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Download PDF - Medupi ISIZA DPS _Page 2_


                                                                                             ESKOM INFRASTRUCTURE
   Eskom’s power generation capacity will be significantly boosted when
     the new dry-cooled, coal-fired power station’s six generating units
   start to come on line towards the end of 2011 at an estimated total
                                            project cost of R130-billion.
LARGEST OF ITS KIND                                14.5-million tons of coal a year for the next             Scaffolding was called upon to provide
Located on a 883 ha greenfield site at             40 years. A full environmental impact study               innovative formwork solutions for the
Lephalahle in Limpopo province, the power          was carried out through the Department of                 construction of the condenser slab and tie
station consists of six boilers which will each    Environmental Affairs and Tourism (DEAT)                  beams for the second to sixth power
drive a 800 MW turbine. Once all six units         and a licence was granted by the National                 generation units. Each condenser unit has
are commissioned, Medupi will have the             Energy regulator.                                         four corner columns constructed of concrete
potential to add between 4,200 and 4,500                                                                     rising up 20 m to support a 9 m square
MW of electricity to the national grid. It is      INNOVATIVE SOLUTION REQUIRED                              concrete slab.
recognised as the world’s largest dry-cooled,      Civil engineering and construction work is
coal-fired power station.                          well underway and formwork solutions are                  Two horizontal tie beams between all four
                                                   playing a serious role in the condenser                   columns on each condenser are required for
The Lephalale site near Ellisras was selected as   section. Two condensers are required for                  increased structural strength and are situated
it is near Exxaro’s Grootgeluk coal mine,          each generating unit for a total of 12 in all.            approximately 7 m apart. To construct these
which has been contracted to supply up to          Formwork specialist Wiehahn Formwork &                    tie beams, Wiehahn designed and made up

       Huge columns dominate the Medupi site.                        Special Wiehahn structural steel support to 9 m x 9 m x 1.5 m deep top slab.

                                                                                                         MEDUPI POWER STATION
                                                                                                         MAIN CONTRACTOR
                                                                                                         Medupi Power Station Joint Venture
                                                                                                         (a Murray and Roberts, Grinaker-LTA Civil
                                                                                                         Engineering and Concor consortium)

                                                                                                         Contracts manager
                                                                                                         Adrian Steele

                    Crane-handled Quickshore Tower for safe access to 8 m high column.                   Eskom

eight sets of heavy duty brace frames in a             shoring and crane-handled into position
cantilever position, allowing two sets per             18 m above ground level.”
                                                       LIGHTWEIGHT SLAB FORMWORK
EIGHT METER HIGH SHORING                               For the slab base, SRZ walers and GT24
Wiehahn technical manager Pieter Potgieter             wooden girders and a plywood soffit were
said the brace frames were crane-lifted into           used with stop-ends 1.5 m deep. Wiehahn’s
position.                                              lightweight, panel PERI DOMINO formwork
                                                       system was employed as it does not require a
“An access system was also designed using              crane and is easy to handle. “The DOMINO
Wiehahn’s Quickshore heavy duty shoring                system was deliberately designed to work as
system, eight metres high per unit, was crane          a single-sided form, thereby eliminating the
lifted and placed on the already cast                  need for 9 m-long ties, which would
columns, cantilevering out on CB brackets              definitely move,” said Potgieter.
that were fixed on two corners of the
columns. This allows the steel reinforcing to          “The system was supported by props with
be fixed for the next concrete pour as well as         the tensile loads going back into the soffit
making the arrangement of the formwork                 which was designed to take such a load.”
required much easier and safer to execute.             Wiehahn is also involved in the formwork for
This procedure is then repeated for the next           the construction of fifteen 3 m x 3 m
horizontal tie beam.”                                  concrete tunnels, each 200 m long, which
                                                       carry electrical cables to the various units
“The tie beams are 1.5 m deep and 1 m wide             within the overall power station.
                                                                                                                 Head Office      021 880 7777
with steel reinforcing.” The slab which forms                                                                    Cape Town        021 907 2100
the foundation of the condenser at the top of          LIGHTWEIGHT WALL FORMWORK                                 Midrand          011 729 2300
the 20 m vertical columns is large, being 9 m          The base wall and vertical walls of the tunnels           Durban           032 533 9307
square and 1.5 m deep.                                 are being constructed with Econoform panels               Nelspruit        013 758 1521
                                                                                                                 Bloemfontein     051 433 3150
                                                       and Wiehahn deployed its PERI SKYDECK, a                  Port Elizabeth   041 463 1141
SPECIAL SUPPORT SYSTEM                                 lightweight aluminium panel formwork                      George           044 878 0105
“For the top slab support a special bracket            system which was the formwork solution best               Polokwane        015 298 8511
and steel beam support system is used, on              suited to the construction of the tunnel                  East London      043 731 2807
                                                                                                                 Richards Bay     035 797 5299
top of which there are mini purpose-                   soffits. In some instances the side walls and             Rustenburg       014 592 2816
designed beam trusses pre-assembled and                the soffit were executed in a single pour.                Klerksdorp       018 462 1408
delivered to the Medupi site. These keep the                                                                        National ☏ 0861 70 80
system as light as possible and allow for              Contracts have been placed with Hitachi to         
easier placement.                                      supply the boilers and Alstom to provide the
                                                       steam turbines. At R33.6-billion, these are the       Authorised               distributor
The shoring on top of the steel beam support           biggest single contracts ever placed by
were all pre-assembled Quickshore standard             Eskom.

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