Sivhili Injhiniyeringi June 2008 Vol 16 No 6 ONE SOLUTION TO WATER SUPPLY PROBLEMS LIES HIDDEN IN THE ROCKS P CA THE LIKELIHooD OF A GLOBAL DROUGHT IN 2009–2016 A W A R D S W I N N E R 2 0 0 7 FOR EXCELLENCE IN MAGAZINE PUBLISHING AND JOURNALISM VRESAP to be operational by November Implementation of the reserve at the Berg River Dam and Supplement Scheme Outeniqua Coast Water Situation Study 24 MONTHS TO FIFA 2010 P CA A W A R D S W I N N E R 2 0 0 7 FOR EXCELLENCE IN MAGAZINE PUBLISHING AND JOURNALISM Tshivenda ON THE COVER One of GEL’s new Beretta T46 drilling rigs installing lateral support to the Western access tunnel at the Soccer City Stadium ON THE CovER where the 2010 FIFA World Cup final will be played. This tunnel was constructed under the existing West grandstand, with Ensuring solid foundations for the FIFA supported faces of up to 9 m high; in total, World Cup’s flagship stadium 46 approximately 500 m2 lateral support was installed to three tunnels and the multi- WATER ENGINEERING OTHER PROJECTS storey parkade Potable water reservoir under construction 49 One solution to water supply problems Cape Town Terminal expansion on track 50 lies hidden in the rocks 2 Anglian Water’s biggest ever project 53 Dynamic planning process for water Recycling our roads 57 and sewer infrastructure 5 Boost for safer crane operations 55 Berg Water Project reserve releases: Traffic control centres for Limpopo 59 Implementation of the reserve at the Berg PUBLISHED BY SAICE/SAISI Block 19, Thornhill Office Park, River Dam and Supplement Scheme 8 PEOPLE 61 Bekker Street, Vorna Valley, Midrand Private Bag X200, Halfway House, 1685 Tel 011-805-5947/48, Fax 011-805-5971 http://www.civils.org.za How has the ecological reserve influenced the [email protected] HISTORY AND HERITAGE design and operation of the Berg River Dam? 12 EDITOR Past Master 17: Sir John Coode 62 Sarie Moolman [email protected] Tel 012-804-2754, Cell 082-376-2652 Outeniqua Coast Water Situation Study 16 EDITORIAL PANEL IN BRIEF 65 Elsabé Kearsley (chair), Irvin Luker (vice-chair), Johan de The likelihood of a global drought Koker (president), Wally Burdzik, Huibrecht Kop, Jeffrey Urban water management challenge Court ruling on Mahachi, Jones Moloisane, Hermien Pieterse, Eben Rust, Marco van Dijk, Michelle Theron, Sarie Moolman in 2009–2016 22 water ‘global precedent’ Lusip Dams, Swaziland (editor), Barbara Spence (advertising), Verelene de Koker (secretariat), Dawie Botha (executive director), Water awards Dutch water innovation Zina Girald, Marie Ashpole Towards sustainable development: Achieve Hydroelectric dams in Asia Class of ’58 Business ANNUAL SUBSCRIPTION RATE SA R560,00 (VAT included), International US$120,00 development potential, support key on the move Record year for cement Upgrading ADVERTISING of Knysna Road PDNA commended Concrete Barbara Spence, Avenue Advertising ecosystems and provide poverty relief 27 [email protected] pavement paper wins SAICE award Nanowires may Tel 011-463-7940, Fax 011-463-7939 Cell 082-881-3454 VRESAP to be operational by November 33 boost solar cell efficiency Global award for Gautrain DESIGN AND REPRODUCTION Fire door orders for two 2010 stadia Umhlanga’ s Marketing Support Services, Menlo Park, Pretoria International water distribution systems Ridgeside development Transport conference at CSIR PRINTING Ultra Litho, Johannesburg conference for Kruger 37 Golder’s new Mozambique office Road rehabilitation The South African Institution of Civil Engineering project in Free State ‘Dearth of disabled facilities’ accepts no responsibility for any statements made or opinions expressed in this publication. Consequently Refurbish, repair or replace? 39 nobody connected with the publication of the magazine, in particular the proprietors, the publishers and the editors, will be liable for any loss or damage sustained Tough water usage challenge ahead 41 SAICE AND PROFESSIONAL NEWS by any reader as a result of his or her action upon any statement or opinion published in this magazine. Honorary degree conferred on James L Barnard 80 Mbashe North project nearly completed 42 ISSN 1021-2000 Sad news … 81 BLISHE PU RS Gijima: Branch visits 2008 E Reservoir built with hollow-core precast 82 N I Z A G A A S M F concrete slabs: A South African first Diarise this! 84 O 44 N A I O S S O C I AT Civil Engineering | June 2008 1 Info Dr Ricky Murray Groundwater Africa T 021-881-3082 [email protected] WATER ENGINEERING One solution to water supply problems lies hidden in the rocks THE SECURITY AND QUALITY of the 1 water supply is a major issue facing every South African community. From tiny dorps to big cities, the demands for po- table and industrial or agricultural usage water are ever increasing. Some areas are fortunate to have either or both consistent rainfall and suf- ficient river and dam capacity, but many municipalities are subject to seasonally distorted rainfall patterns and some face radical demand spikes (for example Plettenberg Bay, which has a huge jump in usage in the peak of summer). In the past, the solution provided by consulting engineers in bigger com- munities has been to build dams and in water table and ‘bank’ the water for later concept in other parts of the world. smaller towns to extract groundwater via usage. Buried in the rocks there is no The Indian government recently pro- boreholes. Both these approaches have now evaporation loss – which can amount to a duced a master plan for artificial recharge become problematic. Most potential major drop in water levels up to 3 m per annum and is committing R33 billion to the con- dam sites have been utilised and there is in dams – and the dangers of contami- cept over ten years in an effort to capture growing awareness of the massive envi- nation are markedly reduced. Unless a over 36 000 million cubic metres of water ronmental damage and subsequent hidden scheme is poorly designed, virtually all across 450 000 km2. cost in dam construction. And the over- recharged water can be recovered and Amsterdam receives 60 % of its use of boreholes has caused an alarming techniques can be used to reverse hy- drinking water from a scheme that in- drop in the water table in many areas and a draulic gradients causing even ‘lost’ water volves spreading treated river water over subsequent decline in water quality. to flow back into the well field. 40 recharge ponds covering 86 ha which Increasingly, the answer for engineers The water usually needs to be treated have an infiltration rate of 20 cm/day engaged in water projects is to explore before it is sent below to prevent clog- and an average sub-surface travel time the possibility of managed artificial re- ging of the surface of the basins or the of 90 days. The water is then recaptured charging of aquifers. Artificial recharge boreholes, although in many European through drains and open canals situated (AR), as the technique is widely known, countries the process itself is used for about 60 m from the infiltration basins. involves transferring river or dam water water treatment purposes with the sandy Mt Gambier in South Australia is underground by means of infiltration aquifers serving as giant natural filters. an isolated city in an arid region and basins or borehole injection to boost the Artificial recharge is a widely used channels all of its stormwater into an 2 Civil Engineering | June 2008 2 3 Main natural recharge area underlying karst aquifer using more than 4 300 drainage wells producing an annual Proposed main articial recharge of up to 6,2 million cubic metres. recharge area Articial recharge Unsurprisingly, the Israelis have to replenish wellelds pioneered artificial recharge – the biggest Auas Mountains Group 12 of their schemes in the Dan Region uses boreholes the aquifer media to supply irrigation Group 4 Group 3 Group 9 boreholes boreholes needs from Tel Aviv’s treated reclaimed boreholes City centre Spring wastewater – but it’s the United States Year 1950 water level that has the most extensive history in the technique and there has been a notice- Year 2000 water level able increase in usage in the past twenty Regional decline, creating a vast storage area years. The largest existing operation is in Localised depression, creating the Las Vegas Valley which has a recovery a limited storage area capacity of 0,59 million cubic metres per day, but the Florida Everglades, New York City and San Antonio all run AR schemes. also to provide a regulatory framework for 1 Las Vegas Valley, USA: artificial An American Water Works implementation. The strategy is being im- recharge injection point Association survey shows that most plemented by DWAF’s Directorate: Water 2 Karkams, Namaqualand: artificial recharge schemes are used primarily for municipal Resource Planning Systems. sand filter with pump house in the background supplies and for seasonal storage, but Dr Ricky Murray, a hydrogeologist 3 Fracturing in the Windhoek quartzites secondary benefits are also often cited like engaged by DWAF to implement their ensures very high permeabilities. Injection recovery of groundwater levels, preven- strategy, points out that ‘many of our local rates of up to 60 ℓ/s can be achieved tion of saltwater intrusion, protection of geological formations contain appropriate 4 Windhoek’s artificial recharge approach habitats and improvements in ground- aquifers that could be used to enhance water quality. Although most schemes the water supply at far cheaper and more planning borehole injection tests into the use surface water as their sole source of efficient rates than dams’. The capital cost local aquifer and if the results are positive, injection, a number involve transferring of a typical AR scheme is often well under they will be able to save on the cost of con- water from one aquifer to another.