MUD FLOW MANAGEMENT AT SIDOARJO MUD RESERVOIR

• Main Author: Zain, Khilmi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49377
• Institution: Institut Teknologi Bandung

Sidoarjo mudflow eruption occurred on 29 May 2006 until now. The center of the eruption is located at Siring village, Porong sub district, Sidoarjo Regency, East Java. Mudflow from this location to Porong River must be carefully managed with the appropriate proportion of mud and water to ensure that the mud will not cause sedimentation in the river. Therefore, it is highly important to study the mudflow to provide a recommendation for managing it. It is hoped that the mudflow can flow from the center of the eruption to Porong River while still retaining minimal impact on the environment Mudflow is different from water flow and the one in Sidoarjo includes clay material. Therefore, FLO-2D software is used to simulate this flow. Mudflow modeling will be conducted to evaluate the mudflow pattern and to find out an alternative management scenarious. After the mudflow pattern is known, an alternative solution for mud-streaming management will be proposed. Mudflow from the blast center is modeled in four modeling scenarios, namely the existing condition scenario, scenario 1, scenario 2 and scenario 3. The modeling of mud from the overflow channel to the Porong River is modeled in two conditions namely conditions of dry and wet season. Based on the modeling results, mud can flow into the Porong River. Then, two alternative solutions are proposed, namely alternative 1 (without the use of overflow channel) and alternative 2 (using an overflow channel). In addition to these two alternatives, a backup system is prepared in case of extra mudflow according to the value of standard deviation. Based on the calculation results, the capacity of pumps needed are 896.23 liters/sec for the slurry pump and 512.53 liters/sec for the water pump, while the capacity of the water pump for the backup system is 1,359.80 liters/sec. Based on the modeling results of the mud reservoir operating pattern, in alternative 1 there are 7 mud pumps and 11 water pumps need, while in alternative 2 there are 5 mud pumps and 8 water pumps needed, whereas for the backup system 2 mud pumps and 3 water pumps are needed. The location of the mud pump and water pump placement is adjusted to the location of the mud buildup based on the result of numerical modeling. Both the two alternative solutions and the backup system budget plan are calculated. The planned budget for the control and maintenance of mudflow in the existing conditions is IDR 175,820,468,000.00. While, in alternative 1, the planned budget for the control and maintenance of mudflow is IDR 181,444,214,628.57, with construction costs of IDR 92,577,949,136 and a 5-year overhaul plan costs of IDR 29,882,744,751. In alternative 2, the planned budget for mud control and maintenance is IDR 175,232,881,961.91, with construction cost of IDR 86,284,465,030 and a 5-year overhaul cost of IDR 21,988,796,743. For the backup system, the planned budget for mud control and maintenance is IDR 164,509,946,304.76, with construction cost of IDR 62,644,052,072 and a 5-year overhaul cost of IDR 10,761,428,888. Furthermore, from these two alternative scenarios, the NPV value is calculated for a period of 20 years with an inflation rate in Indonesia at 5.2%. Based on the calculation of the NPV value, if the mudflow is predicted to stop within 6 years, alternative 1 is more profitable to be implemented than alternative 2. However, if the mud is predicted to stop after more than 6 years, alternative 2 is more profitable to be implemented than alternative 1.