Desain Saluran Drainase Pada Area Pertambangan Tanah Liat

Abstract

Runoff mengakibatkan timbulnya genangan pada area pertambangan tanah liat PT Solusi Bangun Indonesia Tbk berpotensi menghambat aktivitas tambang dan menurunkan kestabilan lereng. Penelitian ini dilakukan untuk mengevaluasi efektivitas settling pond dalam menampung limpasan serta merancang saluran drainase terbuka sesuai kondisi pertambangan. Data primer berupa observasi lapangan dan pengukuran dimensi, data sekunder berupa curah hujan 10 tahun terakhir dan peta kontur wilayah tambang. Metode Mononobe digunakan dalam memperoleh intensitas hujan, perhitungan debit limpasan dengan metode rasional, serta perhitungan dimensi saluran dengan persamaan Manning. Hasil analisis menunjukkan curah hujan rencana periode ulang 50 tahun sebesar 715,93 mm dengan debit limpasan total 3,50 m³/detik. Settling pond eksisting memiliki kapasitas 39.434,08 m³, tidak mampu menampung volume limpasan namun memerlukan pemeliharaan. Rancangan saluran drainase berbentuk trapesium mengukuti standar teknis dengan koefisien manning 0,03, kemiringan 1,73 (60°), dan tinggi jagaan disesuaikan dengan debit di setiap DTH.

Runoff in the clay mining area of PT Solusi Bangun Indonesia Tbk causes ponding that may hinder mining activities and reduce slope stability. This study was conducted to evaluate the effectiveness of the settling pond in accommodating runoff and to design an open drainage channel suited to mining conditions. Primary data were obtained from field observations and dimensional measurements, while secondary data included 10 years of rainfall records and contour maps of the mining area. The Mononobe method was applied to determine rainfall intensity, the Rational Method was used to calculate runoff discharge, and Manning’s equation was employed to determine channel dimensions. The analysis results showed that the 50 year return period design rainfall was 715,93 mm with a total runoff discharge of 3,50 m³/s. The existing settling pond has a capacity of 39,434.08 m³, which is n0 sufficient to accommodate the runoff volume but requires maintenance. The designed drainage channel has a trapezoidal section following technical standards with a Manning coefficient of 0,03, a side slope ratio of 1,73 (60°), and a freeboard height adjusted to the discharge in each catchment area (DTH).