We used a Delphi questionnaire in this study. The 9 identified
criteria were given to 10 experts through Delphi questionnaires
for determining the level of significance for all criteria for landfill
site selection (Sumathi et al., 2008). Experts were selected
among potential organizations, academics and experienced individuals
in the field of environmental management. The experts
gave their opinion about each of the criteria in form of degrees,
with 0–10 as importance values.