| (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: (1) installation of bottom liners. Where synthetic liners are used, a leakage-detection system must be installed immediately below the liner to ensure detection of any major failures. This is in addition to the groundwater monitoring program conducted as provided in subsection (cc) of this section. Where clay liners are proposed or relatively thin, in situ clay soils are to be relied upon for seepage control, tests must be conducted with representative tailings solutions and clay materials to confirm that no significant deterioration of permeability or stability properties will occur with continuous exposure of clay to by-product material solutions. Tests must be run for a sufficient period of time to reveal any effects that may occur; (2) mill process designs that provide the maximum practicable recycle of solutions and conservation of water to reduce the net input of liquid to the by-product material impoundment; (3) dewatering of by-product material solutions by process devices and/or in situ drainage systems. At new sites, by-product material solutions must be dewatered by a drainage system installed at the bottom of the impoundment to lower the phreatic surface and reduce the driving head of seepage, unless tests show by-product material solutions are not amenable to such a system. Where in situ dewatering is to be conducted, the impoundment bottom must be graded to assure that the drains are at a low point. The drains must be protected by suitable filter materials to assure that drains remain free-running. The drainage system must also be adequately sized to assure good drainage; and (4) neutralization to promote immobilization of hazardous constituents. (m) Technical specifications must be prepared for installation of seepage control systems. A quality assurance, testing, and inspection program, which includes supervision by a qualified engineer or scientist, must be established to assure that specifications are met. If adverse groundwater impacts or conditions conducive to adverse groundwater impacts occur due to seepage, action must be taken to alleviate the impacts or conditions and restore groundwater quality to levels consistent with those before operations began. The specific seepage control and groundwater protection method, or combination of methods, to be used must be worked out on a site-specific basis. (n) In support of a by-product material disposal system proposal, the applicant/licensee must supply the following information: (1) the chemical and radioactive characteristics of the waste solutions; (2) the characteristics of the underlying soil and geologic formations particularly as they will control transport of contaminants and solutions. This must include detailed information concerning extent, thickness, uniformity, shape, and orientation of underlying strata. Hydraulic gradients and conductivities of the various formations must be determined. This information must be gathered by borings and field survey methods taken within the proposed impoundment area and in surrounding areas where contaminants might migrate to groundwater. The information gathered on boreholes must include both geologic and geophysical logs in sufficient number and degree of sophistication to allow determining significant discontinuities, fractures, and channeled deposits of high hydraulic conductivity. If field survey methods are used, they should be in addition to and calibrated with borehole logging. Hydrologic parameters such as permeability must not be determined on the basis of laboratory analysis of samples alone. A sufficient amount of field testing (e.g., pump tests) must be conducted to assure actual field properties are adequately understood. Testing must be conducted to make possible estimates of chemisorption attenuation properties of underlying soil and rock; and (3) location, extent, quality, capacity, and current uses of any groundwater at and near the site. (o) If ore is stockpiled, methods must be used to minimize penetration of radionuclides and other substances into underlying soils. (p) In disposing of by-product material, licensees must place an earthen cover over the by-product material at the end of the facility's operations and shall close the waste disposal area in accordance with a design that provides reasonable assurance of control of radiological hazards to the following: (1) be effective for 1,000 years to the extent reasonably achievable and, in any case, for at least 200 years; and (2) limit releases of radon-222 from uranium by-product materials and radon-220 from thorium by-product materials to the atmosphere so as not to exceed an average release rate of 20 picocuries per square meter per second (pCi/m2 s) to the extent practicable throughout the effective design life determined in accordance with paragraph (1) of this subsection. This average applies to the entire surface of each disposal area over a period of at least one year, but a short period compared to 100 years. Radon will come from both Cont'd... |
