Hydrogeology and Groundwater Modeling in the Mining Area of Pt. X in Berambai Area, Kutai Kartanegara Regency, East Kalimantan Province

Abstract

The world of mining, especially coal mining, is an activity that can cause changes in geological, hydrological, morphological and land use conditions. Changes in these conditions also have an impact or influence on the mining and post-mining processes. The location of the research was carried out in the mining business area of PT. X which is located in the Berambai area, Kutai Kartanegara Regency with a research area of 2,6 km². This study aimed to determine the hydrogeological conditions and model the direction of groundwater flow in the research area. This study uses primary data like direct geological mapping and rainfall in the mining area, while secondary data in the form of regional geology, coring data, groundwater level observation data, climate data and literature studies. The method used in modeling the direction of groundwater flow is the finite difference grid method. The research area is part of the Separi Besar watershed so the research area is determined as a rain catchment area. The groundwater recharge value obtained is 930,4074 mm mm/year. The research area belongs to the Typology of Sandstone-Claystone Sedimentary Aquifer System, the types of aquifers found are unconfined aquifers and confined aquifers. The hydrostratigraphy of the research area consists of aquifer, aquitard and aquiclude layers. The hydrogeological boundaries of the research area are river boundaries, groundwater divide and impermeable boundaries. From the results of the model that has been calibrated and analyzed for sensitivity, that is, groundwater flow in the unconfined aquifer layer is not found in the Eastern part of the study area, while groundwater flow in the confined aquifer layer is still visible, this is because the unconfined aquifer layer is not continuous. The direction of groundwater flow is towards the lower area, namely the constant network (river) and the mining pit area.