The effect of coal stockpile on shallow groundwater aquifer: Study case Tarahan

This paper aims to determine the existence of groundwater contamination due to coal stockpile activity in shallow groundwater. The research area is located in a stockpile that has been operating since 1986. We conducted chemical content analysis at several points around the coal stockpile and outside the stockpile area to see the impact of pollution on the surrounding residents' areas. This study also uses geoelectric methods and direct observations to identify shallow groundwater levels (water table). The research area has a groundwater depth of about 2 m from the surface, and groundwater flows from northeast to southwest (sea). The chemical content analysis results show that each sample taken around the stockpile is below the water quality standard threshold, so it can be concluded that coal stockpile activity does not contaminate the shallow groundwater. However, there is nitrate contamination from shallow groundwater located outside the stockpile area taken from dug wells and drilling wells with a depth of 8 m shows a value of 14.08-23.67 ppm (>10 ppm threshold). We suspect that this pollution is caused by the large number of mining activities carried out in the north of the study area.