In this paper, Melen Bosphorus Tunnel Project, the geological characteristics of Bosphorus Tunnel's location and some information about the selected machine are presented in general.
In İstanbul, 685 million m3 of surface water (dams, lakes and dikes) and 30 million m3 of ground water for a total of 715 million m3 of drinking water is being produced. In addition, by use of Istranca Streams, 235 million m3 of water is supplied in annual average. In İstanbul, the annual reel consumption of gross water per capita is 235 liters per day. According to İstanbul Water and Sewerage Works' master plan by the year 2040, foreseen consumption of 276 liters water per capita, to meet the needs of 11 million population per day, 1.1 billion m3 of water was needed. However in 2005, this population was accessed, and the city's population has been growing rapidly since then. Considering the population growth rate with the data current; in 2025, Istanbul's population is estimated to exceed 22 million, and it is clear that water resources, close to city of İstanbul would not be sufficient, when the population growth is taken into account.
In this regard, Yeşilçay System was put into service on 31 May 2003, in order to meet Istanbul's urgent water need as soon as possible. Thanks to Melen System, planned for meeting İstanbul's long term drinking and service water need, city's water requirement shall be met by 2040 with 268 million m3 (8,5 m3 /sn) water supply per year at the first stage and 1180 billion m3 water supply per year at the end of the third stage.
Bosphorus Tunnel, starts from the Ayazağa Entrance, diameter of 6.15 m, constructed beneath 135 m. sea level, 5551-m-long, continues with the slope of 7.4 % along 2347 m, and then continues horizantally with the slope of 0.14 % along 1081 m, finally in 145 m. deep, tunnel reaches the shaft, diameter of 8.1.Tunnel has been excavated by TDM, whose trademark is Herrenknecht and which could be started up with the both off mode (EPB) and on mode.