Kajian Teknis Sistem Penyaliran Tambang Terbuka di PT X Site PT Kijang, Kabupaten Muara Enim, Provinsi Sumatera Selatan

Abstract

The water issue occurred in the pit of PT X, the pit's catchment area could not accommodate the incoming water, thereby hindering mining activities. A study on the drainage system in this pit has not yet been conducted. Therefore, an analysis is necessary, which includes calculating the inflow of water to the mining area, dimensions of open channels and culverts, dimensions and volume of the sump, pumping system, and dredging time of the settling pond. The drainage system study utilizes daily rainfall data from the past 10 years (2014-2023). The planned rainfall analysis uses Gumbel, Normal, Log Normal, and Log Pearson III distributions, which are then analyzed using Chi-Square and Smirnov-Kolmogorov methods for a 5-year rainfall return period. The runoff discharge is determined using the rational method as a reference for assessing the dimensions of open channels, sump volume, pump capacity, and settling pond volume. The planned rainfall calculation for the 5-year return period indicates a Gumbel distribution of 130.53 mm/day, with an average rainfall duration of 2.335 hours and intensity of 25.71 mm/hour. The runoff discharge at DTH I, with an area of 0.078 km², is 0.5017 m³/s, while at DTH II, with an area of 0.019 km², it is 0.0814 m³/s. The actual sump volume is 1,869 m³, with the incoming water flow sourced from runoff at 0.5017 m³/s, a pumping capacity of 0.105 m³/s, and an actual settling pond area of 399.108 m². Based on analysis, the actual dimensions of sump can handle the incoming discharge. However, the actual sump volume is insufficient to accommodate the inflow, necessitating a recommendation to increase it to 4,800 m³. The actual settling pond area can accommodate the pumped water from the catchment. The required dredging times for each compartment are 25 days, 19 days, 20 days, and 25 days, respectively.