Electronic Theses and Dissertation

Perancangan sistem dewatering memegang peranan penting dalam mendukung kelancaran operasi tambang terbuka, khususnya pada kondisi hidrogeologi yang kompleks dan curah hujan tinggi. Salah satu permasalahan utama di Pit 4 PT Tata Bara Utama adalah lokasi drainase eksisting yang berada pada elevasi RL 70 meter di atas lereng highwall, yang menyebabkan rute pipa menjadi curam, menurunkan efisiensi pompa, dan berpotensi mengganggu kestabilan lereng. Untuk mengatasi hal tersebut, perusahaan merencanakan pemindahan drainase ke area disposal pada RL 45 meter. Penelitian ini bertujuan merancang sistem dewatering yang optimal dengan mempertimbangkan topografi, debit air masuk, serta efisiensi sistem. Berdasarkan analisis, curah hujan rencana sebesar 149,32 mm dengan intensitas 15,1 mm/jam menghasilkan debit total 58.054 m³/hari. Kapasitas lima unit pompa yang tersedia sebesar 52.975,2 m³/hari belum mencukupi, sehingga diperlukan tambahan satu unit pompa MF-385. Sistem dirancang menggunakan pipa HDPE sepanjang 1.415 meter, pompa beroperasi pada 1.400 RPM, dengan jam kerja efektif 20,8 jam/hari dan mechanical availability 87%. Estimasi konsumsi bahan bakar mencapai 2.008,8 liter/hari dengan biaya operasional harian sebesar Rp45.989.000,00/hari, pada kondisi seluruh pompa tersedia running secara bersamaan selama 20,8 jam/hari. Rancangan ini diharapkan menjadi acuan teknis pengelolaan air tambang yang efisien dan berkelanjutan.

The design of the dewatering system plays a crucial role in supporting the smooth operation of open-pit mining, especially under complex hydrogeological conditions and high rainfall. One of the main issues in Pit 4 PT Tata Bara Utama is the location of the existing drainage at an elevation of RL 70 meters above the highwall slope, which causes the pipe route to be steep, reduces pump efficiency, and potentially disrupts slope stability. To address this issue, the company plans to relocate the drainage to the disposal area at RL 45 meters. This study aims to design an optimal dewatering system by considering topography, incoming water discharge, and system efficiency. Based on the analysis, the planned rainfall of 149.32 mm with an intensity of 15.1 mm/hour results in a total discharge of 58,054 m³/day. The capacity of the five available pump units, which is 52,975.2 m³/day, is insufficient, so an additional MF-385 pump unit is needed. The system is designed using 1,415 meters of HDPE pipe, with pumps operating at 1,400 RPM, an effective working time of 20.8 hours/day, and a mechanical availability of 87%. The estimated fuel consumption reaches 2,008.8 liters/day, with a daily operational cost of Rp45,989,000.00/day, under the condition that all pumps are operating simultaneously for 20.8 hours/day. This design is expected to serve as a technical reference for efficient and sustainable mine water management.