Page - 1076 - in Book of Full Papers - Symposium Hydro Engineering

release water from this dam so that the operation and maintenance of this spillway structure is very important. The shift of the dam body construction toward the upstream than the planned has shifted the center of gravity of the dam causing the concrete fracture connecting the spillway-structure with the access gallery. This cracks then named as join 0. The water leakage from this cracks are collected and channeled into the drainage channel to monitor the quantity and the quality of leakage. The leakage monitoring activity conducted every two weeks. There are 37 points of surface marker installed in this morning glory spillway-structure, 3 points placed on the top floor of the morning glory spillway- structure, 3 points on the floor in the powerhouse. While on the wall of the powerhouse is placed 31 points of surface marker, 11 mounted on the inside wall named interior circle, and 20 others mounted on the outside wall named exterior circle. The monitoring activity by measuring the movement of these surface markers conducted every month. The measurement of the spillway-crest on 14 spillway-windows has conducted twice, on August 2001 and on October 2017. Based on surface-marker monitoring results, this spillway has experienced movement and the monitoring data record shown the average cummulative settlement is 11 cm, and the largest cummulative settlement reached 15 centimeters at the point of window number 12, with elevation 106,8438 meters above sea level. The movement of this spillway is influenced by the elevation of the reservoir water level (RWL), when the elevation of the RWL reach the normal elevation the spillway-structure moves down, and vice versa. The movement of the spillway-structure also impact to the leakage at join 0. The leak is still monitored until now and it shown the largest discharge of 190 ml per second. The water quality of the leakage is monitored and did not indicate it carry the embankment material, visually it looks clear and clean. 1076