Английская Википедия:Dikgatlhong Dam
Шаблон:Use dmy dates Шаблон:Infobox dam The Dikgatlhong Dam is a dam near the village of Robelela on the Shashe River in Botswana, completed in December 2011.Шаблон:Sfn When full it will hold Шаблон:Convert. The next largest dam in Botswana, the Gaborone Dam, has capacity of Шаблон:Convert.Шаблон:Sfn
Purpose
The dam is located on the Shashe River three kilometers below the confluence with the Tati River, about Шаблон:Convert northeast of the town of Selebi Phikwe. It is Шаблон:Convert upstream of the Botswana - Zimbabwe border.Шаблон:Sfn The project should increase the secure supply of water for Gaborone, Francistown, and towns and villages along the north–south route for the foreseeable future.Шаблон:Sfn It will eventually deliver another Шаблон:Convert per second of raw water delivery to the north–south carrier pipeline.Шаблон:Sfn Water will also be fed to the Palapye coalfields and to the proposed 1,200 MW power station at Mmamabula. Project costs for the dam were around P1,134 million (US$300 million).Шаблон:Sfn The pipeline would cost another P1,127 million.Шаблон:Sfn The reservoir may also attract tourists drawn by wildlife, water sports and local food, if facilities are developed.Шаблон:Sfn
Structure
The dam is a zoned earthfill structure, Шаблон:Convert high and Шаблон:Convert long. The earthworks contain about Шаблон:Convert of material, including Шаблон:Convert of clay core from borrow pits and Шаблон:Convert of embankment shell obtained from the spillway channel excavation.Шаблон:Sfn The quality of available clay was marginal and required careful selection, treatment and quality control. A layer of broken rock riprap Шаблон:Convert thick protects the upstream side from wave action, and a layer of less coarse rockfill Шаблон:Convert thick protects the downstream side. The rock, and aggregate for concrete production, came from an on-site quarry.Шаблон:Sfn
The geology of the reservoir is very variable. A Шаблон:Convert long grout curtain incorporating 6,700 tonnes of cement was needed to seal against leakage.Шаблон:Sfn The main spillway is a concrete ogee structure Шаблон:Convert long with energy dissipators, on the upper left flank of the dam about Шаблон:Convert north of the river. There is also a Шаблон:Convert long auxiliary spillway to handle conditions of extreme flooding.Шаблон:Sfn When filled, the reservoir will have backwater reach of about Шаблон:Convert up river.Шаблон:Sfn
A Шаблон:Convert high concrete intake tower Шаблон:Convert in diameter with five gate openings feeds a Шаблон:Convert long steel pipe Шаблон:Convert in diameter that passes under the dam embankment and then splits to a pump station and a river outlet. A Шаблон:Convert steel bridge connects the intake tower to the top of the dam embankment. The project also included building housing and power supply, and upgrading Шаблон:Convert of road between the villages of Mmadinare and Robelela. As of 2012 the pump station had yet to be built, as had the Шаблон:Convert long Шаблон:Convert pipeline to carry raw water to the existing North-South Carrier Pipeline (NSC), which in turn carries water south to Gaborone.Шаблон:Sfn The pipeline will connect to the NSC at the BPT1 break pressure tank at Moralane.Шаблон:Sfn
Construction
Before construction could begin, the bodies of people buried in the Matopi and Robelela villages had to be exhumed and relocated. This was explained at village dikgotla meetings to gain community approval. Some farms were purchased upstream. The government also arranged for counselling services on AIDS both to construction workers and to residents of the Mmadinare, Robelela, Matopi, Matsiloje, Chokwe and Patayamatebele villages. Preparations were made for additional demands for health and policing services.Шаблон:Sfn
A joint venture of Bergstan Africa of Botswana and Jeffares & Green of South Africa undertook technical design and construction supervision.Шаблон:Sfn The dam was built for the Department of Water Affairs by Sinohydro Corporation of China.Шаблон:Sfn At times, the language barrier caused problems, when the engineers were unsure whether the contractor understood what was required, since interpreters without technical training were being used.Шаблон:Sfn PPC Cement of Botswana supplied cement. Concrete was manufactured onsite using onsite quarries.Шаблон:Sfn
Construction began in March 2008.Шаблон:Sfn Unseasonal flooding in the dry season in June 2009 disrupted the construction project.Шаблон:Sfn The contractor managed to recover lost time through hiring additional workers. Sinohydro announced completion in December 2011, ahead of the planned February 2012 date.Шаблон:Sfn Sinohydro received a takeover certificate in January 2012.Шаблон:Sfn A diversion channel was left open in the embankment for the river flow while the dam was built over the Shashe River. Final closure of the diversion channel and the spillway was scheduled for October 2012 in time to start impounding the wet season's rains.Шаблон:Sfn
In June 2012, stakeholders were told that construction of the pipeline was behind schedule. This part of the project had started in October 2011 and was due for completion in October 2013. The contractors, China State Construction Engineering Corp and the local Excavator Hire, had 350 employees, 75 of whom were Chinese. The delay was caused by failure of a factory in Palapye to produce pipes of acceptable quality. There were some concerns that further delays could occur if there were problems with blasting along the section from the Letsibogo Dam to Moralane. Along this stretch, the new pipeline runs parallel to the NSC pipeline, and great care must be taken to ensure no damage is done to the NSC.Шаблон:Sfn
References
Sources
- Шаблон:Cite web
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Шаблон:Refend Шаблон:Dams and reservoirs in Botswana
