NAC445A.22725. Contamination of groundwater: Order by Director for corrective action; request for exemption; exception.

     1. Except as otherwise provided in this section, the Director may require an owner or operator to take corrective action if the release of a hazardous substance, hazardous waste or a regulated substance contaminates groundwater and the level of contamination exceeds the action level established for the groundwater pursuant to NAC 445A.22735.

     2. An owner or operator may, before initiating corrective action or after the termination of remediation pursuant to NAC 445A.22745, submit a written request to the Director for an exemption from the provisions of subsection 1. The request must be accompanied by such supporting information as the Director may require. The Director may grant the request if:

     (a) The following conditions are satisfied:

          (1) Each source of the contamination of the groundwater is identified and controlled or no source of the contamination remains based upon the age and nature of the release;

          (2) The magnitude and extent of the contamination of the groundwater is known; and

          (3) Data are available from at least 3 years of quarterly monitoring or another period specified by the Division based upon the magnitude of the contamination of the groundwater and the data do not show a trend of increasing concentrations of the contamination in the body of the plume of the contamination;

     (b) A demonstration is made which indicates that natural attenuation is sufficient to reduce any concentration of the contamination below action levels or to prevent any migration of the contaminant to a receptor or another point of demonstration established by the Division at concentrations that are greater than action levels, if the demonstration relies upon analytical or numerical models of diffusion and dispersion or any other calculations of physical or chemical processes of retardation or degradation that are approved by the Division; and

     (c) The groundwater contaminated by the release is not a source of drinking water and is not likely to be a source of drinking water in the future because:

          (1) It is economically or technologically impractical to recover the water for drinking because of the depth or location of the water or render the water fit for human consumption; or

          (2) A legal restriction or institutional control is in effect concerning the use of the groundwater based upon the depth of the groundwater, the presence of a municipal system, the use of an environmental covenant or other controls accepted by the Division.

     3. In addition to any calculations of physical or chemical processes required pursuant to paragraph (b) of subsection 2, a demonstration made pursuant to that paragraph may also rely upon:

     (a) Any known mechanism of biological degradation and any evidence obtained for the site relating to metabolic activity and the presence of the appropriate redox potential which supports biological degradation of the contamination;

     (b) Any indication of degradation based upon the presence of any daughter products; or

     (c) Any other applicable factors specified by the Division which are appropriate for making a decision based upon risk.

     4. The Director shall not require an owner or operator to take corrective action pursuant to subsection 1 to achieve the remediation standard required by the Division if the owner or operator files with the Division a study which is acceptable to the Division and which demonstrates that, based on a review of available technology and the prohibitive cost of the corrective action, it is not feasible to achieve the required remediation standard.

     (Added to NAC by Environmental Comm’n, eff. 10-3-96; A by R189-08, 8-25-2009)