MINE DRAINAGE FACILITY PLANNING AT OUT-PIT DUMP C1 SITE BINUNGAN MINE OPERATION 2 BLOK 8 PT BERAU COAL, EAST KALIMANTAN

• Main Author: Clara Chika Giri Asta P, Putu
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69380
• Institution: Institut Teknologi Bandung

In open-pit mining, the overburden material needs to be excavated or blasted to a certain depth. The material will be transported to the disposal area according to the planned progress plan. When there is heavy rain, the disposal material will be eroded due to its characteristic as a loose material. Therefore, it is necessary to design drainage facilities that can reduce the impact of erosion so that the water quality meets the effluent standards in the post-mining period. The design of the drainage facility begins with analyzing rain data at BMO2 Station for the period 2005-2021 using a partial duration series and Gumbell distribution which produces rainfall intensity of 15.08 mm/hour. From the topographic data, the total catchment area is 114.7 ha which is divided into 4 sub-catchments. Then, the erosion prediction was calculated using the USLE formula considering the rain data, sediment data and the distribution of the catchment area. The runoff discharge that will enter the drainage facility is determined using the hydrograph method of the synthetic soil conservation service (SCS). The result of erosion prediction using 2880.61 mm/year of annual rainfall and available sediment data is 63.22 tons/ha/year. Based on these results, the required mine drainage facilities are open channels, drop structures, and control boxes. The open channel is divided into 3 categories in the form of a trapezoidal cross section with a bottom width varying from 0.5-1 m and a height varying from 0.5-1 m, drop structure with a height of 1.40-2.44 m, and 31 control boxes with a volume of 3 m3 each.