Mills Completes
Bui Dam

Professor John Evans Atta Mills continues to confound his critics with his extraordinary accomplishments within the last forty months that he has been in office as President.

The latest in the chain of unprecedented achievements chalked by his government is the expected scheduled completion of the nearly US$800 million 400 megawatt Bui hydro-electric power dam in the Tain District of the Brong Ahafo Region.

The Bui Power Authority (BPA), managers of the project, confirm all is set for the completion and commissioning of the dam in June next year.

However, the first 133 megawatts of power supply from the dam, which is now 92% complete, is expected by the end of this year, Mr. Gabriel Apatu, External Relations Assistant of the BPA told the Ghana News Agency (GNA) in an interview last Wednesday at the exhibition grounds of the four-day Brong Ahafo regional policy fair currently underway at the Sunyani Polytechnic.

A civil engineer at the dam site Mr. Peter Acheampong also confirmed to the GNA that work on the power house, where most of the mechanical components of the dam were installed, was also on course.

What makes the completion of this project, (initially budgeted for US$622 million) unique and unparalleled is the fact that, like the gang-of-four road projects began by the Kufuor administration; this is the first time in Ghana’s political history that a government starts such a major project and being continued to completion by a succeeding government, especially when it entails additional financial commitments.
Preparatory works on the Bui power project which began under ex-President John Agyekum Kufour on the 24th of August, 2007 experienced a funding shortfall arising primarily from unanticipated effects of global upheavals as well as unforeseen essential external works.
The National Democratic Congress (NDC) government of President Mills had to source for an additional 168 million US dollars from the Chinese Government and the Exim Bank of China before the dream of Ghana having a third alternative hydro power supply dam comes to fruition.
Explaining how the shortfall of a USD 168 million came about, given that the original cost of the entire project had been initially budgeted and pegged at US$ 622 million, Chief Executive Officer of the BPA Jabesh Amissah Arthur said, “with projects of such nature, you will never know the real cost until the final stage,” and on a daily basis, they have had to amend details such as inadequate budgetary provision for price escalation, physical contingency, engineering and administration from the original plan.
All these, he said, have led to the shortfall in funding.
Additional costs, Mr. Amissah said, are being spent on the resettlement exercise of some 1,216 households whose places of abode and habitats were affected in the construction of the Dam.
History
The Bui hydro-electric dam has first been envisaged in 1925 by the British-Australian geologist and naturalist Albert Ernest Kitson when he visited the Bui Gorge. The dam has been on the drawing board since the 1960s, when Ghana’s largest dam, the Akosombo Dam, was built further downstream on the Volta River. By 1978 planning for the Bui Dam was advanced with support from Australia and the World Bank. However, four military coups stalled the plans. At the time Ghana began to be plagued by energy rationing, which has persisted since then. In 1992, the project was revived and a first feasibility study was conducted by the French firm Coyne et Bellier.
In 1997 a team of students from Aberdeen University carried out ecological investigations in the area to be flooded by the reservoir. The Ghanaian environmental journalist Mike Annan, who was included in UNEP’s Global 500 Roll of Honour for 1998, called the dam an “environmental disaster” and a “text book example of wasted taxpayer money”.
In his article he quoted the investigation team, but apparently somewhat exaggerated the environmental impact of the dam. The leader of the investigation team, the zoologist Daniel Bennett, clarified that “the opinions (Anane) attributes to our team are unfair and misleading”. He continued to say that “Contrary to Mr Anane’s claims, we are unaware of any globally endangered species in Bui National Park, nor did we claim that the dam would destroy the spawning runs of fish.”
Although Daniel Bennett always maintained a neutral stance towards the construction of the dam, in April 2001 the government of Ghana banned him from doing further research on the ecology of the Bui National Park. The government stated that the issue was “very sensitive” and Bennett’s “presence in the National Park was no longer in the national interest”. One of the journalists who criticized the government for banning Bennett was Mike Anane.
In 1999 the Volta River Authority, the country’s power utility, signed an agreement with the US firms Halliburton and Brown and Root to build the dam without issuing a competitive bid. In December 2000 President Jerry Rawlings, who had ruled the country for the two previous decades, lost elections and was replaced by John Kufuor. In October 2001 the new government shelved the dam project. According to Charles Wereko-Brobby, then CEO of the Volta River Authority, Bui Dam was not considered the least–cost option and could not meet “immediate” energy needs. Instead gas-powered thermal power plants were to be built, producing electricity at what was said to be half the cost of Bui. Furthermore, a severe drought in 1998 exacerbated the energy crisis due to low water levels in Akosombo Dam. As a consequence, the government wanted to reduce its dependence on hydropower at the time.
However, as soon as in 2002 the project was revived. An international call for tender was issued, but only a single company submitted a bid and the tender was cancelled. In 2005 the Chinese company Sinohydro submitted an unsolicited bid for the dam together with funding from the Chinese Exim Bank. The government accepted the bid and the Ministry of Energy signed contracts for an environmental impact assessment in December 2005, as well as for an updated feasibility study in October 2007. In August 2007 the government created the Bui Power Authority to oversee the construction of the dam and the associated resettlement, as well as to operate the dam and power plant. The responsibility for the dam was thus taken away from the Volta River Authority, which until then had been responsible for the development and operation of all power projects in Ghana.
Field investigations for the dam began in October 2007. In January 2008 preparatory construction began and in May 2008 the first people were resettled. In December 2008 the river was diverted and a year later construction on the main part of the dam began. The filling of the reservoir is expected to begin in 2011 is serving as the main contractor while Coyne et Bellier is the consulting engineer.
Design
The Bui Dam will be a gravity roller-compacted concrete-type and have a height of 108 m (354 ft) above foundation and 90 m (295 ft) above the riverbed. The crest of the dam will be 492 m (1,614 ft) meters long and sit at an elevation of 185 m (607 ft) above sea level (ASL). The main dam’s structural volume will be 1,000,000 m3 (35,314,667 cu ft). Southwest of the dam there will be two saddle (or auxiliary) dams to maintain pool levels and prevent spillage into other areas of the basin. The first and closest to the main dam is Saddle Dam 1. It is 500 m (1,640 ft) southwest of the main dam and will be a rock-fill embankment dam. The dam will rise 37 m (121 ft) above ground level and have a crest length of 300 m (984 ft). Being constructed 1 km (1 mi) southwest of the main dam is Saddle Dam 2. This dam will be a zoned earth-fill type and have a height of 7 m (23 ft) ASL and a crest length of 580 m (1,903 ft). Both saddle dams will have a crest elevation of 187 m (614 ft) ASL.
The reservoir that the main and saddle dams create will have a maximum capacity of 12,570,000,000 m3 (10,190,665 acre•ft) of which 7,720,000,000 m3 (6,258,706 acre•ft) is active (or “useful”) for power generation and irrigation. The reservoir’s maximum operating level will be 185 m (607 ft) ASL and the minimum 167 m (548 ft) ASL. At the maximum level, the reservoir will have a surface area of 440 km2 (170 sq mi) while at minimum it will be 288 km2 (111 sq mi). The reservoir’s volume at minimum level is 6,600,000,000 m3 (5,350,707 acre•ft). The average length of the reservoir will be 40 km (25 mi) with an average depth of 29 m (95 ft) and a maximum 88 m (289 ft).
Just downstream of the dam on the left bank will be the dam’s power station. Just above it and at the top of the dam, the intake will feed water through three penstocks which in turn will supply water to three separate 133 MW Francis turbine-generators. The power station will have an installed capacity of 400 MW and an estimated average annual generation of 980 GWh. The power station’s switchyard will be located 300 m (984 ft) downstream and will convert the electricity to 161 kV before it reaches main the transmission lines.
The dam’s spillway will be near the right bank and consist of five radial gates, each 15 m (49 ft) wide. The spillway will sit at an elevation of 169 m (554 ft) and have a maximum discharge of 10,450 m3/s (369,038 cu ft/s) which correlates to a 1-in-10,000 year flood. The dam’s outlet works will consist of a single outlet on the right bank converted from one of the diversion tunnels.
Benefits
The Bui hydropower plant will increase the installed electricity generation capacity in Ghana by 22%, up from 1920 MW in 2008 to 2360 MW. Together with three thermal power plants that are being developed at the same time, it will contribute to alleviate power shortages that are common in Ghana. Furthermore, like all any hydropower plants, the project avoids greenhouse gas emissions that would have occurred if thermal power plants had been built instead. An additional expected benefit is the irrigation of high-yield crops on 30,000 hectares of fertile land in an “Economic Free Zone”. The current status of the irrigation project is unclear.
Cost and financing
The total project costs are estimated to be US$622 million. It is being financed by the government of Ghana’s own resources (US$60m) and two credits by the China Exim Bank: a concessional loan of US$270 million at 2% interest and a commercial loan of US$292 million. Both loans have a grace period of five years and an amortization period of 20 years. The proceeds of 30,000 tons per year of Ghanaian cocoa exports to China, which are placed in an escrow account at the Exim Bank, serve as collateral for the loan. Once the dam becomes operational, 85% of the proceeds of electricity sales from the hydropower plant will go to the escrow account. If not all the proceeds are needed to service the loan, the remainder reverts back to the government of Ghana

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