Tall order: spotlight on CFRDs15 August 2014
IWP&DC spotlights the 10 tallest concrete faced rockfill dams completed in the world, and takes a look at the largest under construction and at pre-feasibility stage
Shuibuya, China, 233m
At 233m high, Shuibuya dam is currently the tallest CFRD in the world. Completed in 2008, the dam is part of the 1840MW Shuibuya hydro power project located in Badong County in the middle reach of Qingjiang river, a tributary of the Yangtze river. Total reservoir volume for the project is 15.64Mm3.
State of the art CFRD techniques were applied to the dam construction, including: optimized rockfill construction steps, dynamic compaction of riverbed foundation, introduction of a new type of waterstop, permanent horizontal joints, GPS recorded compaction tracks and advanced instrumentation.
The successful completion of Shuibuya dam not only broke the theory among dam engineers that CFRDs could only be built under 200m, but it also made technical breakthroughs with regards to construction of these types of dams in a karst region.
In Shuibuya, the compaction was also very strict. Fibres were incorporated into the concrete in order to reduce the frequency of cracks on the slab, which often occurred during construction.
Jiangpinghe, China, 219m
The dam is located on the Loushui River near Jiangpinghe village, in Hefeng County, Hubei Province, China. The multi-purpose dam provices hydroelectric power generation, flood control and irrigation. The project has a total installed hydroelectric capacity of 500 MW. Construction on the dam began in 2005 and the first generator went online in July 2012. The dam is 219m high with a reservoir storage capacity of 1,366,000,000 cubic metres
La Yesca, Mexico, 209m
Las Yesca dam is a major part of the 750MW La Yesca hydroelectric project, a facility of the hydraulic power system on the Río Grande de Santiago river in Jalisco and Nayarit states, which also includes the completed 975MW Aguamilpa and 750MW El Cajon projects.
The dam was built by a consortium led by contractor Ingenieros Civiles Asociados (ICA) and comprising Promotora e Inversora Adisa, La Peninsula Compania Constructora and Constructora de Proyectos Hidroelectricos.
The dam was inaugurated by President Felipe Calderón on 6 November 2012.
Bakun, Malaysia 205m
The Bakun Hydroelectric Project is the largest hydropower project in Malaysia with an installed capacity of 2400MW. Located on the Baliu river in Sarawak, the project features a 205m high dam with a reservoir surface area of nearly 70,000 hectares, and a crest length of 748m.
The project was developed by Sarawak Hidro Sdn Bhd, a wholly-owned subsidiary of the Minister of Finance Incorporated Malaysia. Main civil works on the scheme began in 2002, following formation of the Malaysia-China Hydro Joint Venture.
As well as the dam, the project features a spillway with four radial gates, 15m wide by 20m high, each with a 50m wide concrete chute, 680m in length that ends in a flip bucket.
Eight power tunnels are concrete or steel lined with an intake diameter of 8.5m, a descending diameter of 7m and a varying length of 670-760m. The powerhouse is located at the base of the dam and houses 8x300MW turbines.
Campos Novos, Brazil, 202m
Campos Novos dam is located on the Canoas river in the Brazilian state of Santa Catarina. Construction of the 202m high, 12Mm3 dam began in October 2001 and was completed in February 2005. The rockfill embankment, originated from basalt rock, was divided into zones so that the upstream third and the central area of the dam material - denominated as 3B and 3D - were compacted in layers 1m thick, wetted at the rate of 200 l/m³. The voids factor of these zones was equal to 0.22 on average and the compacted unit weight is 2.14 tonnes/m³.
The downstream third, consisting of materials of the 3C/3D type, was compacted in layers of 1.6m without wetting; the average unit weight of this zone being 2.02 tonnes/m³. The transitions under the slab - materials 2B and 3A - were compacted in layers of 0.5m reaching void factors of about 0.20.
The rockfill embankment was implemented in three stages and the concreting of the slabs of the face in two stages. The rockfill embankment was first raised upstream and the slabs concreted up to el.568m, which corresponded to approximately 52% of the final height of the dam and flood recurrence period of 1:500 years.
The downstream rockfill embankment was then raised to el. 570m and later to el. 660m. Slab concreting was carried on after the completion of the rockfill embankment. The average production of compacted rockfill was 700,000m³/month, while the 16m wide slabs were implemented at an average speed of 2.9m/hr.
Kárahnjúkar dam, Iceland, 196m
Completed in 2008, the 690MW Kárahnjúkar project features a number of dams - the largest one being Kárahnjúkar dam which is about 700m long and 196m high. The dam is the highest of its kind in Europe. Two smaller rockfill dams with earthern core, 68m and 29m high respectively, were built on each side of the Kárahnjúkar dam.
The Kárahnjúkar CFRD has a rockfill volume of 9Mm3 and was built by Impregilo of Italy. The rockfill was produced from a quarry inside the reservoir just upstream from the dam and was partly transported into the dam after crushing and screening by conveyor belts. The concrete face slab was cast in 15m wide bays by slip forming.
The dam crosses a deep canyon with vertical cliffs. It was designed to cross the canyon on the upstream side, with a massive 50m high concrete toe wall in three separate monoliths, instead of a more conventional concrete foundation plinth at the toe of the face slab. The toe wall is designed to withstand fault movements using elastic joint sealing measures and the dam as a whole to withstand a heavy earthquake.
Sogamoso, Colombia, 190m
Located on the Sogamoso River in northern Colombia, the 820MW Sogamoso project includes a 190m high, 300m long dam and an underground power station housing three Francis turbines.
The US$1.74 billion dam and power plant is owned by Isagen. Ingetec designed the dam in the 1990s and Impreglio was awarded the contract for construction.
The structure dams a 4.8Bm3 reservoir, and features a spillway on its left bank controlled by four radial gates. The spillway is designed with a maximum discharge of 17,100m3/sec. The project is due to enter full operation this year.
El Cajon dam, Mexico, 188m
El Cajon hydro power dam is on the Santiago river in the Mexican state of Nayarit. It is located 80km east of Tepic City, 60km upstream of the existing Aguamilpa project. Construction began in 2003 and was completed in June 2007, at a cost of US$800M.
The 640m long dam has a maximum height of 188m. Its reservoir capacity of 5x109m3 is used to help regulate basin runoff and benefit the Aguamilpa region. Operated by the state-owned company Comision Federal de Electricidad, the 750MW scheme is capable of supplying 2% of Mexico's electricity demands.
Aguamilpa, Mexico, 187m
The 187m high, 660m long Aguamilpa Dam is located on the Río Grande de Santiago in the Mexican state of Nayarit. The 960MW hydroelectric project became operation in 1995 following a five-year construction period. The dam's reservoir has a capacity of 6.95Bm3. The dam features a spillway with six 19m high and 12m wide radial gates.
Barra Grande, Brazil 185m
Situated on the Pelotas river, 43km from its confluence with the Rio Canoas in Brazil, the Barra Grande dam is 185m high and 665m long. It has a face slab thickness of 0.3+0.002H>0.005H, with an upstream slope of 1.3 and downstream slope of 1.4. The structure is built with basalt rockfill and has a rockfill volume of 1Mm3.
Construction of the project began in 2001, and was completed in 2005. However, in September 2005 extensive rupturing of the concrete face under compression occurred. Reservoir leakage was at a constant 150 l/sec and reached 1280 l/sec by the end of January 2006 (although throughout this time the dam remained inherently safe and operation was not affected). To help combat the problem, plastic sheets were placed over the curb elements used on the dam to produce a bond-breaker effect. In June 2007 soil material was dropped over the crest in order to reduce leakage. Consequently leakage dropped to 800l/sec.
Reaching new heights
China has plans for CFRD's that will reach new heights - the five largest in the world are planned for the country, with the tallest over a 100m higher than the current tallest operating CFRD, Shubiya.
Rumei - 340m
Shuangjiangkou - 314m
Gushui - 310
Songta - 307m
Lianghekou - 305m