active life of the impoundment. (j) By-product materials must be managed to conform to the following secondary groundwater protection requirements. (1) Hazardous constituents, as defined in §336.1105(16) of this title (relating to Definitions), entering the groundwater from a licensed site must not exceed the specified concentration limits in the uppermost aquifer beyond the point of compliance during the compliance period. (2) Specified concentration limits are those limits established by the agency as indicated in paragraph (7) of this subsection. (3) The agency will also establish the point of compliance and compliance period on a site-specific basis through license conditions and orders. (4) When the detection monitoring established under subsections (bb) and (cc) of this section indicates leakage of hazardous constituents from the disposal area, the agency will perform the following: (A) identify hazardous constituents; (B) establish concentration limits; (C) set the compliance period; and (D) may adjust the point of compliance if needed in accordance with developed data and site information regarding the flow of groundwater or contaminants. (5) Even when constituents meet all three tests in the definition of hazardous constituent, the agency may exclude a detected constituent from the set of hazardous constituents on a site-specific basis if it finds that the constituent is not capable of posing a substantial present or potential hazard to human health or the environment. In deciding whether to exclude constituents, the agency will consider the following: (A) potential adverse effects on groundwater quality, considering the following: (i) physical and chemical characteristics of the waste in the licensed site, including its potential for migration; (ii) hydrogeological characteristics of the licensed site and surrounding land; (iii) quantity of groundwater and the direction of groundwater flow; (iv) proximity of groundwater users and groundwater withdrawal rates; (v) current and future uses of groundwater in the area; (vi) existing quality of groundwater, including other sources of contamination and cumulative impact on the groundwater quality; (vii) potential for human health risks caused by human exposure to waste constituents; (viii) potential damage to wildlife, crops, vegetation, and physical structures caused by exposure to waste constituents; and (ix) persistence and permanence of potential adverse effects; and (B) potential adverse effects on quality of hydraulically-connected surface water, considering the: (i) volume and physical and chemical characteristics of the by-product material in the licensed site; (ii) hydrogeological characteristics of the licensed site and surrounding land; (iii) quantity and quality of groundwater and the direction of groundwater flow; (iv) patterns of rainfall in the region; (v) proximity of the licensed site to surface waters; (vi) current and future uses of surface waters in the area and any water quality standards established for those surface waters; (vii) existing quality of surface water, including potential impacts from other sources of contamination and the cumulative impact on surface water quality; (viii) potential for human health risks caused by human exposure to waste constituents; (ix) potential damage to wildlife, crops, vegetation, and physical structures caused by exposure to waste constituents; and (x) persistence and permanence of the potential adverse effects. (6) In making any determinations under paragraphs (5) and (8) of this subsection about the use of groundwater in the area around the facility, the agency will consider any identification of underground sources of drinking water and exempted aquifers made by the United States Environmental Protection Agency (EPA) and the commission under Chapter 331 of this title. (7) At the point of compliance, the concentration of a hazardous constituent may not exceed the following: (A) the agency approved background concentration in the groundwater of the constituents listed in 10 Code of Federal Regulations (CFR) 40, Appendix A, Criterion 13; (B) the respective value given in §336.1133 of this title if the constituent is listed in the table and if the background level of the constituent is below the value listed; or (C) an alternate concentration limit established by the agency. (8) Alternate concentration limits to background concentration or to the drinking water limits in §336.1133 of this title that present no significant hazard may be proposed by licensees for agency consideration. Licensees must provide the basis for any proposed limits including consideration of practicable corrective actions, evidence that limits are as low as reasonably achievable, and information on the factors the agency shall consider. The agency may establish a site-specific alternate concentration limit for a hazardous constituent, as provided in paragraph (7) of this subsection, if it finds that the proposed limit is as low as reasonably achievable, after considering practicable corrective actions, and that the constituent will not pose a substantial present or potential hazard to human health or the environment as long as the alternate concentration limit is not exceeded. In making the present and potential hazard finding, the agency will consider the factors listed in paragraph (4) of this subsection. (k) If the groundwater protection standards established under subsection (i) of this section are exceeded at a licensed site, a corrective action program must be put into operation as soon as is practicable, and in no event later than 18 months after the agency finds that the standards have been exceeded. The licensee must submit the proposed corrective action program and supporting rationale for executive director approval prior to putting the program into operation, unless otherwise directed by the executive director. The licensee's proposed program must address removing or treating in place any hazardous constituents that exceed concentration limits in groundwater between the point of compliance and downgradient licensed site boundary. The licensee must continue corrective action measures to the extent necessary to achieve and maintain compliance with the groundwater protection standard. The executive director will determine when the licensee may terminate corrective action measures based on data from the groundwater monitoring program and other information that provides reasonable assurance that the groundwater protection standard will not be exceeded. (l) In developing and conducting groundwater protection programs, applicants and licensees must also consider the following: Cont'd... |
