Construction World December 2020

Category: CIVIL ENGINEERING CONTRACTORS

ROGGEVELDWIND FARM Remotely located in an area of rough terrain and challenging topography, Roggeveld Wind Farm in the Karoo demanded innovative construction design and implementation, as well as careful scheduling, logistics and environmental management.

L everaging its experience in wind energy facilities, Concor FRQVWUXFWHG VSHFLDOO\ GHVLJQHG FRQFUHWH EDVHV IRU ZLQG WXUELQHV 7KH FRPSDQ\ DOVR EXLOW NP RI URDGZD\ ZLWK DSSURSULDWH gradients to facilitate access for readymix trucks as well as the large, specialised vehicles that must haul the turbine towers DQG HTXLSPHQW :LWK D FRQVWUXFWLRQ IRRWSULQW RI KHFWDUHV WKH SURMHFW GHDOW ZLWK UHDFKLQJ LQDFFHVVLEOH DUHDV WR EXLOG WKH EDVHV DQG KDUGVWDQGV 7KH KLJKHVW SRLQW RI WKH SURMHFW DUHD LV PHWUHV KLJKHU WKDQ WKH VLWH RͦFH ZLWK PDQ\ FRQVWUXFWLRQ DUHDV GLͦFXOW WR DFFHVV HYHQ XVLQJ [ YHKLFOHV 7KH P RI FRQFUHWH UHTXLUHG IRU WKH SURMHFW ZDV EDWFKHG RQ VLWH EXW WKH QHDUHVW WXUELQH ZDV NP IURP WKH EDWFKLQJ SODQW $JJUHJDWH KDG WR EH VRXUFHG IURP NP DZD\ 8QOLNH PRVW ZLQG HQHUJ\ SURMHFWV WKH WXUELQH WRZHUV DW 5RJJHYHOG :LQG )DUP DUH FRQVWUXFWHG IURP FRQFUHWH QRW VWHHO This required several innovations from Concor Infrastructure including establishing a yard for placing and preparing tower sections as well as pre-assembly slabs – or ‘doughnuts’ – for WKH WUHVWOHV XVHG LQ WKH HUHFWLRQ RI WRZHUV The heavier weight of concrete towers impacted the design and FRQVWUXFWLRQ RI WKH IRXQGDWLRQV DQG WKH SUH DVVHPEO\ VODEV (DFK tower required the construction of the concrete doughnut-shaped VODEV DW LWV EDVH RQ WRS RI ZKLFK WKH ͤYH NH\ VWRQHV PDNLQJ XS WKH ERWWRP WRZHU VHFWLRQ ZHUH SODFHG The hilly rugged topography of the area – combined with strict environmental controls – had an impact on concrete slab FRQVWUXFWLRQ GHPDQGLQJ WKH VL]H RI WKH KDUGVWDQGV EH VPDOOHU Topography limited the reach of the new roadway network,

VKHOI VKXWWHU GHVLJQV ZRXOG QRW EH ͤW IRU SXUSRVH )LIWHHQ VHWV RI four slabs – one set for each turbine tower – had to be built, using MXVW WZR VHWV RI VKXWWHUV Given the challenging topography, the two main access roads had to appropriately graded to facilitate heavy vehicles hauling on WKHVH URDGV 7KLV PHDQW FXWV RI XS WR WKUHH PHWUHV EXW ZLWK EODVWLQJ NHSW WR D PLQLPXP WR DYRLG HQYLURQPHQWDO GLVUXSWLRQ 7KH SURMHFW̵V KLJKHVW SRLQW LV PHWUHV ZLWK WKH VLWH RͦFHV EHORZ DW PHWUHV &RQVLGHUDEOH LQQRYDWLRQ LQ GHVLJQ ZDV GHPDQGHG E\ WKH SURMHFW̵V FRQVWULFWLQJ PHWUH HQYLURQPHQWDO IRRWSULQW 7KLV UHVWULFWHG VWHHS FXWWLQJV RU KLJK ͤOOV GXULQJ WKH HDUWKZRUNV QHFHVVDU\ WR DFKLHYH WKH JUDGLHQWV WKDW ZRXOG EH PDQDJHDEOH E\ KDXO WUXFNV 7KLV DOVR UHTXLUHG ͤQHO\ EDODQFHG FXW DQG ͤOO SODQQLQJ WR HQVXUH QR VXUSOXV PDWHULDO DV OLPLWHG VWRFNSLOH DUHDV ZHUH DYDLODEOH :DONLQJ WKH VLWH ZDV QHFHVVDU\ WR PDNH DGMXVWPHQWV WR URDGZD\V ZLWK VRPH PLFUR VLWLQJ RI WKH KDUGVWDQGV &DUHIXO consideration in hardstand design was given to how the ‘doughnut’ slabs would be positioned, meeting the parameters of the main crane lift while not blocking access on the single roadway for through- WUDͦF (DFK RI WKH KDUGVWDQGV QHHGHG LWV RZQ FRQͤJXUDWLRQ ƒ

PROJECT INFORMATION

• Company entering: Concor • Client: Nordex Energy South Africa • Start date: May 2019 • End date: October 2020 • Main Contractor: Concor • Principal Agent: Concor • Consulting Engineer: BVi Consulting Western Cape

ZKLOH WKH SURMHFW IRRWSULQW ZDV FRQVWUDLQHG by the area’s sensitive ecology, leaving only a PHWUH FRUULGRU LQ ZKLFK WR ZRUN A precast yard had to be built for the construction of the ‘doughnut’ slabs, from where they were transported to the KDUGVWDQGV 8VLQJ SUHFDVW VODEV LQ WKLV application is not common practice in South Africa, although it is routinely DSSOLHG LQ (XURSH Each tower base required blasting, excavation and cleaning, after which EOLQGLQJ ZDV SRXUHG /HYHOOLQJ OHJV ZHUH installed on top of the blinding to hold the OHYHOOLQJ WHPSODWH LQ SODFH GXULQJ FDVWLQJ $SSUR[LPDWHO\ WRQQHV RI UHLQIRUFLQJ VWHHO ZHUH XVHG IRU WKH WXUELQH EDVHV The considerable weight of the concrete ‘doughnut’ slabs meant they had to be cast in two pieces, facilitating WUDQVSRUWDWLRQ DFURVV VLWH 2QFH PRYHG WKH WZR LWHPV PXVW EH ͤWWHG WRJHWKHU ZLWK tight tolerances demanding accurate and SURIHVVLRQDO FDVWLQJ The unusual shape of these slabs required special shutters to be made up, as off-the-

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