With respect to property that is subject to valuation as mining or mineral property, the initial base year value of a leach pad, tailing facility, or settling pond on that property shall be the full cash value of that leach pad, tailing facility, or settling pond as of the first lien date upon which that pad, facility, or pond is subject to assessment. Each leach pad, tailing facility, or settling pond shall be considered a separate appraisal unit for purposes of determining its taxable value on each lien date subsequent to the lien date upon which the initial base year value was determined for that pad, facility, or pond.