STUDI PERENCANAAN BANGUNAN PELIMPAH (SPILLWAY) PADA BENDUNGAN BINTANG BANO KABUPATEN SUMBAWA BARAT NUSA TENGGARA BARAT

Bintang Bano Dam is located in West Sumbawa Regency, West Nusa Tenggara. The existing design of the Bintang Bano dam is planned to use a side spillway type with a combination of gated spillways. In this study, a study was carried out to plan a spillway building using a direct spillway without a door with proper considerations through the existing technical aspects. In this study, the design flood return period of Q1000th is controlled using QPMF in accordance with existing requirements. Technically, from the planning results, the spillway width is 85.00 m, the threshold height is 5.00 m. The width of the transition channel upstream is 30.00 m and then it widens downstream to 40.00 m. The length of the transition channel is 72.00 m, the width of the transition channel decreases from 40.00 m to 30.00 m with a flat transition channel slope. The length of the launch channel is 180.00 m, the width is 30.00 m with a slope of 0.228. The energy absorber uses USBR type II with a length of 42.00 m and a width of 30.00 m. For the calculation of the stability of the planned spillway, it has met the stability requirements. Both in terms of stability against overturning, shearing, and the bearing capacity of the soil under normal and flooded water levels, the overall results show that they meet the required safety requirements. Meanwhile, the planned retaining wall complies with the existing stability requirements both in flooded and empty conditions