GROUNDWATER VULNERABILITY ANALYSIS ON COAL MINING WITH DRASTIC METHOD

This research is focused on knowing how vulnerable the ability of groundwater is to be affected by mining activities. Supporting analysis includes mine design using the stripmine method and research on hydrological and hydrogeological characteristics. Field activities include observation, measurement, testing of groundwater potential with the slugtest method in the study area. Testing of groundwater potential is carried out based on 6 core drill holes, namely GT-01, GT-02, GT-03, GT-04, GT-05, GT-06. Analysis of this study uses the DRASTIC method as a weighting and valuation method. In the DRASTIC method of groundwater vulnerability influenced by several factors, namely, the depth of the groundwater, rainfall, topography (slope), lithology, soil texture and hydraulic conductivity. The types of aquifers found in the study area were free aquifers with a depth of 3.15 – 4.7 m, divided south while aquifers were depressed with a depth of 12.1 - 55.5 m in the northern and central parts. The index value varies when the minimum rainfall is 72-146 with a low level vulnerability and when rainfall is high 96-165 the level of vulnerability is low to high, then the effect of mining activities is the cutting off of aquifer layers