(35 ILCS 200/10-180)
    Sec. 10-180. Developed coal. Developed coal shall be assessed at 33 1/3% of the developed coal reserve economic value determined as follows:
    Developed Coal Reserve Economic Value equals the present value of the anticipated net income from the property during the life used to determine the developed coal.
    (a) The interest rate to be used for determining present value shall be the arithmetic average prime interest rate quoted by the 4 largest United States banks as measured by total assets located within the Chicago metropolitan statistical area as defined by the United States Department of Commerce as of the current assessment date and the 2 preceding assessment dates, plus 3%.
    (b) Net income means 4% of the average spot market price for Illinois coal as published in a recognized publication prescribed by the Department, as of the current assessment date and the 2 preceding assessment dates, multiplied by the number of recoverable tons per acre.
    (c) Recoverable coal tons per acre equals 1,742 tons per foot acre multiplied by seam thickness, and then multiplied by the recovery ratio.
    (d) Coal seam thickness means the average thickness of the coal seam or seams where coal is initially extracted.
    (e) Recovery ratio means the lesser of 80% for coal extracted by surface mining methods and 50% for coal extracted by underground mining methods or the actual historical recovery ratio for the mining operation.
    (f) The total assessed value of developed coal shall be attributed equally to the coal acreage that is anticipated to be mined.
    (g) Change in the per acre assessed value of coal shall not exceed 10% in any one year except when a change of acreage classification occurs.
(Source: P.A. 85-1359; 88-455.)