UBC Theses and Dissertations

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UBC Theses and Dissertations

Designs for dewatering and optimization of pit slopes in saprolite overburden : a case study of the PT. Kayan Putra Utama Coal project Lesmana, Antony


Effective dewatering and environmental program poised to have a significant impact on the feasibility of saprolite mining operations. It is therefore necessary to strike a balance between an effective dewatering program and sound environmental policy. Using assessments such as rainfall, climate studies, groundwater flow, and aquifer characterizations, the Separi coal dewatering program includes the construction of water channels, flood protection levees, water wells, and placing various environmental monitoring sites. The construction of water channels and flood protection levees has reduced the water runoff that entered the mining area by approximately 75%. For a six-month testing period, the average pumping rate of the dewatering well was 24.78 m³/day. These pumping rates were determined to result in groundwater level that would generally be 10 meters below the lowest mining benches at all times. Ten meters is the recommended single bench height based on the slope stability analysis. After six months of dewatering, the groundwater level was lowered 10.88 meters, permitting the mining project may begin its mining operation to commence. A re-design of maximum pit slope angle is indicated in this research. During the testing period, the environmental management plan did not show any negative impacts of dewatering programs on surface and groundwater resources. The monitoring sites all yield acceptable range of water quality parameters, such as Electrical Conductivity (EC), Total Suspended Solids (TSS), Total Dissolved Solids (TDS), and pH value. The company continues to monitor the water resources to maintain acceptable water quality in the study areas.

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