Heavy Metal Pollution Index of Ground Water of an Abandoned Open Cast Mine Filled with Fly Ash: a Case Study

Ground water samples were collected from the periphery of a fly ash filled open cast mine, from within the mine property, and from a half kilometre away from the site. Concentrations of metals such as Cu, Zn, Cd, Pb, and Cr were consistently below the permissible limit for drinking water, but concentrations of Fe and Mn were above the permissible limit. The data were used to calculate a heavy metal pollution index (HPI). The HPI of the ground water of the ash filled mine was 36.67, which was below the critical index limit of 100. The HPI of Dhanbad Township ground water, from very near to the mining area, was 11.25. The results indicate that leachate from the fly ash filled mine has apparently contaminated the ground water to a limited extent.