ONLINE RESOURCE 2– METHODOLOGY FOR CALCULATING SUB-PARAMETER SCORES

Article Title: A Model for Prioritizing Sites and Reclamation Methods at Abandoned Mines

Journal of Environmental Earth Sciences

Authors:

Owen E. Kubit (California State University at Fresno, )

Dr. Christopher J. Pluhar

Jerome V. De Graff

Ratios were determined for each sub-parameter condition representing its importance relative to the other possible conditions. In some cases a formula was developed that captures the importance of a sub-parameter as a function of other variables. In all other cases, the ratios were directly assigned or calculated with the revised Analytic Hierarchy Process (AHP). An overall ‘Score’ was determined for each potential condition representing the product of two weighting factors and the ratio. The formula for the Scores is provided below:

Score = Main parameter weighting factor x Sub-parameter weighting factor x Sub-parameter condition ratio

The methodology for calculating the Scores is illustrated with the following example for the sub-parameter ‘Mobility of Contaminated Soil’.

  1. The main parameter ‘Soil Contamination’ has a weighting factor of 0.24 (see Table 2, Delphi Method Phase II). i.e. according to this model, 24% of the overall mine hazard for any mine stems from soil contamination.
  2. The sub-parameter ‘Mobility of Contaminated Soil’ has a weighting factor of 0.36 (see Table 2, Delphi Method Phase II). i.e. 36% of the hazard associated with soil contamination derives from the contaminated soil’s mobility.
  3. ‘Mobility of Contaminated Soil’ was assigned three possible conditions: buried under 0.6 meters of soil (based on criteria established by USEPA (1992)), on surface (low potential), and on surface (high potential). These conditions have ratios of 0.32, 0.46, and 1.0, respectively, which were determined with the revised AHP. ‘On surface (high potential)’ has a ratio of 1.0 since it represents the worst case of the three possible conditions.
  4. If a site has soil contamination that is buried under 0.6 meters of soil, then the final Score would be 0.24 (Soil Contamination) x 0.36 (Mobility of Contaminated Soil) x 0.32 (Buried under 0.6 meters of soil) = 0.028. This value was multiplied by 1,000 resulting in a score of 28 (see Figure 5).