Indonesia Conference Directory

The settling pond is a reservoir of water from the mining area which carries it heavy metal particles to be sedimentation first before its flowing out of the area mining. so that it does not cause pollution. The problem in this research area is Dimensions of the setting pond could not accommodate incoming water discharge when rainfall is high, and it makes the water overflows and directly enter the coastal waters so it is indicated to arise heavy metal pollution. The purposes of this research are to examine the dimensions of the settling pond, determine erosion hazard level and countermeasures carried out. In accordance with the rainfall data, it can calculation of the mine drainage system is carried out, namely (1) The planned rainfall using the Gumbel method obtained at 156,046 mm/day. (2) The intensity of rainfall was obtained at 28,731 mm/hour. (3) The catchment area is DTH I with an area of 0,43 km2, DTH II with an area of 0,11 km2, DTH III covering an area of 0,43 km2, (4) runoff discharge obtained by DTH I of 2,36 m3/sec, DTH II of 0,79 m3/sec, and DTH III of 2,66 m3/sec . (5) The total discharge of runoff water from 3 DTH so that it was obtained at 5,82 m3/sec. According to the discharger and settling speed of 0.000997 m/sec, the settling area is obtained the pond is 5839,46 m2 and the settling pond volume is 23.520 m3 with 4 m inside the volume is greater than the actual volume in the field. Another cause is erosion so that runoff water flows directly into the pond settling without going through open channels which causes fast water, this is evidenced by the calculation of erosion hazard levels with the USLE equation the average erosion rate (A) is 540,5646 tons/ha/year so that it is included in class V with erosion hazard level in very heavy category (B). Then the countermeasures are carried out by revegetation on the slope so that if revegetation has been carried out then the average value erosion rate (A) is 172,98 tons/ha/year so the erosion hazard level is reduced to class III with medium category (S).