IMIESA June 2018 by 3S Media

www.infrastructurene.ws

IMESA The official magazine of the Institute of Municipal Engineering of Southern Africa

infrastructure development • Maintenance • service delivery

Johannesburg Water Building future water capacity

Trenchless Technology Rehabilitating the Black Mac

Environmental Engineering

Desert reservoirs

ISSN 0257 1978

Municipal Focus

Johannesburg’s accelerated delivery

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INSIDE

volume 43 no. 06 June 2018

www.infrastructurene.ws

IMESA The official magazine of the Institute of Municipal Engineering of Southern Africa

INFRASTRUCTURE DEVELOPMENT • MAINTENANCE • SERVICE DELIVERY

Johannesburg Water Building future water capacity

Trenchless Technology Rehabilitating the Black Mac

Environmental Engineering

Desert reservoirs

ISSN 0257 1978

Water, PIPES & VALVES

Nut shells and filtration

Municipal Focus

Johannesburg’s accelerated delivery

V o l u m e 4 3 N o . 6 • J u n e 2 0 1 8 • R 5 0 . 0 0 ( i n c l . VAT )

It’s not every day or year that Johannesburg Water gets to launch two water reservoirs in less than six months. The Orange Farm and Diepsloot reservoirs were launched in January and March 2018, forming distinctive landmarks. P6

The business case for plastic pipe

Odour Control Intelligent chemistry

Environmental Engineering Desert reservoirs

Walls of stone

Regulars Editor’s comment

Landfills

President’s comment

Waste strategies explored

Index to advertisers

Roads & Bridges Municipal Focus | Johannesburg

More than a footbridge

Surfacing the city

Better, faster delivery

Ensuring water security through dynamic master plans

Water, Pipes & Valves

Namibian plant hire

Paving the way for future mobility

Vertical digging

Big strides in after-sales

Plugging the leaks

Reducing network leakage and demand

Cement & Concrete

The business case for plastic pipe

Art and construction

Flexible drainage solutions

Excitement builds for TCC 2018

Preparing to plaster

Rehabilitating the Black Mac

SASTT TRENCHLESS NEWS Rehabilitating the Black Mac

Transport, Logistics, Vehicles & Equipment

Nut shells and filtration

SASTT Trenchless News

ODOUR CONTROL Intelligent chemistry

Cement & Concrete Flexible drainage solutions

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EDITOR’S COMMENT

Smarter cities

Publisher Elizabeth Shorten MANAGING EDITOR Alastair Currie SENIOR JOURNALIST Danielle Petterson JOURNALIST Liesl Frankson Head OF DESIGN Beren Bauermeister Chief SUB-EDITOR Tristan Snijders SUB-EDITOR Morgan Carter ContributorS Gavin Clunnie, Cobus Compion, Peter Telle, Annejan Visser Production COORDINATOR Jacqueline Modise financial Director Andrew Lobban DISTRIBUTION MANAGER Nomsa Masina Distribution coordinator Asha Pursotham SUBSCRIPTIONS subs@3smedia.co.za Printers United Litho Johannesburg +27 (0)11 402 0571 ___________________________________________________

hen we hear the term ‘smar t cities’, we imagine futuristic scenarios where artificial intelligence is a mainstay and superfast interconnectivity a given, with commercial drones and robotics commonplace in the home and workplace. That’s an exciting prospect, and in many parts of the world, it’s already happening. Prime city examples include Seoul, Tokyo, Paris and London. Here, the end purpose is to employ technology that advances sustainability goals in terms of social and economic development, with a major emphasis on renewable energy and efficient transportation. Information and communication technologies (ICT) are purely there to facilitate the process. This view is supported by the UK Department for Business, Innovation and Skills’ broad definition of smart cities, which regards them as “a process rather than a static outcome, in which increased citizen engagement, hard infrastructure, social capital and digital technologies make cities more liveable, resilient and better able to respond to challenges.” After Asia, Africa is the next fastest region when it comes to urbanisation, so this presents major opportunities for the continent’s city planners to shape unique platforms. In some cases, cities will be installing modern-day ICT systems for the first time and a number of these could well be funded as public-private partnership projects or via special bond releases. Hopefully, these ICT initiatives will also promote intercontinental trade among African countries. For now though, the focus should be on affordability and scalability. When it comes to communications in Africa, cellular networks still dominate. They also tend to come at

Advertising Sales Jenny Miller Tel: +27 (0)11 467 6223 Email: jennymiller@lantic.net ___________________________________________________

Publisher 150 Rivonia Road, Morningside, 2196 PO Box 92026, Norwood 2117 Tel: +27 (0)11 233 2600 Fax: +27 (0)11 234 7274/5 www.3smedia.co.za Annual subscription: R600.00 (INCL VAT) ISSN 0257 1978 IMIESA, Inst.MUNIC. ENG. S. AFR. © Copyright 2018. All rights reserved. ___________________________________________________ IMESA CONTACTS HEAD OFFICE: Manager: Ingrid Botton P.O. Box 2190, Westville, 3630 Tel: +27 (0)31 266 3263 Fax: +27 (0)31 266 5094 Email: admin@imesa.org.za Website: www.imesa.org.za BORDER Secretary: Celeste Vosloo Tel: +27 (0)43 705 2433 Fax: +27 (0)43 743 5266 Email: celestev@buffalocity.gov.za EASTERN CAPE Secretary: Susan Canestra Tel: +27 (0)41 585 4142 ext. 7 Fax: +27 (0)41 585 1066 Email: imesaec@imesa.org.za KWAZULU-NATAL Secretary: Ingrid Botton Tel: +27 (0)31 266 3263 Fax:+27 (0)31 266 5094 Email: imesakzn@imesa.org.za NORTHERN PROVINCE Secretary: Rona Fourie Tel: +27 (0)82 742 6364 Fax: +27 (0)86 634 5644 Email: np@imesa.org.za SOUTHERN CAPE KAROO Secretary: Henrietta Olivier Tel: +27 (0)79 390 7536 Fax: +27 (0)86 629 7490 Email: imesasck@imesa.org.za WESTERN CAPE Secretary: Michelle Ackerman Tel: +27 (0)21 444 7114 Email: imesawc@imesa.org.za FREE STATE & NORTHERN CAPE Secretary: Wilma Van Der Walt Tel: +27 (0)83 457 4362 Fax: +27 (0)86 628 0468 Email: imesafsnc@imesa.org.za All material herein IMIESA is copyright protected and June not be reproduced either in whole or in part without the prior written permission of the publisher. The views of the authors do not necessarily reflect those of the Institute of Municipal Engineering of Southern Africa or the publishers.

a higher cost when compared to developed nations. Therefore, ICT pricing needs to be realistic, since communication should never be considered a luxury.

Huge investments It’s exciting to see that there are big numbers being mooted for ICT projects, as reported in the International Data Corporation’s (IDC’s) recently released ‘Worldwide Semiannual Smart Cities Spending Guide’. For the Middle East and Africa region, investments in technology and related infrastructure are rising sharply, with an amount of US$1.26 billion (R15.7 billion) forecasted for 2018. This annual expenditure figure could growth to around US$2.30 billion (R28.7 billion) by 2021. Smart technologies are good for business and their implementation enables city managers to deliver on a range of services far more effectively, and profitably. It also means that smart systems, like water and electricity metering, will help to ensure budgeted revenue inflows are maintained: a critical factor, since a portion of this money needs to be reinvested for routine maintenance and future infrastructure upgrades. Intelligent systems create unlimited opportunities. For example, municipal engineers will be able to monitor and prevent pipeline water losses with far greater accuracy; perfect traffic management systems that minimise congestion; and deploy drones that will do just about everything else. Free Wi-Fi is great, but carefully thoughtout ICT is essential. It’s a multifaceted tool that has real-time benefits for society and the economy.

Alastair Currie To our avid readers, check out what we are talking about on our website, Facebook page or follow us on Twitter and have your say.

struc www.infra

@infrastructure4

IMESA

turene.ws

Infrastructure News

magazine The official of the Institute l Engineer ing of Municipa Africa of Southern

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• SERVIC • MAINTE NANCE

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Cover opportunity

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Technology Trenchless the ilitati ng Rehab Black Mac

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In each issue, IMIESA offers advertisers the opportunity to get to the front of the line by placing a company, product or service on the front cover of the journal. Buying this position will afford the advertiser the cover story and maximum exposure. For more information on cover bookings, contact Jenny Miller on +27 (0)11 467 6223.

Environmenta Engineering Deser t reser

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IMIESA June 2018

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09/05/2018 12.4

President’s comment

IMESA

Engineering

solutions

he recent audit results of South African municipalities for 2016/17 shows that there is room for major improvement. The report, released in May 2018 by South Africa’s Auditor-General, Kimi Makwetu, highlights the fact that a number of key recommendations put forward in previous audit findings are still not being adhered to. The downstream effects include an increase in irregular expenditure and a significant wastage of funds. For the 2016/17 period, 257 municipalities and 21 municipal entities were audited. According to the repor t, only 33 municipalities (13%) were fully compliant and therefore received a clean audit (down from 48 for the 2015/16 financial year). In monetar y terms, this is significant when you consider that the total municipal expenditure budget for the 2016/17 period was R362.13 billion; municipalities with clean audit options only represented R25.68 billion or 7% of this amount. The audit outcomes for South Africa’s eight metros also regressed. As the repor t states, “Although six of the metros produced unqualified financial statements, only 50% had credible per formance repor ts and all of them had material non-compliance findings.”

The Auditor-General identified the financial health of municipalities, fruitless and wasteful expenditure, and the deliver y and maintenance of municipal infrastructure as the three main impact areas requiring corrective action. Regarding the last of the three, the repor t says that factors included the underspending of grants, delays in project completion, poor-quality workmanship, and inadequate monitoring of contractors. However, the construction industr y, in some instances, must also take responsibility from a design-and-build perspective when it’s a case of substandard work. As the Institute of Municipal Engineering of Southern Africa, we are committed to working with our stakeholders, which include the South African Local Government Association, to remedy obstacles that hamper project deliver y. Professionalism is what we stand for and our members, whether employed in the private or public sector, have years of experience that collectively can help to rectify present challenges from an engineering standpoint. This includes ensuring that advice, mentorship, or programme management input is provided by professionally registered IMESA members. Accountancy is outside our domain, but when it comes to accurate and realistic project pricing, we can definitely provide

valuable input. That includes discussions on fit-for-purpose designs, new technologies, proven applications, plus an emphasis on specifying products that comply with South African and international quality standards. IMESA also hosts training workshops and seminars nationally and with the par ticipation of local municipalities. These and other initiatives have a direct bearing on optimal procurement and supply chain management. Let’s make ever y cent count.

IMESA president Gavin Clunnie

IMIESA June 2018

Cover story

Building future water capacity It’s not every day or year that Johannesburg Water (JW) gets to launch two water reservoirs in less than six months.

he Orange Farm and Diepsloot reser voirs were launched in January and March 2018, respectively. These are big, wide concrete structures that form distinctive landmarks. Diepsloot’s stands 12 m tall with a 55 m diameter and the Orange Farm Reservoir is 13 m high and 64.5 m across. Even though they’re imposing in terms of scale, people only really see their true significance if the taps ever run dry. JW is a municipal entity, wholly owned by the City of Johannesburg as sole shareholder, and mandated to provide water and sanitation services to the residents of Johannesburg. The company’s strategic objectives are linked to the shareholder objectives through the Service Delivery Budget Implementation Plan (SDBIP) and cluster plans. JW is assigned to the Sustainable Services cluster. The relation between the company and shareholder is governed through the Service Delivery Agreement (SDA), which is reviewed from time to time. JW provides water and sanitation services to an area stretching from Orange Farm in the south to Midrand in the north, Roodepoort in the west and Alexandra in the east.

IMIESA June 2018

It’s not every day or year that Johannesburg Water (JW) gets to launch two water reservoirs in less than six months.

The company employs 2 655 people and functions within operating regions, with 10 network depots and six wastewater treatment plants. The entity supplies 1 515 MLD of potable drinking water, procured from Rand Water, through a water distribution network of 12 066 km, including 122 reservoirs and water towers, and 37 water pump stations. The spent wastewater is then collected and reticulated via 11 576 km of wastewater networks and 38 sewer pump stations. JW treats 841 MLD of sewerage at its six wastewater treatment works (WWTW), which include one of its biogas-to-energy plants where methane gas is converted to electricity.

The water entity has maintained consistency in building key infrastructure, keeping pace with the growing number of people coming into the city and ensuring a constant water supply to all residents.

Orange Farm Reservoir An analysis of the water network was conducted and it was identified that areas within the Orange Farm water subdistrict required infrastructure upgrading in order to improve residual and peak pressures, and also to accommodate future developments. The analysis identified that the storage capacity in the Orange Farm district had to

COVER STORY

be increased by constructing an additional 33.5 Mℓ reservoir to eliminate current deficiencies in the network and cater for future water demands within the subdistrict. This initiative of constructing the new reservoir was imperative in supplying sustainable water to a developing community.

Feasibility process Building reservoirs is not cheap, and definitely not an overnight job. It can take years and even cost tens of millions of rands to erect a finished product. For instance, it cost in the region of R65 million to fully construct the Diepsloot Reservoir. The project began in 2012 and took five years to complete due to delays in land acquisition.

Diepsloot Reservoir The Diepsloot area was previously supplied directly through a Rand Water bulk main, which was connected to the Pretorius Rand Reservoir. This feed did not provide storage for Diepsloot and surrounding areas including Dainfern and the new Steyn City. The absence of a dedicated water storage facility was a risk in terms of continuous supply and water security to the area. In addition, water requirements for the new development of Steyn City had also become a priority. The objective of this project was mainly to provide adequate water storage capacity for the residents of Diepsloot, Dainfern, Timsrand and Steyn City with a storage retention time of 28 hours. The need for a water upgrade infrastructure project was guided and informed by Johannesburg Water’s network hydraulic analysis and model, which justified the need for this and the other water upgrade project that was implemented in Diepsloot. The project is also critical and strategic for JW’s water supply and distribution in complying with new requirements stipulated by Rand Water. JW now distributes water directly into its network: with the previous arrangement, most water supplied into Diepsloot was directly fed by Rand Water. This project is also a demonstration of JW’s commitment to upgrading services in low-income areas in a sustainable and cost-effective manner in line with its mission statement.

Round or square? “The building of a reservoir starts off with the acquisition of land,” says Nthabiseng Seopela, project engineer, JW. “Reservoirs are one of those structures that cannot be built just anywhere.” The next stage of construction is the planning phase. This involves designing the reservoir, asking questions such as: What will it look like? Will it be round? How tall will it stand? Both the Diepsloot and Orange Farm reservoirs are a similar circular shape. “A circular shape requires less surface area than a square shape that holds the same amount of water. Therefore, it will also require less building material,” explains Nthabiseng. “A circular reservoir is more structurally stable in handling outward directed forces (tension forces). They require less steel for tension. This makes them cheaper than square reservoirs.” After the designing is done, an important aspect that needs to be catered for is the stakeholder consultation. Without proper consultation and approval from stakeholders, it can result in unrest and costly delays for the project. Nthabiseng agrees: “All stakeholders are important, regardless of how minimal their involvement is in the project: they’re essential to the project’s success.” During the 20-month construction period of the Orange Farm Reservoir, 64 skilled

labourers were employed, 14 semi-skilled labourers, and two locals. These were absorbed by Murray & Roberts as part of their incubator programme. They were trained to be general construction foremen, with the possibility of working for the contractors on a full-time basis. With the Diepsloot Reservoir, subcontracting opportunities were created for the local community in the following areas: - brickwork and guardhouse construction - brickwork to valve chamber housings - paving - hand excavation (around existing services) - erection of the entire security fencing.

Future projects JW has already started planning future projects to ensure that residents within the city are assured a constant water supply. These projects include the construction of a Diepsloot tower and a second Diepsloot reservoir.

www.johannesburgwater.co.za

IMIESA June 2018

Municipal Feature | Johannesburg

Surfacing the city

he Johannesburg Roads Agency (JRA) is forging ahead with a range of strategically important projects to keep Gauteng’s economy flowing and growing. The focus is on rehabilitation, upgrades and the building of new infrastructure. The following are some key project examples: • The reconstruction of the Bridge Street Bridge in Klipspruit West. The project began in Januar y 2018 and is scheduled for completion by year end. • The redesign of Jan Smuts Avenue from a single to a dual carriageway: valued at R87 million, this project is being carried out from Nor thwold Drive to Bolton Drive and from 8th Avenue to Kent Road in Rosebank. In addition to reducing congestion on this busy arterial route, the stormwater infrastructure is being upgraded. • The upgrade of the M2 West highway/ Main Reef Road and linked extensions. This project is meant to ease congestion and improve access to the M1, M7, N1 and the R24.

•C onstruction of a pedestrian bridge in Diepsloot is intended to offer residents a safe passageway over moving water and to make provision for future flood events. • The upgrading of gravel sections to surfaced roads in growing communities. So far, the JRA has upgraded around 22.39 km during 2017 and going into 2018. The JRA is close to achieving the 27 km 2017/18 target. • The R30 million rehabilitation of the M2 highway Kaserne Bridge. As part of the scheduled scope of works, the M2 East, M2 West and Mooi Street off-ramp will be affected with phased works. The project will include repairs to bridge joints, bearings, corbel and replacement of guard rails, stolen road furniture and concrete works. • Rehabilitation has also resumed on the iconic M1 Double Decker Bridge. The R169 million project commenced on 5 Februar y and is expected to reach completion by 5 December 2019. The 22-month maintenance and rehabilitation of the 1.02 km bridge is

being rolled out in a phased approach. The scope here includes asphalt sur facing, replacement and repairs to parapets, expansion joints, bearings, and rehabilitative works on concrete members in the super and substructures. Additional carbon-fibre strengthening, replacement of lighting and road signs and repairs to the existing drainage system will also be carried out.

Johannesburg’s road challenge Gravel roads make up 1 168.53 km of the city’s 13 599 km road network. As per the 2017 roads condition study, 72% of gravel roads are in a poor or very poor condition and require reshaping and re-gravelling. A total of 2 852 km of surfaced roads require resurfacing and 3 968 km of very poor and poor roads require reconstruction. The city is presently faced with an R11.8 billion backlog required for the surfacing and gravel roads upgrades. A total of R7.1 billion is required for surfaced roads and R4.7 billion for the upgrading of gravel routes.

Johannesburg’s iconic M1 Double Decker Bridge

IMIESA June 2018

Municipal Focus | Johannesburg

Better, faster delivery Executive Mayor Herman Mashaba

107 billion litres of water was lost through the network in 2016/17

The City of Johannesburg, with its more than four million inhabitants, is facing some serious challenges when it comes to infrastructure and ser vice deliver y. But Executive Mayor Herman Mashaba has a plan: an increase in maintenance and better, faster ser vice deliver y in order to ef fect change.

ashaba highlighted some of the challenges the city faces in his recent State of the City Address (SOCA). However, spend on repairs and maintenance now stands at over 6%, up from less than 2% when he took office.

Roads In 2017, over 3 900 km of roads fell into the classification of being in poor or very poor condition – the equivalent length of road that would take someone from Johannesburg to Nairobi. In addition to this, 100 000 potholes are the result of a R11.8 billion backlog in the road network, while a R56 billion backlog in stormwater drainage contributes to the increasing structural decline of the road network. A further R6.5 billion is needed to address the 78% of Johannesburg’s 900 bridges that are in poor or very poor condition.

Over the past two years, the road network has been prioritised, with 181 000 potholes repaired and 520 km of roads resurfaced. “Our road users on our 13 500 km of road network must experience better roads, fewer potholes and clear road markings. Roads must be dug up and re-laid where they have been allowed to decline to the point where pothole repair is futile. Our 1 000 km of gravel roads, much of which exists in our informal settlements, must start to disappear,” said Mashaba.

Water In the 2016/17 financial year, 107 billion litres of water was lost through the dilapidated water network. “The truth is, Johannesburg would not be able to fight off a drought with the state of our water network,” Mashaba emphasised. “Our water network can be likened to a cartoon character, with their fingers and toes

78% plugging the leaks of bridges are in of a ship. Available poor or very poor data from 2016/17 condition shows that the water network suffered 45 000 leaks per year. This is despite the fact that we know water will be one of the greatest challenges of bulk transformers in our future. are beyond their “While the responuseful lifespan sibility for bulk water supply is that of national government, we as a city must start preparing for a water-constrained future,” he said. To do this, Mashaba has called for investment in water-saving technology and, more importantly, a change in attitudes to support the responsible use of water. Contributing to this, Joburg Water successfully refurbished 37 km of the city’s water pipes in this financial year.

27%

Electricity The city’s electrical infrastructure backlog sits at a staggering R17 billion, with over 27% of bulk transformers ranging between 48 and

IMIESA June 2018

Municipal Feature | Johannesburg

91 years old and operating beyond their useful lifespan. The result is residents suffering 170 000 low-voltage outages in the current financial year alone. According to Mashaba, 39 substations have now undergone complete refurbishment, and repairs and maintenance have been undertaken on 37 transformers.

Housing The housing list stands at 152 000 people, with a need for 300 000 city-produced housing opportunities. However, Mashaba says the unofficial backlog, including those in the ‘missing middle’ of the housing market, is much, much larger, as can be seen in the legacy of backyard dwellings, landlessness and illegal land occupation.

With the spatial mismatch between communities and jobs, studies reveal that most South Africans spend up to 70% of their limited household income on food and transport. To address this, Mashaba called for a diversification of existing townships to include more job opportunities and amenities, as well as the provision of new housing in areas closer to jobs, schooling and public transit hubs. However, he called for the private sector to play a bigger role in the provision of affordable housing. “While government has a number of tools for affordable housing provision, we believe that government cannot address the problem alone,” he said. In this context, the City of Johannesburg, through its Development Planning and Housing departments, is set to introduce an inclusionary housing policy, with the draft currently out for public comment. The draft policy proposes that every new development of 10 dwelling units or more must include 20% inclusionary housing. “I am all too aware of the fact that, for us to stand a chance of providing dignified housing to

Infrastructure Backlogs

Roads: R11.8 billion Stormwater: R56 billion Electricity: R17 billion Housing: 300 000 housing opportunities our residents, we must strike a balance between our objective and incentivising business to buy in to our plan. Our vision is that inclusionary housing, when managed privately, should cater for households with an income of R7 000 or less per month,” said Mashaba.

Effecting change “The job of keeping our infrastructure working will require a delicate balance between repairs, maintenance and refurbishment. This is a monumental task viewed against a background of historic failure,” said Mashaba. In line with this, planning for the 2018/19 budget will focus on rolling out new services as well as ensuring more reliable provision of services for those already receiving them. Ultimately, it means delivering better and faster than before, in order to effect the change so needed in the city.

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Johannesburg is South Africa’s largest city with a population of 4.4 million, projected to reach 7 million by 2040. By Cobus Compion

ohannesburg’s population growth rate of 3.2% (between 2001 and 2011) is well above the national average of 1.7%. This growth has stimulated numerous major development nodes, some as big as small towns – such as Jukskei View, Waterfall City, Main Reef, Modderfontein and Steyn City, to name but a few. Furthermore, the city’s vision to establish a Polycentric City by 2040 will also lead to major densification of the inner city and within the so-called Corridors of Freedom.

Joburg’s big picture Johannesburg Water (JW) has been proactive in ensuring water and sanitation infrastructure expansion, and upgrading is done optimally to meet the growing demand. Realising the benefits of having comprehensive hydraulic models as the basis for planning, JW first appointed GLS Consulting in 2003 to help achieve this

GLS utilises specialist modelling software, Wadiso (water) and Sewsan (sewer), for analysis and evaluation of the systems. The Swift software is utilised to load the hydraulic models with actual water consumption figures extracted from JHB’s SAP billing system. A new version (v. 6) of the GLS software suite has just been launched, which is now fully integrated with a powerful GIS (www.glssoft.com). In addition, stormwater (HydroSWMM) and electricity (Edisan) modelling and planning software packages have been added, and now cover all services.

Municipal Feature | Johannesburg

Ensuring water security through dynamic master plans important milestone. It took nearly four years to establish the original models currently comprising 12 000 km water and 11 600 km sewer pipelines, as pieced together from over 60 000 record plans. Since then, JW has continued this journey by enhancing the hydraulic models and GIS asset databases, which provided the basis for: • dynamic master planning for optimal capital expenditure • risk-based pipe replacement prioritisation • prioritised water conservation/water demand management interventions • calculation of key performance indicators such as non-revenue water and remaining useful life • improvement of Blue Drop performance through water quality modelling • revenue enhancement through the identification of unmetered stands • rapid turnaround of more than 100 impact investigations for new developments • establishment of a reliable corporate GIS and technical asset register • comprehensive and seamless access to management and operational information through a web-based spatial viewer (IMQS). GLS has provided the above specialist services at numerous municipalities, ranging from small towns to large cities, including five of the eight metros in South Africa. However, GLS is particularly proud of its long-term relationship with Johannesburg Water. Unlike normal consulting work, where the focus is on the detail design of infrastructure projects, understanding the big picture in a fast-changing city is

Cobus Compion, senior executive, GLS Consulting

vital to making optimal planning decisions and is a major institutional benefit to the city.

Establishing water-sensitive cities In the next decade, the need to establish water-sensitive or resilient cities, spurred by climate change and growing customer awareness, will present some major challenges for the municipalities of which the impact on the master plans will need to be considered, namely: 1. Revenue security: The increasing awareness of customers to climate change will gradually change their behaviour and water footprint. Continuing with business as usual will reduce revenue from water sales. 2. Water-sensitive design (WSD): Developers increasingly realise the benefits of WSD, which has the objective of harnessing all water sources integrated into the design of the development. Supporting by-laws and operational control will need to be put in place. 3. Smart systems: Technology such as smart meters or smart controllers for pressure management will play a vital role in optimising systems through live monitoring, control and predictive analysis. However, municipalities should consider their readiness by establishing a Smart Cities Roadmap before full-scale implementation. With GLS’s software and services, Johannesburg Water is empowered to make informed planning and operational decisions that increase the reliability of its service provision.

www.gls.co.za IMIESA June 2018

SAâ&#x20AC;&#x2122;S LARGEST PRODUCER OF ACTIVATED CARBON

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Nut shells and filtration Until recently, activated carbon sourced from macadamia nut shells has not been a mainstream choice for industrial users, but an innovative breakthrough by South African pioneer Rotocarb is now leading the way with this cheaper and SANS-compliant alternative.

ctivated carbon has incredible filtration properties due to its adsorption ability and significant sur face area on pore structures. Due to these properties, it is used as a filter medium in water treatment systems (removing contaminants, toxins, bacteria, odours and tastes), the foods industr y (for decolouring downstream products like sugars and wines) and in the mining sector, where it is employed in the carbon-in-pulp or carbon-in-leach process for gold recover y. The largest consumers are the water treatment and the mining processing sectors. “South Africa consumes 800 t per month of activated carbon, over 95% of which is imported – which presented a major

opportunity for us to establish a local production facility to bring down the cost of supply,” explains Jonathan Oldnall of Rotocarb. “We commissioned our first plant in Q2 2017 and commenced commercial production for the South African market in Q4.” Robocarb’s successful compliance to SANS 52903: ‘Products used for treatment of water intended for human consumption – Powder Activated Carbon’ was a vital step in confirming the suitability of Macnut Activated Carbon in the water treatment industry. “Rotocarb values the precious commodity of water and recognises the importance of being able to reduce wastage, and recycle and reuse wastewater,” Oldnall continues.

Rotocarb’s R& commence D initiatives d in 2014 and includ a pilot-sca ed le plant, w hich confirmed the busine ss case fo fully fledg ra ed comme rcial facil ity

“Having an activated carbon product compliant with the standard is core to Rotocarb’s vision of being the leading producer to the water treatment industry in South Africa.”

Activated carbon sources Traditionally, activated carbon is chiefly derived from sources like coal, coconut shells, peat and petroleum-based residues. Rotocarb’s decision to use a macadamia nut shell composition takes an unconventional, but logical approach. South Africa is a major producer of macadamia nuts and the shells are a waste stream with very little prior commercial value. “Our trial work, in conjunction with findings from Australia, also a leading macadamia producer, proved that it is a high-quality

Rotocarb’s first activated carbon facility in Levubu, Limpopo

IMIESA June 2018

Water, Pipes & Valves

source of raw material, well suited for the production of activated carbons, achieving desirable pore structures, high adsorption rates, suitable density, low ash, low moisture and high fixed carbon values,” Oldnall explains. According to Rotocarb, a concer ted emphasis on innovation and efficiency has enabled the company to produce macadamia-derived activated carbon at unprecedented levels in South Africa and its technology has sparked interest from global producers. The company’s focus is on establishing a market for macadamia nut shell activated carbon that places itself between bituminous coal and coconut shell. Oldnall says early adopters are very interested in the findings contained in the company’s analysis repor ts, which has encouraged independent in-house testing to confirm their product’s suitability as a replacement for imported activated carbon materials. Rotocarb has been working closely with these interested parties and the results to date have been promising, particularly in the water treatment and food processing industries.

The charring of macadamia nut shell raw materials

“We’re also receiving strong interest from the regional and broader African market, where we are capable of supplying relatively large orders at far more competitive rates than overseas imports,” says Oldnall, adding that a number of smaller tonnage sales have already been concluded.

Future outlook South Africa’s macadamia industr y is booming and rapidly expanding, with a tenfold increase in shell availability

forecast over the next three to five years. Rotocarb has an agreement in place granting access to a significant amount of this shell resource. “Once the market has fully accepted macadamia nut shell activated carbon, we will expand our product offering into coal- and wood-based derivatives, which already have established applications and markets,” he expands. Longer-term business expansion opportunities, alongside macadamia sources, could include activities in countries like Mozambique or Ghana where coconut shells are readily available. “The growth potential is vast, but we cannot underestimate the strength and experience of our competition. For now, we remain focused on our core product in order to establish a respected brand. “Our greatest challenge lies in educating and proving to the market that a local alternative is available that can match imported quality at local prices. It has been a ver y interesting journey and we are truly excited to see what the future holds for Rotocarb,” Oldnall concludes.

Suppliers of pumps and valves to the mining and industrial sectors for over 66 years.

Water treatment industry

Passion for Pumps

Tel: 011 824 4810 Web: www.matherandplatt.com

Fax: 011 824 2770

Email: info@matherandplatt.com

Physical Address: 26 Nagington Road, Wadeville, 1422, Gauteng

Water, Pipes & Valves

Plugging the leaks Municipalities are faced with a myriad of challenges when it comes to water, including a national non-revenue water average of 41%. By Danielle Petterson

ccording to the Department of Water and Sanitation, municipalities are losing about 1 660 million m³ per year through non-revenue water. At a unit cost of R6/m3, this amounts to R9.9 billion each year. Speaking at the recent WaterLoss2018 conference in Cape Town, Mbali Matiwane, head: Water Quality and Revenue Management, Ekurhuleni Metropolitan Municipality, highlighted some of the challenges South African municipalities face when it comes to water infrastructure and addressing water losses.

Non-revenue water (NRW) All municipalities have plans in place to address NRW, both in the short and long term; However, according to Matiwane, NRW figures don’t seem to decline, despite a spend of roughly half a billion rand per annum on water loss reduction projects such as pipe replacements, pressure management and community engagement. The municipality cannot use minimum night flows to assist with NRW because there are either no district meters areas (DMAs) or, where DMAs exist, they are not metered, or are rendered irrelevant because standby teams have opened all the valves at night.

Free basic water Municipalities are required to supply 6 000 litres of free basic water every month to indigent households. While the intention is to provide low-income households with access to water, some municipalities still supply free basic water to all households, even those capable of paying for services. Municipalities who allocate free basic water only to the indigent and not all households save at least R77 million per annum, says Matiwane.

Ageing infrastructure and inappropriate technical solutions “We repair at least 3 000 pipe bursts per month,” says Matiwane. These are largely recurrent burst pipes, which are not the pipes prioritised for replacement based on the replacement models. The result is that pipes that are often still in decent condition are replaced, while those with recurrent leaks and bursts are not, explains Matiwane. She believes this speaks to a lack of alignment

IMIESA June 2018

between the knowledge available within the municipality and the processes put in place to address the infrastructure challenges. Furthermore, the KPI for pipe replacement within municipalities is expenditure, she explains. Because of this, pipe replacements are rolled out with clear prioritisation and old pipes are often never decommissioned. Pressure management is also often rendered useless by teams on the ground. While pressure management has been used successfully to reduce water losses, Matiwane has seen an increase in vandalism

Water, Pipes & Valves

by repair teams who receive fewer call-outs at night (and less overtime pay as a result) due to fewer bursts, as a result of lower pressures. Leak detection is another solution that works, but it is often poorly implemented and teams frequently dig in places where there are no leaks. There are also too many leaks logged on the system for operations teams to respond to timeously. “Smart metering is a new concept. We don’t understand it much and we are still learning and doing benchmarking,” said Matiwane. In some cases, smart meters are installed without ICT infrastructure and the data is not well understood or properly integrated into the billing system, often creating more problems.

Budget constraints “As water services, we generate at least 40% of the municipal revenue. But when it comes to allocation, we only get 9% of the total budget for the year,” says Matiwane. With this 9%, the target is to reduce NRW by 20%. Matiwane believes that there is always budget available, but it is a matter of politics

H5000 Hybrid Woltmann Water Meter

when it comes to ensuring that budgets are allocated to water projects. Worse still, budgets are often not spent when they are allocated. This is largely because it takes too long to develop and award tenders, as well as implement projects within the financial year.

By-law enforcement While Matiwane believes there are good policies and by-laws in place to govern South Africa’s water, these laws are not enforced. An example is the water restrictions during the recent drought in Gauteng. Despite strict regulations, there is no one available to enforce these restrictions and ensure that offenders are fined accordingly.

Poor metering and billing systems Matiwane describes metering and billing as every municipality’s worst nightmare. This is because many municipalities bill customers based on interim readings, or estimated consumption trends. This is for a number of reasons, including not having access to meters, poorly

installed or damaged meters, obscured numbers on meters, and illegal connections. In many cases, these are not reported by the meter reader. There is also the challenge of unmetered consumption, where new low-cost developments are built in unregistered townships. Because these are not registered, accounts cannot be opened for these households. To address these serious challenges, Matiwane believes municipalities need both technical and management support, political and community buy-in, particularly for water saving initiatives, and sustainable solutions moving forward.

• This meter records ultra-low flows while supporting high flow capabilities, all with one register. • H4000 body can be retro-fitted with new H5000 measuring cartridge (40 -100mm only). • Convert existing bulk meters to combination meter equivalent – field exchangeable mechanism. • Electronic register pre-equipped for AMR/AMI with pulse, encoder, M-Bus L-Bus outputs.

The first choice for municipalities For more information, please visit Elster Kent Metering (Pty) Ltd www.elstermetering.com or call +27 (0)11 470-4900 © 2016 Honeywell International. All rights reserved.

Water, Pipes & Valves

Reducing network leakage and demand Many of South Africa’s water networks are faced with high losses. However, the possibility exists to reduce both leakage and demand at usage points through the use of simplified control elements. By Peter Telle*

ressure reduction in networks ensures reduction of losses through leaks, which are present in most pipe networks.

Ultra ACV pressurereducing valve

Pilot-operated pressure-reducing valves (POPRVs) Traditional pressurereducing valves (PRVs) are pilot operated. These valves normally have two adjustment elements to set the downstream pressure and reaction time of the valve. Although this type of PRV is commonly used worldwide, it is vulnerable to tampering and requires regular maintenance. In the technology of reducing unaccounted-for losses by changing pressures in networks to lower levels during low-demand times,

Maric flowcontrol valve

is tamperproof and virtually maintenancefree. If one wants to reduce pressure from say 12 bar to 4 bar, one installs a 3:1 ratio valve. When the upstream pressure changes, the downstream pressure will change in proportion to the ratio. In other words, if the 12 bar becomes 15 bar, the downstream pressure would increase to 5 bar, which in most cases is not a problem. Careful sizing is also not required with these valves as they have a ver y large ‘rangeability’, which makes them ver y forgiving when there is a large variation of flow rates. They are also ver y resistant to cavitation damage and can handle up to a 5:1 reduction ratio.

Flow control electrically driven controls are added to these valves. This has been proven to save large amounts of water, particularly in areas where leakages are large. The only problem with these valves is their degree of sophistication, which requires a high level of technical expertise and effective maintenance programmes by the end user. On the African continent, maintenance is not high on the agenda and often the only way to ensure continued operation of these systems is to implement expensive maintenance programmes with control valve companies.

By reducing flow rates to usage points, consumption will be greatly reduced. Think about flow from a shower head – if the pressure is higher than say 2 bar, an excessive flow rate will be delivered when the tap is opened. While this may be no problem for most, think of the wastage of water if pressure at the shower head is,

Ratio-reducing PRVs (RRPRVs) These valves reduce pressure in a ratio between upstream and downstream pressure and operate without pilots. It is the simplest form of pressure reduction,

Ratio-reducing valve

IMIESA June 2018

Water, Pipes & Valves

say, 4 bar or even 6 bar. Through the installation of a ver y simple flow-control valve at each usage point, large volumes of water can be saved. One such device uses simple control rubbers, which are calibrated for a particular flow rate and available in sizes from 10 mm to 400 mm. Larger sizes can be engineered without difficulty. *Peter Telle is the CEO of Ultra Control Valves.

Pilot study Below is a water and electricity cost-savings calculation for domestic households in Australia. Maric flow-control valves automatically maintain a fixed, maximum constant flow rate, and are often used to save water in homes, motels and commercial buildings in the following outlets: showers, kitchens, sinks, and bathroom basins. The following calculations demonstrate how an average home can save A$447.00 (approx. R4 200) per year after installing Maric flow controllers to just the shower alone. The fitting of flow controllers to kitchen and bathroom basins, etc., will further increase savings. Assumptions Water saving calculations: Assume an 8 ℓ/min shower flow controller is installed. 8 ℓ/min will be saved x 40 minutes = 320 ℓ/day. 320 x 365 days = 117 000 ℓ per year saved. 117 kℓ x $1.634 per kℓ = $191.00 per year saved. Electricity saving calculations: Lift in temperature required is 27°C (43°C shower temp, minus 16°C incoming temp). If 1.0 kWh heats 100 ℓ by 8.5° C, 1.0 kWh heats 31.5 ℓ by 27° C. Therefore, 3 714 kWh heats 117 kℓ (saving) by 27°C. 3 714 kWh x $0.069 per kWh = $256.00 per year saved. Total annual savings: Savings per year for water: $191.00. Savings per year for electricity: $256.00. $447.00 total annual savings per hotel room or family home in the shower only. Further savings will be made by installing valves in the kitchen and bathroom basins also. Conclusion: if Maric valves retail in Adelaide for around $20, it will take around one month for the valve to pay for itself. • Family size: four people • 4 x 10 minute showers per day = 40 minutes • Shower consumption without Maric valve = 15 ℓ/min x 40 = 600 ℓ of warm water • Average ambient water temperature 16°C • Average shower water temperature 43°C • Cost of water 1 kℓ = $ 1.634 • Cost of electricity $0.069 per unit (1 unit = 1 kWh) • 1 kWh heats 100 ℓ by 8.5°C (this is a known constant) The above example can be used in any domestic, commercial or industrial scenario where water is used. A pilot study is currently being implemented in a large Cape municipality using both ratio-reducing valves and Maric flow controllers.

Water, Pipes & Valves

The business case for The Southern African Plastic Pipe Manufacturers Association (SAPPMA) is the industry’s quality control gatekeeper and its members are bound by a code of conduct. IMIESA recently accompanied Jan Venter, CEO, SAPPMA, on a visit to one of its members to view excellence in practice. By Alastair Currie

iven the critical importance of water and sanitation infrastructure, the correct specification and installation of plastic pipe products and systems is non-negotiable; however, in South Africa, there are times when lowest-cost pricing

impacts on the end result. SAPPMA’s members contribute around 70% of the overall supply and the aim is to progressively bring the rest of the non-member producers into the fold. “SAPPMA membership is voluntar y, but with it comes an agreement to adhere to strict standards, which includes permission to allow regular factor y audits to ver-

Jan Venter, CEO, SAPPMA

ify compliance,” Venter explains. “Where problems are identified, members are given ever y opportunity to rectify quality issues. Non-compliance will result in the termination of membership, since the

Manufactured products stored at Marley Piping Systems’ facility in Rosslyn

IMIESA June 2018

Water, Pipes & Valves

Maintaining the SAPPMA mark • Members must be ISO 9001 listed or alternatively pass a SAPPMA systems audit • The member’s CEO is required to sign a code of conduct and letter of undertaking annually • Members must agree to regular and unannounced factory audits • Product samples must be submitted for testing at certified laboratories according to the applicable national standards • No heavy metal stabilisers are allowed in the manufacture of PVC pipes and fittings

right to carr y the SAPPMA mark cannot be compromised despite the cost pressures facing our industr y due to subdued construction activities.” Over the past years, the average raw material price for high-density polyethylene has increased by approximately 75%. Around 50% of this material is supplied locally by Safripol, with the balance imported and affected by the rand/dollar exchange rate and oil price fluctuations. For the same period, the average selling price for pipe only went up by around 26%. That translates into a raw cost currently of approximately R22/kg,

IMIESA June 2018

There are polymers specifically designed for pipe applications to ensure their durability according to SABS stipulations

and an end-product selling price of close to R28/kg. Once overhead costs are subtracted, this allows for a ver y narrow profit margin, with minimal funds available to reinvest in business processes. The risk that this scenario presents is that some manufacturers may be tempted to take shortcuts to stay in business, which is definitely not going to be sustainable in the longer term.

Industry statistics Around 140 000 t of plastic pipe is produced annually in South Africa, representing sales of more than R2.5 billion. About 85% of the polymer used is locally produced, consisting predominantly of PVC and HDPE. Plastic pipe has now captured a dominant share of the South African water distribution and sewage disposal markets.

Water, Pipes & Valves

SI ST

AL O

THE SAPPM

The SAPPMA stamp of approval appears on every product produced by members and serves as a quality guarantee

AL O

Given the correct processes, plastic pipes will last more than 100 years, providing an excellent return on investment. For this reason, there are polymers specifically designed for pipe fabrication to ensure this durability according to SANS specifications. These polymers can represent up to 80% of the product manufacturing cost, but form the essential base component. Substandard pipes might look the part, but they will fail within a few years of installation, which could result in catastrophic incidences, like the formation of sinkholes following leakages, a factor that needs to be taken into account particularly in the Gauteng region. Then there are the broader potential health risks to communities. The decisions taken today will have a lasting impact, positively or negatively, on South Africa’s infrastructure environment. SAPPMA is currently drawing up a product quality plan, which will set out the minimum manufacturing standards. This will then be used as the minimum level for auditing. It might also become part of the ISO 9001 system adopted by companies, becoming an integrated component of their quality management procedures. “Private and public sector clients have a responsibility to ensure that ever y plastic pipe specified carries the SAPPMA mark,” Venter concluded.

Virgin material only There are instances, for example, where non-SAPPMA members purchase scrap plastic pipe from the secondar y market and recycle it without knowing where it was previously used. For example, these second-hand products might have been employed in a sewage application, or exposed to chemical contamination. That’s a major issue for SAPPMA, since one of its assumptions is that members do not use second-hand recycled materials, given the downstream risk for potable water users. Therefore, no provision has been made for the chemical testing of pipes and the onus for responsible manufacturing rests with the industr y. “As an industr y, we need support from the market and recognition of the vital importance of maintaining the highest standards to protect consumers,” said Brett Kimber, managing director, Marley Pipe Systems, speaking during the visit to the company’s Rosslyn factor y. “We’d also recommend setting a minimum gate price to preser ve the sustainability of the plastic pipe manufacturing sector. We stand behind SAPPMA’s initiatives. It’s

Importance of polymers

“It is very difficult to visually detect poor-quality pipe.”

all about positive education so that the market understands the essential cost of quality.”

SASTT Trenchless News

Rehabilitating the Black Mac The Black Mac is one of the largest single sewer projects undertaken in South Africa and a showcase for the innovative use of cured-in-place pipe (CIPP) lining technology .

onstructed in 1983, the original 14.4 km long Black Mac bulk sewer consisted of epoxy tar-coated asbestos cement pipes, ranging in diameter from 400 mm to 1 000 mm. This system drained an area of 24 km2, which included Blackheath Industria, Dennemere, Eerste River, Kleinvlei and Macassar, culminating at the Macassar pump station and wastewater treatment works (WWTW). The sewer crosses under several roads, including the N2 national highway (via a DN 1 117 jacked concrete pipe, with false invert and low-flow channel) and under the Eerste River by means of two parallel DN 300 siphons.

With the construction of the new Delft bulk sewer in 2008, the flows from the upper drainage areas were diverted to the Zandvliet WWTW to alleviate the hydraulic overloading at the Macassar WWTW. Flows from the lower catchment (Kleinvlei and Macassar) continued draining into the Macassar WWTW. With subsequent increasing flows into Zandvliet WWTW, the City of Cape Town then decided to reconnect the upper and lower Black Mac catchments. However, the hydraulic performance and condition of the sewer first had to be assessed, with Aurecon South Africa appointed as the consultant for the project. As-built information, including as-built drawings to confirm the original pipeline properties, such as age, pipe material, wall

Black Mac UV light for the DN 1 200 pipe

IMIESA June 2018

Project statistics Client: City of Cape Town Consulting engineer: Aurecon South Africa Trenchless contractor: Tuboseal Contract value: R34 148 440 Completion date: 16 November 2017 • 3.4 km of DN 800 thermally cured unreinforced CIPP liners with thicknesses from 12.5 mm to 17.5mm • 60 m of DN 1 000 thermally cured unreinforced CIPP liner with thickness of 19.5 mm • 70 m of DN 1 117 non-circular UV-cured reinforced CIPP liner with thickness of 14 mm • Inversion lengths ranging from 70 m to 171 m • 132 894 kg resin used

thickness and internal diameter, formed the basis for the condition assessment. A topographical survey confirmed the pipeline gradient, cover and physical constraints. This information was combined to determine the extent of corrosion and the system’s remaining useful life, considering the loss of wall thickness in conjunction with the actual external loads. Based on this, the most appropriate rehabilitation technique was chosen and the impact of this on the hydraulic capacity determined.

SASTT Trenchless News

The new sewer was constructed parallel to the existing Black Mac sewer. Once the new line was completed, the existing sewer was then decommissioned, cleaned and filled with a bentonite mixture

Condition assessment findings The assessment concluded that the sewer reaches upstream of the Black Mac screening station were not severely corroded and had an estimated remaining life of 30-plus years, which was adequate. However, the severity of the corrosion increased as it proceeded downstream.

Along some reaches downstream of the siphon, as much as 20% of the pipe walls had been lost, reducing pipe strength by up to 63%. The original pipe’s internal bitumen coating had offered some corrosion protection. However, in the lower portion, this protective coating had dissipated.

CIPP approach

The most suitable rehabilitation method was deemed to be CIPP. It was decided that the reaches upstream of Old Faure Road had an adequate remaining life and did not require rehabilitation immediately. Between Old Faure Road and the Eerste River siphon, the sewer would be rehabilitated using CIPP. Meanwhile, the section downstream of the Eerste River siphon up to the Macassar pump station was replaced with a new sewer to ensure sufficient capacity. The new sewer, ranging in diameters from DN 900 to DN 1 200, was constructed parallel to the existing Black Mac sewer. Once the

new line was completed, the existing sewer was then decommissioned, cleaned and filled with a bentonite mixture. This will ensure that the integrity of the decommissioned sewer is maintained and can be reactivated in the future, if required. The final reach of the sewer (DN 1 000) immediately upstream of the Macassar pump station was also rehabilitated using CIPP technology. It would have been excessively expensive to replace it due to the restricted area available at the pump station.

Rehabilitation contract Construction commenced on 1 November 2016 with all works completed just over a year later. Tuboseal Services was appointed as the contractor. Following bulk cleaning, physical measurements were taken to confirm the host pipe ovality so the CIPP liner could be designed to the thickness required. Once the structural design was confirmed, the CIPP liners were ordered from a leading manufacturer in Europe. The 26 liners were all unique in terms of their length, diameter and wall thickness, which underscored the

WINNER SASTT AWARD OF EXCELLENCE 2017 FOR WORLD-FIRST PIPE REAMING IN TSHWANE

YEARS

Pipe Bursting • Sliplining • CIPP UV Cure • CIPP Ambient Cure Ribloc Expanda • Ribloc Ribline • Ribloc Rotoloc • Pipe Reaming Horizontal Directional Drilling • Guided Rock Drilling • Bores of 1400mm Lengths up to 1000 metres • Microtunnelling • Pipe Ramming

www.trenchless.co.za +27 (0)86 006 6344 info@trenchless.co.za

SASTT Award of Excellence 2007, 2009, 2015 & 2017

SASTT Trenchless News

importance of working accurately and to the highest installation standards.

Installations Each installation involved a carefully coordinated sequence of events taking around 48 hours. The working window before the resin-impregnated liners start to cure meant that once the process started, it could not be interrupted. Teamwork was critical: the consequence of liners curing prematurely would have severe financial implications, as would the time delays required to ship in a replacement liner. The installation team completed the final cleaning and inspection on each reach, while the impregnation team prepared the felt liner tube by impregnating it under factory conditions with up to 7 tonnes of catalysed resin. Each liner was transported to site submersed in ice and installed by an inversion process, during which the liner is folded inside out using water pressure. A 1 450 kW hot water boiler was used to initiate curing of the resin over a period of about 15 hours, during which the temperature

and other parameters were carefully monitored and controlled to ensure liner consistency and integrity. Each cured liner was carefully cooled down, trimmed and inspected by CCTV. A test sample from each section was submitted to an independent lab for verification of its mechanical properties. All manhole chambers were rehabilitated using specialist materials designed to withstand chemical and sewer gas attack, ensuring that the lifespan of the manhole structures could be extended to match that of the CIPP liners. The manhole rehabilitation also included replacement of step-irons, cover slabs and improving the hydraulics by amending the benching. Where it was found that the existing manhole design negatively influenced the system’s hydraulic performance, complete new manhole structures were constructed.

N2 crossing The contract included the rehabilitation of the jacked crossing under the N2, which posed quite a technical challenge. Through collaboration, an effective solution was found. Originally, the intention was to remove

the false invert, rehabilitate the badly corroded sections of the DN 1 117 pipe by replacing the lost reinforcing steel and apply a structural repair grout before installing a circular CIPP liner to prevent any further corrosion. The removal of the 70 m long false invert proved too time consuming and dangerous within the confined working space inside the pipe. Tuboseal proposed to leave the false invert and design the CIPP liner as a non-circular section. After evaluating both unreinforced and reinforced liners for this crossing, a 14 mm UV-cured reinforced liner was considered the most appropriate solution. The UV-cured liner was procured from Saertex in Germany and installed under the guidance of Saertex technicians. The Black Mac project demonstrated that the use of world-class pipeline rehabilitation techniques is highly feasible and effective and underscores the engineering and design prowess of South Africa’s trenchless rehabilitation industry. As in Cape Town’s case, municipal clients can reap significant benefits from the reduced costs, timelines and environmental impacts that CIPP technology has to offer.

Odour Control

Intelligent chemistry Odour control has moved from an afterthought to a primary design consideration for most collection and treatment facilities. By Annejan Visser*

ntensive urbanisation, incremental population growth, and seasonal temperature rises within metropolitan areas have increased the likelihood of exposure to odour generating facilities. This, together with the additional need for corrosion control of waste pipelines and the health and safety of municipal personnel, has made odour control requirements more prevalent in recent times. Quality Filtration Systems (QFS) identified the local need for improved odour control measures at wastewater treatment plants and other odour generating sources, which led to the company concluding a technology partnership with Integrity Municipal Systems (IMS). Based in Poway, California, IMS is an odour-specific engineering company with over 20 years’ experience devoted to the design, manufacture and supply of innovative, preassembled odour solutions for the water and wastewater industry. Cost-effective vapour phase technologies available include: • biofiltration – a biological technology with low operating costs (I-BOxTM Biological Oxidation Systems) • wet or chemical scrubbing – a reliable technology for chemical treatment • adsorption – a well-established technology using dry media (BCS Series bulk carbon adsorbers).

In selecting a cost-effective odour control solution, it’s important to note the following important parameters: • required air flow or ventilation rate • the peak and average hydrogen sulfide (H2S) concentrations in the odorous air • the required level of odour removal (concentration of H2S and odour units). What sets IMS’s systems apart from other commercially available high-volume chemical scrubbers is the small construction footprint required for treating large air volumes. The chemical package system offered provides key advantages, such as: • unitary construction of the treatment vessel • a fibreglass exhaust fan with longer durability • a vessel deck for ease of access to equipment. Current developments have also been made with IMS to provide ‘high-capacity’ activated carbon for towers that are: • water regenerable • naturally high in minerals • sulfur selective. Biotrickling filters (utilising sulfur-oxidising bacteria to biologically oxidise the H2S and other sulfur compounds to soluble sulfates) is another technology proving popular at municipal facilities.

Among the benefits of the I-BOx biotrickling system is its ability to accommodate high air flow rates. For example, the I-BOx can accommodate flow rates of 450 m3/h per m2 compared to 100 m3/h per m2 for conventional organic biofilters. Other advantages include the long media life of the inorganic media utilised, due to the preferential development of autotrophic bacteria, and quick acclimation of bacteria on media to start immediate H2S removal. The system targets inorganic (H2S) and organic odours, has a compact design due to a skid-mounted assembly, and a low operating cost. The other great advantage of the biotrickling system is the longevity of the media compared to carbon absorbers. Important to note with biotrickling filtration is the generation of sulfuric acid, which requires adequate sealing and bunding of the system, as well as the proper disposal of the waste sulfuric acid generated. QFS recently installed and now operates six I-BOx systems at Cape Flats valve chambers, with another system installed at Reeston WWTW in East London. Both are functioning optimally. *Annejan Visser is a process engineer at QFS.

IMIESA June 2018

Environmental Engineering

Desert reservoirs

MSE constituent materials

Constructed in 2009, Trekkopje Uranium Mine’s reservoirs have proved the benefits of mechanically stabilised earth (MSE) technology, successfully withstanding the Namib. Fast-tracked construction was a key consideration for going the MSE route, plus the need to counter aggressive corrosion and elevated temperatures. Another factor was the 70-year design life required.

uring January 2008, tenders were called for various aspects of the water supply scheme for the proposed greenfield Trekkopje Uranium Mine, located in west-central Namibia. This included the construction of a terminal water storage facility that would be connected via a 50 km pipeline extending inland from the Atlantic seaboard. This facility’s purpose: to store desalinated seawater for use in the uranium recovery process. Sealing of joints

IMIESA June 2018

The design brief called for the building of six adjacent and interconnected reinforced concrete water retaining structures, complete with concrete roofs. Each reservoir was to have a capacity of 9 Mℓ, making the total capacity 54 Mℓ. The project needed to be completed in eight months. One of the tenderers, Target Projects, argued that it was not possible to complete the construction of the required design in the stipulated period and offered an alternative solution. This consisted of two 27 Mℓ units composed of MSE walls with lined vertical inside faces and a 1V:2H outer embankment slope. The sidewalls and floors of the containment area would be covered with an impermeable geosynthetic liner. The alternative concept also provided for a rigid concrete roof, as per initial design requirements: the sidewall construction would be MSE; the roof would be a reinforced concrete skeletal structure with precast slab covering units. The roof requirement was subsequently omitted by the client. In the end, the alternative proposal was accepted for the following reasons: • shorter completion time

• s impler process to dismantle and rehabilitate at the end of the mine’s life • ver tical sides to accommodate a rigid roof structure (although not subsequently adopted) • cost advantages • flexibility and suitability for poor founding conditions. (The geology consists of granite overlain by residual granite sand of varying depth. These residual soils have a high chloride and sulphate content.) The design and supply of the materials for the construction of these MSE reservoirs was provided by Reinforced Earth South Africa (Pty) Ltd.

Reservoir geometry The original water depth of 6.5 m was retained giving a reservoir size of 64.5 m x 64.5 m x 6.5 m deep. The overall depth of 7.5 m (0.5 m freeboard and 0.5 m embedment) was the maximum height. A precast concrete cladding 1.5 m x 1.5 m x 0.14 m thick was selected. This shape and thickness obviated the need for any reinforcing and minimised the joint lengths. The cladding was cast on-site by the contractor.

Environmental Engineering

Rubber pads placed on the horizontal joints provided cladding flexibility. The joints are 20 mm wide ship lap joints backed with a polypropylene geotextile to allow moisture, but prevent loss of fines through the joint. Geosynthetic reinforcing strips are connected to the cladding by way of a fully synthetic connection. To meet the required 70-year service life, strength, and an assumed temperature of 25°C, the following reduction factors were taken into account before applying an additional safety factor of 1.25: • damage to the reinforcing strips during installation – 0.98 • creep – 0.89 • chemical and biodegradable loss – 0.63.

Lined MSE walls provide economical and stable containment for open reservoirs.”

The completed reservoir

Constituent materials The locally available sands were used for both the common and MSE backfill. The high salt content of the backfill falls out of the specification for metallic reinforcing strips, whereas backfill with a pH between 3 and 9 is acceptable for polyester reinforcement. A synthetic strip comprising high-density polyester fibres bound in a low-density polyethylene sheath was selected. Synthetic sleeves were cast into the panels, providing a fully synthetic connection.

Internal and overall stability The internal stability was designed according to the coherent gravity method. In this

method, the tensile forces to be resisted at each layer of reinforcement in the structure are calculated and sufficient reinforcement is provided to ensure the following internal failure modes do not occur: • tensile rupture at any point along the length of the reinforcement • tensile/shear failure at the connection between the reinforcement and the facing element • loss of frictional bond (adherence) between the reinforcement and the soil fill.

About MSE

Having determined the tensile forces at each layer of reinforcement, the number of strips required to resist them was calculated. This was based on the long-term design strength of the strips/connections and the frictional force (adherence) that can be generated between the strip and the fill. The overall stability was checked for two cases as follows: • the outward failure of the embankment fill (away from the water) with the reservoir being full and a range of leakage rates through the vertical wall lining • the failure of the central wall between the two compartments, with one compartment being full and the other being empty.

Drainage MSE is a composite material comprised of granular backfill, reinforcement and a discrete cladding. The cladding can be of various sizes and materials. In the case of reservoirs, this usually takes the form of unreinforced, square or rectangular precast concrete panels. Waterproofing is achieved using an impermeable geosynthetic membrane.

Select granular fill Reinforcement Facing

A grid-type underdrainage system, comprised of standard slotted pipes surrounded by crushed stone and wrapped in a nonwoven geotextile, was provided to detect the location of any leakage. A design assumption was that no phreatic line would exist within the MSE mass. A saturated soil mass would cause a reduction of the friction angle under effective state conditions, as well as reduced adhesion to the reinforcements.

IMIESA June 2018

Environmental Engineering

The case for MSE Reservoirs

The cover membrane lining was welded and positively attached by means of an anchor sheet cast into the coping

This scenario could arise should a significant leak occur in the reservoir’s side lining. To prevent the risk of leakage, a vertical drainage system was sandwiched between the liner and the MSE cladding, with the flat side against the cladding. A conduit was thus provided to lead possible water leakage from the reservoir side walls to the underfloor drainage system. The cladding joints represent 3.3% of the cladding area. Any leakage from the lining would be accommodated by the joints, which were linked to the drains beneath the cladding.

Hydraulic considerations Top inlets were provided to each reservoir to accommodate a flow rate of 900 ℓ/s. The inlet bases were surrounded by a 4 m diameter concrete apron, which serves as a support base for four struts that support the vertical glass reinforced plastic (GRP) pipe. The concrete base also serves as a splash pad when the reservoir is empty. The outlet was a 1.5 m diameter sump type manufactured from GRP. The depth of

Despite flash flooding, the kerbing and down pipes have prevented any erosion of the embankment

the outlet from the sump was sufficient to prevent vortex formation within the storage volume. An upstand was also provided to prevent sludge being drawn into the outlet. The siphon overflow has a capacity of about 5 000 ℓ/s; and the TWL rise in order to spill 900 ℓ/s was 280 mm. Other design considerations included an internal stainless steel access ladder complete with safety cage, which was provided for each reservoir, and 4 m x 3 m reinforced concrete manhole to accommodate two valves on both the inlet and the outlet.

Follow-up visit After the initial pilot stage ended in 2013, full-scale production at the mine

Lining and inlet structures (2016)

The basic principle of an MSE reservoir is to provide a structure for a vertical wall reservoir that can be waterproofed using a geosynthetic material. The advantage of this is that a roof can be added. Many local authorities have security issues around floating roofs and protection is warranted. Excluding the roof, the structure can be built without any metallic reinforcement elements in the MSE wall: no reinforcements are needed for the concrete cladding panels and geosynthetic strips to support the soil volume behind the cladding. This improves structural durability in an aggressive environment. MSE reservoirs require suitable soil backfill material to accommodate frictional and drainage needs. In many cases, this may be achieved by partially excavating the planed area of the reservoir to lower its planned base level and using the excavated material as the backfill. The mass gravity nature of MSE sidewalls requires a larger footprint than conventional reinforced concrete sidewalls. It is, however, often a requirement to aesthetically improve reinforced concrete structures by covering them with soil. The MSE reservoir does not attract this extra cost.

was mothballed pending optimal economic conditions. During an inspection in 2016, the two reservoirs were at 20% and 30% capacity, respectively. Reser voir water is being used for drinking water, mine maintenance and leach pad trials. No leaking has been detected from the reservoirs after seven years of operation. Since the reservoirs are not covered, loss of water is solely due to evaporation, which is approximately 2 m per annum at the mine. The lining appears to be in good condition and no maintenance or replacement lining is envisaged in the foreseeable future. This is also true of the GRP inlet pipes. Overall, the most recent analysis underscores how well MSE reservoirs withstand the test of time. This is an edited version of a paper written by Andrew Smith (Reinforced Ear th), Louwtjie Maritz (Reinforced Earth), and M Bosman (Target Projects). IMIESA June 2018

Environmental Engineering

Walls of stone

With the right approach, gabions will last for many decades, but designers must take into account the soil erosion and water ingress factors, for both land-based and river structures. Louis Cheyne, managing director, Gabion Baskets, expands on the best techniques, citing recent projects and an aesthetic example. By Alastair Currie

here are various standard design options when it comes to constructing gabion riverbank protection structures. However, practical experience has shown that a cross pollination needs to be adopted in perfecting a model that optimises the final structural integrity: each site has its own unique soil characteristics and hydrology. The right approach depends on the river depth from a founding perspective and, in all cases, an integrated gabion mattress configuration is needed to counter erosion – since this could lead to subsequent undermining. In some instances, the wall will rest on the riverbed itself, or on a mattress, loose rock or sausage gabions. A detailed site assessment will determine how the designer should proceed. “Any structure that you build in a river is going to be tested. Designers need to conduct a detailed anaylsis of the hydrology to ensure that gabion structures effectively channel the passage of water, for example, by always ensuring that adequate wing walls are in place. Otherwise, they end up being outflanked, submerged or even swept away during storm and abnormal flood conditions,” Cheyne explains. “It’s always best to ensure a fail-safe solution.”

Deep river erosion A recent example in Franschhoek, Western Cape, underscores this observation on a residential estate bordering a river where up to 6 m of embankment erosion occurred. As an indication, the river depth during flood conditions is around 20 m. The original gabion baskets were installed here up to 40 years ago, which isn’t a major issue in terms of longevity.

IMIESA June 2018

Bank protection structures Structure with deep foundation

Gabion structure built on apron

Environmental Engineering Structure with loose stones

THE FOUR MAIN BANK PROTECTION OPTIONS Structure with deep foundation A gabion wall founded to a depth of at least 1 m below the anticipated scour hole. Structure built on top of a loose rock fill The rock material fills in the undulations on the riverbed, providing a levelled area for the building of the gabion retaining wall. However, there’s always the risk that high water velocities can wash away parts of this rock foundation. A better and more durable alternative is to place a gabion mattress on top of the rock layer for extra structural integrity, followed by the retaining wall.

Structure with cylindrical gabions

Structure built on cylindrical gabions Here, the retaining wall rests on a bed of sausage gabions (also known as cylindrical gabions). These are usually 2 m long, 650 mm diameter baskets packed to 75% of capacity. Unlike a conventional box-shaped gabion, the cylindrical variety has an intentionally looser fill so that it uniformly blends in with other overlapping sausage gabions. Structure built on an apron mattress A gabion wall built on top of a flexible mattress apron should have a minimum recommended length of 2 m. If the mattress length is too short, this will result in erosion and the subsequent sagging or collapse of the gabion wall.

However, the baskets had been incorrectly placed and the percentage of voids between the stones was too high. The consequent movement of the stones then caused extensive failure of some of the baskets given the intensity of the water velocity. Another contributing factor was the non-galvanised wire material used, which led to extensive corrosion and subsequent failure. In addition to importing fill material, the contractor constructed a 44 m long wall, which follows the natural river contour. The wall varies in height from 1 m to approximately 2.3 m and rests on a mattress apron. In some cases, new wall sections have been built on top of

the existing gabion baskets – the latter having been rebuilt. All gabion structures are now galvanised and PVC coated for an envisaged life of at least 50 years. Mature trees are also protected by boxing them in with gabions to divert the water from their root systems. For this project, 2.7 mm diameter mesh was specified: a 3.0 mm thickness is also available where longer-life durability is a requirement in more extreme conditions.

Thembalami Care Centre “The intensive rate of urbanisation is inevitable,

but it also means that the increase in hard surface areas takes a massive toll on river systems,” Cheyne continues. “One of the recommended and now legislated interventions is the construction of attenuation ponds that capture stormwater run-off from residential and commercial developments, slowing down the rate of seepage into river systems. The upside is that these ponds can also provide productive features alongside environmental interventions.” A recent example is the construction of an 80 m x 40 m stormwater control dam for the Thembalami Care Centre in Lombardy, Johannesburg. The design also caters for

IMIESA June 2018

Environmental Engineering THEMBALAMI CARE CENTRE

A Gabion Baskets instructor demonstrates the correct placement for the gabion mattress on top of the geotextile

A completed outlet section designed to feed into the attenuation pond

The downstream spillway connects to the river and caters for overflows from the attenuation pond

rainwater harvesting, with water run-off from the roofs in the development channelled through to the pond. As a further plus, the residents of this retirement village now use the stored water to irrigate a viable market garden. Gabion Baskets assisted with the design, gabion material supply, bill of quantities, site training, and commercially sourced stone.

Building systems Alongside their river applications, gabions have been used for centuries as wall retaining structures for a wide range of building uses and also increasingly as aesthetic elements. A case in point is the installation of a series of walls at a major hospital in Alberton, Johannesburg. Here, low-lying gabion walls proved to be the most robust solution for the containment area around the facility’s helipad. A 1 m high and 0.5 m thick gabion wall also forms part of the hospital’s entrance. These have been purpose-designed with recessed sections to make provision for plants. The installations employ square welded mesh as opposed to the hexagonal woven mesh configuration used for river systems. As Cheyne points out, hexagonal wire mesh is designed to cater for some level of flexibility. Welded mesh should never be used for rivers, as it’s too rigid and will shear under sustained hydraulic pressure. “Gabions have become a mainstay for architectural designs and sometimes clients specify Class B or C wire (which is lightly galvanised and so tarnishes a lot quicker), or black wire, which is completely nongalvanised: the intention being to create a deliberately ‘weathered’ or rusted appearance,” Cheyne continues. “Class A (heavily galvanised) wire, and Galfan, which is a 5% aluminium alloy wire, are the top-of-the-range products. Galfan wire generally offers double the life expectancy of Class A galvanised: it will tarnish to light grey but, beyond that, remains unaffected by the elements. Add a PVC coating and it will last for a lifetime,” he concludes.

Landfills

Waste strategies explored Projects identified in the first phase were based on comprehensive feasibility studies developed by JG Afrika and RWA

ies developed by JG Afrika and RWA. The municipalities selected the best suited scenarios and the firms also assisted them in drafting implementation plans that were both practical and financially viable.

Key personnel and participants Richard Emery, a specialist integrated solid waste engineer and strategist at JG Afrika, will once again lead the South African team. Other key JG Afrika personnel include Stuart Gower-Jackson, a specialist environmental scientist and statistician, and Jefrey Pilusa, a biomass-to-energy champion and process engineer. Emery says JG Afrika’s long track record in the African waste management sector, depth of experience and individual qualifications place the firm in an ideal position to gain further momentum during the second phase of the project. Work on the second phase started in November 2017, commencing with engagements, waste characterisation studies and site visits at the various municipalities. Similar to the pilot phase, one metropolitan and five local municipalities will participate. They comprise Buffalo City Metropolitan Municipality, JB Marks Local Municipality, King Sabata Dalindyebo Local Municipality, Steve Tshwete Local Municipality, Mogalakwena Local Municipality and Newcastle Local Municipality.

Reducing landfill greenhouse gas emissions can also unlock commercial opportunities, the key to which is equipping municipalities with viable action plans. A landmark programme is under way to achieve this.

ollowing the successful completion of the pilot project, JG Afrika will continue with the second phase of a groundbreaking environmental initiative. The focus is on helping municipalities formulate business plans and strategies that divert organic waste from their landfill sites. Key components include selfsustaining job creation opportunities at various skills levels. The project also makes provision for learnership and the training of officials. In the broader context, the intention is to identify areas for strategic intervention that advance the objectives of both the National Climate Change Response Policy and the National Waste Management Strategy. Each individual project in the pilot and second phase focuses on emission re-

duction, including methane with its greater global-warming potential than carbon dioxide. The project is also part of the South African Department of Environmental Affairs’ (DEA’s) Near-Term Priority Waste Management Flagship Programme. It is being funded by the German Federal Ministr y for the Environment, Nature Conser vation, Building and Nuclear Safety, and implemented by the Deutsche Gesellschaft für Internationale Zusammenarbeit in partnership with the DEA. In round two, JG Afrika will again be working with a strong multidisciplinary team, including RWA, a Europe-based cooperative of specialist waste and climate change advisors, and Pegasys Capital, with its team of financial and institutional experts. Projects identified in the first phase were based on comprehensive feasibility stud-

Lessons from round one Emery says that many lessons were learnt during the pilot phase that will be applied this time round to significantly improve interaction with and between municipal representatives. “We want to increase the frequency of time spent on formalised learnership

IMIESA June 2018

Landfills The challenge of managing municipal waste needs urgent interventions

A waste classification exercise being undertaken by JG Afrika team members

Projects identified in the first phase were based on comprehensive feasibility studies developed by JG Afrika and RWA.” with the municipal representatives and ensure that the meetings continue to be intensely interactive, as opposed to mainly evaluating data and literature,” he explains. “JG Afrika, RWA and Pegasys have developed unique methods, including system simulation cards, to stimulate dialogue and debate during engagements.”

Officials will also be given the opportunity to engage with the peer group that participated in the pilot phase, namely Mangaung Metropolitan Municipality, City of Mbombela, Msunduzi Municipality, uMhlathuze Local Municipality, Rustenburg Local Municipality and Emfuleni Local Municipality. Emery concludes that he looks forward to

further work on a project that has already received so much acclaim. The previous phase was nominated as the Environmental Engineering Project of the Year and the Most Outstanding Civil Engineering Project for Environmental Engineering at the 2017 South African Institution of Civil Engineering Awards.

A Proud Past. A Bright Future. Great reputations are built over time. Proudly independent, proudly South African and proud to service Africa, JG Afrika has built a strong reputation for offering innovative and sustainable engineering and environmental consulting services of the highest quality. 34 IMIESA June 2018

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www.jgafrika.com

Roads & Bridges

More than a

footbridge Footbridges are built to improve road safety for pedestrians and motorists and must, first and foremost, be functional and low-maintenance structures. However, for designers, there is the question of whether they can be more than that.

ootbridges of unique character can fit into any environment and add a pleasing quality to such. They can be hardy and robust, and still become visible markers that good design can improve the public space,” says John Anderson, functional general manager: Structures, SMEC. SMEC has been involved in the design development of three concrete footbridges across varying landscapes within South Africa. Designed to relate to their surroundings and survive theft, vandalism and limited preventive and routine maintenance, SMEC used bespoke in situ concrete forms rather than standard precast concrete sections.

ABOVE Pacaltsdorp pedestrian bridge

Pacaltsdorp Pedestrian Bridge The Pacaltsdorp Pedestrian Bridge, situated in George, Western Cape, connects people from a low-cost housing development to work opportunities in the nearby town. The bridge is a 65 m long continuous four-span, self-anchored, arch-supported stress ribbon bridge with a maximum span of 21.2 m. It has semi-integral abutments and a slender 220 mm thick concrete stress ribbon deck that spans up to 12.6 m between the crests of the arch sections. “The project was not about urban regeneration or creating recreational routes; it was

John Anderson, functional general manager: Structures, SMEC

about getting people who walk to work off the highway. It was evident that the design process must find the pedestrian’s preferred route and then serve that route to draw people on to it,” explains Anderson “It can, therefore, be argued that every footbridge is unique because the people that use it are unique; purely in where they have come from and where they are going. If designers ignore this basic starting point, there

IMIESA June 2018

Roads & Bridges

South African context, structures that minimise materials and maximise labour input help uplift poorer communities.

Ergo Road Pedestrian Bridge

is a high chance that the intended end-users will respond by ignoring their footbridge.” The bridge superstructure was built in situ in layers. This process was labour-intensive and provided work for a significant number of skilled carpenters and artisans. In the

The Ergo Road Pedestrian Bridge on the N17 highway in southern Johannesburg was an urgent necessity for the residents of an adjacent informal community, with work opportunities and schooling on the other side of the highway. The challenges at Ergo Road were the flat terrain and convincing the community to use the bridge and avoid the temptation to run across the highway. The concept for the bridge, therefore, had to serve the pedestrians’ needs and follow their desired route. Once again, the use of a continuous castin-situ structure allowed for a bespoke structure that could be tailored to the specific needs of the site. In this instance, there was a strong need to reduce the depth of the deck below the walking surface to reduce the grade separation and, therefore, the length of the required ramps up on to the bridge.

Regents Park Bridge A close neighbour of the Ergo Bridge on the N17 is the Regents Park Bridge. Again, the design of this bridge was driven by the basic need to provide an attractive and direct route for pedestrians. The site was especially dangerous for pedestrians and, in the end, a crossing with a 58 m long main span was conceived to enable the future highway widening. Integrating the users’ needs with the need for a long span crossing proved a challenge. After reviewing myriad options, the use of a simple, self-anchored suspension bridge with an in situ concrete deck slab cast on staging proved to be the most economical option. “These projects have proved that limited construction budgets are not a real constraint for designers,” concludes Anderson. “The limits are set by the designer’s input and investment into the project. The process of letting the function and context of the site lead the design process will usually produce an attractive structure that sits comfortably in its location.”

Transport, Logistics, Vehicles & Equipment

Namibian plant hire

indhoek Renovations, a construction plant hire company located in Windhoek, Namibia, was founded by Robby Wirtz in 1987 and has experienced sustained growth over the ensuing decades. The company’s earthmoving fleet has also seen major expansion and now numbers more than 90 machines and various attachments. One of its largest plant hire projects currently is at the Neckartal Dam, situated on the Fish River in the Karas region. Neckartal will be the largest water storage dam in Namibia, supporting an almost 5 000 ha irrigation scheme for fruit cultivation. This is a curved gravity structure with a height of about 80 m and a crest length of 518 m. Construction commenced in 2013, with all works due for completion towards the end of 2018. The main contractor is Salini Impregilo. Having completed the excavation of almost 800 000 m3 of earth and rock on the riverbed and the construction of abutments on either side of it, the construction team started building the dam foundation. The roller-compacted concrete (RCC) method is being employed. One of the contractor’s primary challenges from the onset was to find reputable and well-equipped Namibian plant hire companies. This would minimise the need to import earthmoving plant from South Africa or abroad. Windhoek Renovations was appointed to provide a range of plant hire solutions. “We started off on a small scale by subcontracting to another subcontractor,” Wirtz explained. “In time, we expanded our share of the project to include plant hire, as well as direct contracting services.” Bell machines are a key component of the plant hire mix. “As the local agents for Liebherr, we naturally support the brand, but whatever they can’t supply, we source from Bell Equipment,” Wirtz added. “In 2008, we purchased our first Bell 770D grader. We’ve subsequently expanded our Bell grader fleet to include 772G and 670G models as they are sought after in the hire market.” In 2014, Windhoek Renovations identified the need for a 30 t articulated dump truck (ADT) and it decided to purchase a new Bell B30E, which is being used specifically for RCC operations at the dam. Initially, rigid tippers were used to convey the concrete, but their narrow tyres left marks in the wet concrete. The wider and high-flotation tyres of the Bell B30E and its low ground impact made it the ideal haulage machine to convey the concrete to the dam wall. Aggregates for the dam’s concrete works have been sourced from a nearby quarry, with heavy haulage carried out by Windhoek Renovations’ larger Bell B40D and B30D ADTs. Another key ADT model in the mix is the 23 000 ℓ capacity Bell B25D water tanker, often working together with Windhoek Renovation’s Bomag BW212 and BW213 compaction rollers.

Windhoek Renovations meets the plant hire needs for the massive Neckartal Dam project.

3 1. W indhoek Renovations believes that when it comes to working in the 42ᵒC heat and dust of a quarry, hauling heavy dolomite rock to the crusher, nothing can match its fleet of Bell ADTs in terms of performance and durability 2. Windhoek Renovations added a new Bell B30E ADT to its fleet in 2014 and the truck is proving its worth on the Neckartal Dam project: its wider, high-flotation tyres and low ground impact make it the ideal haulage vehicle to transport concrete to the dam wall 3. W olfgang Schweiger (GM of Bell Equipment Namibia) with Johan van Wyk (Windhoek Renovations), John Collins (GM: Bell Equipment Cape and Namibia Region) and Mike Lipman (site foreman on the Neckartal Dam Project, Windhoek Renovations)

IMIESA June 2018

82ND IMESA CONFERENCE

31st October to 2nd November 2018

2018

PORT ELIZABETH INNOVATIVE INFRASTRUCTURE SOLUTIONS

Registration has opened E A R LY B I R D R E G I S T R AT I O N

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GOLF R480, excl. Golf cart and caddy

CO M PA N I O N TO U R R900 per person

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Transport, Logistics, Vehicles & Equipment

Paving the way for future mobility The Mobility Centre for Africa (MCA) is a registered non-profit company that aims to bring together government, industry and academia to collaborate in finding lasting solutions to some of the country’s major mobility challenges. By Liesl Frankson

n initiative of TT Projects and Royal HaskoningDHV, the MCA was establishing owing to a need to start a dialogue on and plan for the disruptive forces that are shaping the transport industry. According to Duncan Mason, director, MCA, this is essential to ensure that government and the industr y evolves and remains responsive to the goals and objectives of the National Development Plan (NDP). “Technology is advancing at an everincreasing rate, so we have the option to keep pace or get left behind,” says Mason, who is also the director: Transport & Planning for Africa, Middle East and India, Royal HaskoningDHV South Africa. “As a developing country, we cannot get left behind because, if we do, we run the risk of becoming the dumping ground for outdated technology. This kind of thinking

pushes us back and ensures that we stay a developing or third-world country, which is something we are working to overcome,” he explains.

to star t educating people to show them what’s coming because there’s a chance for people to upskill themselves.”

An integrated approach

Developing a legislative framework

Keeping up with technology is a must for a continent that faces different mobility challenges compared to its developed counterparts. Africa requires an integrated approach to the adoption of disruptive technologies because the mobility space is comprised of numerous modes of transport, both formal and informal. “When we look at mobility in South Africa, we can’t look at as just one mode of transport in isolation. One needs to look at how the different modes interact and what the most effective modes of transport are,” he notes. Similarly, the adoption of disruptive technologies in mobility cannot be viewed in isolation.

Dealing with disruption While new technologies and transpor t operating models have the potential to solve some of the country’s major problem areas – which include road crashes, congestion, emissions, legislative requirements and the affordability of transport – industry stakeholders need to remain mindful of the consequences associated with the adoption of disruptive technologies. Ivan Reutener, smart mobility expert at the MCA, agrees: “We need to ask ourselves what happens when disruptor technology hits our shores. For many people, the arrival of disruptor technology means job losses but it’s not all doom and gloom. We need

For Victor Radebe, executive director and co-founder of the MCA, the only way South Africa can proactively manage the disruptive forces in mobility is to first develop a legislative and policy environment that is conducive to these. “While other stakeholders have a role to play in developing future mobility solutions, government’s role cannot be overemphasised in creating the right environment,” he insists. To address the policy and legislature issues that need attention from government as well as other issues around future mobility, the MCA hosts roundtable discussions. Mason points out that the aim of the roundtable discussions is ultimately to drive the changes needed in the industry and the legislation that governs everything. To this end, the MCA has convened three successful roundtable events with representatives from government, public entities, academia and industry. All of this is paving the way for the launch of the MCA scheduled for later this year, where the centre will invite other role players to join the operation to become part of planning for the future of mobility in Africa. “Whether we achieve those goals and become more proactive in driving these changes will be the true measure of success for the organisation,” Mason concludes.

IMIESA June 2018

BIENNIAL PROJECT EXCELLENCE AWARDS

TUESDAY 30TH OCTOBER 2018 PORT ELIZABETH

CALL FOR

ENTRIES CATEGORIES To recognise outstanding achievements in municipal infrastructure, we are calling for entries that showcase projects which demonstrate the best of civil engineering as a science and how engineering enhances the lives of the local communities, through excellence in: planning and design construction methods innovation and originality meeting social and technical challenges contributing to the wellbeing of communities

1. ENGINEERING EXCELLENCE IN STRUCTURES & CIVILS E.g. Projects demonstrating engineering science, use of alternate materials, innovative construction processes, etc 2. COMMUNITY UPLIFTMENT & JOB CREATION E.g. Projects demonstrating labour intensive construction, skills development, community awareness/participation, etc 3. ENVIRONMENT & CLIMATE CHANGE E.g. Environmental rehabilitation, renewable energy, drought solutions, coastal initiatives for rising sea levels, pollution control, educational/technical initiatives, etc

ATE FOR SUBMISS D G ION SIN O S: L C 18 JULY 2018

Only projects that have reached practical or substantive completion by 30 June 2018 will be accepted for the Excellence Awards. Adjudicators reserve the right to reallocate entries in the 3 categories.

IMESA

ENTRY FORMS AND AWARD CRITERIA are available for download: www.imesa.org.za QUESTIONS Debbie Anderson – IMESA – 031 266 3263 conference@imesa.org.za

THE INSTITUTE OF MUNICIPAL ENGINEERING OF SOUTHERN AFRICA (IMESA)

Transport, Logistics, Vehicles & Equipment

Vertical digging

he Wacker Neuson EZ53 zero tail excavator excels in hard-to-reach places because at no point does the rear of the machine project over its undercarriage. This compact performance makes the EZ53 well suited for a wide range of building and civil applications, particularly where space and accessibility are issues. Additionally, up to five auxiliary control circuits make it possible to use a variety of attachments. The cabin interior is spacious and ergonomic, with a clear design arrangement that enables safe and comfortable operation. All maintenance components such as fuel, air, oil and hydraulic filters, as well as the water and hydraulic coolers, are easily accessible thanks to the laterally placed engine and the tiltable cabin. The cabin or the canopy can easily be removed by loosening four screws. These compact, robust machines can optionally be fitted with the Vertical Digging System (VDS),

The Wacker Neuson EZ53 has a 5.2 t operating weight

where the revolving superstructure of the excavator can be continuously tilted by up to 15 degrees. This feature allows for vertical digging, even on sloped surfaces, which makes the machine even more flexible. Slopes of up to 27% can be effectively compensated, while the operator remains seated upright and in a comfortable position. According to Wacker Neuson, productivity and ef-

fectiveness are measurably increased by employing VDS during excavation work. Overall, VDS can provide material and time savings of up to 25% when excavating and backfilling. On the go, power is delivered by a turbo diesel engine with an output of 36 kW, which provides optimum digging performance and efficient materials handling. IMIESA June 2018

CLOSE TO OUR CUSTOMERS

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Transport, Logistics, Vehicles & Equipment

Big strides in after-sales

AW SA has made a concerted effort to set industry-leading after-sales benchmarks to which its dealers and branches have to adhere. As a result, all FAW dealers are operating at a higher level than ever before. FAW SAâ&#x20AC;&#x2122;s efforts have resulted in a comprehensive programme of action to standardise its dealer operations and after-sales departments, including parts, service and warranties nationwide, and believes that customer satisfaction is the ultimate indicator of where it stands. Over the last two years, specifically, FAW SA has meticulously developed industry standard criteria, which embody dealer and branch facilities and the proper management thereof. It has also developed a reporting structure in order to measure and better manage the performance of its South African dealers and after-sales departments.

Total Quality Care FAW SA has also introduced processes to increase dealer stockholding and quicken parts supply. Simultaneously, it is busy

Martin Fick won first place in the biennial FAW SA National Service Technician Competition

introducing FAW TQC (Total Quality Care) in South Africa. TQC is a worldwide programme that was launched two years ago by FAW in China. It is a framework and umbrella brand that represents all of the initiatives being done in the FAW after-sales environment globally. FAW dealers in South Africa will need to be accredited by FAW SA in order to reach TQC level. To this end, various training and technical improvement courses, ranging from beginner to advanced, have been implemented by FAW SA over the last year. All FAW technicians are required to attend certain service courses to fast-track their technical development. Central to this process is the overall customer experience, part of which includes the training of technicians â&#x20AC;&#x201C; which culminated in the FAW National Service Technician Competition. Held in February, the biennial event was won by FAW technician Martin Fick.

The competition was aimed at the FAW dealer network, including Botswana and Namibia, with the goal of finding the best three technicians and workshop managers regionally and developing them further by sending them overseas. Assessment of the competitors was done during classroom and practical exercises, with technicians scored on their fault -finding and -fixing proficiency. The competition was designed to mirror what happens inside FAW dealerships on a daily basis. The overarching idea is to motivate FAW technicians, while improving their ability to find and fix problems on customer vehicles in a practical manner. The competition further sought to motivate workshop managers to increase the scope and frequency of technical training offered to staff.

IMIESA June 2018

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IMIESA June 2018

Cement & Concrete

Art and construction A household name in Southern Africa, AfriSam ensures exacting materials quality, positively contributing to a lasting and sustainable difference. South Africa’s Western Cape is a case in point where expansion plans seek further market penetration. By Alastair Currie

Zeitz Mocaa construction facts

he Zeitz Mocaa museum, situated within Cape Town’s Victoria & Alfred (V&A) Waterfront precinct, is an iconic architectural achievement, which transformed a 100-year-old, redundant grain silo installation into a work of art that integrates a cultural site with a leading hotel constructed above, and tying in with, the structure. It’s an exceptional and award-winning design and AfriSam is the proud sponsor

IMIESA June 2018

Early stages of contruction at the Zeitz Mocaa silo development

of the concrete employed in its reconstruction. AfriSam is also the sponsor for the visitor architectural audio tour at the museum, which introduces a wide range of local and international visitors to the cutting edge of South African and African contemporary art. “Our commitment to Zeitz Mocaa underscores our concerted support for

• Executing UK architect Thomas Heatherwick’s design, sections of the internal silo bins were carved away to form a large oval-shaped cavity that now comprises the atrium of the building. • Main building contractor WBHO cut almost 60 km of concrete to execute Heatherwick’s unique vision for the project. • To create the museum gallery, the edges of the bins around the structure were left intact, while some of the inner 33 m by 5.5 m silos were almost completely removed. • Top-down and bottom-up construction continued even while the main concrete cutting and shaping of the atrium, as well as other works, was under way. • Another major challenge was to remove portions of the silos without affecting the strength of the 100-year-old structure during the construction process. • The original concrete facades of the elevator building were demolished from the roof level down to the top of the silo bins. These were replaced with unique ‘pillowed’ windows. • In order to construct the museum inside the silo bins, a new building had to be constructed within the old. This could only be done once the façade had been retained. This was done by resleeving the old tubes with a new semi-circular concrete structure, 200 mm thick and separated from the old with a spray of insulation. • Special shuttering based on the shape of the expanded grain had to be designed to assist in forming the cut-out on the west side of the silo where the atrium was to be cast. • This was complicated as it required each tube forming part of the atrium cut to be set out in visual isolation from the next, with the concrete poured to the exact curve of the atrium cut. • This required some major innovation as the tapering edge of the cut in numerous areas was less than 50 mm thick, as well as tapering upwards at the base of the atrium. • Special hanging platforms suspended from the top of the silos were used to perform these activities at 30 m above the ground.

Cement & Concrete development in Cape Town and the broader Western Cape region,” says Richard Tomes, sales and marketing executive, AfriSam, during a visit to the museum and the company’s Peninsula Construction Materials (CM) operation, which was established in 1962. This is one of two AfriSam quarries in the region, the other being Rheebok in Malmesbury, both of which have estimated reserves of at least 30 years. AfriSam is now the largest concrete materials business in Southern Africa, ranking first in readymix, as well as in aggregates, and second in cement, making it the overall leader in the country. As an aside, Africa accounts for close to 5% of global cement demand, which in South Africa translates to a produced volume of approximately 13 Mt. Per capita consumption locally is around 240 kg per person, against a global average of some 670 kg. Historically, in 1926, some 100 million tonnes of cement was produced worldwide, which has grown 50-fold in the last 90 years. South Africa does import a low volume of cement from regions like Pakistan, India and China. However, in terms of supply and demand projections, Tomes says the

An external view shows the main entrance to the museum

current local capacity remains in oversupply so imports are not a serious threat to South African demand, where cement pricing is now at levels considered unsustainable by the cementitious industry.

Western Cape activity Within the Western Cape, growth continues to be relatively buoyant in terms of commercial and private sector residential developments, but infrastructure investments are struggling to keep pace. The size of the Western Cape cement market is approximately 1.6 Mt annually and AfriSam’s share, which is in the lower teens, is much lower than where the company would like it to be – hence its focus on growing its share and creating a much more competitive market for the users of cement and other concrete-related products. Despite South Africa’s generally subdued construction sector, the upside for this region is that cement consumption remains above the national average, at approximately 270 kg per person.

“AfriSam is in a strategic position to support a long-awaited upswing in economic activity,” Tomes points out, adding that it supports Cape Town’s cement requirements from its Ulco plant in the Northern Cape. This complements

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Cement & Concrete

the company’s aggregate operations from its Peninsula and Rheebok aggregate plants, as well as a number of its readymix concrete plants throughout the region. In terms of future expansion options, AfriSam owns a lime stone deposit in the Jacobs Bay area, north of the port of Saldanha, with a mining permit in place. The company also has EIA and DME approval to construct a fully integrated cement plant at the port. Mining is currently active on the quarry within the approved mining zone. Rheebok and Peninsula CM combined have an aggregate producing capacity of 1.5 Mt per annum, of which the Peninsula facility accounts for roughly 1.2 Mt. This makes AfriSam the largest aggregate producer in the Western Cape, supplying about 35% of the estimated demand. The rock crushed at Peninsula is a greywacke sedimentary material with blue granite, extracted at Rheebok. This type of rock is ideal for an area like the Western Cape, where there has generally been a problem with alkali/silica reaction, more commonly known as ‘concrete cancer’. Having quality aggregates and cement was crucial to AfriSam’s readymix concrete plants being able to supply the highly specified concrete for a project like the Zeitz Mocaa museum, where a total of 9 800 m3 of concrete was used. The main concrete mix supplied was a 30 MPa compressive strength with a 9 mm stone used for the silo sleeves, which form key elements of the new internal design. Aggregates were an important factor in the final mix, as the surface finish had to meet the architect’s stringent specifications. On average, there were two daily pours of 4 m³ each and the discharge time was two hours to accommodate the complexity of pouring into the formwork in the silos. “AfriSam has been a key supplier on a number of South Africa’s landmark building and civil projects, but the Zeitz Mocaa stands out as one of the most challenging and visionary in our more-than-80-year history so far. It’s testimony to AfriSam’s materials supply capability and technical expertise, and our vision of being a permanent part of the Western Cape landscape,” Tomes concludes.

Sections of the internal silo bins were carved away to form a large oval-shaped cavity that now comprises the atrium of the museum

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Cement & Concrete

The Beany Block has been designed for use in conjunction with SABS Fig. 3 and Fig. 4 barrier kerbs and can be used in any application where high inlet capacity is required

Flexible drainage solutions

rainage that is ineffective causes a multitude of issues when roadways, parking lots, walkways and areas around buildings become swamped with large volumes of non-dispersing water. Here, Technicrete’s Beany Block provides an efficient and practical solution due to its large flow capacity/unit weight ratio, making it a more cost-effective solution than conventional kerbing and drainage offerings. Some of the traditional problems experienced with conventional drainage that the Beany Block system eliminates include insufficient fall, conflicting levels of service mains and cables, ponding adjacent to low points, traffic safety and control on existing freeways. The system comprises a series of base blocks

of standard channel section and top blocks of inverted channel section with an opening in one side face. The top block oval openings provide for greater inlet capacities compared to conventional kerb inlets. Each standard top and base block is 500 mm in length and weighs approximately 85 kg. When laid end to end, they form a combined kerb and surface water drainage unit that is strong enough to withstand normal traffic loading. They have also been designed to withstand accidental 80 KN axle loading. Additional cost savings can be achieved on projects that have wide freeways and footways, freeways that have ‘flat’ longitudinal falls, rock in sub-grade, shallow outfall and existing ser vices or foul drainage at conflicting levels.

IMIESA June 2018

ENDING EROSION Technicrete Armorflex erosion control system provides an alternative for a wide variety of erosion control and drainage projects. When your project calls for protection that can withstand severe applications and climatic conditions, with quick installation with no in-situ concrete or even under water, Armorflex from Technicrete is the engineered solution. Suitable for:

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friSam has underscored its commitment to the industry’s associations with its headline sponsorship of The Concrete Conference 2018 (TCC). The conference is being held between 1 and 2 August 2018 at the Birchwood Hotel & O.R. Tambo Conferencing Centre and is being co-hosted by The Concrete Institute, the Concrete Society, the Concrete Manufacturers Association and the Southern Africa Readymix Association (Sarma). Other corporate companies invested are Chr yso, PPC, Sephaku Cement, and KonkreteGlobal with sponsorships of breakaway events such as the Concrete Quiz, which takes place the night prior to the conference at High Flyers on the same premises, as well as refreshments, lunch and pre-dinner drinks. Underlining the importance of this joint event is the strong support from some of the bestknown names in the industry. These include AfriSam, Mapei, Chryso, Sika, Nissan, Basilisk Self-Healing Concrete, Isuzu and Carmix, all of which will be exhibiting. “Basilisk will be launching their self-healing concrete at the conference – imagine that: concrete that heals cracks – while KonkreteGlobal will showcase the first robotic non-entry readymix truck cleaning system in South Africa,” comments TCC organiser Johan van Wyk. “At the same time, Isuzu Truck World will have a surprise for readymix concrete operators and several other exhibitors will launch new ranges of equipment, concrete additives, adhesives and so much more.” The first day’s proceedings will culminate in a gala dinner where the Sarma Awards will be presented.

Highlights and speakers •P rof Henk Jonkers from Delft University of Technology, the Netherlands, will be presenting a paper on the technology behind self-healing concrete. • Max Moyo, world-renowned speaker, will motivate and lead delegates into the future. • Leon van der Westhuizen from BrainRx will do some brain training. • Allesandro Bernacchia from Germany and Andrea Bonomi from Italy will be presenting case studies on extrusion kerbing and mobile batching, respectively. • TCC will also feature feedback on the state of concrete standards, including concrete test methods, aggregate test methods, water retaining structures and design codes. • There will also be a feedback and panel discussion on the consolidation of the concrete industry associations. • Other speakers will discuss energy-efficient concrete roofs, cellular concrete and case studies on the Bosjes Chapel, Fourways Mall precast concrete project and the Zeitz Mocaa museum in Cape Town. For sponsorships or more info, email johan@sarma.co.za or go to bit/ly/2qmMszG for booking information.

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Johan van Wyk is the chairman of the organising committee for The Concrete Conference 2018

Cement & Concrete

Preparing to plaster Incorrectly applied plastering inevitably leads to problems, as shown by the consistently high level of queries received by The Concrete Institute (TCI). Bryan Perrie, managing director, TCI, homes in on one important aspect of plastering: the preparation of the surfaces.

urface preparation starts with the accurate setting out and construction of the walls and soffits. The aim should be to provide a surface that can be plastered to the required lines and levels by applying a coat (or coats) of uniform thickness. It should be remembered that excessively thick plaster – or plaster of uneven thickness – will never disguise inaccurate work. Where zones of the substrate surface deviate from the required plane (or curved) surface by more than about 10 mm, the first option is to remove high areas by hacking or cutting. If this is not practical, undercoats should be applied to low areas in such a way that the final coat is of uniform thickness. In cases where above-average thickness is required, it is advisable, and safer, to

Bryan Perrie, MD, The Concrete Institute

mechanically anchor the plaster to the substrate, e.g. with stainless steel studs. This is also recommended when plastering dense, non-absorbent substrates.

Roughness Background surfaces should ideally be at least as rough as coarse sandpaper or rough-sawn timber. Suitable surface roughness can be achieved in the following ways: • using formwork with a rough surface, e.g. sawn timber for substrate concrete • stripping formwork early and wire brushing the concrete • hacking

Technical tips The practical skills component of the Introduction to Concrete (SCT10) training course offered by the TCI’s School of Concrete Technology includes basic plastering skills. In addition, the Institute publishes two free leaflets containing detailed guidelines on plastering. - Successful Plastering provides the technical information necessary to ensure that plastering is done correctly. It deals with selecting materials (including assessing the suitability of sands), calculating mix proportions and provides guidelines for preparing the surface of various types of substrate and then applying the plaster. - Common Defects in Plaster discusses whether plaster is acceptable and covers the most common defects in this part of the building process. The leaflet includes structural and nonstructural cracking, debonding, lack of hardness, grinning (the term used when mortar joints are clearly visible through the plaster), expansion and popping. The causes and repair methods for each are discussed.

IMIESA June 2018

Cement & Concrete

• abrasive blasting (e.g. sand blasting) • raking out mortar joints in masonry substrates to provide a key: a depth of about 10 mm is normally adequate • applying a spatterdash layer. Spatterdash is a mixture of one part of cement (preferably CEM I or CEM IIA) to 1.5 parts of coarse sand, with enough water for a sluggishly pourable consistence. A polymer emulsion should be substituted for part of the mixing water (usually a quarter to a third, but in accordance with the manufacturer’s instructions). The mixture is then flicked on to the substrate as an initial coating to provide a key on dense or smooth substrates with poor suction. The spatterdash should cover the substrate surface completely and form a rough texture with nodules about 5 mm high. Spatterdash must not be allowed to dry out for at least three days and if a polymer emulsion is included in the mix, then curing should be in accordance with the manufacturer’s instructions. It should be tested for adhesion and strength by probing with a screwdriver or knife before plaster is applied to it.

Cleanliness The surfaces to be plastered must be free of loose material, such as dust, and films that can interfere with bonding, such as curing compounds. Substrate surfaces may be cleaned by water jetting, blowing with oil-free compressed air, or vacuum cleaning. Bear in mind that brushing solvents should not be used to remove films formed by curing compounds; such films must be removed by mechanical means.

Absorption The simplest way to assess absorptiveness is by throwing about a cupful of water against the surface. The surface will respond in one of three ways: • no water will be absorbed • some water will be absorbed, but most will run off • most of the water will be absorbed. If no water is absorbed, a spatterdash coat that includes a polymer emulsion should be applied. Typical surfaces here include hard-burnt clay face bricks, glazed bricks and very dense high-strength concrete. Such surfaces must not be pre-wetted. Where most of the water runs off, these surfaces will not require any treatment to control suction. However, in situations where most of the water is absorbed, the surfaces should be wetted thoroughly for at least an hour and then allowed to surface dry before the plaster is applied.

IMIESA June 2018

PROFESSIONAL AFFILIATES AECOM siphokuhle.dlamini@aecom.com Afri-Infra Group (Pty) Ltd banie@afri-infra.com AJ Broom Road Products ajbroom@icon.co.za ALULA (Pty) Ltd info@alulawater.co.za AQUADAM (Pty) Ltd sales@aquadam.co.za Arup SA candice.thorne@arup.com Aurecon Fani.Xaba@aurecongroup.com Aveng Manufacturing Infraset cgroenewald@infraset.com Averda claude.marais@averda.com Bigen Africa Group Holdings otto.scharfetter@bigenafrica.com BMK Group brian@bmkgroup.co.za Bosch Munitech info@boschmunitech.co.za Bosch Projects (Pty) Ltd mail@boschprojects.co.za BVI Consulting Engineers marketing@bviho.co.za Civilconsult Consulting Engineers mail@civilconsult.co.za Corrosion Institute of Southern Africa secretary@corrosioninstitute.org.za Development Bank of SA divb@dbsa.org.za DPI Plastics mgoodchild@dpiplastics.co.za EFG Engineers eric@efgeng.co.za Elster Kent Metering Leonardus.Basson@honeywell.com ERWAT mail@erwat.co.za Fibertex South Africa (Pty) Ltd rcl@fibertex.com GIBB yvanrooyen@gibb.co.za GIGSA secretary@gigsa.org GLS Consulting nicky@gls.co.za Gudunkomo Investments & Consulting info@gudunkomo.co.za Hatch Africa (Pty) Ltd info@hatch.co.za Henwood & Nxumalo Consulting Engineers cc pmboffice@hn.co.za Herrenknecht schiewe.helene@herrenknecht.de Huber Technology cs@hubersa.com Hydro-comp Enterprises dan@edams.co.za I@Consulting louis_icon@mics.co.za INGEROP mravjee@ingerop.co.za Integrity Environment info@integrityafrica.co.za IQHINA Consulting Engineers & Project Managers info@iqhina.co.za iX engineers (Pty) Ltd hans.k@ixengineers.co.za JBFE Consulting (Pty) Ltd issie@jbfe.co.za JG Afrika DennyC@jgafrika.com KABE Consulting Engineers info@kabe.co.za Kago Consulting Engineers kagocon@kago.co.za Kantey & Templer (K&T) Consulting Engineers info@kanteys.co.za Kitso Botlhale Consulting Engineers zimema.jere@gmail.com Knowledge Base info@knowbase.co.za Lektratek Water general@lwt.co.za Lithon Project Consultants (Pty) Ltd info@lithon.com Makhaotse Narasimulu & Associates mmakhaotse@mna-sa.co.za Malani Padayachee & Associates (Pty) Ltd admin@mpa.co.za M & C Consulting Engineers (Pty) Ltd info@mcconsulting.co.za

Maragela Consulting Engineers admin@maragelaconsulting.co.za Marley Pipe Systems info@marleypipesystems.co.za Martin & East gbyron@martin-east.co.za Masithu Consulting & Project Management info@mcpm.co.za Mhiduve adminpotch@mhiduve.co.za Mogoba Maphuthi & Associates (Pty) Ltd admin@mmaholdings.co.za Moedi Wa Batho Consulting Engineers (Pty) Ltd info@wabatho.co.za Mott Macdonald Africa (Pty) Ltd johannesburg@mottmac.com Much Asphalt bennie.greyling@muchasphalt.com NAKO ILISO hans.hartung@nakogroup.com Nyeleti Consulting ppienaar@nyeleti.co.za Odour Engineering Systems mathewc@oes.co.za Pumptron info@pumptron.co.za Royal HaskoningDHV francisg@rhdv.com SABITA info@sabita.co.za SAFRIPOL mberry@safripol.com SALGA info@salga.org.za SARF administrator@sarf.org.za.co.za SBS Water Systems mava@sbstanks.co.za Sembcorp Siza Water info-sizawater@sembcorp.com SiVEST SA garths@sivest.co.za Sizabantu Piping Systems (Pty) Ltd gregl@sizabantupipingsystems.com SKYV Consulting Engineers (Pty) Ltd kamesh@skyv.co.za SMEC capetown@smec.com SNA stolz.j@sna.co.za Sobek Engineering gen@sobek.co.za Southern African Society for Trenchless Technology director@sasst.org.za Southern Pipeline Contractors (Pty) Ltd spc@vinci-construction.com SRK Consulting jomar@srk.co.za Syntell julia@syntell.co.za TPA Consulting roger@tpa.co.za Ulozolo Engineers CC admin@ulozolo.co.za UWP Consulting nonkululekos@uwp.co.za V3 Consulting Engineers (Pty) Ltd info@v3consulting.co.za Vetasi south-africa@vetasi.com VIP Consulting Engineers esme@vipconsulting.co.za VUKA Africa Consulting Engineers info@vukaafrica.co.za Water Institute of Southern Africa wisa@wisa.org.za WAM TECHNOLOGY CC support@wamsys.co.za Water Solutions Southern Africa ecoetzer@wssa.co.za Wilo South Africa marketingsa@wilo.co.za WRP ronniem@wrp.co.za WRNA washy@wrnyabeze.com WSP Group Africa sam.herman@wspgroup.co.za

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IMIESA June 2018

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