Evaluasi Ketersediaan Kolam Pengendapan dalam Menampung Debit Limpasan di Area Disposal PT XYZ, Kalimantan Selatan

Abstract

Mine drainage systems play an important role in controlling runoff and preventing flooding in mining areas. The mine drainage system in the disposal area of PT XYZ is constrained by the limited capacity of the settling pond to accommodate runoff discharge. As the disposal elevation increases over time, runoff discharge also increases, while the relatively small settling pond capacity limits the pumping discharge from the sump to the settling pond. Consequently, water accumulates in the sump, causing overflow that may flow into open channels connected to the river. This study aims to calculate the total runoff discharge entering the disposal catchment area, evaluate the adequacy of the settling pond capacity, and determine the optimal settling pond dimensions and pumping capacity. A quantitative research method was employed using secondary data, including daily rainfall data (2015–2024), topographic data, pumping and piping specifications, and settling pond design data. Design rainfall was determined using the Gumbel Distribution Method, while runoff discharge was calculated using the Rational Method based on the runoff coefficient (C), rainfall intensity (I), and catchment area (A). The results indicate that the total runoff discharge entering the catchment area is 1.9695 m3/s, equivalent to 28.579,724 m3. The existing settling pond, with a capacity of 15.482,376 m3, is insufficient to support the drainage system because the maximum pumping discharge is only 8.425,4 m3/day, resulting in water accumulation of 20.154,324 m3 in the sump. The proposed design recommends a pumping capacity of 28.800 m3/day using three pumps, each with a capacity of 480 m3/h operating for 20 hours/day, and a settling pond with a total capacity of 127.692 m3. This design complies with Minister of Energy and Mineral Resources Decree Number 1827/K/30/MEM/2018 and is expected to prevent sump overflow while improving the effectiveness of the mine drainage system.