top 5 tunnels

Construction: Top 5 World's longest tunnels for water distribution

Top 1 The Thirlmere Aqueduct is a pioneering section of water supply system built by the Manchester Corporation Water Works between 1890 and 1925. At 96 miles long, it is the longest tunnel in the world.

The aqueduct was built to carry approximately 55,000,000 imperial gallons (250,000 m3) per day of water from Thirlmere Reservoir to Manchester. The construction of the reservoir and aqueduct was authorised by the Manchester Waterworks Act of Parliament. The first phase was completed in 1897 and, for the pipeline sections, subsequent phases were completed in 1925. The first water to arrive in Manchester from the Lake District was marked with an official ceremony on 13 October 1894.








Top 2:Delaware Aqueduct is the newest of the New York City aqueducts. It takes water from the Rondout Reservoir through the Chelsea Pump Station, the West Branch Reservoir, and the Kensico Reservoir, ending at the Hillview Reservoir in Yonkers, New York.

The aqueduct was constructed between 1939 and 1945, and carries approximately half of the New York City water supply of 1.3 billion US gallons (4,900,000 m3) per day. The Delaware Aqueduct leaks up to 36 million US gallons (140,000 m3) per day.
At 85 miles (137 km) long and 13.5 feet (4.1 m) wide, the Delaware Aqueduct is the world's longest continuous underground tunnel. The second longest is Päijänne Water Tunnel in Finland, which is 120 kilometres (75 mi) long.








Top 3: The National Water Carrier of Israel is the largest water project in Israel. Its main task is to transfer water from the Sea of Galilee in the north of the country to the highly populated center

and arid south and to enable efficient use of water and regulation of the water supply in the country. Up to 72,000 cubic meters (19,000,000 U.S. gal; 16,000,000 imp gal) of water can flow through the carrier each hour, totalling 1.7 million cubic meters in a day. Most of the water works in Israel are combined with the National Water Carrier, the length of which is about 130 kilometers (81 miles). The carrier consists of a system of giant pipes, open canals, tunnels, reservoirs and large scale pumping stations. Building the carrier was a considerable technical challenge as it traverses a wide variety of terrains and elevations.






Top 4: Päijänne Water Tunnel located in Southern Finland, is the world's second longest continuous rock tunnel (after the Delaware Aqueduct in the USA). It is 120 kilometers (75 mi) long and runs 30–100 meters under the surface in bedrock. The purpose of the tunnel is to provide fresh water for the million plus people in Southern Finland in the cities of Helsinki, Espoo, Vantaa, Hyvinkää, Järvenpää, Kerava, Kauniainen, Kirkkonummi, Sipoo, and Tuusula. The former Porvoo Rural Municipality, now merged with the municipality of Porvoo, also took part in the building of the scheme but has never drawn water from it for domestic use.

The tunnel starts at Asikkalanselkä in Lake Päijänne, which is the second largest lake in Finland, with an area of 1,080 square kilometres. The tunnel slopes slightly downhill so that water flows naturally. Water from the southern portion of Lake Päijänne is of rather good quality at the water tunnel intake and is usually drinkable without processing. The tunnel ends at the Silvola reservoir in Vantaa in the Greater Helsinki area. From the reservoir covering 0.5 square kilometres, water is pumped to water treatment plants in Pitkäkoski and Vanhakaupunki. Since the constant low temperature in the deep tunnel ensures high quality during transport, only minimal processing is required before use.
Tunnel construction started in 1972 and was completed in 1982 at a cost of approximately €200 million (adjusted for inflation). In 2001, portions of the tunnel required repair due to rock falls. In 2008, the tunnel underwent an extensive renovation. The southern part of the tunnel was reinforced in order to prevent cave-ins. During the renovation, from April 15 to December 31, 2008, the raw water for the Greater Helsinki metropolitan area was drawn from the Vantaa River.
The tunnel has a cross section of 16 square metres (wide enough for a truck) and enables a water flow of 10 cubic metres per second. At current water usage rates, treatment plants take water at a rate of about 3.1 cubic metres per second for drinking water processing. The tunnel can be used as an emergency water reserve during water supply disruption.



Top 5: The Dahuofang Water Tunnel is a large reservoir diversion project that will transport water from high rainfall areas to the dry, heavily industrialized Shenyang region of China. The total length of the tunnel is 85.3 Kilometres (53 miles) with over 60 Kilometres (37 miles) being driven by tunnel boring machines (TBM) — one of the world’s longest TBM-driven tunnel

The project owners awarded construction contracts in three lots, each about 20 Kilomettres (12 miles) long. Lot 1, awarded to Beijing Vibroflotation Engineering Co Ltd, chose an 8.03 m (26.3 ft) diameter Robbins Main Beam TBM for the project. The machine is responsible for a 20 kilometres (12 miles) bore in migmatite and orthopyre geology. The Lot 3 contract was awarded to The Bureau of Water Conservancy and Hydroelectric Power Construction, who chose a nearly identical 8.03 m (26.3 ft) diameter Robbins Main Beam TBM for a 16 Kilometres (10 miles) long bore. This section of tunnel also passes through migmatite geology, but about two-thirds of the tunnel contains a complex mixture of heavily weathered and fractured rock.