The first of four 333 MW pump turbine units at State-owned power utility Eskom’s Ingula pumped-storage scheme is expected to be commissioned in the first quarter of 2014, with the remaining units to start commercial operation in 2014.
The pumped-storage scheme, which is located in the Drakensberg mountain range, on the border between the Free State and KwaZulu-Natal, will comprise an upper dam (Bedford) and a lower dam (Braamhoek). The distance between the upper and lower reservoirs will be 4.6 km, with an elevation difference of about 470 m.
Underground waterways will connect the dams through an underground powerhouse, which will house the four 333 MW pump turbines that have a total capacity of 1 332 MW.
Eskom senior GM of project execution Kobus Steyn tells Engineering News that the Ingula pumped-storage project is currently 33% complete, on schedule and within budget. Out of the R21.4-billion allocated for the project, which excludes borrowing costs capitalised, R8.5-billion had been spent by December last year.
He adds that the Bedford dam was completed within the required timeframe despite contractual issues.
“Major civil construction on the Bedford dam was completed within contractual time. This is evidenced by the project obtaining permission from the Department of Water Affairs to impound the dam on April 6,” he says.
However, contractual completion was not certified, as the employed contractor did not complete rehabilitation and has yet to deliver or install the access bridge that connects the dam wall to the inlet tower.
Steyn attributes this slow project execution to geological inconsistencies within the Drakensberg region, which led to more leakages around the dam wall foundations than expected. “It took the contractor about three months to seal off the northern end of the dam, while rehabilitation and the construction of the bridge still have to be completed.”
However, he expects rehabilitation to be completed by August and contract com- pletion to be reached this year.
Successfully completed and commissioned in April, the Braamhoek dam stands 1 270.5 m above sea level. The dam is currently full, while the Bedford dam will only be filled when the project machinery is commissioned in December 2013.
Steyn says recruitment and training of maintenance staff will start in September, while training programmes for operating staff are already in place.
Training will be done internally and by original-equipment manufacturers (OEMs). Operators will be trained in general hydroelectric power station and pumped-storage scheme operation at the Drakensberg pumped-storage scheme on the southern side of Ingula.
OEMs will undertake training in terms of equipment unique to Ingula.
Steyn says the wetland area near Ingula will be affected by the project, as it will prevent critical natural flooding. To tackle this problem, licensing for the dams requires Eskom to create artificial flooding on a three-year cycle in order to maintain the ecosystem within the wetland.
“The flooding cleans the wetland, which is crucial for the ecosystem,” he notes.
Flood discharges can range from minimum environmental flows of tens of litres a second to discharge flows of 77 m3/s. In extreme floods, the overflow spillway can discharge in excess of 700 m3/s.
Eskom has installed measuring instrumentation calibrated to ensure accurate measurement of environmental water releases from the Braamhoek dam through four release valves.
The releases are measured over a gauging weir immediately downstream of the dam and recorded continuously by a data logger within the outlet house.
Steyn explains that flows are correlated with a flow meter in the outlet pipe of one of the 200 mm valves. The total flow is aggregated on a continuous basis to ensure that the minimum environmental releases are achieved.
Further, he says Ingula’s sustainability programme adopts an integrated approach whereby Eskom, surrounding land owners and dwellers will share beneficiation of environmental services.
“Ingula is currently in the process of obtaining the necessary approval from the Department of Environmental Affairs (DEA) for the formal proclamation of the property as a conservation area. Consultation is under way between Eskom, the DEA, provincial authorities and other interested parties, such as the South African National Biodiversity Institute,” he says.
Social benefits have accrued through the relocation of dwellers to new housing units constructed by Eskom within 10 km of Ingula. However, only those who were affected by the operations and the dam catchment area were relocated.
Further, formal tenure of land will be completed when title deeds are transferred to the dwellers. Each family will own a piece of land ranging from 5 ha to 10 ha, depending on its cattle grazing capacity.
The families will also be supported through service infrastructure such as water and sanitation, as well as training in sustainable farming practices and educational interventions such as school infrastructure and curriculum support.
On the economic front, Steyn says formal sustainable employment oppor- tunities will be generated from the ope- ration of the proclaimed conservation area through programmes such as land management (fire management and rehabilitation of historic erosion) and ecotourism activities that could employ field guides.
Steyn says Eskom’s safety programmes and procedures that are aligned with its ‘zero harm’ policy have been imple- mented at Ingula.
These include a full incident-tracking programme that monitors the lost-time- injury frequency rate, the absenteeism frequency rate, the number of medicals and first aid attendances and near misses. Incidents are also investigated, during which the implementation of corrective actions is identified.
As Ingula’s safety requirements are subject to the Mine Health and Safety Act, a team of safety officers and project staff with experience in the mining and tunnelling fields have been contracted to oversee the safety programme, Steyn says.
The Ingula project is also part of the recently launched Blue Flag programme that was initiated by Eskom and is applicable to all its project sites. The Blue Flag programme recognises business units that can prove their commitment and achievement of world-class safety, health and environmental practices and performance.
Steyn says flags are displayed at ope- rations where blue flag standards are upheld.
Further, numerous proactive measures have been implemented, including visible, felt leadership and behaviourally based safety observations.
“The project team has also initiated focus group discussion sessions targeting contracting staff, from management level down to team leader level, to discuss health and safety issues at Ingula,” he adds.
Three fully equipped clinics have been established on site to undertake entry, periodic and exit medicals. The clinics are able to dispense antiretroviral drugs in line with Eskom’s initiatives in tackling HIV/Aids.
In the operational phase, a standard biannual medical check will be compulsory for each employee.
The site will also comply with the requirements of the National Occupational Safety Association.
The 2009 fossil discoveries made at Ingula’s upper site, in the Free State, resulted in excitement within local paleontologist circles, as preliminary indications pointed to the possibility of the discovery of the largest and smallest Gorgonopsid skulls ever found.
Gorgonopsids were dinosaurs that resembled both mammals and reptiles and stood between 1 m and 3 m tall.
Steyn says about 150 fossils have been removed thus far, including almost complete skeletons and fragments. “We do expect to find more,” he notes.
Preliminary dating indicates that the fossils fall within the Permian period, placing them in the 250-million- to 300- million-years age bracket.
The process of removing the surround- ing rock from the fragile fossils was started in January this year. Following the excavation, they were sent to the Bloemfontein National Museum where they are currently being prepared for a two-year investigation period.
He adds that no production time was lost during extraction of the fossilised material.
Palaeontologists appointed by Eskom, complemented by staff from the Bloemfontein National Museum, were on site when the fossil remains were uncovered. Under palaeontologist supervision, contractors assisted in the relocation of fossil-containing rock to a designated site outside the construction footprint to minimise impact on production. This allowed sufficient time for palaeontology staff to investigate fossils for curation.
Steyn says the findings are of great significance.
“Relatively few fossils from the Permian period are available across the world because of the depth of the layers containing the fossils. The Ingula fossil finds will add new information to the body of knowledge of this period. The possibility also exists that there may be a new predator species among the finds,” he concludes.