The Water Tunnel to Jerusalem

The Water Tunnel to Jerusalem

​Like many Mekorot projects, the Fifth Water System for supplying water to Jerusalem project is also a strategic project of national importance, with social, economic, environmental and political implications. The great national importance of the project is reflected in the fact that the National Infrastructure Committee (the “NIC”) approved it as a national infrastructure project, consisting of two sections: the Western part (NIC 24) and the Eastern part (NIC 24/A). The project will  constitute a significant element in the development of the water sector in Israel, because it will supply water not only to Jerusalem itself but also to communities along the route of the pipeline (Mateh Yehuda, Beit Shemesh, the Jerusalem Corridor communities and Ma’aleh Adumim), nearby enterprises, and the Palestinian Authority, in accordance with the political agreements.

The Fifth Water Supply System for Jerusalem is part of the revolution that Mekorot has been spearheading in recent years through the establishment of the New National Water Carrier – a mega project that connects five seawater desalination plants along the coast to the national water supply system. The project consists of sub-projects managed by Mekorot. The new National Water Carrier enables operational flexibility and changes the supply chain: the desalinated water is supplied from west to east and from there in all directions, according to the demand. For example, the National Water Carrier provides desalinated water to residents of the Upper Galilee for the first time in Israel’s history. The Fifth Water Supply System for Jerusalem will also be connected to the New National Water Carrier.

As noted above, this is a mega-project, which consists of many sub-projects managed by Mekorot. Construction of the western section of the Fifth System for Jerusalem has already been completed and it became operational towards the end of 2014. It supplies water to Jerusalem from the Hulda station to Sha’ar Hagai, with a connection to the Fourth Line. EMS Mekorot Projects, a subsidiary of Mekorot, with all its units, has taken upon itself the construction of the eastern section and all the pumping stations and the lines involved in the project, as well as the tight schedule. This is a huge project, the crowning glory of which is the digging of the tunnel for the supply of water to Jerusalem, which is about 13 kilometers long. The digging began about a year and a half ago (in December 2016) and it is being executed by a Tunnel Boring Machine (TBM). The uniqueness of the project, even by international standards, is that it is required to convey water at high pressure, despite its length. This feature also poses a great challenge for those planning the project as well as for those implementing it. While most water tunnels in the world convey water at low pressure, by means of gravity, the water tunnel to Jerusalem will convey water from sea level to 860 meters, at very high flow rates. Conveying water in this tunnel requires especially high pressure, and many conditions must be met to allow the tunnel to withstand these pressures, especially when it comes to such a large flow rate of water. 

One of the conditions for meeting this challenge is the use of unique pumps that are to be installed at pumping stations. The Fifth System for Jerusalem includes the construction of four large pumping stations, which will be equipped with huge and special pumps and motors, which have high flow rates and a high degree of energy efficiency, and which have been designed specifically for the project, and which will make it possible to convey water under high pressure over this long distance. To put things in perspective, with regard to the number of pumping stations, it can be said that since the construction of the National Water Carrier, no pumping stations of this magnitude have been built in Israel. 

Two of the pumps will be used by the eastern section and the water tunnel. The giant pumps will be located in two huge pumping stations built for this purpose. This is a large, closed building, which has a tower crane above the ground. The first station, which is called Kisalon Station, is located near the Eshtaol junction and the second is in Ein Karem. Construction of the Kisalon Station is underway, including the construction of the pumps, a substation for the supply of electricity and buildings to house chemical installations. The station will consist of six horizontal pumping units with a capacity of 10,700 m3/h, and in the first stage four units will be installed. The station includes the laying of suction and delivery lines of 100 meters and the use of large diameter fittings that are suitable for high pressure. Ein Karem is currently in the process of preparing the ground and carrying out earthworks, and the planning has been completed. In the coming months, EMS will begin with the construction of the station. EMS’s factories will manufacture the pumping equipment for the Ein Karem Station, including the pumps, pump heads, boilers and adjustments.

EMS is currently laying the  Ein Karem-Motza line, which is about three kilometers long. The work is well underway from the Motza junction to the Halilim Station, including crossing Highway 1 with horizontal drilling. In addition, the Mevo Horon bypass line will be extended to Modi’in, for about seven and a half kilometers. EMS is preparing to lay additional lines in the area of the Teachers Pool and in the Modi’in area. In the framework of the project, the existing pumping stations, the Natifim Station and the Yishi Station, will also be extended and upgraded, and a new station will be built for the community of Har Adar.

The Fifth Line Project is a complex engineering challenge because of its physical size, and because of the terrain - the installations will be installed in a rocky area with many plants and trees. In addition, the routes of the lines are characterized by large inclines, and the pipe diameters and thickness are extraordinarily large, which is necessary for adapting to the high pressures.

In May 2018, during the process of digging the tunnel, a Karst cave was discovered 3,525 meters from the entrance to the tunnel. The cave is situated at a depth of approx. 285 meters below the surface, making it the deepest cave ever found in Israel. It is about half a meter in height, its width ranges between 50-80 cm, and its capacity is approx. 1,800 cubic meters. The cave is divided into several separate spaces connected to each other by narrow passages, and one of the special features of the cave is that there are six large active water pools. The geological formation of the cave is dated between 100-113 million years before our time, and it consists mainly of thick layers of limestone, with layers of dolomitic chalk.

In order to continue making progress with the project and at the same time to minimize damage to the various parts of the cave, the following solution was provided: The space inside the cave was filled with the least amount of concrete required to continue working with the machine. About two weeks after the digging machine penetrated the cave, the digging works resumed.

This method of dealing with the cave characterizes Mekorot’s attitude to the environment. The entire project is being carried out in a narrow strip in order to minimize environmental and ecological damage, while adhering strictly to directives for safeguarding nature and the landscape, monitoring noise and dust, and adhering to the stringent requirements of the quality of the environment and the green organizations. An effort has been made to connect to existing infrastructures. In addition, EMS conducted an ecological survey of the route of the line, with the aim of identifying rare plants for the purpose of relocating and protecting them in a special habitat during the period of the works, and returning them to their original place after completion of the works, all as part of the landscape restoration work along the route of the line. The line has been planned while taking into consideration various elements of the environment (ecology, landscape, acoustics), in coordination with national infrastructures, the Israel Nature and Parks Authority and the Jewish National Fund, which are providing advice on the project.

The tunnel will enable the transportation of desalinated seawater from the west to the peaks of Jerusalem in the east. The water will be pumped through the tunnel, under pressure, between these two pumping stations, from Kisalon to Ein Karem, and at the endpoint, this system will connect to the city of Jerusalem as the final consumer. The Gihon corporation will receive the water and supply it to residents of Jerusalem and the surrounding area. The new water system will create operational flexibility in the supply of water and will facilitate a reduction in pumping from boreholes in the mountain region. In addition, the system will also improve the reliability of the supply of water to consumers.

With its expected completion in early 2021, the Fifth System for Jerusalem is likely to supply approx. 210 million cubic meters per year in the first stage, and in the second stage, with the increase in consumption, the system will supply about 450 million cubic meters per year. The cost of establishing the system, in its entirety, is approx. NIS 2.5 billion. Digging the water tunnel to Jerusalem is a significant step in completing the Fifth Water Supply System for Jerusalem. The project is expected to increase consumption to four times the capacity of existing systems, and to provide a solution to these areas in the coming decades. The new system will solve the future water problem in Jerusalem and its environs until the year 2065.