HYDROLOGICAL EVALUATION OF WMP 48 ST CAPACITY AT THE SAMBARATA COAL MINE

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ABSTRAK

Pengelolaan air tambang terbuka memerlukan kapasitas sediment pond dan Water Monitoring Point (WMP) yang sesuai dengan karakteristik hujan dan limpasan. Penelitian ini mengevaluasi kapasitas WMP 48 ST pada Pit C2HU, Blok B East, Site Sambarata. Data hujan maksimum 2010–2024, pemompaan, dan topografi dianalisis menggunakan distribusi Gumbel, persamaan Mononobe, metode Rasional, serta delineasi DEM-ArcGIS. Curah hujan rencana 10 tahunan sebesar 431,24 mm dengan intensitas 59,33 mm/jam. Catchment area pit dan disposal masing-masing 3,685 km² dan 0,455 km² menghasilkan debit 54,70 m³/det dan 6,75 m³/det. Kapasitas minimum kolam sebesar 92.880 m³, sedangkan kapasitas rencana 120.000 m³. WMP 48 ST dinilai memadai untuk menampung limpasan dan air pemompaan serta mengendalikan sedimen sebelum pelepasan ke badan air.

Kata kunci: Analisis Hidrologi, Water Monitoring Point (WMP), Sediment Pond, Debit Limpasan, Pertambangan Batubara

ABSTRACT

Open-pit mine water management requires sediment pond and Water Monitoring Point (WMP) capacities suited to rainfall and runoff. This study evaluates WMP 48 ST at Pit C2HU, Block B East, Sambarata Site. Annual maximum rainfall data for 2010–2024, pumping records, and topography were analyzed using the Gumbel distribution, Mononobe equation, Rational Method, and DEM-ArcGIS catchment delineation. The 10-year design rainfall was 431.24 mm with an intensity of 59.33 mm/hour. Pit and disposal catchments of 3.685 km² and 0.455 km² produced runoff discharges of 54.70 m³/s and 6.75 m³/s. The required pond capacity was 92,880 m³, below the planned 120,000 m³. WMP 48 ST is therefore adequate for runoff and pumped-water storage while controlling sediment before discharge.

Keywords: Hydrological Study, Water Monitoring Point (WMP), Sediment Pond, Runoff, Coal Mining