APPLICATION OF HYDROLOGY AND HYDROGEOCHEMISTRY IN ANALYZING DISSOLVED METAL LOAD AND EROSION RATES AROUND NICKEL MINING OPERATIONS AT PT XYZ

• Main Author: Permana, Satya
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/85194
• Institution: Institut Teknologi Bandung

Nickel mining at PT XYZ in Morowali Regency using the open-cast mining method faces one of its challenges in the form of surface runoff. Runoff from a catchment area of mining operations will affect the water quality of rivers around the mining operation area which becomes the outlet of a catchment. The results of modeling and calculation of catchment characteristics show that it belongs to a very small catchment with an area of 15.67 km², 6.22 km², 69.12 km², and 7.15 km² respectively, which is influenced by the morphology and topography of the research location which is undulating and tends to be rough. The shape of all catchments tends to be elongated from the calculation of the shape ratio (Ff), roundness (Rc) and elongation (Re) which causes the concentration time (tc) of discharge accumulation to last a little longer and the flood discharge is relatively small, the results of discharge calculation (Q) actual rivers A, B, C, and D are 0.53 m³/s, 0.33 m³/s, 1.09 m³/s, and 0.16 m³/s respectively. Runoff from this catchment is likely to carry various solids resulting from erosion influenced by rainfall in an area. Erosion estimation using the USLE method in each catchment shows different erosion rates, including very light erosion rates in forest areas for all catchments with erosion rates in catchments A, B, C, and D sequentially being 2.07 tons/ha/year, 4.63 tons/ha/year, 4.63 tons/ha/year and 2.07 tons/ha/year. In open land areas, it shows a high erosion rate for both catchments A and D, which is 414.02 tons/ha/year, and a very high erosion rate for catchment B in open land areas with a value of 925.46 tons/ha/year. Erosion from this catchment will also affect the water quality of the river, especially in the river which is the outlet point of a catchment. Based on the results of Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) tests from Rivers A, B, C, and D, it has met the Water Quality Standards of PP No. 22 of 2021 for each river class except for the physical and chemical parameters of Dissolved Oxygen (DO) due to fluctuations so that there are days that do not meet the standards due to turbid river water. The concentration of dissolved metal elements in the samples of River D has the highest concentration, especially Fe and Cr compared to other samples, caused by the catchment from the open land area of mining operations and is located on local geology of ultramafic rocks are rich in ferromagnesian minerals such as olivine, pyroxene, and amphibole. Additionally, they are also rich in hematite, goethite, and chromite minerals. Based on the results of calculating the Maximum Pollution Load (MPL) and Actual Pollution Load (APL), it was found that the value of APL < MPL for all samples so it is still safe.