Imiesa June 2017

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

infrastructure development • Maintenance • service delivery

MUNICIPAL INSIGHT Dries van Taak

Manager: Water Services, Stellenbosch Municipality Addressing bulk infrastructure backlogs

APE Pumps leaders in pump innovation for

years African Infrastructure

Establishing win-win partnerships

Roads & Corridors

Expanding the N1-N4 corridor ISSN 0257 1978

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volume 42 no. 06 JUNE 2017 www.infrastructurene.ws

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

INFRASTRUCTURE DEVELOPMENT • MAINTENANCE • SERVICE DELIVERY

MUNICIPAL INSIGHT Dries van Taak

Manager: Water Services, Stellenbosch Municipality Addressing the bulk infrastructure backlog

43 APE Pumps

Geogrid stabilises Bloem route R30 million project to ease M2 traffic congestion

LEADERS IN PUMP INNOVATION FOR

25 26

YEARS African Infrastructure

Establishing win-win partnerships

Skills Development

Roads and corridors

Expanding the N1-N4 corridor ISSN 0257 1978

The ‘one team’ approach

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Dams & Water

The year 2017 marks a key milestone for APE Pumps as it celebrates its 65th year in business, underscoring its design, manufacturing and project management capabilities. P6

Securing the ground anchors Water reuse depends on ultrafiltration

Forming Drakenstein’s new bulk sewer line Bringing sewers back to life

3 5 11 56

Cover Story Leaders in pump innovation

6

Municipal Insight Addressing Stellenbosch’s bulk infrastructure backlog

ROADS & CORRIDORS N1-N4 toll route

36 39

Resuscitating G1 Crushed Stone to its rightful place Expanding the N1-N4 corridor

dams & water Hazelmere Dam

Proactive approach needed to Africa’s development

42

Transport, Logistics, Vehicles & Equipment A future underpinned by smart technology Over three decades of oscillation Taking compaction to new levels

45 46 48

Public Lighting 12

Roads & Corridors

31

34

FIDIC GAMA 2017

Editor’s comment President’s comment Africa round-up Index to advertisers

22

31

Trenchless News

Regulars

INSIDE

28

Structural steel for public lighting

50

Cement & Concrete 19 22

Concrete sustainability vital for municipal infrastructure Paving durability cast in concrete

45

Transport & Logistics Smart technology

51 54

EDITOR'S COMMENT

Building South African capacity

Publisher Elizabeth Shorten MANAGING EDITOR Alastair Currie SENIOR JOURNALIST Danielle Petterson ONLINE JOURNALIST Rianté Naidoo Head OF DESIGN Beren Bauermeister DESIGNER Ramon Chinian Chief SUB-EDITOR Tristan Snijders SUB-EDITOR Morgan Carter ContributorS Gavin Clunnie, Alaster Goyns, John Roxburgh, Kate Stubbs CLIENT SERVICES & Production MANAGEr Antois-Leigh Botma Production coordinator Zenobia Daniels financial manager Andrew Lobban MARKETING MANAGER Mpinane Senkhane HEAD: DIGITAL MARKETING Roxanne Segers Administration Tonya Hebenton DISTRIBUTION MANAGER Nomsa Masina Distribution coordinator Asha Pursotham SUBSCRIPTIONS subs@3smedia.co.za Printers United Litho Johannesburg +27 (0)11 402 0571 ___________________________________________________

S

outh Africa’s manufacturing capabilities are central to its future success and need to be refocused and nurtured as the country’s macro-economy repositions itself for meaningful growth, skills and employment creation. This applies to infrastructure products in general, as well as a multitude of industries that seek to build secondary opportunities in the domestic market, an example being the steel sector, which is under pressure from lower-priced imports.

Addressing a Black Business Council engagement dinner in May 2017, Minister of Finance Malusi Gigaba said, “We must move to a diversified industrial and knowledge-based economy, which is regionally integrated with Southern Africa and Africa as a whole, and integrated globally as a significant exporter of high-valueadded goods. This is absolutely critical.”

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

Publisher: media No. 9, 3rd Avenue, Rivonia 2056 PO Box 92026, Norwood 2117 Tel: +27 (0)11 233 2600 Fax: +27 (0)11 234 7274/5 www.3smedia.co.za Annual subscription: R550.00 (INCL VAT) ISSN 0257 1978 IMIESA, Inst.MUNIC. ENG. S. AFR. © Copyright 2017. All rights reserved. ___________________________________________________ IMESA CONTACTS HEAD OFFICE: Manager: King Singh 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

FIDIC GAMA In this issue, we report back on the FIDIC GAMA Conference, held during May in Cape Town, where leading consulting engineers from across Africa came together to talk about the way forward for inter-country and inter-professional cooperation.

There’s no doubt that in order to facilitate change, business enterprises and governments need to create viable platforms. African consulting firms and contractors need to pool their resources and capabilities if they’re going to compete effectively against global multinationals, which currently tend to dominate and lead project opportunities on the continent.

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

On a positive note, South Africa remains Africa’s preferred investment destination, receiving the lion’s share of foreign direct investment (FDI).

WESTERN CAPE Secretary: Michelle Ackerman Tel: +27 (0)21 444 7114 Email: imesawc@imessa.org.za

So where does that place South African construction at present? According to the Construction Industry Development Board, the mood among SMME companies was ‘pessimistic’ during its Q1 2017 survey.

The building segment is fairly buoyant, depending on the contractor grade, recording a two-year high in terms of activity. For grades 3 and 4, general builder confidence levels were recorded at 55 index points (50 being a neutral status), which is indicative of improved SMME support. However, for builders in grades 5 to 8, “profitability remained under pressure”.

Confidence among civil contracting companies fell by four index points to 37 in Q1, which is the worst level in five years. For both building and civils, this is the seventh consecutive quarter where confidence levels are below the 50-point neutral mark. So it’s clear that times remain tough, but a recovery is definitely in sight, and it will all come together with proactive participation.

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.

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turene.ws

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IMESA

Infrastructure News

magazine The official of the Institute l Engineeri ng of Municipa Africa of Southern

INFRAST RUCTUR

E DEVELO PMENT

• MAINTE NANCE

• SERVICE DELIVER

Y

L MU NIC IPA INSIGHT

Cover opportunity

Taak sch Dries vanWater Services, Stellenbo

All material herein IMIESA is copyright protected and may 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.

CIDB confidence survey

South African investor outlook

SOUTHERN CAPE KAROO Secretary: Henrietta Olivier Tel: +27 (0)79 390 7536 Fax: +27 (0)86 629 7490 Email: imesasck@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

South Africa also currently ranks 25th as the preferred global investment destination, according to AT Kearney’s 2017 FDI confidence index. That’s certainly encouraging news and this ranking is based on South Africa’s long-term investment potential in manufacturing.

Manager: Addressing the bulk Municipality backlog infrastructure

ps APE pum

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.

PUMP LEADERS IN FOR INNOVATION

YEARS struc ture Afric an Infra partne rships

Estab lishing

win-w in

corri dorsor Road s andN1-N4 corrid

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President’s comment

IMESA

International exchanges

are the future Jyväskylä, Finland, was the host city of the recent board meeting of the International Federation of Municipal Engineers’ (IFME’s) member countries, held between 10 and 12 May 2017, and I attended this global gathering and allied general conference as the South African representative.

T

he takeaways are many and significant, with a central focus on future impacts that we need to prepare for as municipal engineers, and these are common across the board for Africa and the greater developed and developing communities that make up our diverse planet. The three primary areas highlighted were technology, the effects of globalisation (namely investment shifts), and changes in country demographics (which includes younger and older populations and the rising trend of urbanisation, with its related and pressing infrastructure requirements).

Countries attending were very diverse, ranging from the UK and China, to the USA, Canada, New Zealand and Fiji (representing the South Pacific islands). From all countries represented at IFME, the request was for greater knowledge sharing and the exchange of inter-country technical visits to establish best practices.

Common challenges It’s important to note that South Africa is not alone when it comes to finding the best solutions in terms of financing and implementing key infrastructure challenges. That, for me, was especially noteworthy. Our more developed IFME members also face skills shortages in the specialist municipal engineering field, which has its own unique career development paths, and there is a definite need internationally to attract new entrants to this professional discipline. Plus, South African partnerships with developed countries could result in direct foreign investment initiatives.

Potential new memberships include BRICS member Brazil, which faces similar challenges to South Africa in terms of poverty alleviation, and Ghana, one of West Africa’s shining stars in the emerging markets.

One of IFME’s major initiatives is the introduction of international competency standards for municipal and public works engineers. It also plans to introduce a

professional certificate in asset management planning, plus IFME’s proposed online mentoring programme has real and excellent potential for our South African municipal engineers to learn from the best in the business globally, and there’s funding support.

Southern Cape Karoo branch meeting Upon my return from Finland, I immediately started the next round of my presidential visits with the IMESA Southern Cape Karoo branch meeting. I’m proud to say that this is a very organised IMESA branch, and the seminar hosted on the day was well attended by public and private stakeholders. The opening address by the deputy mayor was also IMESA president indeed insightful.

Gavin Clunnie

IMIESA June 2017

5

COVER STORY

Leaders in

pump innovation

Year anniversary

The year 2017 marks a key milestone for APE Pumps as it celebrates its 65th year in business, underscoring its design, manufacturing and project management capabilities.

F

rom its inception in 1952, APE Pumps has been an innovator in the field of fluid transfer solutions across applications and industries that include water utilities, mining, petrochemical, pulp and paper, ports and harbours, and the power station sector – a comprehensive skill set that is aligned with its sister company, Mather+Platt, which traces its own heritage back to England in 1845. Both companies are owned by WPIL Limited, based in India, which has manufacturing operations in its home country, as well as the United Kingdom, Thailand, Australia and Italy. “APE Pumps has succeeded because, from inception, we’ve always focused on our employees,” says Peter Robinson, managing director of APE and Mather+Platt South Africa.

“Our training and development focus is one of the main reasons we’re market leaders today.” APE and Mather+Platt serve specific markets with purpose-built pump solutions. Since 1952, APE has rolled out

a series of product innovations that are the direct result of constant industry engagement. “Our customers appreciate this because our research and development focus and downstream products are designed and manufactured based on their requirements and experiences. This is especially the case when it comes to purpose-built customisations and retrofits, which are some of our specialities. We listen and deliver because we have a vested interest in our client’s business,” says Robinson.

Malawi bulk water upgrade Two turnkey projects (entailing design, supply and installation) were recently completed in Malawi for the Blantyre Water Board (BWB) and serve as excellent examples of ‘out-of-the-box’ solutions. These were led by APE’s Projects Division, established in 1998 and currently graded as a 7 ME contractor by the Construction Industry Development Board. Core areas for the Projects Division include the supply and installation works of pumps, motors, electrical switchgear, transformers, valves and spares for mechanical, electrical and civil works.

The first project in Malawi entailed the completion of rehabilitation and renewal works at BWB’s Walker’s Ferry raw water intake and high-lift pumping station, while

the second entailed the upgrading of the Chileka booster pump station. Both are vital installations in terms of ensuring Blantyre’s water security. Combined, these contracts were valued at around R200 million, with the Chileka project awarded in April 2013 and Walker’s Ferry in October 2013. All works were completed by August 2015 and the defects liability period concluded in September 2016.

At Walker’s Ferry, situated alongside the Shire River some 60 km from Blantyre, water is pumped through a water treatment plant to two high-lift pump stations. After transferring to the purification plant, two further pump stations, each housing three operational pumps in parallel (depending on water level requirements) and one on standby, transfer the water NB 750 m3/h and 500 m head to Chileka over a distance of around 26 km.

From there, pipelines carry the water a further 13 km to feed reservoirs to supply the city of Blantyre. These two pipelines were also refurbished during the project works. The scope of works at Walker’s Ferry was extensive. Critical infrastructure works included the supply and installation of common header deliver y pipes (800 NB), and the installation and commissioning of six new raw water pump sets,

APE PRODUCT MILESTONES SINCE 1952

1952

APE Pumps enters the market under the name Sangus 6

IMIESA June 2017

1953 1965 Sangus range of submersible pumps

APE split-case range from 50 mm to 450 mm

1970

APE Nimbus end- suction 80 mm to 300 mm range

1974

APE range of endsuction pumps from 32 mm to 150 mm

1977

Introduction of the Byron Jackson petrochemical range

1979

APE vertical turbine range of pumps from 150 mm to 1 100 mm

Cover story

each with a capacity of The general 1 350 m3/h and a head of manufacturing 35 m. At Chileka, the scope workshop included the installation of eight new 750 m3/h in-house manufactured pump sets, including connection pipework to the new suction and delivery headers.

“On both projects, we pooled the collective experience of APE, Mather+Platt and WPIL to deliver an exceptional result on what was effectively a total refurbishment and replacement of all the major pump and valve elements, some dating back to the 1960s, plus transformers and switchgear, and all the associated concrete and allied housings,” says Richard Harper, project manager, APE. “Just to illustrate the scale, we installed the equivalent of 52 km of cabling.” The mechanical, electrical and civil works were carried out by the group. WPIL designed and manufactured Optional the electrical components, with APE responpolyurethane coatings on internal sible for the mechanical and civil phases, pump casings and Mather+Platt for supplying the pumps. following detailed “Precise planning and excellent teamwork studies in this area all came together despite very demandand market demand for extended life ing deadlines. One of the conditions of the contract was to maintain uninterrupted water supply to the city of Blantyre during ongoing introduction of pump developments all stages of construction. The minimum over the past 65 years. Externally, APE also threshold stipulated was a 70% supply at all works with specialist leaders to enhance times, which was consistently met and there its designs. This includes the recent offerwasn’t a single day without water during the ing of optional polyurethane coatings on its entire course of the project.” That equates internal pump casings, following detailed to between 2 700 m3/h and 3 000 m3/h throughout the approximately 18-month constudies in this area and market demand for struction programme. At peak, APE had 189 extended life. people on-site.

As Harper points out, these coatings reduce the friction factor, providing much Innovations more efficient flow characteristics, plus From the beginning, APE has embraced innothere is a reduction in electricity consumpvation and this is well demonstrated by its tion due to the enhanced fluid movement.

1980

APE submersible range of dewatering pumps

1983

APE Robushi chemical process pumps

1985 1997 APE VacSeal range of pumps

Introduction of the new range of APE submersible pumps from 100 mm to 250 mm

2002

Walker's Ferry new high-lift pump station

Chileka high-lift pump station refurbished

“Corrosion and rust prevention are always concerns for customers and, with these coatings, we can counter up to 62 aggressive chemicals and confidently offer better warranties,” says Harper.

Retrofits and the Pattern Shop Whatever the age or date of installation, APE has the ability to design, fabricate and

APE Byron Jackson range of petrochemical pumps, 8th edition

2007

PSV Holdings acquires Pump Division

2012

WPIL India acquires APE and Mather+Platt South Africa IMIESA June 2017

7

COVER STORY

APE's general workshop area

retrofit. Not an easy task, but one it can successfully deliver on thanks to its wooden pattern-maker expertise. In fact, APE is one of the few companies in South Africa that provides apprenticeship training in this field, and it’s an essential one, especially when tackling retrofits on pumps that no longer have available design drawings to work from. This A horitzontal splitcase pump

is underscored by a recent example where there was a client requirement for the replacement of a Mather+Platt water pump model installed in the 1960s.

“The drawing and the pattern were no longer available since this is a pump model that was discontinued years ago with the advent of new technologies. In this specific example, the client’s units were small multistage pumps that were succeeded in the market by the introduction of end-suction pumps,” says Harper. However, these multistage pumps could not be replaced with a modern version because of the pipework layout at the client’s facility.

So APE took a sample casting of one of the units and, from there, made a new pattern and a perfect replica of the 1960s version. A similar example entailed the refurbishment of two pumps for a major South African water utility. These pumps were installed some 40

Sixty-five years in the field of precision engineering is an exceptional achievement.

We’ve invested in our personnel and they’re at the heart of our operation.” years ago and were in need of an overhaul. They have now been refurbished with updated materials and come with a 20-year APE lifespan. The efficiency ratings achieved to date far exceed the originals.

“Standard, customised or retrofitted, APE has the solution for every fluid transfer industry, and we’ve been doing this for 65 years, backed by a multinational group that pioneered pump development during the peak of Great Britain’s Industrial Revolution in the late 1800s. We’re more than ready for the next 65 years, thanks to our concerted design and manufacturing, and our professional and committed team,” adds Harper.

www.apepumps.co.za

8

IMIESA June 2017

81ST IMESA CONFERENCE 25 th-27 th OCTOBER 2017

GAUTENG

SUSTAINABLE ENGINEERING: back to basics for the future Has technology in design made us forget the basic principals of engineering design?

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INFRASTRUCTURE NEWS

FROM AROUND THE CONTINENT

Ghana's Bridge Power plant will run on liquefied petroleum gas

Ghana Securing long-term power supply The 400 MW Bridge Power project in Tema will be Africa’s first liquefied petroleum gas (LPG)-fired power plant and the largest plant of its kind globally.

The project is being developed by the Early Power Limited (EPL) consortium – comprising Endeavor Energy, Sage, and GE – under a Power Purchase Agreement with the Electricity Corporation of Ghana. The fuel-flexible plant, capable of running on LPG, natural gas or diesel, will ultimately add 400 MW to the grid, equivalent of up to 17% of the countr y’s capacity.

Kenya Reduced road building costs Kenya has been able to significantly reduce road construction costs by Sh60 million (around R7.6 million) per kilometre thanks to a new road design. The design, which is based on traffic load, reduces the cost of construction from Sh140 million per kilometre down to Sh80 million. Government has also been able to reduce the cost of building rural roads from Sh70 million per kilometre to Sh35 million.This comes as the country is engaged in several high-cost road projects including the Sh2.6 billion 4.5 km Kisumu Boys-Mambo Leo Road, the 21 km Meru East and West bypasses at a of cost Sh2.45 billion, and the 115 km Garsen-Lamu Road at Sh10.8 billion.

Zambia Drought hits hydro hard Zambia is being forced to diversify its energy mix as the ongoing drought across Southern Africa continues to hit the region’s main source of energy – hydropower.

The country has been rationing electricity for almost a year and the electricity

deficit is now an estimated 1 000 MW. The Kariba Dam, one of the main sources of hydropower, is roughly only a quarter full, which has reduced power generation and threatened economic growth.

However, Zambian President Edgar Lungu has said that government is keen to diversify the power generation mix by promoting renewable energy.

“Solar, wind, thermal, and geothermal sources will be part of Zambia’s energy mix and, going forward, we will examine the nuclear option as part of efforts to ensure we are energy secure,” he said. New generation projects are expected to add 420 MW to the national grid from this year, almost halving the national deficit.

Construction of the power house for the electricity generation plant is already underway by Italian contractor Salini Impregilo. The project is expected to take three months, after which government will appoint a contractor to build the power generation plant.

The plant is expected to improve electricity supply in Masvingo and, once complete, it will have the capacity to serve the whole province. The Tokwe-Mukosi Dam, which cost nearly $260 million to build, was completed in December last year and is already 70% full. Tokwe-Mukosi is now Zimbabwe’s largest inland water body with a capacity of 1.8 billion litres.

Zimbabwe Hydro project underway Work has begun on a 15 MW mini hydropower project on the recently completed TokweMukosi Dam in Masvingo.

fast facts

400 MW

The expected generation capacity of Ghana’s Bridge Power plant

R7.6 MILLION

Kenya’s new cost saving on road construction per km

1.8 BILLION ℓ

The capacity of Zimbabwe’s new Tokwe-Mukosi Dam

IMIESA June 2017

11

municipal insight

Addressing Stellenbosch’s bulk infrastructure backlog By 2011, Stellenbosch Municipality had a huge backlog in the availability of bulk infrastructure, hampering development and growth in the region and leading to a moratorium on all new developments.

By Danielle Petterson

T

he reason for this was the rapid urban expansion of Stellenbosch, which was not equally matched by the expansion and upgrade of bulk infrastructure by the municipality. In the water services sector, the municipality faced the following main concerns: • insufficient wastewater treatment capacity for present and future needs • insufficient reservoir storage and bulk water supply capacity.

Having identified these shortfalls in 2011, the municipality embarked on a process to make more funds available for the upgrading and expansion

12

IMIESA June 2017

of bulk infrastructure. The budget for water services capital projects saw a significant increase of 142% between the 2014/15 and 2015/16 financial years. Water services now accounts for 51% of the municipality’s current budget.

Prioritising spend The biggest challenge was to decide which services most needed the limited budget for bulk infrastructure upgrading and then prioritise spending accordingly.

According to Dries van Taak, manager: Water Services, Stellenbosch Municipality, the municipality previously identified high-priority projects to improve the situation, which were then used as a guiding principle.

The capital budget was prioritised to support bulk infrastructure in areas where development applications were already tabled that supported Stellenbosch’s Integrated Development Plan (IDP) and Spatial Development Framework (SDF).

“At the end of the day, it was decided to concentrate on specific bulk infrastructure that would support the development of the town,” explains Van Taak.

“We also allowed for phased and concurrent development where infrastructure provision would take some time to complete.

Through this, we achieved some momentum in development, although the full bulk infrastructure would only be completed when the second phase of the development was ready for implementation.”

Two of the key priority projects identified were the upgrade and expansion of the Stellenbosch Wastewater Treatment Works (WWTW) and the construction of a reservoir and pipeline in Franschhoek.

municipal insight

Increasing capacity at the Stellenbosch WWTW

T

he Stellenbosch Wastewater Treatment Works (WWTW) is the only treatment works currently serving the town of Stellenbosch and surrounding suburbs.

The works was originally commissioned in 1924 and currently has a hydraulic capacity of 20 Mℓ/day. The rapid urban expansion of Stellenbosch and surrounds has placed severe pressure on the operations of the existing WWTW, and is currently hindering development, especially within the urban edge of the town.

In addition to the overloading of the existing Stellenbosch WWTW from a hydraulic and organic perspective, several of the assets, particularly the sludge treatment facilities, have exceeded their life expectancy. The current treatment process is not suitable to ensure environmental compliance of the effluent discharge, presenting a major risk to downstream users and ecosystems in the Eerste River – an important water resource for the agricultural sector in the surrounding region.

The municipality started planning the refurbishment, upgrade and extension of the WWTW in 2012 to meet future growth within Stellenbosch and surrounds, and to improve effluent quality, thereby mitigating the risk of polluting the water catchment downstream

TABLE 1 Annual average daily sewage yield projection

of the WWTW. A portion of the treated effluent will be reused for non-potable purposes in future, in line with Stellenbosch Local Municipality’s water conservation and demand management strategy.

Designing the plant The municipality requested that the following requirements be incorporated into the design philosophy of the new plant: • Provide a treatment process that will ensure a high-quality effluent The final effluent quality discharged into

Project Team Consulting engineer: Aurecon

Civil contractor: CSV Construction

Mechanical contractor: Veolia Water Solutions and Technologies

Electrical contractor: Devcotech

Aurecon brings ideas to life to design a better future. Imagining what is possible, we turn problems into solutions. www.aurecongroup.com

the Veldwachters and Eerste River catchments needed to be improved and the decision was made to install a membrane separation process.

According to Neeren Govender, technical director: Wastewater Engineering at Aurecon, this technology would guarantee a high-quality effluent and also provide a smaller footprint to address the spatial constraints on the existing site.

• Mitigate odour nuisances experienced on the current plant The odour emanating from the existing works had caused a public nuisance and needed to be contained and treated on-site. According to Govender, most of the odour was generated at the inlet works, primary settling tanks (PSTs) and primary sludge treatment facilities. The new inlet works is enclosed with odour control covers and the odour is extracted and treated in an odour control system using a bio-media filtration scrubber.

As part of the upgrade, the PSTs were removed from the main treatment process,

14

thus further reducing odour typically generated from primary sludge. However, PSTs provide a suitable upfront treatment of wastewater, which is beneficial in terms of reducing the organic load on the bioreactor, thereby reducing energy costs due to lower aeration requirements.

The PSTs also produce energyrich primary sludge that needs to be treated and stabilised in an anaerobic digester.

This presents opportunities to utilise gas from the anaerobic digestion process to generate electricity via a combined heat and power process. The Stellenbosch WWTW was designed to allow the facility to be easily retrofitted with PSTs and primary sludge treatment facilities in future. This minor addition would increase the treatment capacity from 35 Mℓ/day to 48.5 Mℓ/day at a very low capital investment. All hydraulic conduits and structures have been designed and sized for this ultimate flow.

• Deliver the project within the specified budget and on schedule The higher capital costs associated with membrane technology required the project to be implemented over a multi-year budget.

The 40-month project had to be split into two phases and designed accordingly. Phase 1 (28 months) comprises the construction of

all new infrastructure required to upgrade the plant to the desired capacity and will reach completion at the end of 2017 – on time and within the original budget. Phase 2 (12 months) involves the upgrade and refurbishment of the existing infrastructure. This phase will commence at the end of 2017 and be completed by the end of 2018.

Upgrading the infrastructure The extension of the Stellenbosch WWTW will comprise an upgrade to a full biological nutrient removal process capable of handling up to 35 Mℓ/day average dry weather flow (ADWF), which will ensure compliance with the National Water Act (No. 36 of 1998) and current Water Use Licence.

It will also cater for the seasonal changes in the influent loading, due to the agricultural harvesting season.

Govender explains that the upgrade and extension comprises the civil, mechanical and electrical works associated with the construction of a new inlet works to replace the old one, a flow splitting and fine screen station to split flow between two treatment lanes, namely a new 27 Mℓ/ day membrane biological reactor (MBR) lane and the existing bioreactor lane that will be upgraded to an 8 Mℓ/day conventional activated sludge plant. The new 27 Mℓ/day MBR lane will utilise the University of Cape Town process configuration: a fine bubble diffused aeration system with ultrafiltration membranes for liquid solid separation.

The existing bioreactor lane (extended aeration process configuration) will be upgraded

IMIESA June 2017

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CIDB, 9CE and 8GB

PO Box 3649, Somerset West, 7129 | Old Main Road, Firgrove, Somerset West 7130 Tel: 021 842 0013 | Fax: 021 842 0017 | www.csvconstruction.co.za

municipal insight Once commissioned, the Stellenbosch WWTW will be the largest ultrafiltration membrane WWTW in South Africa

to a full biological nutrient removal system (UCT process configuration) with secondary settling tanks (SSTs), and new closed vessel UV disinfection with a backup chlorine dosing facility. The sludge treatment facilities will treat a combination of waste activated sludge from both lanes, which will be thickened using dissolved air flotation technology and then stabilised in an aerobic digester.

The waste activated sludge will then be dewatered using belt presses before being discharged into a sludge silo for collection and off-site disposal. A new administration building will house a fully equipped laboratory, control room, offices, kitchen and change rooms for the operational staff. A centralised machine building is also being constructed to house all pumps, blowers, UV vessels, chemical dosing and motor control centre equipment.

The project includes the construction of an emergency generator building, pump stations, interconnecting pipework, reticulation networks, roads and stormwater, as well as the cleaning of maturation ponds for final effluent polishing and landscaping.

The majority of the civil work on Phase 1 has been completed and CSV Construction is currently busy completing the roadworks and landscaping. The electrical contract has also progressed and Devcotech is presently focused on installation and finalising the automation works.

“In any project environment, time is of the essence. While mechanical and electrical design is being finalised, the challenge is always to freeze the design at the correct time,

Keeping the existing works fully functional during the construction process posed significant challenges

allowing enough time to implement,” says Deon Laubscher – electrical, control and instrumentation engineer at Devcotech. “In an ideal world, one would like to have uninhibited access to the plant, but this is hardly ever possible. Devcotech is working in parallel with the mechanical installation team, doing our bit to complete the project within the timelines.”

Once complete, the upgraded plant should have sufficient capacity to supply the region for the next 15 to 20 years, with the ability to expand the treatment capacity to 48.5 Mℓ/ day at a relatively small capital cost.

Optimising treatment The new Stellenbosch WWTW will utilise an MBR process – an advanced wastewater treatment process that uses ultrafiltration membranes for liquid solid separation instead of conventional clarifiers. The use of ultrafiltration membranes for liquid solid separation allows the process to operate at a higher reactor concentration (8 000 mg/ℓ to 15 000 mg/ℓ) compared to a conventional system, thus reducing the volume of the bioreactor. Once commissioned, this WWTW will be the largest ultrafiltration membrane WWTW in South Africa. “The use of MBR technology is beneficial in terms of the small footprint of the bioreactor, especially considering the current spatial constraints of the site, and the production of a high-quality effluent that presents opportunities for reuse,” explains Govender.

Furthermore, the introduction of UV disinfection technology for wastewater has been

The new Stellenbosch WWTW will be fully automated and controlled via a SCADA system

imperative in finding an environmentally friendly solution over the conventional chlorine disinfection methods. The UV technology emits short-wavelength radiation that disrupts and kills a wider spectrum of harmful microorganisms, and is effective against chlorine-resistant pathogens like Cryptosporidium parvum and Giardia.

Overcoming challenges Among the first challenges to overcome were funding constraints. Van Taak explains that when the initial planning of the upgrade and extension commenced in 2012, it became evident that the large capital cost of the project would be a constraint to its successful implementation.

At this stage, the municipality entered into discussions with the Department of Water and Sanitation to secure funding from the Regional Bulk Infrastructure Grant (RBIG) for the project.

The R450 million upgrade is currently funded by a combination of both RBIG and internal municipal funds.

Keeping the existing works fully functional during the construction process posed significant challenges. With the

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municipal insight

project being implemented on a live WWTW site, one of the biggest considerations was limiting electrical downtime. “Unlike water treatment works, WWTWs cope poorly with electrical downtime, scheduled or otherwise,” explains Laubscher.

“Making extensive modifications to the medium-voltage reticulation feeding the existing plant, while limiting downtime, was key.”

Alex Pospech, director, CSV Construction, explains that diverting the existing electrical and sewer network around the construction area as well as dealing with unknown services were also major challenges. Flow diversions and the rerouting of existing services needed to be carried out between midnight and 04:00 when flows are low, thus minimising disruption to the existing works.

CSV Construction also experienced delays with the construction of the new 27 Mℓ/day MBR structure after encountering large outcrops of Cape granite that had to be blasted from 7.5 m deep excavations, but were still able to meet all scheduled milestones.

To successfully manage the project, the construction process had to be planned thoroughly to minimise downtime to the existing WWTW and mitigate any impact on the opera-

ing efficiency. The system will control all main process units including the aeration blowers, sludge wasting, pump stations and rotation of all on-duty and standby equipment to maximise the equipment run time, and ensure optimal energy efficiency on all processes typically impacted by the daily variations in flow and load.

Effluent discharged from the plant will be monitored at various points by automatic samplers that will be tested onsite in the new laboratory. The security on the plant will include 24-hour/day monitoring with infrared CCTV linked to both the control room and guardhouse. tions and final effluent. Van Taak commends the excellent cooperation between all stakeholders involved throughout this complex engineering project, which has contributed to its success thus far.

Automating the plant The new WWTW will be fully automated, allowing it to be monitored, recorded and controlled via a centralised SCADA system. This was considered necessary due to the size and complexity of the upgraded plant, and to optimise the process control and operat-

Upskilling Once complete, the project includes a threeyear operation/maintenance assistance and training period, where the mechanical and electrical contractors will support and train the municipal operation and maintenance staff employed at the Stellenbosch WWTW. “The ability to operate and maintain this advanced facility in accordance with the specifications will be critical to ensuring the works performs optimally to give the municipality full value for its capital investment,” concludes Govender.

municipal insight

Building water storage capacity

T

he Stellenbosch Water Master Plan indicated that water infrastructure was needed to provide sufficient water capacity and a reliable supply to the existing consumers and future developments within Franschhoek and the surrounding township.

The town and its surrounds were originally supplied with water from two sources: the Perdekloof source in the adjacent mountains east of the town, and water purchased in bulk from the City of Cape Town through a bulk connection point on the Wemmershoek

The infrastructure upgrades provide a huge benefit to poor and lowincome settlements

pipeline north-west of the town. However, the reliability of water supply from Perdekloof was a major concern for Stellenbosch Municipality. The whole of Franschhoek is now supplied only by the Wemmershoek Water Scheme – the more reliable source – as per the Franschhoek Water Master Plan.

The Perdekloof water source will serve only as a supplementary supply in the case of emergencies.

A new reservoir for the town An all-town reconnaissance study conducted

by Stellenbosch Municipality used low-, medium- and high-growth percentages of 1.5%, 2.0% and 2.5%, respectively, to determine the future storage capacity requirements for Franschhoek. To ensure a reliable, constant water supply to the existing and future demands of the region, the decision was taken

to build a new reservoir and pipeline, connected to the Wemmershoek Water Scheme.

This involved constructing a new 5 Mℓ reservoir and potable water rising main from the existing Groendal Pump Station, which was upgraded, as well as a gravity supply pipeline from the new reservoir to the town.

The new pipeline was mechanically excavated and the pipes were installed on a sand bedding layer and backfilled with a sand blanket layer. JVZ Construction installed 4.4 km of Duroflo uPVC pressure pipes, manufactured by DPI Plastics to SANS 9661 specification. These included 315 mm and 355 mm diameter pipes with pressure classes of 9, 12 and 16. “To deliver water to the new reservoir, two new pumps were fitted to the Groendal pump station,” explains Buks Zeeman, technical director, Aurecon.

The original Groendal pump station was fit-

IMIESA June 2017

17

ted with two end-suction pumps, operated in a duty/standby configuration. The duty-flow of the new pumps is 50 ℓ/s, but can be upgraded to 70 ℓ/s in future.

Construction challenges Due to the steepness and mountainous topography of the site, special care had to be taken during bulk earthwork activities. Ground improvements were undertaken to avoid settlement and resultant structural damage to the reservoir.

Special consideration also had to be given to the management of stormwater run-off from the reservoir site to ensure that no erosion or excessive sheet flow was caused as a result of the reservoir’s construction. The in-situ ground conditions and topography also complicated

the development of access roads, which was further exacerbated by inclement winter weather conditions. In some areas, access roads had to be improved or reconstructed to ensure safe and permanent site access.

Farming activities located in close proximity to the reservoir site and pipeline route had to be considered, and all agricultural vehicles had to be given right of way over construction vehicles.

Any agricultural practices also took preference over any construction-related activities and the contractor had to ensure that dust generation was minimised to protect damage to natural vegetation and crops. Lastly, a berm had to be constructed to screen the reservoir from surrounding areas and from the Main Road in Franschhoek. The berm

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was landscaped with indigenous plant species similar to those found on-site.

Benefitting poor communities The project was completed in July 2015 when Franschhoek’s average water demand was approximately 4 050 kℓ/day and there was a shortage in reservoir capacity of approximately 2 Mℓ. The new 5 Mℓ reservoir addressed this shortage and added an additional 3 Mℓ spare capacity to accommodate future developments.

According to Van Taak, these infrastructure upgrades provide a huge benefit to poor and low-income settlements within the Franschhoek township areas such as Mooiwater, Langrug and Groendal. An additional planned 1 300 lowincome households in Langrug will also benefit from these upgrades in the future.

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Resuscitating G1 Crushed Stone

to its rightful place

A

G1 Crushed Stone was once widely used for base course work in South Africa but, over the last 20 years, the necessar y knowledge and skills to produce it seem largely to have been lost.

By Danielle Petterson

ccording to Eduard Kleyn, a private consulting engineer with more than 50 years of experience in the roadbuilding industry, it has become increasingly difficult to find a site where inspec G1 material is delivered or correctly constructed towards the achievement of G1 Crushed Stone base-courses. While the technology to produce G1 Crushed Stone material is still available, the correct construction of a G1 Crushed Stone base course seems to have largely fallen by the wayside, with arguments of it being too difficult, too time-consuming or uneconomical.

structed G1 Crushed Stone is superior to most other materials in terms of load-bearing capacity, especially as used in the well-known “South-African Inverted Pavement” composition.

It is used on many of the country’s major highways and is specified by SANRAL and other roads authorities for high traffic volume and heavy load roads. However, what is delivered all too often falls short of expectations, explains Kleyn. The process of producing G1 Crushed Stone, although simple, has to be executed to precision.

The difference lies first in the material and, second, in the construction method.

What is G1 Crushed Stone?

G1 material

G1 Crushed Stone is defined as a layer of continuously graded minus 37.5 mm crushed rock, refusal interlocked to a minimum density of 88% of Apparent Relative Density. It is built using G1 material, a premium and very precisely made crushed aggregate. It is a hybrid, South African developed form of crusher run which started in the mid-1960s and is arguably the strongest granular base course for road construction. According to Kleyn, tests conducted with the South African Heavy Vehicle Simulator show that properly con-

It is critical that high-quality G1 material is used. According to Kleyn, there are many inferior-quality products available in this highly competitive market, and not everyone can tell the difference.

The material is continuously graded according to the Fuller/Talbot method. It is produced by a crusher to very exact specifications, which requires machines to be set up precisely in order to produce it. The result is crushed rock from 37.5 mm all the way down to -0.075 mm (dust). The intention is that each particle should virtually fit

into its own space in the finished product, taking it as close as possible back to the solid rock state from which it came. “The larger particles must interlock to form a matrix that is virtually as strong as the original parent rock,” he explains.

The key is in the slushing The key to producing this highly interlocked matrix is what is termed “slushing”. G1 material is a premium material that comes at a premium price. To treat it as you would a normal gravel – that is to compact without slushing – will not achieve the necessary interlocking that delivers the load-bearing ability for which properly constructed G1 Crushed Stone is known, explains Kleyn.

FAST FACT Eduard Kleyn currently conducts training courses on G1 Crushed Stone for Sanral. To learn more, contact him on ekleyn@ffg.net.

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ROADS & CORRIDORS

Slushing, or slush-compaction, is a high water content compaction process, which expels the excess fines (-0.075 mm material) in the aggregate matrix.

If these fines are not removed to secure the aggregate interlock, it will leave behind an aggregate matrix, much like ordinary gravel, which will be susceptible to traffic deformation, especially under overload conditions, over time.

It is important to saturate the layer fully during this process or the desired outcome will not be achieved, he cautions.

The water truck and compactors should run very close together to maximise the process and minimise wasteful water runoff. This will also assist the rollers in “sucking” out the fines.

20

Compaction to perfection Compaction is the other critical factor in delivering G1 Crushed Stone. The aggregate must be compacted to refusal, says Kleyn. This will give the layer what he calls the ability to “make muscle”, meaning it will increase in loadhandling ability in step with the traffic load because the layer is properly supported and interlocked.

The process begins with normal compaction, as with any gravel, up to about 85% of Apparent Relative Density (ARD). Only then is the layer stable enough to handle the copious amount of slushing water and the slushing process can begin. The slush compaction must continue until the layer reaches a minimum of 88% of ARD, at which point, G1 Crushed Stone should be achieved. Kleyn

IMIESA June 2017

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explains that the slushing process will result in bubbles as the air is forced from between the stone during compaction. Once the aggregate is interlocked to refusal no more air will escape and the bubbles will stop. The water will also clear up such that one will be able to see the interlocked aggregate mosaic through the water – an indication that the slushing process is complete. Over compaction, especially by vibratory and steel tired, can result in crushing of the aggregate that will ultimately change the grading of the material so that it will not properly interlock. This means starting again from scratch. To avoid this, it is essential to use the right method and equipment.

“Apply rollers sensibly. A roller cannot be allowed to roll endlessly because it can do too little or too much, based on its ability,” cautions Kleyn. A vibratory roller, for example, will compact up to a point, after which it will de-compact and re-compact endlessly to a lesser degree each time. “You have one chance to get the maximum density for that roller,” he says. “You need to know when to stop.

Measure the density. If you’ve used the right rollers, it should be correct.”

How do you know if you’ve got it right? The layer should make a ringing sound if hit with a geological hammer rather than make a dull sound, and should not heave under the roller, says Kleyn. “It’s all about using your senses – knowing what to look, feel and listen for.”

Building on solid foundations Even if the correct materials and methods are used, G1 Crushed Stone cannot be achieved without a properly constructed sub-base layer, which provides a water insensitive anvil on which to compact. If the sub-base layer heaves or ravels, the G1 base layer will be contaminated with sub-base material which will cause it to be of inferior quality and performance. It is therefore essential that the sub-base is properly constructed using a cement-stabilised gravel and that it is impervious to water (given the slushing process).

When to specify G1 According to Kleyn, while G1 Crushed Stone may be considered to be the ‘gold standard’ of granular road bases, it is relatively expensive to build and not always necessary for the traffic at hand. However, as the traffic load increases, a stronger base-course material becomes necessary, making G1 Crushed Stone ideal for high-traffic-volume and heavy-load roadways.

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Closing comment “G1 is a relatively expensive material. Do it right the first time if you want a G1 Crushed Stone layer,” says Kleyn. “This method is not necessarily more time consuming or more difficult to construct than other base-course types. In fact, it is actually quite simple and fast once you master the handling of the material and understand the aim of the process. The answer lies in working accurately.”

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Expanding the N1-N4 corridor IMIESA talks to the Bakwena Platinum Corridor Concessionaire about current and future plans on its strategic N1-N4 toll route.

By Alastair Currie

M

anaging a 385 km network along some of South Africa’s most trafficked roads, including the City of Tshwane as a major transit hub, is the responsibility of the Bakwena Platinum Corridor Concessionaire (Bakwena), which has achieved major success as a publicprivate partnership (PPP) venture, with new upgrades now under way.

From inception to final handover to the South African National Roads Agency (Sanral) in 2031, the estimated investment by Bakwena will amount to around R3.7 billion. The current capex committed for construction projects going into 2017 is around R1 billion for a range of works that include key toll plaza expansions to facilitate faster transit times, especially for haulage vehicles.

Bakwena’s extensive network consists of a 90 km section of the N1 running from Tshwane northwards to Bela-Bela (Warmbaths), and a 295 km stretch of the N4 from

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IMIESA June 2017

Tshwane westwards through Rustenburg and Zeerust to the Botswana border. The construction programme since inception has involved a combination of road upgrades, as well as approximately 100 km of greenfields development that translates into a return on investment for road users in terms of travelling times and speed of access to markets.

Detailed traffic studies are in place to predict future traffic demand and, every year, Bakwena carries out deflection tests on all routes to determine surface conditions, such as cracking and rutting, in accordance with predetermined standards. “This enables us to forecast accurately when specific sections will need resurfacing and this is built into the financial model,” explains Liam Clarke, commercial manager, Bakwena.

New developments A series of projects are currently running in parallel. This includes a R34 million reseal of the N4 in Dinokana, which is scheduled

Bakwena approximate daily tolled vehicle traffic volumes Carousel Pumulani Zambesi Stormvoël Doornpoort Brits Marikana Swartruggens

18 000 24 500 44 000 20 000 41 500 13 500 12 000 3 600

for completion in May 2017; and a R95 million contract entailing reconstruction works on the N4 between the towns of Zeerust and Lehurutse, which commenced in February 2017 for scheduled completion in December 2017. Also on the N4, major reconstruction works were completed in March 2017 between Zeerust and Vaalkop, at an approximate value of R250 million, with an additional R7.7 million allocated for stormwater upgrades.

From Vaalkop to the Groot Marico boundary on the N4, an estimated R273 million reconstruction contract is scheduled to be awarded in July 2017, with an anticipated duration of 20 months. In the meantime, a R164 mil-

Current and future construction projects N4 reseal in Dinokana Contractor: Actophambili Contract duration: October 2016 to May 2017 Construction value: R34 million

Reconstruction of the N4 from Zeerust to Lehurutse Contractor: Contract duration: Construction value:

New Road WBHO JV February 2017 to December 2017 R95 million

Reconstruction of the N4 from Zeerust to Vaalkop Contractor: G4 Civils Completed: March 2017 Construction value: R250 million

Reconstruction of the N4 from Vaalkop to the Groot Marico boundary Contractor: Estimated project duration: Estimated construction value:

Pending tender award 20 months R273 million

Reconstruct N4 from Groot Marico boundary to Swartruggens Contractor: G4 Civils Contract duration: September 2016 to November 2017 Construction value: R164 million

Plaza expansion at Brits and Marikana Contractor: Contract duration: Construction value:

G4 Civils February 2017 to December 2017 R50 million

3rd lane at Doornpoort N4 East Contractor: Contract start date: Construction value:

G4 Civils February 2017 R12 million

Reconstruction of N1 North from Pumulani to Hammanskraal Contractor: M&R Contract duration: February 2017 to December 2017 Construction value: R117 million

lion works contract between the Groot Marico boundary and Swartruggens is progressing well, with a completion date scheduled for December 2017.

Bakwena has also awarded a R117 million reconstruction project on the N1 North between Pumulani and Hammanskraal, which commenced in February 2017 for completion by year-end. All Bakwena projects have

a minimum 15% SMME component, with unskilled and semi-skilled labour sourced from the local community.

Extra toll plaza lanes Allied to these road upgrade initiatives are two projects at the Marikana and Brits toll plazas, valued at around R50 million, which commenced in April for scheduled comple-

ROADS & CORRIDORS

PPP framework Bakwena signed a concession contract with Sanral to construct, manage, maintain and upgrade the N1 and N4 roads on 4 October 2000. To date, Sanral has successfully met and exceeded expectations on these routes.

The toll road is being operated and maintained by Pt Operational Services, a special-purpose company consisting of Abertis, a Spanish operator, and Tolcon, an SA-based toll operator within the Murray & Roberts group of companies.

The concession will hand the route back to Sanral in 2031.

tion by October 2017. At both plazas, the scope of works entails the installation of two additional lanes to cater for incoming and outgoing traffic.

“In the interim, Bakwena has also added new lanes at the Zambesi, Pumulani, Stormvoël and Doornpoort toll plazas, which were completed on schedule in December 2016 and are already reducing delays during peak periods,” says Clarke. At Doornpoort, for example, vehicles per hour passing through the plaza at peak increased from 3 300 to 3 800, a 15% improvement. Each of these plaza upgrades includes new e-tag lanes.

CSR initiatives As part of its corporate social responsibility (CSR) commitment, Bakwena works with local municipalities – like Zeerust, Madibeng, Rustenburg, and Swartruggens along the N1-N4 route – to add back to the community. Bakwena’s CSR focus has four pillars, namely road safety, health, environment and heritage, and economic development.

CSR examples include a R15 million stormwater project in Zeerust, which coincided with a Bakwena route upgrade, in conjunction with Sanral, which has taken over responsibility for the R49 travelling through the town.

Swartruggens is another example where Bakwena has invested in the upgrade of the town’s sidewalks over the past four years, at an estimated value of R11 million. Various stormwater upgrades have also been undertaken in other towns along the platinum corridor network. “Toll roads are a growing part of the landscape worldwide on vital routes, where PPP ventures take on an often substantial project risk,” adds Clarke.

“With the roll-out of the N1-N4 project, we’ve created a world-class facility based on detailed experience and analysis and, in the process, have made a major difference for commercial and private travellers, and South Africa’s GDP. That’s why we’re confident our latest R1 billion investment is good for the economy.”

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Geogrid stabilises Bloem route

Shallow excavation depths require an ‘out-of-the-box’ design to cope with heavy traffic loads.

The compacted stabilising layer ready for the 40 mm asphalt overlay

R

unning through a bustling commuter hub, high traffic volumes on Bloemfontein’s McGregor Street – predominately from buses and mini-bus taxis – were taking a severe toll on the road surface, necessitating an overhaul. The Mangaung Metropolitan Municipality stepped in, approving a rehabilitation project, with Nako Iliso Engineering appointed as the consultants.

On-site inspections revealed a shallow road surface and poor sub-base material, which severely limited the excavation depth, requiring the engineers to create a completely unique design. Kaytech’s TriAx geogrid was selected as the ultimate solution.

Manufactured from extruded sheets of polypropylene, the rigid triangular geometry of TriAx is a revolutionary design providing near uniform stiffness through 360 degrees.

As Kaytech’s Garth James explains, “The unique structure of TriAx incorporates several characteristics that combine to create an optimised product that outperforms all biaxial geogrids in trafficking trials. TriAx can reduce base thickness, increase traffic load,

TriAx 160 was laid on the prepared sub-compacted surface

increase bearing capacity, control differential settlement and cap weak deposits.”

Restricted to a maximum excavation depth of only 500 mm, a 250 mm thick sub-base was designed. Installed by contractor Down Touch Investments, the milling operation was executed in two stages, the first being to separate the existing asphalt and goodquality G4 base course material from the poorer subbase material. In order to produce a high-quality bitumen-stabilised material (BSM), the second phase involved recycling the good-quality materials and blending them with commercially sourced G4 material in a foamed bitumen mill.

Once installed, the sub-base was covered with a layer of TriAx TX 160 (24 000 m2 in total) secured in place using cable ties and nails with head plates. Using a paver, two lifts of BSM (125 mm thick) were placed at ambient temperature over the TriAx geogrid

TriAx 160 held in place using nails with head plates

and subsequently compacted. To complete the rehabilitation, a 40 mm asphalt layer sealed the surface of the road.

“When combined with suitable aggregate, TriAx produces a mechanically stabilised layer with exceptional performance,” James explains. “The product’s tensile stiffness, in three principle directions, produces a truly multidirectional product with near isotropic properties.”

Severe site constraints on McGregor Street transformed what should have been a routine project into one that could have presented enormous challenges. However, by incorporating Kaytech’s TriAx into their design, the consultants were able to opt for a shallower box-cut excavation that still achieved the desired performance.

IMIESA June 2017

25

Easing congestion on Joburg's M2 The addition of a new lane on Main Reef Road, several new turning lanes, and improved traffic signals are expected to ease congestion on Joburg’s M2. By Rianté Naidoo

T

he Johannesburg Roads Agency (JRA) has launched a R30 million upgrade project on the M2 freeway to ease congestion on major routes.

Main Reef Road, on the M2 west highway, will undergo construction over the next six months. This key arterial route plays a critical role in Johannesburg’s road network, which spans more than 13 428 km. It links the M1, M2, M7, N1 and R24, which are some of the major freeways forming the backbone of the city’s road network.

According to Dr Sean Phillips, managing director, JRA, a major contributing factor to congestion along this road is the intense development currently underway between Production Road and Miriam Makeba Street.

Traffic study As a result, the JRA carried out a network study that re-evaluated roads in the region.

Factors such as freight, public transport,

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IMIESA June 2017

spatial development, and other pertinent planning in the area were taken into account. During peak hours, traffic counts were taken at key intersections along Main Reef Road and key extension roads. Findings showed that during a 12-hour period along Main Reef Road and the Production Road/Dorado Avenue intersection, 44 089 vehicles passed through.

Based on these traffic volumes and turning movements, and taking into account future vehicle and population growth across the city, it was clear that the existing road layout required measures to alleviate traffic congestion.

Construction Provisions for an additional road lane on Main Reef Road, new turning lanes, improved road markings and the reconfiguration of improved traffic signals have been made. Mpho Kau, head: Infrastructure Development, JRA, said the project will also in-

Mayoral committee member for transport Nonhlanhla Makhuba at the sod-turning on Main Reef Road in May

clude traffic accommodation, the relocation of services, and the extending and repairing of stormwater systems. The project is expected to be completed by December 2017.

Procurement and passenger safety Kau said 30% of the project will be retained by local SMMEs, with a minimum of 25 local labourers employed. In an attempt to prioritise commuter safety, construction will take place at night between 19:00 and 05:00.

Mayoral committee member for transport Nonhlanhla Makhuba marked the start of construction at a sod-turning ceremony.

She emphasised the role that roads play in facilitating business across the city and said investors, whether local or international, take decisions to locate

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30 % of the project will be retained by local SMMEs, with a minimum of 25 local labourers employed.” businesses in areas based on the quality of their infrastructure.“We will continue to commit more resources, better technology and in novative solutions to address issues relating to transport and mobility in the city,” she said.

She added that construction along this route was part of the city’s broader objective to achieve a minimum of 5% economic growth for Johannesburg. “We are confident that we can achieve this by clamping down on years of maladministration, corruption, and the skewed allocation of resources,” she said. “We are creating a city that works, because we know that if Johannesburg works, all of South Africa will work.”

Mpho Kau, head: Infrastructure Development at the JRA

MMC for Transport Nonhlanhla Makhuba

SKILLS DEVELOPMENT

The ‘one team’ approach Developing today and tomorrow’s engineers is a top priority for leading consulting engineering group Knight Piésold.

Mevashnee Naidoo, HR Director

through to professional registration.“It’s an exciting journey for our young candidates and we have structured programmes in place to get the best results,” explains Mevashnee Naidoo, human resources director, Knight Piésold.

A

daptability, professionalism, excellence, sustainability, and teamwork are all core values that define the way Knight Piésold engages and grows its presence in the engineering and environmental sectors. These values also form the basis for the company’s talentacquisition strategy, as well as its training and development programmes at all levels, with a major focus in South Africa on selecting, mentoring and growing young engineers

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IMIESA June 2017

Stakeholder engagement “Clearly defining our values is important, because it provides stakeholders with a key insight in terms of our operating model.

Let’s start with adaptability,” Naidoo continues. “At Knight Piésold, we have the ability to learn from experience and we realise that market needs are constantly changing. The way in which we recruit the skill sets we require has evolved and our talent-selection processes have changed to suit this.

“As a company, professionalism is an overriding priority. We are considerate and we respect others (i.e. clients, staff and

competitors); however, excellence is a value that all our staff practise and live by in terms of our service offering and project delivery.

“Our workplace and employment practices are very future oriented when it comes to sustainability, both in terms of minimising environmental impacts and from a business perspective. We offer employee well-being and career development programmes, which drive employee engagement. Our people are our assets and are central to our plans on engineering the future.

“This all comes together through teamwork. We build effective and efficient teams by giving all staff the experience they require to develop. We don’t work in silos and that is what our young leaders appreciate.” Mentorship is at the heart of Knight Piésold’s success and permeates throughout. Naidoo believes that it should be reflected as Knight Piésold’s sixth value. “We are a learning

organisation and there are no glass ceilings. Our registered ECSA mentors are committed to a formalised programme where their mentoring time is logged and measured. Our mentees are registered on the same programme and relationshipbuilding starts here. You don’t have to be a formal mentor at Knight Piésold to make a difference. Our directors, managers and senior specialists mentor all the time.”

The mentorship approach Knight Piésold has a three-tiered approach to mentorship that runs as parallel programmes: Mentorship programme

Formalised candidacy mentoring This programme focuses on young engineers who are mentored for a period of three to four years after graduation, until they have acquired the relevant experience to apply for professional registration with ECSA. The programmes require quarterly reports from candidates and mentors, combined with engagement and constructive feedback. “Alongside our own in-house training, some of our candidates are also registered on CETA-funded programmes. This financial assistance enables us to increase the size of our candidate employee complement,” says Naidoo.

Currently, Knight Piésold has 38 employees registered on its candidacy mentorship programme, which is a significant number of the total South African staff component. In the last three years, seven young engineers and technologists have been professionally registered, with four to five now writing up for professional registration.

Mentorship of senior and professional staff This is a formalised process: career pathways and goals are set, training and developmental activities outlined, with progress then measured as a continuous cycle.

During this stage of mentorship, the focus is on the professional’s career aspirations, leadership readiness and personal growth.

This is where an engineer’s career kicks off in terms of having an increased level of responsibility. “As an employer of choice, we value our senior staff and want to engage with them constantly,” claims Naidoo.

Equipping for leadership This is the mentorship of management-level staff or staff already in senior positions

within Knight Piésold. “We believe that no matter your age or stage in a company, there will always be new opportunities available and there should always be room for development. This is assessed through a less structured approach to mentoring. We don’t formalise the process (other than through our formal performance development programme) because we empower people who are in these positions to ask for mentoring in order to grow.

“Some engineers are leaders in their technical abilities while others wish to develop their people management skills. Either way, we’re creating the next generation of leaders. It will be their responsibility to build and grow our company,” Naidoo explains.

Bokomoso outreach initiative In parallel with its internal development focus, Knight Piésold has partnered with a school in Lenasia, Gauteng, as part of its Bokomoso (‘their future’) CSI initiative to add back to communities and nurture future engineering talent. The project started in 2012 with the sponsorship of textbooks and science kits. This year, Knight Piésold is rebuilding a computer learning centre at the school.

For the 2017 CESA ‘Job Shadow’ initiative, Knight Piésold selected learners from grades 9 to 11 to attend an open day at Johannesburg Water’s Northern Wastewater Treatment Works. Six of Knight Piésold’s young engineers were on board for the day, each of which was allocated a team of learners to lead and mentor. Naidoo elaborates: “We’re developing a buddy system and hoping that these learners will bond with our

young engineers in terms of future external tutoring outcomes. Our goal is to instill an understanding and appreciation for maths and science as foundational skills in engineering, as well as for a wide range of other career disciplines. As we perfect the model, other schools will be identified.”

The Knight Piésold difference So what sets Knight Piésold apart as a consulting firm? “We believe in inclusivity when it comes to project delivery and business decision-making. Our management team has clear expectations that are communicated to the general staff,” adds Naidoo.

“This creates and promotes self-empowerment and excellent stakeholder engagement. In fact, we often hear that, despite our size, we punch above our weight. That’s largely owing to our ‘one team approach’, enabling us to deliver in the most efficient, cost-effective and professional manner, and our successes are celebrated together,” she concludes.

www.knightpiesold.com

IMIESA June 2017

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81ST IMESA CONFERENCE GAUTENG SUSTAINABLE ENGINEERING: back to basics for the future Has technology in design made us forget the basic principals of engineering design?

25 - 27 OCTOBER 2017

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

S TA N D A R D R E G I S T R AT I O N

L AT E R E G I S T R AT I O N

Register and pay BEFORE 31 July 2017

Register and pay BEFORE 31 August 2017

Register and pay AFTER 31 August 2017

• Members: R5 200 • Non-members: R5 700

• Member: R5 400 • Non Member: R6 000

• Members: R5 900 • Non Member: R6 600

ACCOMMODATION

The 2017 IMESA Conference will be hosted at the Emperors Palace, Gauteng Special rates have been negotiated with the Hotels listed below for IMESA Delegates.

Book NOW and quote the unique booking code found on the IMESA Conference website.

Peermont Mondior Hotel

From R1650

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From R1440

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Peermont Metcourt Hotel

From R1080

TRANSPORT Airport shuttles will run FREE of charge to and from any Peermont Group hotel.

This includes the hotels listed above.

Organiser THE INSTITUTE OF MUNICIPAL ENGINEERING OF SOUTHERN AFRICA (IMESA)

t +27 (031) 266 3263 email conference@imesa.org.za

DAMS & WATER

Specialised admixtures play a vital role in forming structural extensions to a vital KwaZulu-Natal dam.

Securing the ground anchors

S

ituated on the Mdloti River, the Hazelmere Dam was officially opened in 1977 and has since been one of KwaZulu-Natal’s main sources of bulk water supply for agricultural, industrial and domestic users in the surrounding region. A Category 3 concrete gravity structure, Hazelmere is located some 40 km north of Durban and the supply area extends from KwaDukuza (Stanger) in the north to Verulam in the south.

Growing demand, combined with the impact of the recent spate of extended droughts, motivated a decision by the Department of Water and Sanitation (DWS) to raise the dam wall by 7 m to meet current and future supply demand, and to improve future water security. The new extension will increase the capacity from around 23.9 to 43.7 million cubic metres.

Consulting engineering company Ingeprop South Africa was appointed to come up with an effective design solution with Group Five appointed as the main contractor. Construction commenced in August 2015 with the overall project scheduled for finalisation during 2017. The critical spillway construction phase was completed in January 2017.

The project scope includes repair works to the grout curtain to reduce leakage under the dam wall, the construction of

Once all project phases are completed, the end result will be an enduring solution that will serve the rapidly growing population of the KZN North Coast region

Construction in progress at Hazelmere Dam: a total of 83 anchors will be inserted along the entire dam wall, which is being raised by 7 m

piano key weirs to increase the stored water height, and ground anchors to strengthen the wall to take the increased loads.

Construction innovation The design called for the installation of 83 ground anchors into the spillway and the dam wall itself, with this task assigned to SRG, an Australia-based company. SRG was subcontracted to drill, install and post tension the anchors.

Grouting these anchors is a critical part of the installation process and SRG carried out a series of trials to perfect the overall approach by placing four test anchors 40 m deep below the dam wall. First trials commenced in December 2015.

SGS commenced on-site with the actual works in February 2016, drilling 355 mm diameter holes at depths varying between 55 m and 95 m along the spillway at 1.5 m intervals, while on the dam wall, the holes were spaced 7.5 m apart.

The stringent requirements for the water cement grout mix (exclusive of any aggregates or sands) included an initial flow time of 12 seconds, reaching 15 seconds after 60 minutes; a maximum of 2% bleed after two hours; 60 MPA at 28 days; an OPC Cement Cem I specification; and a grout density of around 1 900. Sikadur-AP was specified for use on the nose cones of the anchors. The 250 mm diameter anchors, each requiring an average of 80 steel cables for post tensioning, were inserted into the holes.

Extended workability The first of two admixtures specified was Sika ViscoFlow-25 ZA, specially designed

IMIESA June 2017

31

DAMS & WATER

Figure 1 This dam wall cross-section illustrates how the anchors are being placed and their penetration depth

Figure 2 An illustration showing how each individual anchor is installed

Anchor Sikadur-42 ZA (Base Plate)

7,5m to the next anchor

55m 1,5m between each anchor

95m

e.g. of Anchor Grout - Cement Water ViscoFlow-25 ZA Stabiliser-229 ZA Sikadur AP Nose Cone

for concrete and grout mixes with extended workability requirements, as well as improved flow characteristics. Compared to conventional dispersants, Sika ViscoFlow-25 ZA provides higher stability and workability time. Since Sika ViscoFlow-25 ZA contains no chlorides or any other ingredients that promote the corrosion of steel, it is ideally suited for use in reinforced and prestressed concrete structures. Sika Stabiliser-229 ZA, the second specified admixture, increases the

32

cohesion and plasticity of grout, reducing bleed and segregation.

Sikadur-42 ZA was used at the top of the base plates. It has a fluid consistency, is self-levelling, suitable for dry or damp concrete surfaces and provides high initial and ultimate mechanical strength.

Once all phases of this megaproject are completed, the end result will be an enduring solution that will serve the rapidly growing population of KwaZulu-Natal’s North Coast region, adding approximately 10 million cubic metres of capacity, and significantly alleviating critical water shortages in KwaZulu-Natal.

IMIESA June 2017

Close-up view showing anchor sections: there are 80 cables grouped per anchor

Dams & Water

Water reuse depends on ultrafiltration

S

outh Africa’s water scarcity and current extended drought periods remind us daily of the high value clean water holds. Take one look at the City of Cape Town’s Theewaterskloof Dam level and the severity of the problem hits home. By mid-May 2017, Theewaterskloof’s storage capacity was down to 15% compared to 31.3% for the same period in 2016.

The dam is the city’s largest in terms of capacity, at 480 188 Mℓ, and is now close to running dry.

Quality Filtration Systems (QFS) firmly believes that a sustainable solution to this problem is wastewater reuse. “Treating secondary effluent is a highly effective way of saving water: an immeasurable amount of water is literally going down the drain, and could instead be reused to help preserve our natural resources,” says Herman Smit, managing director, QFS.

Reuse projects QFS specialises in ultrafiltration (UF) and reverse osmosis (RO), which are essential components in wastewater reuse applications. QFS recently designed, engineered, manufactured, installed and commissioned solutions at two municipal wastewater reuse plants – one in the Western Cape and the other in KwaZulu-Natal. Both employ the new compact modular MEMCOR CP II UF system supplied by QFS. The 3 Mℓ/day secondary effluent treatment plant in Ballito, KwaZuluNatal, achieved some truly impressive results, recovering 91.5% of the plant’s original feed water. In De Doorns, Western Cape, the municipality’s wastewater reuse plant treats secondary water for irrigation purposes. This helps to free up source water at a rate of 1.5 Mℓ/day (soon to be upgraded to 2.5 Mℓ/day).

These reuse plants generally employ a form of pretreatment and then a UF process, followed by an RO process in certain instances. “There is hardly any debate that UF provides the best pretreatment to RO or other process water treatment equipment,” says Smit. UF tarInstallation at the De Doorns gets the suspended solids in the treatment works feed water resulting in NTU levels of less than 0.1. In RO terms, UF provides feed water to the RO at SDI levels of less than 1.

The removal of the suspended solids enables the RO to do the work of dissolved solid removal with less bio fouling and sludge blockage in the spacers.

Additionally, UF allows the client to reduce downtime on the RO, use less chemical cleanse and lower operating pressures.

“Life-cycle costing is thus less with UF as an RO pretreatment,” concludes Smit.

34

IMIESA June 2017

TRENCHLESS NEWS

Forming Drakenstein’s new bulk sewer line Page 36

Bringing sewers back to life Page 39

TRENCHLESS NEWS

Forming Drakenstein’s

new bulk sewer line Constructing a pipeline extension under a heavily trafficked route calls for a creative geotechnical response to combat a cobble layer, with the core response entailing jet grouting.

K

eller’s Franki Africa has developed a reputation for being able to deliver cost-effective geotechnical solutions using a wide range of appropriate technologies in a host of different and often challenging ground conditions. “We have worked in Southern Africa for many decades and have a profound understanding of the different soil conditions and the optimal geotechnical solutions for them,” says Byron Field, trenchless technology manager, Franki Africa.

He adds that this knowledge often enables the company to be proactive in solving problems that, on the face of it, sometimes seem unsolvable. “The Drakenstein Municipality’s bulk sewer pipeline is an excellent example of this,” says Field.

Franki’s jet grouting rig installing raker columns beneath the N1 highway

The prepared 8.5 m shored jacking pit ready to start pushing the jacking shield

The challenge

tween 6 m and 8 m. According to Field, the main challenge was the relatively unstable ground conditions, which comprised sands of up to 4 m deep, with loose cobbles and boulders from depths of 4 m to 8 m, and a very high water table.

He adds that the South African National Roads Agency also had strict wayleave conditions, prohibiting the Drakenstein Municipality from conducting works beneath the national highway unless it was able to prove that every conceivable precaution was taken to protect the highway and to ensure uninterrupted use. It was obvious that a trenchless methodology, like pipejacking, was required in order for the new sewer to

The path of the sewer pipeline – which is in the Paarl, Western Cape, area – included a ±105 m stretch across Arboretum Road and the N1 highway, followed by a ±10 m section, which runs parallel to the Boschenmeer Golf Estate boundary wall at a depth of be-

Jet grouting was Franki’s preferred method of treatment.”

Contract No. CES 14/2015

Exposed trial jet grout column, clearly showing dense cobbles that are bound together after treatment

Client:

Drakenstein Municipality

Engineers: Lyners

Main contractor: Vakala Construction

Specialist geotechnical contractor: Franki

Contract commencement/ completion: August 2016 to February 2017

Scope of specialist geotechnical work: Pipejack gantry

run under the roads without interrupting traffic. Additionally, the depth of the pipeline and its proximity to the Boschenmeer Golf Estate boundary wall made open excavation unpractical in this area.

The cobble layer The ground conditions were analysed and a new challenge was encountered. Field explains: “Firstly, the level of the sewer passed directly through the cobble layer between a depth of 4 m to 8 m, and when pipejacking through this type of ground, it is virtually impossible to prevent the collapse of the cobbles during excavation. Secondly, the high water table tends to draw fines from the surrounding ground towards the jacking shield.

Both of these things could have led to overexcavation, resulting in ground level settlement,” he says.

Jet grouting solution Franki then approached the Drakenstein Municipality with a proposal to treat the ground beneath Arboretum Road and the N1, as well as alongside the Boschenmeer

215 m 1 780 ø OD pipe jack; 250 m³ grouting

Golf Estate boundary wall. The proposal entailed jet grouting, which involves the mixing and partial replacement of the in situ soil with cement slurry, to consolidate the in situ ground condition along the sewer centreline and between the depths of 4 m to 9 m, and then installing a pipejack through the treated ground.

“The treatment of the ground would prevent the collapse of the sand and cobbles during pipejack excavation and would reduce the ingress of water to manageable levels,” Field says. He adds that jet grouting was Franki’s preferred method of treatment as high-pressure jetting can be used to consolidate in situ ground at exact levels and can provide up to 2.5 m diameter columns with only an 80 mm drill stem.

The municipality’s design team found the proposed solution acceptable, included it in a tender document for this phase of the works and, in August 2016, Franki was appointed by the main contractor, Vakala Construction, to carry out the specialist geotechnical works as per their envisioned specification.

Field says that the result could not have

Excavating at the jacking face

been better. “The jet grouting work went according to plan and was carried out with zero impact on traffic. In addition, once the jet grouting was completed and the site was cleared, there was no remaining evidence at ground level that the ground beneath had been treated,” he says.

As for the pipejacking, Field says the entire operation went smoothly with the ground treatment “working beyond even our highest expectations”. The subcontract work was completed by Franki on time and on budget in February 2017.

www.franki.co.za

IMIESA June 2017

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TRENChLESS NEWS

Bringing sewers back to life

Sewer replacement is extremely disruptive and costly due to the depth at which these pipelines are normally placed. Instead, extending their ser vice life through rehabilitation using trenchless techniques is generally far more cost-effective and causes minimal, if any, social and environmental disruption. By Alaster Goyns*

W

ith South Africa’s first outfall sewers, there was little idea of their service life or how to predict this. But the technology to provide data for assessing their condition and the know-how to predict their remaining life is now available. Trenchless techniques are now used throughout the world to provide the most cost-effective and least disruptive means of rehabilitating old sewers and, in many cases, installing new ones.

Condition assessment The condition assessment of a sewer involves determining the hydraulic performance and physical condition of this asset at a given date and comparing these with the specified

requirements of the asset when it was first put into service. This means determining the original requirements, locating sections where problems are likely to occur, and walking the route to search for telltale indications of problems, accessibility for inspection equipment, and surface constraints.

This will provide a realistic overview of the surface conditions.

Data must be gathered and evaluated from as many sources as possible to identify, categorise, and describe the problems in terms of their location, extent, severity and the underlying causes. It is import to identify any critical sections of the sewer where spot inspections via manholes may be necessary to determine whether sections need cleaning before internal inspection, and whether the

camera and other recording devises should be transported through the sewer on a tractor or a pontoon. Together with the surface inspection of the site, this greatly assists in planning inspections.

Internal inspection The use of reliable and affordable CCTV inspection systems to inspect gravity pipelines has probably been the major driving force behind the development of trenchless rehabilitation techniques.

CCTV cameras provide high-resolution colour images and can be fitted with a variety of lenses. The simplest have a fixed, forwardviewing head, while the more sophisticated ones have a pan-and-rotate head. They can also be fitted with zoom lenses to obtain

IMIESA June 2017

39

Internal inspection is essential to extending a sewer's life

close-up views. The cameras are waterproof and able to operate in a partly full-flowing gravity system. Adjustments can be made to the lens height so that it remains above the flow level anticipated in the pipeline. Most cameras are mounted on selfpowered tractors operated from a vehicle parked on the surface; however, at times, it may be necessary to place a camera on skids or a float so that it can move through a pipeline operating under specific conditions. While CCTV inspections identify defects and their location, extent and severity, they do not show conditions below effluent surface, do not give physical measurements, and do not provide information about the conditions in the surrounding soil. However, lasers for above-surface scanning and sonars for underwater scanning can now be added to a pontoon carrying the CCTV camera and provide a digitised profile of the whole pipe surface including its internal dimensions at very close intervals.

Physical inspection While the internal inspection provides valuable information, it is recommended that a few spot physical measurements be made.

Sections of sewer where severe corrosion is anticipated and that can be easily exposed from the surface should be identified and an inspection window cut – as shown in Figure 1. This can be done concurrently with a CCTV inspection to provide a comprehensive understanding of the sewer condition.

Remedial measures The final stage of the condition assessment is the risk analysis. The probability of failure and the resulting consequences must be weighed against the risk of not rehabilitating or replacing a sewer. Trenchless rehabilitation techniques currently available in South Africa are: • Sliplining A continuous string of the liner pipe is created by welding sections of new pipe together on the surface and then inserting this smaller diameter liner pipe into the larger diameter host pipe. The main advantages are the ease, speed and economy of installation, while ensuring a water-tight section of sewer is provided. As this is not a tight-fit solution, this technique will reduce the inner diameter of the conduit and is therefore only suitable where capacity is not critical. A further disadvantage is the space required for the launching pits.

TRENChLESS NEWS

Figure 1 Illustration of an inspection window

TRENCHLESS IN SA

Crown wall 120-degree arc

Wall at any section

Outside to invert

Invert wall Outside diameter

• Cured-in-place pipe (CIPP) This involves inserting a resin-impregnated, soft liner into a sewer before reinverting and curing it by heated water or ultraviolet light. It is quick to install, causes minimal disruption, and the thin, tight-fitting liner has a minimal impact on the capacity. In fact, there is usually a slight increase in capacity.

The liner is both highly resistant to chemicals and can be structurally designed should the existing host pipe have deteriorated so badly that collapse is imminent. Because it is a close fit, it will conform to the shape of the host pipe, which may be a problem if there are sharp changes in pipe profile, causing the liner to be locally over-stressed.

• Spiral-wound lining This involves feeding profiled uPVC or HDPE strips into a mandrel placed in a manhole to form a continuous, spirally wound pipe whose external diameter is slightly smaller than the internal diameter of the host pipe.

When this liner is extended along the host pipe, it is expanded to fit tightly inside the

CCTV inspection systems to inspect pipelines have probably been the major driving force behind the development of trenchless rehabilitation techniques

pipe while still keeping its circular shape and causing minimal flow reduction. The preferred technology for a particular sewer will be based on the hydraulic and structural requirements, as well as whether or not the flow in the pipe can be diverted and whether the technology can be used in a live or partly live system. On reticulation and collector sewers that have deteriorated and have insufficient capacity, the most frequently used in-line replacement technique is pipe cracking/upsizing, which provides a new sewer of a larger diameter and greater capacity.

Other trenchless technologies include CIPP patch repair and grouting for sealing joints, which are often used where there are isolated defects over short sections of sewer where point repairs from the surface are inconvenient and rehabilitation from manhole to manhole is not economically justified. This technique, contrary to the common perception, is actually labour intensive as the excavations needed are small and the use of mechanical means is impractical.

Trenchless rehabilitation techniques currently available in South Africa: 1. Sliplining 2. Cured-in-place pipe 3. Spiral-wound lining

and that the appropriate pipe is selected. While this may incur a slightly higher initial capital cost, it will reduce operational costs and significantly delay the need for rehabilitation.

South Africa can no longer afford shortterm solutions; we need solutions that are technically sound and cost-effective in the long term. With the condition assessment tools available, there is no reason why existing sewers cannot be rehabilitated to serve future generations. Doing this will release more resources for installing new sewers when needed in new developments. *Alaster Goyns is the owner of Pipeline Installation and Professional Engineering Services.

Concluding comments With the technical information currently available, there is no reason why new outfall sewers cannot be cost-effectively designed and installed to last for 100 years or longer. The secret lies in making sure that both designer and contractor are competent,

IMIESA June 2017

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FIDIC GAMA

Partnering for African

development

FIDIC’s Group of African Member Associations (GAMA) came together at its annual conference, held this year at the Cape Town International Convention Centre between 7 and 10 May, where presenters and delegates explored the way forward.

By Alastair Currie

S

outh Africa, like the rest of Africa, needs to grow its economy, but that largely depends on sourcing the public and private sector funding needed to alleviate the infrastructure backlog standing in the way of meaningful progress. Proactive ways to counter this include African inter-country cooperation, combined with collective

42

IMIESA June 2017

Cape Town’s executive mayor, Patricia de Lille, delivering the keynote address at FIDIC GAMA 2017, having been introduced by CESA CEO Chris Campbell (left)

teamwork by FIDIC GAMA consulting engineers to win and lead on major projects. African firms face fierce competition from major multinationals, which tend to dominate at present.

Cape Town’s executive mayor, Patricia de Lille, delivered the keynote address and shared some of the ways the Mother City is responding to the challenges. She said the City of Cape Town has taken a decision to grow business opportunities between itself and African cities in line with its enhanced African agenda to strengthen ties and facilitate mutually beneficial partnerships and investment opportunities.

The city invests around R6 billion annually on infrastructure projects. Around 60% is spent on new works and the balance on maintenance. In both areas, this takes into account future climate change implications. Cape Town, for example, is facing its worst drought in 100 years so alternative responses like the introduction of separate wastewater reticulation systems for water reuse are on the cards.

Green bond To back these and other projects, De Lille said that cities need to find creative ways to generate funds, citing Cape Town’s launch of its Green Bond initiative as an innovative response. The city plans to raise around R1 billion through the sale of its first Green Bond to prospective South African and international investors for projects that include energy-efficient buildings, and water and wastewater management infrastructure.

Taking the initiative CESA president Lynne Pretorius outlined that the conference came at a time when the environment in which business is being conducted is “extremely challenging”.

“South Africa has its own economic challenges currently, along with various social

financial shortfall According to the African Development Bank, the infrastructure need of sub-Saharan Africa exceeds $93 billion annually over the next 10 years.

To date, less than half that amount is being provided, thus leaving a financing gap of more than $50 billion.

FIDIC GAMA

FIDIC GAMA map (not shown is the Ivory Coast, which is the most recent GAMA member)

and political dynamics. These are all mirrored to some extent in the rest of Africa, as well as in the rest of the world – developed and developing countries alike. With global changes afoot, it is clear that the world as we know it and the consulting engineering environment are changing. Within this dynamic environment, CESA remains resilient and relevant in enabling consulting engineering excellence in South Africa, the SADC bloc and further across our borders.”

GAMA president elect James Mwangi said that with the growing local content requirements in many African countries, partnerships are important in ensuring capacity building, skills development and transfer.

“So far, we’ve seen more partnerships between consulting engineers from outside Africa and African firms than partnerships between African firms,” pointed out FIDIC GAMA 2017 local organising committee chairperson and GAMA honorary secretary Abe Thela. “Partnerships to facilitate infrastructure development across our borders are crucial to the sustainable growth and development of the consulting engineering profession in Africa, as well as in integrating our regions.”

Challenges that need to be overcome include insufficient investment in infrastructure development, corporate governance failure in both the public and the private sectors, and requirements designed to exclude African consulting engineers from projects implemented by the Development Finance Institutions (DFI). These requirements are perceived to favour consulting engineers from the DFI’s country of origin and are often supported by inappropriate procurement strategies. Manfred Uken, director: Strategic Business Development, Transport and Planning for Africa at Royal HaskoningDHV, mentioned that accessibility and mobility are some of the most fundamental prerequisites of sustainable development and need focused attention in Africa. Similarly, African logistic costs are unacceptably high and a serious barrier to growth and development on the continent.

Sustainable construction Funding gaps will exist for many years to come, so alternative design and construc-

tion solutions sometimes need to be adopted to stretch budgets and build capacity.

Professor Robert McCutcheon, from Malani Padayachee & Associates, addressed delegates on the topic of modern labour-based construction techniques as a well-proven practice for roads, both in terms of the end result and as a jobs and skills creator.

As McCutcheon’s presentation pointed out, labour-based methods have been shown to deliver the same result as those taking a predominately mechanised approach without compromising on time, cost and quality. The emphasis is on re-engineering products and processes. For example, in South Africa, labour intensities of 40% have been achieved for high-standard urban bus routes and for elements of provincial road.

Bankable projects “It’s time to kick sustainability into action,” said CJ Venter, executive director, Bigen Africa, during his presentation entitled ‘Establishing Win-Win Partnerships to Achieve Sustainable Development’.

Venter pointed out that the funding and development of infrastructure projects on the African continent are inhibited by various factors, the most significant being the absence of a pipeline of well-prepared bankable projects. According to the Infrastructure Consortium for Africa, the major problem is not a lack of funding; instead,

The major problem is not a lack of funding; instead, it is the lack of packaged bankable projects it is the lack of packaged bankable projects – which, in turn, points to a need for better project preparation.

As Venter stated in his presentation, “Project preparation is a process which comprises the entire set of activities undertaken to advance a project from concept to implementation – the primary objective being to develop the project idea to the point where it will demonstrate bankability, attract financier interest and motivate funding.”

Estimated costs for project preparation vary; the general consensus, according to an Infrastructure Project Preparation Facility study, is that it is around 10% of capital expenditure. The finance gap for project preparation is estimated to amount to US$25 billion between 2016 and 2040.

It’s clear, then, that sustainable development requires responsible investment practices, combined with secure ease of access to markets. Here, GAMA members have a key role to play in expanding the infrastructure network across Africa through the power of strategic partnerships.

IMIESA June 2017

43

Delivering the right product to the right place at the right time

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Transport, Logistics, Vehicles & Equipment

A future underpinned by

smart technology The way products are designed and shipped to market is changing rapidly and has major implications for project managers and supply chain experts. By Kate Stubbs*

F

aced with ongoing disruption, largely fuelled by technology and innovative software development, almost every industry is being forced to rethink traditional strategies and operational approaches.

By examining the current landscape and taking into account the state of technology today, it is clear that certain trends will be shaping every aspect of supply chain management and logistics. Chief among these are the emergence of autonomous vehicles, 3D printing, big data, blockchain technology and the role of online marketplaces.

According to research firm Frost & Sullivan, most moving vehicles within logistics – from forklifts to delivery fleets – will be semi-autonomous and some fully autonomous in the not-too-distant future. For the supply chain, autonomous logistics will be felt in areas like autonomous guided vehicles, truck platooning, autonomous cargo rail, and drones for last-mile delivery.

Data-driven decisions taking over As more unstructured data becomes integrated into daily analysis and evolves into structured data, it will undoubtedly lead to enhanced efficiencies and quicker, calculated decision-making within the supply chain.

For the wider industry and logistics stakeholders, predictive and prescriptive analytics are already presenting a number of applications. These include route optimisation in real time, ‘control-on-the-go’ as mobile devices are used to increase enterprise visibility, and product tracking data to understand customer purchasing behaviour and support requirements.

For business leaders, the critical element of big data is to understand where and how

this surge of information can be harnessed to benefit the supply chain.

Blockchains and smart contracts Although it is a term more frequently associated with finance, blockchain technology is poised to impact key functions within logistics. In short, the blockchain refers to distributed cryptography based on an open-source and real-time data platform.

Essentially, blockchain technology enables a strong and secure exchange for shared logistics, coordinating a vast array of activities – from sharing unutilised space in a shipping container or warehouse to optimising truck fleets.

Stakeholders can eliminate supply chain opaqueness by having a record of all logistics transactions in blocks. It can, for example, provide insights around drivers, routes and on-the-move goods and services. Added to this, blockchain technology can yield important benefits with regards to B2B transactions – such as cross-border payroll processing and smart contracts.

3D printing marches forward Another technology making headway is 3D printing, where capabilities are improving daily. It has vast potential when it comes to freedom of design and can also lower production costs by up to 50%. For example, a low-cost home design layout can be printed within a day.

Another remarkable example is the breakthrough by GE Aircraft, which has developed the world’s largest commercial jet engine using 3D printed metal parts for its GE9X twin-engine plane. One of the parts includes 3D printed nozzles, replacing conventional nozzles that previously had over 12 welded

Kate Stubbs, managing executive: Business Development & Marketing, Barloworld Logistics

parts. This technology trend is set to impact the shipping industry as well, especially given that 95% of the goods that are currently shipped could, in future, be 3D printed.

Factory in a box As 3D printing capabilities come to the fore, we may also witness the introduction of a ‘factory-in-a-box’ approach, dispensing with the need for multiple machines to make a single product.

In the near future, each individual 3D printer could have the capability to print several different materials using multiple processes in various, decentralised locations. As a result, logistics and supply chain management could be drastically transformed, servicing only nimble, innovative, ‘garage-sized’ industries. While these technologies and trends are arguably still in the development stage, they are forcing businesses to shift their approach and to begin the process of future-proofing and implementing sustainable processes, right now. *Kate Stubbs is the managing executive: Business Development & Marketing at Barloworld Logistics.

IMIESA June 2017

45

Over three decades of oscillation

Oscillation offers a wide range of benefits, enhancing efficiency, quality, productivity and profitability in both asphalt and soil applications.

D

uring the 1980s, HAMM pioneered the development of oscillation compaction and became the first manufacturer to offer an oscillation drum for tandem rollers. While other OEMs have since entered the market, HAMM remains a leader in this field. In the past five years alone, HAMM has delivered more than 3 000 machines equipped with this innovative technology and there are currently more than 30 models in the range. Additionally, HAMM is believed to be the only OEM that builds oscillation tandem rollers in the compact class

46

IMIESA June 2017

(which range from 2.5 t to 4.5 t), as well as soil compactors with oscillation compaction capability. The HAMM portfolio encompasses tandem rollers for asphalt paving ranging from 2.5 t to 15 t. Pivot-steered rollers in HAMM’s DV+ series are a popular choice for demanding roadbuilding projects. In 2016, for example, around 40% of all DV+ series rollers were delivered with oscillation drums.

The oscillation principle But what exactly happens in an oscillation drum, and how does oscillation differ from vibration? With vibration, a single, unbal-

A HAMM HD+ 120i OV tandem roller compacting the surface course of a busy highway

anced shaft generates the upward and downward movement of the drum, causing it to strike the ground at a rapid rate. In oscillation drums, on the other hand, two unbalanced shafts rotate synchronously, driven by a toothed belt. The unbalances are offset by 180 degrees relative to one another. As a result, the drum performs a rapidly alternating forward/backward rotary movement.

Transport, Logistics, Vehicles & Equipment

Oscillation involves two unbalanced shafts rotating synchronously. The unbalances offset each other by 180 degrees

Due to this movement, the drum directs the compaction force into the substrate tangentially to the front and rear in the form of shear forces.

Here, unlike vibrating drums, the compaction force acts continuously on the substrate because the oscillation drum is in contact with the ground at all times.

This is why oscillation rollers compact dynamically as well as statically with their intrinsic weight the whole time.

Maximum wear resistance HAMM’s experience of more than 30 years is also reflected in the way in which the technology is incorporated in the design.

An example of this is the drum shell. On oscillation drums, this shell is inevitably subjected to greater stresses, due to the constant ground contact, than is the case with vibrating drums.

Thanks to ongoing product and materials development, the operating life of HAMM oscillation drums is, today, nearly the same as that of vibrating drums. This is made possible by using highly wear-resistant finegrain steel for the drum shell.

In addition, an integral reinforcing ring ensures that the drum is extremely hard-wearing. This is why HAMM confidently provides a remarkable warranty against wear of at least 4 000 operating hours.

Use for all layers Oscillation rollers can be used to compact all earthworks and roadbuilding layers. They come into their own in earthworks applications where re-loosening of the upper layers has to be effectively prevented. Another

HAMM offers over 30 different rollers with oscillation

important application is the compaction of soils in vibration-sensitive areas – for example, above gas, water and other pipework.

For asphalt paving, base courses, binder courses and surface courses can be reliably compacted with oscillation rollers. They perform especially well in the compaction of generally hard-tocompact asphalts such as SMA or in the case of polymer-modified material mixes. This is because, in contrast to vibration compaction, the effective direction of the vibrations during oscillation promotes the desired redistribution of long-chain binding agents.

Other applications include work on thin layers (e.g. surface courses and thin overlays) in vibration-sensitive areas (bridges, confined urban spaces, buildings or parking decks) and wherever the mix cools quickly (thin layers, windy or cold environments).

Also of particular importance is joint compaction where the hot asphalt is to be compacted without damaging the adjoining cold asphalt.

Drums can potentially leave impressions in the still-soft asphalt, especially in curves.

Impressions of this nature would have to be rerolled afterwards, wasting time, lest they remain visible in the asphalt and compromise quality. Both issues are avoided from the outset thanks to HAMM’s design solution, which involves giving all drum edges a slight chamfer. This chamfer can also be found on all of HAMM’s vibrating drums.

Last but not least, oscillation has also proved its worth on large projects. Here, the rapid increase in compaction ensures an optimised process that can be carried out with fewer rollers, making this technology a preferred choice for contractors worldwide, especially when it comes to speed and quality.

Today, one in four tandem rollers made by HAMM is equipped with an oscillation drum

Six benefits of HAMM oscillation 1. High compaction power – great efficiency Oscillation rollers compact very quickly. The reason for this is the superimposition of dynamic shear forces with the permanent load from the roller’s own weight. As a result, considerably fewer passes are needed, especially on large areas.

2. Easy operation The appropriate amplitude is set automatically according to the rigidity of the material to be compacted. This happens so quickly that compaction is always adjusted perfectly, even with varying substrates.

3. Smooth, skid-resistant surfaces Oscillation rollers produce surfaces with excellent longitudinal evenness, resulting from the drum remaining in contact with the ground at all times.

Surface rippling does not occur, not even at high working speeds.

4. Low vibration emissions Oscillation drums do not lift off the ground while compacting. With oscillation drums, only around 15% of the vibration is directed into the substrate around the roller.

5. Material-friendly compaction Oscillation avoids detrimental aggregate crushing and over-compaction.

Moreover, oscillation compaction produces watertight, long-lasting joints without damaging cold asphalt.

6. Wider temperature window Oscillation widens the temperature window in which compaction is possible: even at lower temperatures, it can be used to compact without damage. For this reason, oscillation is particularly suited to the compaction of thin layers or on fast-cooling surfaces such as on bridges.

IMIESA June 2017

47

MSS UD CRONER 001

• Lower Maintenance Costs • UD Telematics Services* • Full Automatic Transmission • Longer Service Intervals • More Fuel Efficient • 2 Year Warranty** Product in photograph is for illustration purposes only and is subject to stock availability.

Talk to your UD Trucks Dealer to find out how they can make every moment count.

Go to udtrucks.co.za, to locate your nearest dealer.

Call our 24-Hour Roadside Assistance 0800 008 800 (in breakdown situations) Going the Extra Mile

* Country Specific

** Relevant to SA supplied product

Transport, Logistics, Vehicles & Equipment

Taking compaction to new levels

D

ynapac launched its first-generation CC40 roller in 1964 and the model’s success marked the starting point of a series of subsequent product launches in the large double-drum compaction class.

The latest development is the 2017 introduction of the sixth-generation range – models CC4000 to CC6200. These models are ideally suited for modern thin-layer applications that need to be compacted fast to meet short material cool-off windows.

Orders for the new range have already been secured in South Africa and the first units were scheduled for handover to customers in June 2017. For the local market, machines come equipped with a Tier III engine. The

latest technology on the sixth-generation simplifies roller operation ensures optimised handling and increases the quality of the compaction result. The start-up procedure is another example of simplicity: the machine intelligence takes care of the preheating, and the engine starts automatically when ready.

Improved offset The offset is increased to 520 mm. Using the front drum for offset as opposed to the rear ensures even better driving accuracy. This advanced steering gives unmatched manoeuvrability, resulting in a very small turning radius when used in combination with the steering hitch. Increasing the offset also improves roller stability when compacting weaker road

Dynapac’s CC5200 VI double-drum vibratory roller

edges, increases the rolling surface capacity when making the final static passes to rid the mat of any marks, and improves operator control of the front drum to follow curb edges and any other obstacles with a high degree of accuracy.

Dynapac has drawn on its reservoir of experience to make the water system – possibly the most important system on an asphalt roller – as reliable as possible. All rollers in the range are equipped with Automatic Water Control, a sprinkler timer, full-flow sprinkler button, dual sprinkler pumps and dual sprinkler bars.

IMIESA June 2017

49

Fast, simple, profitable and sustainable The next generation of state-of-the-art Dynapac CA single drum vibratory rollers feature superior compaction performance to high efficiency ratios for sustainability in the work environment. www.atlascopco.co.za

IMIESA June 2017

49

Public Lighting

Structural steel for public lighting Collectively, the Structa Group and its subsidiaries have 115 years of experience in medium-to-heavy engineering ser vices and the quality of engineering is world-class.

I

ndustries participating in infrastructure development should take note that Structa offers a one-stop shop for structural steel products in key areas such as the distribution of electrification and telecommunication lines, water storage, materials handling and logistics, and minerals processing. Through its subsidiary, Structa Technology, Structa is also a leader in lighting mast technology,” says Piet Coetzer, chairman of the Structa Group of Companies.

Meyerton-based Structa Technology, through its Bowmast product line-up, offers a comprehensive range of lighting masts such as

street lighting poles, Midbow lighting masts, standard high masts, stadium masts and the Abamax hydraulically liftable masts. Full mast kits, “ready to erect” – including mast, electrical elements, lights and precast foundations – can also be supplied to the client.

Midbow masts

LEADERS IN LIGHTING MAST TECHNOLOGY

Street light poles Midbow lighting masts Abamax hydraulically liftable masts Standard high masts Stadium masts

The Midbow masts offered in tubular, mid-hinging masts from 12 m – 18 m and the octagonal mid-hinging masts are supplied in heights from 20 m – 25 m. The masts allow up to six 1 000 W lights or 0.8 m2 wind area. The terrain categories are 2 or 3.

Highbow masts

Specialists in the design, supply and installation of lighting support structures

Street light poles Midbow lighting masts Standard high masts Stadium masts Hydromax hydraulically liftable masts Full mast kits, “ready to erect” including mast, electricals, lights and pre-cast foundations can be supplied

T: 0861 STRUCT (787828) F: 016 362 3608 E: masts@structatech.co.za Meyerton, Gauteng

www.structatech.co.za

STRUCTA TECHNOLOGY is part of the STRUCTA GROUP of Companies

Structa Technology is a Level 3 BBBEE Contributor

The monopole high mast lights range from 15 m – 40 m.

The Abamax type allows hydraulic lowering of masts (20 m – 40 m). The terrain categories are 2 and 3, up to ten 1 000 W lights or 1.2 m2 wind area. The stadium masts are 20 m – 50 m in height, with 10 – 120 luminaires (100 w – 2 000 w).

All lighting masts conform to the requirements of SANS 10225. All masts are hot-dipped galvanised to SANS 121-1462.

The Bowmast product range is backed by a superior manufacturing plant with a sufficient capacity to do large, rapid roll-outs, as well as a design office equipped with the latest CAD and Finite Element-Analysis software.

Bowmast product protection Products fabricated in steel generally require some form of surface protection, and Bowmast is able to offer hot-dipped galvanised coatings to SABS standards, zinc metal spray and anticorrosive primer paint.

Background Subsidiaries within the group take pride in achieving excellent manufacturing standards through: • Quality, health and safety • State-of-the-art machines • A highly skilled and dedicated workforce • State-of-the-art design

CEMENT & CONCRETE

Low maintenance, excellent thermal conductivity and exceptional acoustic performance are just some of the outstanding features of concrete, making it a preferred material for a range of public works projects.

By John Roxburgh*

Concrete sustainability

T

he Bruntland Report, commissioned by the United Nations, defined sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”.

Sustainability, therefore, will include balancing various economic, environmental and social factors (see Figure 1), often referred to as the triple bottom line. Making sure that these three factors are in balance will result in increased sustainability. From a municipal infrastructure development standpoint, this

FIGURE 1 Triple bottom line concept

John Roxburgh, lecturer, TCI School of Concrete Technology

makes both political and economic sense.

Keeping municipal constituents happy by fulfilling their social requirements as economically as possible, with sensible use of resources in a way that will not impact future generations, should be a goal of all municipalities. Concrete, the world’s most commonly used building material, has played – and continues to play – an invaluable role in municipal infrastructural development. Its versatility, durability, affordable cost, and recyclability, make it the logical material of choice for sustainable development in a municipal environment.

Concrete compares well with other construction materials in terms of embodied energy and carbon dioxide emissions. An often quoted figure for the carbon dioxide equivalent (CO2e) is approximately 1 000 kg per tonne of cement. However, this is a figure for cement and not concrete. Typically, the cement content in concrete sits between 12% and 15% by mass. This results in a much lower CO2e for concrete.

Table 1 illustrates that the carbon footprint of cement has been substantially reduced by blending in extenders such as fly ash, slag and ground limestone. When these cements

are combined with aggregate and water to make concrete, the concretes generally have a carbon equivalent footprint ranging from 90 kg to 160 kg per tonne. The structural design process, construction methods employed, the use of carefully chosen low CO2e materials, and the use of secondary industrial or recycled products may produce meaningful resource conservation and reductions in embodied energy. However, research into the long-term cumulative benefits of considering the whole life cycle of structures has shown huge potential for energy savings during the serviceable life of the structure.

Jobs and durability It is within the serviceable life of a municipal structure that concrete graphically demonstrates its sustainable advantage.

Concrete also provides meaningful social benefits. It does this both in the delivery of durable, long-lasting structures and the jobs it creates. For example, the production and installation of concrete and concrete products – such as roof tiles, bricks, blocks, kerbs, poles, pipes and paving – are all suited to labour-intensive processes.

A number of properties contribute to

IMIESA June 2017

51

CEMENT & CONCRETE

Table 1 Average CO2e per tonne of cement

Cement type

CEM I CEM II A-L CEM II A-S CEM II A-V CEM II B-L CEM II B-S CEM II B-V CEM III A CEM IV A CEM IV B CEM V A CEM V B CEM V B

Average emission values (kg CO2e/tonne)

985 840 815 790 720 730 690 560 640 570 590 415 415

concrete’s excellent sustainability during its service life. These are discussed below.

Durability Concrete is one of the most durable materials

52

IMIESA June 2017

used in municipal infrastructure development. If correctly designed for the specific environment in which it will be placed, concrete will perform over its service life with minimum cost and energy-intensive maintenance. Careful material choice, correct proportioning and good site practices are essential in producing a quality, impermeable concrete. Quality and impermeability are key factors for durable concrete.

Thermal mass Thermal mass – also known as thermal capacitance – is the ability of a material to store heat during the hotter part of the day and then release it a few hours later when the ambient temperature becomes cooler.

Concrete has good thermal mass properties.

These include a high specific heat capacity, high density and a moderate thermal conductivity. Thermal mass is a critical, but often forgotten component of the passive solar design of buildings. It has a moderating effect on the internal temperature of

buildings (see Figure 2). Along with effective ventilation, solar shading and building orientation, significant reductions in energy consumption and greenhouse gas emissions can be realised.

Albedo effect The light colour of concrete also has several benefits. Two primary benefits are reduced lighting energy consumption, and a reduction in the “heat island effect” in urban areas.The light colour of concrete enables lighting requirements to be reduced, both internally and externally.

For concrete roads or parking areas, research in the USA has shown that surface reflectance readings on concrete pavements and other surfaces are four to five times higher than other road surfacing materials.

This means increased visibility of the road, pedestrians and other vehicles plus increased security in urban areas. There can be an up to 24% reduction in lighting requirements for urban areas and car parks. The ‘urban heat island effect’ is used to describe how temperatures

CEMENT & CONCRETE

FIGURE 2 Stabilising effect of thermal mass on internal temperature

energy, thereby preventing a large temperature rise within it. Studies have shown that the albedo effect of concrete can be used to cut air-conditioning usage by as much as 18% on summer afternoons.

Acoustic performance

in an urban area can reach between 2°C and 6°C warmer than the adjacent countryside. Albedo is the proportion of the incident light or radiation that is reflected by a surface. Concrete has an albedo that is relatively high compared to other construction materials. This allows concrete to reflect a high proportion of radiant

With housing and business densification and increasing traffic congestion in municipal areas, the control of noise is becoming more impor tant.

Excessive noise has an adverse effect on personal health and productivity. The inherent mass of concrete allows for good sound insulation and reflection. Concrete walls can be used effectively as barriers against airborne sound and to minimise the need for additional layers of materials to meet acoustic requirements.

Conservation Another major environmental consideration is water conservation. Large water amounts of run-off in municipal areas from impervious surfaces can lead to an overload on existing drainage systems, flooding, and the washing of oil and other chemicals into the surrounding rivers and dams.

It also slows down the replenishment of natural aquifers. Pervious concrete, or permeable block paving, can be used to attenuate stormwater, filter pollutants and allow for the replenishment of natural groundwater.

In municipal areas, it can reduce the number and size of drainage infrastructure elements, providing an economic benefit through less material and energy usage, as well as a reduction in future maintenance. These and other examples serve to demonstrate the seemingly endless versatility of concrete. *John Roxburgh is a lecturer at The Concrete Institute School of Concrete Technology.

IMIESA June 2017

53

We are there when you repair

Need to maintain your concrete? Our Information Centre has extensive information on assessment and repair techniques.

Improve concrete with us. www.theconcreteinstitute.org.za +27 11 315 0300

CEMENT & CONCRETE

Paving durability cast in concrete

T

he Aggeneys mining township was developed in 1978 in the Northern Cape by the then Black Mountain Group.

Housing and roadways were built for the group’s employees and local residents.

Technicrete, then known as Concor Precast, operated two block manufacturing plants adjacent to Aggeneys, enabling it to produce the newly designed Zig Zag block pavers for the project.

“That was 39 years ago, and the roads and houses are still in perfect condition, even though traffic throughput has been far greater than the original roadways were designed for,” says Tony van der Berg, technical executive at the IS Group.

“We visited Aggeneys 15 years ago with engineers from the Black Mountain Group, who confirmed that they had conducted no maintenance whatsoever since we supplied the new Zig Zag product in 1978. We had

Today, Technicrete’s Double Zig Zag interlocking pavers offer the same longevity and cost-effectiveness through their continuous, hardwearing surface overlay 54

IMIESA June 2017

also originally supplied a number of black hollow products for the housing project.

When visiting earlier in 2017, the product still has a good surface and appearance.”

Originally, the Zig Zag product was manufactured using a VB4-sized Schlosser machine and a single Besser machine.

Today, far more advanced technologies are employed.

Today, Technicrete’s Double Zig Zag (DZZs) interlocking pavers offer the same longevity and cost-effectiveness through their continuous, hard-wearing sur face overlay. They are particularly suited for areas of heavy traffic such as parking areas, industrial and factory roads, and suburban streets.

Armorflex With the paving mix, Technicrete’s interlocking Armorflex blocks have proven to be well suited to jeep track (strip road) applications, providing access to areas currently either without established roadways or with crumbling cast-in-situ concrete strips.

Sites requiring vehicle traversal – such as rural development and construction areas, agricultural and farm roads, gravel routes, earth tracks and, in particular, locations where roads and embankments are subject to stormwater erosion – would benefit greatly from the installation of Armorflex.

The specialised design of the blocks, with earth-filled gaps and varying height concrete areas, ensures greater traction for vehicles, particularly in mountainous environs and/or wet conditions. The ability to wire-tie the blocks together into long mats and anchor these into the natural soil further assists in stabilisation of the blocks and road surface.

Placement in jeep-track orientation is cost- effective due to a material saving by only paving two strips of approximately 600 mm wide (each) as opposed to paving the entire road width.

Traditionally, gravel roads or earth tracks require costly regular maintenance, such as grading. In situ concrete sur faces start cracking up very soon after installation and degrade very quickly, with large chunks of concrete spalling and breaking off. These types of installations generally require regular repeated applications that become too costly to maintain.

A correctly designed and installed Armorflex jeep track project will offer a closure solution with minimal maintenance requirements that will not crack, break, shift or become unusable for vehicular access. Armorflex jeep track roads can be designed to accommodate low- to highintensity traffic and a variety of loading from cars to heavy trucks.

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 Arup SA rob.lamb@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 Engcor Engineers masham@engcorengineers.co.za Fibertex South Africa (Pty) Ltd rcl@fibertex.com GIBB yvanrooyen@gibb.co.za 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 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 Moedi Wa Batho Consulting Engineers (Pty) Ltd info@wabatho.co.za Mott Macdonald Africa (Pty) Ltd mahomed.soobader@mottmac.com Much Asphalt leon.alberts@muchasphalt.com NAKO ILISO hans.hartung@nakogroup.com Nyeleti Consulting ppienaar@nyeleti.co.za Odour Engineering Systems mathewc@oes.co.za PMA Consulting pragasen@pmaconsultingsa.co.za Pumptron info@pumptron.co.za Pragma nicojobe.mabaso@pragmaworld.net francisg@rhdv.com Royal HaskoningDHV SABITA info@sabita.co.za SALGA info@salga.org.za SARF administrator@sarf.org.za.co.za SBS Water Systems desere@sbstanks.co.za Sembcorp Siza Water info-sizawater@sembcorp.com Servotech (Pty) Ltd finance@servotech.co.za 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 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 craign@uwp.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 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

I M E S A A F F I L I AT E M E M B E R S

IMESA

insight

index to advertisers AECOM Afrisam South Africa

56

20 9

Doosan International

21

DPI Plastics

17 OBC

Aquadam

40

Erwat

Atlas Copco

49

Franki Africa

Aurecon

13

IMESA

Bakwena Platinum Corridor

24

Knight Piésold

Barloworld Logistics

44

Mather+Platt

36 10,31,55

Barloworld SEM

4

Model Maker Systems

Corobrik

2

Much Asphalt

28 OFC 32 18

CSV Construction

14

National Asphalt

IFC

Devcotech Electrical Engineering

15

Oil & Gas Africa

56

Quality Filtration Systems

34

Sika SA

33

Sizabantu Piping Systems

IBC

SMEC South Africa

23

Structa Group

50

The Concrete Institute

53

Tosas

27

UD Trucks

48

UWP

52

IMIESA June 2017

ENGINEERING SUPPLY

CHAIN SOLUTIONS: CLEANER, CHEAPER, FASTER

Visit www.africaogp.com for more information BOOK NOW FOR THE CONFERENCE & ALSO VISIT THE EXPO AT THE CAPE TOWN INTERNATIONAL CONVENTION CENTRE Supporting partners and associations:

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ERWAT

Consistent water plant management requires consistent excellence... ...

EXCELLENCE IN WASTEWATER

... in delivering specialised water-related services.

ERWAT Commercial Business follows a partnered approach offering their customers complete water plant management, whilst continuously striving towards the enhancement of the market and delivering excellence in specialised and innovative water-related services. Professional support and services are provided through an in-depth range of products geared towards managing plants, plant operations, maintenance, process optimisation and technical support. Services include plant audits, plant optimisation, water quality monitoring and compliance monitoring analysis, sludge analysis and classification, Blue Drop and Green Drop support services as well as in-house and off-site implementation of municipal by-laws and tariffs.

East Rand Water

Reg. No. 1992/005753/08 (Association incorporated in terms of section 21)

GPS Co-ordinates: S 26° 01’ 25.8” and E 28° 17’ 10.0” Address: Hartebeestfontein Office Park, R25, Bapsfontein/Bronkhorstspruit, Kempton Park.

Tel: +27 11 929 7007 E-mail: mail@erwat.co.za

uppe marketing A14073

www.erwat.co.za