SA’s first OCGT power plant on schedule for 2007

9th December 2005 By: Nelendhre Moodley

The first open-cycle gas- turbine power plant (OCGT) to be built on power-utility Eskom’s grid is well under way and is on sche-dule for its 2007 completion date.

The civil engineering contract for the OCGT power plant was awarded last month to Roshcon, a wholly-owned subsidiary of Eskom Enterprises and a member of the Eskom group.

The R160-million contract involves the provision of the station terrace, buildings, foun-dations, road infrastructure, sewerage and cable and pipe trenches.

According to Roshcon MD Mark Cawood, one of the foremost reasons for winning the contract aside from the company’s extensive experience in working with similar projects, is its record for successfully completing fast-tracked projects within tight time schedules.

“Design partners, Goba Consulting Engineers, based in Sandton, and Ninham Shand Consulting Engineers, of Cape Town, have already been appointed. “In addition, Nico Bernard from Resonant Consulting Engineers in Centurion has been appointed design project manager,” reports Cawood, adding that the foundation and concrete-work design is currently being completed in readiness for on-site occupation by January 9. Bulk earthworks for 27 000 m2 for each of the sites at Atlantis and Mossel Bay in the Western Cape is scheduled for completion in six to eight weeks’ time.

“Shortly thereafter concrete piling will begin,” says Roshcon divisional manager: civil infrastructure Nico Vermeulen, who adds that the Atlantis site, which is located on sand dunes, poses the greatest challenge for the project team.

As sand dunes are not strong enough to support buildings, concrete sink piles will be constructed for additional strength in support of the main structures .

Vermeulen reports that Rosh-con has extensive experience in working with a large selection of materials, including dune sand and clay.

“These materials are often difficult to work with, especially during the Cape’s wet season,” he says.

In fact, the company recently completed a similar project for a 400 kV substation in Stikland, Brakenveld, in Cape Town.

The R19,5-million contract, which started in February and involved platform and civils work, was completed in November and also involved working with dune sand.

Owing to the sandy, loose soil, which has little cohesion properties, a huge quantity of water was used to compact and increase the soil’s workable property,” he explains.

“We will be doing layer work at the Atlantis site to improve the soil’s carrying capacity,” reports Cawood.

Fortunately, the Mossel Bay plant is located on firmer soil and will, therefore, pose little difficulty, he states.

Besides contending with difficult soil conditions, Roshcon will also be involved in moving 10 000 m3 of soil a day on each site,” reports Vermeulen, who informs Engineering News that conventional construction com-panies move about 1 000 m3 of soil a day.

“In order to ensure the movement of 10 000 m3 of soil a day, we will employ additional teams working double shifts,” he explains.

“The project is besieged by a number of challenges, including training a 80% semiskilled local labour force from the Atlantis and Mossel Bay areas,” states Cawood.

“The challenge in fulfilling the socioeconomic conditions of the contract lies in hiring and training local labour to a level of suitable proficiency to start on-site work in early January,” he points out.

He also adds that, in a bid to curb the high unemployment rate, especially in the Atlantis area, contract stipulations include hiring from black economic- empowerment contractors, black women organisations and small and medium enterprises.

In order to ensure that local resources and suppliers are used, Roshcon is in the process of advertising for labour and resources.

“There is not much training flexibility available, thus training will have to take place over the festive season to ensure that labour is adequately trained for the start of on-site work in January, when earthworks will start, followed by concrete construction in February,” Cawood explains.

Semiskilled labour will be involved in erecting shutters for concrete work, steel fixing, brick laying and general labour.

Although it might be challenging to find suitably-qualified labour in Atlantis, greater construction skills are available in the Mossel Bay area, Vermeulen notes.

As a result of the tight time schedule, bush clearing will be completed by Roshcon. The 4 500 m2 of buildings on each site will include a control and administration block, a storeroom, a workshop, an ablution facility and a security building.

The hand-over of the civil works for the first power-island unit, which will consist of a foundation for a stacker, smoke stack, turbine-generator block, a unit transformer and insulatory works, such as pumps and cooling fans for the unit to the Mossel Bay power plant, is scheduled for May 3.

Every two weeks thereafter a power-island unit will be delivered to each alternate site of the plants, with delivery of the last unit scheduled for August 3.

Although initial infrastructure development around the power- island unit, which includes the construction of access roads, concrete trenches, buildings and stormwater control system will be paralleled with other on-site work, it is, nevertheless, scheduled for completion in early October 2006.

With a strong focus on power-generation projects, Roshcon reports that it is well-positioned to handle the first-ever OCGT project in South Africa.

“We were involved in building an emergency gas-turbine gener-ator with Stewart & Stevenson and Webster & Stone of Canada for the Ubongo power station in Dar es Salaam, Tanzania, in 1995.

“The contract for the 70 MW World Bank-financed project was completed in five months for the Tanzanian Electricity Supply Company,” says Cawood, adding that, although 90% of its work is contracted from Eskom, Roshcon is involved in a significant portion of civil and electrical contracts for power generation, transmission and distribution projects on the African continent, including Zambia, Tanzania, Mozambique, Lesotho and Uganda.

“We have also been involved in a Mauritian Sewerage reticulation project,” he states.

With a R660-million turnover for the current financial year, Cawood reports that the Johannesburg-based company has permanent staff of 200 in its employ and contract staff total-ling about 1 300.

With Eskom’s drive to focus on its core business, there are definite vibrations towards Eskom Enterprises unbundling a number of its wholly-owned companies.

“In fact, a sale process for Roshcon will soon be on the cards,” concludes Cawood.