NAC444.7491. Procedures upon determination of concentrations of Appendix II constituents.

     1. If the concentrations of all constituents listed in Appendix II are shown to be at or below background values, using the statistical procedures set forth in NAC 444.7485, for two consecutive samplings, the owner or operator shall notify the solid waste management authority of this finding and may return to the monitoring procedures set forth in NAC 444.7488.

     2. If the concentrations of any constituents listed in Appendix II are above background values, but all concentrations are below the standard for the protection of groundwater established pursuant to NAC 444.7492, using the statistical procedures in NAC 444.7485, the owner or operator shall continue monitoring in accordance with this section.

     3. Except as otherwise provided in subsection 4, if one or more constituents listed in Appendix II are detected at statistically significant levels above the standard for the protection of groundwater in any sampling, the owner or operator shall:

     (a) Within 14 days of this finding, place a notice in the operating records for the disposal site identifying the constituents which have exceeded the standard and notify the solid waste management authority and all appropriate local government officials that the notice has been placed in the operating records;

     (b) Characterize the nature and extent of the release by installing additional monitoring wells as necessary;

     (c) Install at least one additional monitoring well at the boundary of the municipal solid waste landfill unit in the direction of the migration of the contaminant and sample this well in accordance with NAC 444.749;

     (d) Notify all persons who own or reside on the land which directly overlies any part of the plume of contamination if contaminants have migrated off the site as indicated by the sampling of wells in accordance with this section; and

     (e) Initiate an assessment of corrective measures pursuant to NAC 444.7493.

     4. In lieu of complying with the provisions of subsection 3, the owner or operator may demonstrate that a source other than a municipal solid waste landfill unit caused the contamination or that the statistically significant increase resulted from error in sampling, analysis or statistical evaluation or from a natural variation in the quality of the groundwater. A report documenting this demonstration must be certified by a qualified groundwater scientist, approved by the solid waste management authority and placed in the operating records of the unit. If a successful demonstration is made, the owner or operator shall continue monitoring in accordance with the program for assessment pursuant to this section, and may return to detection monitoring if the constituents are at or below background in accordance with subsection 1. Until a successful demonstration is made, the owner or operator shall comply with the provisions of subsection 3.

     (Added to NAC by Environmental Comm’n, eff. 11-8-93)