ANALYSIS OF DRANAGIE SYSTEM IN NORTH VOID AT PIT ON2 LATI MINE OPERATION SITE PT BERAU COAL EAST KALIMANTAN

• Main Author: Arasy Siswandi, Ichram
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69349
• Institution: Institut Teknologi Bandung

Post-mining is an activity that is planned, systematic, and continues after the end of part or all of the mining business activities to restore the functions of the natural environment and social functions according to local conditions throughout the mining area. Pit ON2 is a post-mining area located at the Lati site. Pit ON2 has 3 voids namely north, east and south voids. The North Void ON2 is planned to be a retention pond that will drain water with a certain discharge to WMP 27. So that the North ON2 Void is needed a drainage facility that can make the void as a retention pond function properly. The design of the drainage facility to control the discharge at the North Void ON2 begins by analyzed the rainfall data for the PIT ON2 station in the period 2012-2022 by using the partial method series and by using the Gumbell distribution. The catchment area is obtained using topographic data which will then be divided into subcatchments based on the direction of flow and the condition of the area. Peak discharge from the catchment area of Void ON2 obtained using the hydrograph method of the synthetic soil conservation service (HSS SCS) unit. The results of the debits from the hydrograph, will determine the need for a drainage facility for Void ON2 North. The debits obtained from the catchment area of 455.3 Ha consisted of 6 subcatchments is 3.8 m3/s. To cope with the incoming discharge, a trapezoidal drainage perimeter is designed to be divided into 2 categories, each of which has dimensions of bottom width x top width x height: 3m x 1m x 1m; 2m x 1m x 0.5m. in order to control the planned output discharge of 1 m3/s, a volume of the incoming water is 250,100 m3 is needed. Determination of volume is calculated from the capacity of the void volume at an elevation of 34 masl to 31 masl. The incoming volume capacity can be accommodated when the void volume is at an elevation of 31 masl. So the required discharge is a canal that can lower the discharge elevation from an elevation of 34 masl to an elevation of 31 masl with a bottom width of 1 m, and an embankment at elevation of 34 masl which has an open channel with a width of 0.2 m. The canal is used to accommodate the volume of incoming water with a water level rise of 2.5 m and the embankment is used to control the outgoing water discharge.