Jun 01, 2012
Construction starts on Eastern Cape damBack
Construction|Engineering|Africa|ARQ Consulting Engineers|Base Resources|Cement|Concrete|Goba|Hydropower|Instrumentation|PROJECT|Project Management|Projects|Resources|Safety|Water|Africa|Australia|China|Kenya|Panama|South Africa|Chuniespoort Dam|Mndwaka Dam|Mukurumudzi Dam|Bentonite-cement-soil Cutoff|Left Bank|Mineral Sands Developer|Spillway Capacity Enhancement Technology|Eastern Cape|Consulting Engineers|Power|Quentin Shaw|Water|Amathole|Eastern Cape|RMC Technology|Spillway Capacity Enhancement Technology
© Reuse this
The R70-million project makes up Phase 1C of the R350.7-million Mncwasa Water Supply Scheme and is aimed at providing water supply storage for the Amathole district municipality.
The scheme, which was initiated in 2010, is being built in phases up to 2012/13 and will provide water to more than 6 000 households.
The Mndwaka dam makes use of rubble masonry concrete (RMC) technology, which blends ancient manual construction methods with state-of-the-art design techniques, Shaw says.
“RMC dam construction has been demon- strated to be an efficient and highly cost-effective method for the labour-based construction of small and medium-sized dams,” he notes.
Structures created through this method are durable and substantially less sensitive to exceptional flooding conditions than a common fill embankment. This durability reduces the requirement for river diversion and allows for a dam to be built safely in phases over an indefinite period, or to be built for future raising, he adds.
Further, RMC dam construction usually creates about five times more employment opportunities than are created during the construction of an equivalent embankment dam and the masonry skills developed through the application of this technology have been found to be of value in many other types of construction, Shaw points out.
Meanwhile, construction on the 24 m earthfill embankment Mukurumudzi dam, which will supply water to Australia-based mineral sands developer Base Resources’ Kwale project, in southern Kenya, started in January.
The Kwale project entails the extraction of titanium and zircon minerals from the dunes in the area south of Mombasa.
The dam is configured as a homogeneous embankment of about 210 000 m3 of silty sand originating from the local area. With little suitable clay materials available, the impermeable membrane of the dam will comprise a central bentonite-cement-soil cutoff constructed progressively with the embankment and will include graded blanket and chimney drains for seepage control.
Flood handling will be managed through an uncontrolled ogee spillway over a saddle on the left bank.
To date, the construction process has included excavation across the full dam footprint, partial excavation of the core trench, partial construction of the river diversion culvert and the establishment of the contractor’s facilities and plant.
The project is expected to be completed in April 2013.
ARQ’s RMC technology, combined with its spillway capacity enhancement technology, was also recently used on the Department of Water Affairs’ (DWA’s) Bospoort and Molepo dams to increase the dams’ spillway capacity fourfold, adds Shaw.
Chuniespoort is a 16-m-high homogeneous earthfill embankment dam.
The rehabilitation project included increasing the spillway capacity, raising the earthfill embankment, installing embankment drainage, up- and downstream erosion protection and upgrading the outlet works.
The granitic fill used for the construction of the dam is dispersive and careful treatment, as well as design and construction specifications, were needed to ensure a durable, low-maintenance solution.
“ARQ’s involvement included the conceptual design, the full detailed design, preparation of tender documents, as well as supervision assistance,” says Shaw.
Changuinola 1 Dam
“The 230 MW hydropower scheme comprises the dam, a 4 km headrace tunnel and a surface power station,” says Shaw.
At a completed cost of about $150-million, the dam consists of a 105-m-high roller-compacted concrete (RCC) arch/gravity structure, with a crest length of 590 m and a concrete volume of 895 000 m3.
“ARQ’s involvement in the design phase of the project included the feasibility design, the full detailed dam design, the spillway design, the instrumentation design, the river diversion design, as well as the foundation rock mass analysis and the design for the EPC contractor,” he says.
The dam was initially configured as a gravity structure, but as more rock mass information became available, the company was able to prove the technical feasibility of an arch/gravity structure to the satisfaction of the project owner.
On the basis of the associated time and cost savings, the design was accordingly revised.
“The Changuinola 1 dam is the first RCC dam built outside China and South Africa,” Shaw points out.
Future of Water Engineering
Compared with the rest of the world, the country’s water engineering industry’s standards were high, until a recent reduction in large projects and an increase in competition in a shrinking international market led to the best minds no longer entering the field of civil engineering, he says.
“Retaining qualified and experienced engin- eers can only be done by accessing bigger markets, which is why ARQ is working on a number of dams and hydropower projects abroad,” he adds.
The biggest potential for South African consulting engineers to grow is to expand further north into Africa, says Shaw.
“We are ideally placed, both geographically and in terms of our understanding of the correct engineering approach to provide services for the development of water resources and hydropower projects in Africa,” he says.
Edited by: Chanel de Bruyn© Reuse this Comment Guidelines
Other Construction News
Recent Research Reports
Real Economy Year Book 2014 (PDF Report)
This edition drills down into the performance and outlook for a variety of sectors, including automotive, construction, electricity, transport, steel, water, coal, gold, iron-ore and platinum.
Real Economy Insight: Automotive 2014 (PDF Report)
This four-page brief covers key developments in the automotive industry over the past 12 months, including an overview of South Africa’s automotive market, trade figures, production and the policies influencing the sector.
Real Economy Insight: Construction 2014 (PDF Report)
This five-page brief covers key developments in the construction industry over the past 12 months. It provides an overview of the sector and includes details of employment in the sector, infrastructure and municipal spending, as well as insight into companies’...
Real Economy Insight: Electricity 2014 (PDF Report)
This five-page brief covers key developments in the electricity industry over the past 12 months, including details of State-owned power utility Eskom’s generation activities, funding and tariffs, independent power producers and prospects for the sector.
Real Economy Insight: Road and Rail 2014 (PDF Report)
This six-page brief covers key developments in the road and rail industries over the past 12 months, including details of South Africa’s road and rail network and prospects for both sectors.
Real Economy Insight: Steel 2014 (PDF Report)
This four-page brief covers key developments in the steel industry over the past 12 months. It provides an overview of the global and South African steel and stainless steel markets, South Africa’s major steel producers and events that have shaped these markets.
This Week's Magazine
Local aerospace company Denel Aerostructures (DAe), part of the State-owned Denel Group, has won a fourth contract to manufacture parts for the Airbus A400M military air transport and air-to-air refuelling aircraft. The new contract, which was won in an international...
Although CEO Mark McChlery and chief marketing officer Bob Skinstad likened themselves to children in a playground when taking on the task of “reengineering and repositioning” the Seartec brand, the “young, dynamic and enthusiastic guys” were like proud...
An increasing number of buyers, in both the new and used car markets, are opting for finance structures that lower their monthly repayments, says asset financing company WesBank. These include the use of large balloon payments (also known as residuals), as well as...
Tertiary education institutions can use search engine giant Google’s Chromebook to provide secure mobile end-point devices for students on which they can share documents, work collaboratively on documents and access education materials and applications being used...
Local ceiling and partition company Abbeycon has beaten global competition at the Saint-Gobain Gypsum International Trophy competition, which was held last month in Berlin, Germany.