DEVELOPMENT OF FLOOD MITIGATION SYSTEM AT BINUNGAN MINE OPERATION BY UTILIZING KELAY RIVER EARLY WARNING SYSTEM, BERAU DISTRICT, EAST KALIMANTAN

• Main Author: Baiquni, Ahmad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75699
• Institution: Institut Teknologi Bandung

<p align="justify"> The development of a flood mitigation system at the Binungan mine site is necessary to minimize the risk of flooding, as river water overflow can enter the active open-pit mine, resulting in casualties and loss of mine operating units due to drowning. In the last 10 years, there have been at least two major floods that entered the active mining pit near the Kelay River. The most recent incident in May 2021 has become a national issue, flooding forced 2,507 households to evacuate spread across 15 villages along the Kelay river floodbank and submerged the active mining pit of another company across the Binungan Mine site. With this incident, PTBC reviewed the initial study of the Flood Safety Early Warning System (SPDPB) that had been made in 2018. This research utilizes the results of the existing SPDPB study in order to implement flood mitigation operational management in PTBC's Binungan mine area. The SPDPB concept approach goes through several stages, namely detection, prediction, warning and emergency response. In the detection stage, realtime AWLR Merasa flood water level (FWL) data and the influence of flood events in the downstream Kelay river, namely water level conditions in the Segah River and tides in the Berau river, are required. The prediction stage used hybrid modeling, a combination of Hecrass hydraulic modeling and Artificial Neural Networks (ANN), obtained by FWL at the Merasa AWLR to predict flood arrival times and flood levels at several monitoring points at the mine site 39 km downstream. To support the accuracy of the analysis, recent data was collected for flood levels, discharge rating curve, river bathymetry and rainfall data. The warning stage is the most important stage in the operational management of flood mitigation, here decision making is carried out based on consideration of the prediction results and the output is the SPDPB standard operating procedure (SOP) for flood mitigation. Furthermore, the emergency response stage is carried out for human and unit rescue efforts carried out by the company's rescue team and the opportunity to take corrective action before the flood arrives to reduce risk. The prediction model results obtained, the flood arrival time is about 5-6 hours and the flood level is +11.93, if the AWLR feels the FWL reaches a maximum of +23.10. The results of the SPDPB analysis can also provide recommendations for flood response levels for construction and SPDPB applies to locations that are below the recommended flood level, such as operating pits, disposals and other mine infrastructure. The application of SPDPB operational management is also given in detail in the case example of the May 2021 flood event in 2 critical areas, namely the 37 East water monitoring point (WMP) infrastructure and the KM17 Hauling Road. In this incident, successful flood management actions were carried out such as blocking the flood-affected area, closing the WMP sluice gate, raising the road elevation in accordance with previous SPDPB recommendations and monitoring the decline in peak elevation and stability of the flood embankment. Evaluation is carried out on an ongoing basis on the accuracy of the prediction model utilization, flood management by building flood embankments and the implementation of SPDPB in other critical areas with strict implementation of Standard Operating Procedures (SOP). The novelty of this research is to utilize technical studies in predicting the arrival time of floods and FWL with a hybrid analysis method between hecrass and JST applications in the mining sector, then applied to become SOPs in SPDPB operational management for flood mitigation. The results of the SPDPB that are running are very satisfying and until now have become a dependency in supporting mining operations from flood hazards due to the overflow of the Kelay river.