'Conquering' the Da River to build Hoa Binh Hydroelectricity

Nearly 80 years ago, when the French poked exploration drills into the riverbed at any location, they met the alluvial layer, and concluded that "Da River was rebellious".

On the morning of November 6, 1979, after the explosion of landmines shook Ong Tuong hill, Prime Minister Pham Van Dong threw a stone into the Da river bed, starting the construction of Hoa Binh hydroelectricity . At the end of 1988, the first set produced electricity. The remaining seven units were operated six years later. In 1994, the factory inaugurated. The largest hydroelectric project in Vietnam and Southeast Asia in the twentieth century was completed after 15 years of construction. 40 years have passed, the memories of the beginning of the birth of this hydroelectric plant are still deeply embedded in the people who participated in the construction.

In the fall of 1971, the North experienced a cataclysm that "met once every 250 years" . 400 km of dike broke, 500 thousand hectares of rice lost white. Red river water rises approximately the surface of Long Bien bridge. The transport industry had to transport a stone train to the bridge to avoid being swept away by the floods.

At that time, Chairman of the Council of Ministers Pham Van Dong then took a high-level Soviet delegation to the flood inspection in Hebei. Standing on the dike overlooking the immense water, he wants the Soviet Union to help Vietnam build a project to cut floods for the Red River Delta."Building a hydroelectric plant" - then chairman of the Supreme Soviet Council Nikolai Podgorny then replied. The visit took place in August, then in October, the Soviet team of experts and equipment to Vietnam to prepare for the survey.

Hoa Binh hydropower project was built in 15 years, designed by Soviet experts.(Photo: Ngoc Thanh).

On October 5, 1971, the first drill of a Soviet expert plunged into the Da River, opening the exploration and selection of the route for 6 years."The first purpose when constructing Hoa Binh hydroelectric power plant is to treat Da river, then the energy issue. Da river hydropower means treating the Red River water, cutting floods for the Northern Delta, protecting the Capital. " , explains Thai Phung Ne, former Minister of Energy.

The river originates from China, flows along Northwestern Vietnam with a length of 543km. The large difference in water flow between the dry and flood seasons causes annual river bottoms to change. Hydrological data in 1971 statistics differed to 24 times, when the water flow in the dry season reached 610m ³ / s, and in the flood season jumped to 14,800m ³ / s. The Da River is the main tributary, "contributing" to nearly 70% of the Red River flood flow. More than half of the total flow of the Red River flows into Hanoi - the main "culprit" of damming dikes, causing floods in 1945 and 1971. To treat the Red River, it must "treat" the Da River. But the river of rebellion also has great economic potential. Particularly, the main storage capacity is over 30 billion kWh, accounting for one third of the national hydroelectric power storage.

Mr. Thai Phung Ne has been present for 14 years on the Hoa Binh Hydroelectricity Site.(Photo: Tran Huan).

Since the 1940s, the French had planned to exploit the Da River after completing the invasion of the Northwest. The Department of Geology of Indochina places the first exploration drills in the riverbed, from Hoa Binh town to Cho Bo and Suoi Rut. The river "hundred and seventy falls, hundred and thirty rapids" , rocky mountains towering on both sides, but the river bed has a layer of alluvium up to 60 meters thick. The bottom is a mixture of pebbles and gravel, to rough sand and fine sand. At that time, technology was not enough to handle this silt layer to build hydroelectric dams. The French only concluded that "Song Da was rebellious".

After the peace was restored in the North, the Central Government also soon planned to rule the waterway, set up the Commission for water treatment and exploitation of the Red River in 1959. The topographic geological survey teams explored the riverbed and built a hydroelectric station. Dispatch tracks the amount of water in both dry and flood seasons. In the 1960s and 1970s, the Committee specially noted the planning of Da River hydropower ladder with four main tasks: preventing floods for the Northern Delta; exploitation of hydropower for socio-economic development; serving agricultural irrigation and developing waterway transport. Before the Soviets began work, Chinese experts also tried drilling and exploration and shook their heads. " It is impossible to do hydroelectric dams on Da river".

Since 1971, Soviet and Vietnamese geologists have been continuously drilling to select the location for the construction of the hydroelectric dam. The selected site had to arrange a plant, a dam body and create a reservoir with a capacity to withstand the 1971 flood. Drills poking into the riverbed all met with sand and silt. Until 1977, the survey team selected six routes, from Hoa Binh town to Suoi Rut, on a 40 km long river. The first line is Suoi Rut, originating from the foot of Moc Chau plateau; the second is Hoa stream from Thanh Hoa to Da river. The third route is Cho Bo; the fourth route is Hien Luong; the fifth route is Hoa Binh on the top and last one is Hoa Binh on the bottom.

Comparing the construction volume, finally the two "feasible" routes were selected as "Hoa Binh on" and "Hoa Binh on" . The route is about 6 km far from Hoa Binh town with narrow and rugged terrain. When construction is not arranged for the site site, difficult to transport materials. The lower route is nearly 2 km from the town, near Ong Tuong hill. This place is relatively flat, easy to gather materials, build houses and auxiliary works for the site. The river came here to meet Ong Tuong mountain range and meandered, narrowed to nearly 300 meters, suitable for dam body and shoulder.

Hoa Binh hydroelectric dam is 128m high, built in 9 years (1981-1990).The dam foundation is treated with a waterproof curtain.(Photo: Ngoc Thanh).

Baku Institute of Hydro-Design in the Republic of Azerbaijan - the unit assigned by the Soviet Union to make economic and technical feasibility studies for the project of choosing the Hoa Binh option. Because "there is a line of limestone that cuts from the lake to the downstream, there are many complex cavities . " The Moscow Institute of Hydraulic Design chose the Hoa Binh route below. Director Nikolai Aleksandrovich Malyshev said that the Soviet Union had enough experts and qualifications to handle that limestone line. He is the chief engineer designing the Aswan hydroelectric dam on the Nile, Egypt. This dam has the same geological characteristics as that of the Da River in Hoa Binh with a layer of alluvium nearly 170 meters thick. Vietnam agrees to select the lower Hoa Binh route.

Hoa Binh hydropower plant has locked the location and gradually grows. In April 1994, when the last set was connected to the national grid, the 500 kV line 1 from Hoa Binh station to Phu Lam, Ho Chi Minh City was also ready to be put into operation. The backbone circuit connecting the three-region electrical system has solved the serious electricity shortage for the Central and the South. Hoa Binh Hydroelectricity has produced nearly 230 billion kWh of electricity during the past 30 years.

Eight units of 1,920 MW of total capacity were installed and constructed underground in the hill bed.(Photo: Ngoc Thanh).

Hydroelectric projects mark many "firsts" in the field of Vietnam's construction. Eight units and auxiliary structures were first constructed underground, installed in the heart of hill 206, only the dam body was exposed. The dam is 128 meters high and 743 meters long for the first time using the curtain method. Experts drilled cement, sprayed clay and grouted to create a waterproofing layer, binding sand and pebbles in the river bed. This technique helps to protect the dam body against a strong earthquake at level 8, because the Da River flows through the geological region at risk of the strongest earthquake in Vietnam.

The river dam creates a water reservoir with a capacity of 9.8 billion m3. The spillway has 12 bottom and 6 side outlets. The maximum discharge capacity is 35,400 m3 / s, which is equivalent to the flood flow of the Red River during the 1971 flood. In 1996, the upstream flood returned with a discharge of 22,650 m3 / s. Hydropower opened 7 outlets, cut floods, kept safe for downstream areas and the Northern Delta.

Many years later, Dr. Thai Phung Ne still considers the construction of works in the difficult situation of the four sides of the country is a bold decision of the Central Government. He remembered the opinion of the late General Secretary Le Duan at that time, that must be enlisted because no one outside the Soviet Union could help Vietnam to build that project. And sure enough, "the more you help there, the more you have to help yourself". The Soviet Union provided technical design, expertise, and construction equipment.

"Our generation went to build century works with unknown beliefs, so the Soviet experts would teach, then we would do it. And now we have," he said.

Hoa Binh hydroelectric construction site has trained the country with a team of management, designers, construction engineers to skilled workers. Tens of thousands of young people who have just finished high school, are "thrown" into that training furnace have become workers digging tunnels, open-pit drills and underground drills. Class of newly graduated engineers has places to practice and know how to handle waterproof screens. This team later continued to build a 500 kV North-South transmission line, Son La hydroelectricity, Hai Van pass tunnel .