NAC445A.437. Minimum design criteria: Tailings impoundments.

     1. A tailings impoundment must utilize a system of containment equivalent to:

     (a) Twelve inches of recompacted native, imported, or amended soils which have an in place recompacted coefficient of permeability of no more than 1x10-6 cm/sec; or

     (b) Competent bedrock or other geologic formations underlying the site which has been demonstrated to provide a degree of containment equivalent to paragraph (a).

     2. An alternate level of containment may be required by the Department for all of the tailings impoundment or for a portion thereof after considering the following factors:

     (a) The anticipated characteristics of the material to be deposited;

     (b) The characteristics of the soil and geology of the site;

     (c) The degree to which the hydraulic head on the impoundment liner is minimized;

     (d) The extent and methods used for recycling or detoxifying fluids;

     (e) Pond area and volume;

     (f) The depth from the surface to all groundwater; and

     (g) The methods employed in depositing the impounded material.

     (Added to NAC by Environmental Comm’n, eff. 9-1-89)—(Substituted in revision for NAC 445.24368)