Abstract. A surface mine is a mining method in which all mining activities are conducted on the surface of the earth, and the workplace is directly related to the atmosphere. Thus, in this method, there are factors from the outside air that will be in, one of which is water. PT. Kalimantan Prima Persada is coal mining company in Pit Langap and has operated 4 pumps on the main sump. To reduce pumps works that required a study that could overcome the water entering the mine like design channel. From the results obtained the study can be calculated Gumbel distribution, Mononobe equation, and the rational formula for runoff discharge. From the results of the calculation, the runoff debit is based on segment 1 = 0.584 m3/s, segment 2 = 1.803 m3/s, and segment 3 = 0.966 m3/s. from calculation result using Manning equation got segment 1 dimension with open length (CW) = 1.308 m, water depth (h) = 0.620 m, and base width of channel (b) = 0.895 m. This channel can overcome the surface flow of 49.75% of the total surface flow into the mine. For water that cant be prevented by using channel then it takes sump to accommodate all water entering so easily discharged by pump, where in one day water enter into Pit 51.373.61 m3/day so that the length and width of sump surface needed is = 96.297 m, then the length and width of base sump = 82,297 m, and sump depth = 7 m. Of the total discharge that enter the pump needs to remove water in the sump as much as 3 pieces of pump type MF420-EX.Keywords: Waterflow, Channel Dimension, Pump, Drainage, DewateringAbstrak. Tambang terbuka adalah suatu metode penambangan yang segala kegiatan dan aktivitas penambangannya dilakukan di atas permukaan bumi, dan tempat kerjanya berhubungan langsung dengan udara luar (atmosfer). Dengan demikian, dalam metode penambangan ini terdapat faktor-faktor dari udara luar yang akan berpengaruh dalam kegiatan penambangannya, salah satunya adalah air. PT. Kalimantan Prima Persada merupakan perusahaan tambang batubara di mana pada Pit Langap telah beroperasi 4 pompa pada main sump. Untuk mengurangi kerja pompa dibutuhkan kajian yang dapat mengatasi air limpasan yang masuk kedalam tambang seperti pembuatan paritan. Dari hasil kajian yang didapatkan maka dapat dilakukan perhitungan distribusi Gumbel, persamaan Mononobe, dan rumus rasional untuk debit limpasan. Dari hasil perhitungan tersebut didapatkan debit limpasan berdasarkan segmen yaitu segmen 1 = 0,584 m3/s, segmen 2 = 1,803 m3/s, dan segmen 3 = 0,966 m3/s. dari hasil perhitungan mengunakan persamaan Manning didapatkan dimensi paritan segmen 1 dengan panjang bukaan (CW) = 1,308 m, kedalaman air (h) = 0,620 m, dan lebar dasar saluran (b) = 0,895 m. Saluran ini mampu mengatasi aliran permukaan sebesar 49,75% dari total aliran permukaan yang masuk ke dalam tambang. Untuk air yang tidak dapat dicegah dengan menggunakan puritan maka dibutuhkan sump untuk menampung seluruh air yang masuk sehingga mudah dikeluarkan oleh pompa, di mana dalam satu hari air masuk ke dalam Pit sebesar 51.373,61 m3/hari sehingga panjang dan lebar permukaan sump yang dibutuhkan adalah = 96,297 m, lalu panjang dan lebar dasar sump = 82,297 m, dan kedalaman sump = 7 m. Dari total debit yang masuk maka kebutuhan pompa untuk mengeluarkan air yang ada pada sump sebanyak 3 buah pompa tipe MF420-EX.Kata Kunci: Debit Air, Dimensi Paritan, Pompa, Pencegahan,Penanggulangan
Abstract: A surface mine is a mining method in which all mining activities are conducted on the surface of the earth, and the workplace is directly related to the atmosphere. Thus, in this method, there are factors from the outside air that will be in, one of which is water. PT. Kalimantan Prima Persada is coal mining company in Pit Langap and has operated 4 pumps on the main sump. To reduce pumps works that required a study that could overcome the water entering the mine like design channel. From the results obtained the study can be calculated Gumbel distribution, Mononobe equation, and the rational formula for runoff discharge. From the results of the calculation, the runoff debit is based on segment 1 = 0.584 m3/s, segment 2 = 1.803 m3/s, and segment 3 = 0.966 m3/s. from calculation result using Manning equation got segment 1 dimension with open length (CW) = 1.308 m, water depth (h) = 0.620 m, and base width of channel (b) = 0.895 m. This channel can overcome the surface flow of 49.75% of the total surface flow into the mine. For water that cant be prevented by using channel then it takes sump to accommodate all water entering so easily discharged by pump, where in one day water enter into Pit 51.373.61 m3/day so that the length and width of sump surface needed is = 96.297 m, then the length and width of base sump = 82,297 m, and sump depth = 7 m. Of the total discharge that enter the pump needs to remove water in the sump as much as 3 pieces of pump type MF420-EX.