PUMPING RESPONSIBLY THE ONLY WAY TO CONSERVE GROUNDWATER

As South Africa increases its use of boreholes to meet growing water needs, users must pay more attention to monitoring and controlling how much groundwater they pump or these resources could be rapidly depleted.

This is according to Stephan Venter, Grundfos product manager water utilities for India, Middle East and Africa, who has been extensively involved in providing pumping solutions for borehole users. 

“The main risk when municipalities, businesses or households make use of groundwater resources is that their extraction from boreholes could exceed the recharge rate of the aquifer,” says Venter. “To avoid this, users need to gather a great deal of information from the start – it’s more than just drilling and pumping.”

An important aspect of ensuring the sustainability of a borehole, he says, is the correct sizing of the pumping infrastructure. This requires data including the borehole’s safe yield, the dynamic water level, the required lift above ground, discharge ratio, friction loss in piping, flow demand and well size. 

He notes that while larger water projects will usually employ the services of a qualified hydrogeologist to generate the necessary data on the aquifer, many smaller users simply proceed with minimal information. 

“This makes it difficult to put the borehole on a sustainable footing,” he says. “Lack of investment in the monitoring equipment also creates challenges in controlling the water abstraction adequately.”

He highlights the importance of taking a conservative view on what levels of extraction the aquifer can accommodate. Even when yield testing is conducted, for instance, there could be other users of that particular aquifer who are not pumping at the time of the tests – leading to an over-estimation of yield capacity.  

“Just to be safe, I tend to advise the user to size their pumping equipment at only 50 to 60% of the borehole’s safe yield,” he says. “This reduces the risk of over-pumping, through which they could possibly even lose this valuable groundwater source altogether.”

There is no substitute for constant monitoring, however, and Venter emphasises the value of digital technology in collecting and transmitting data to keep users informed. Many users still use a manual inspection method to check the level of the borehole and the condition of the pump, but the most effective way is through electronic equipment linked to online platforms.

“This provides updated information at the click of a button, either through a SCADA system for larger users, on a standard computer or even on a mobile phone,” he says. “Monitoring and measuring our groundwater resources is vital in a dry country like South Africa, especially as we work towards becoming more responsible water users.”

Further challenges for borehole users include the unreliable power supply and the rising cost of the electricity required to pump water. Fortunately, solar power generation technology has improved in leaps and bounds, says Venter, and has been well leveraged by borehole pump manufacturers. 

“Solar power now allows water to keep flowing even when mains power goes down,” he says. “The development of high-efficiency pumps – combined with technology like permanent magnet motors and variable speed drives – can reduce pumping costs and ensure constant supply.”

He says that specialised software developed by Grundfos – the world’s largest pump manufacturer – even allows users to go online and select the ideal pump model to suit their borehole specifications, helping to make the most responsible use of the country’s scarce groundwater resources.

DRY-TYPE TRANSFORMERS FROM TRAFO IDEAL FOR COAL MINE

Trafo Power Solutions has customised two dry-type transformers for a coal mine in South Africa’s Limpopo province, allowing the units to be fitted into existing enclosures while meeting the customer’s demanding duty requirements.

“While we would normally supply the transformer together with its enclosure, we are also able to design the solution according to the dimensions available on site,” says David Claassen, managing director of Trafo Power Solutions. 

This required one of the transformers – a specialised 3900kVA unit – to be copper-wound to achieve a smaller footprint suitable to the space constraints without compromising the technical performance. With 11kV capacity on the primary windings, this transformer included four separate secondary windings – for 1810V, 1515V, 1360V and 1210V output respectively. 

“Being located outdoors on a coal mine, the transformer had to be well protected from fine dust and moisture, requiring a specially designed IP54 enclosure,” says Claassen. “At the same time, the transformer’s large size meant substantial heat loss, which needed to be extracted from the enclosure. The design therefore included an air-to-air heat exchanger to recycle cool air in a closed loop.”

The second transformer supplied to the mine was a 1600kVA unit for indoor application, stepping down from 11kV to 550V. Working closely with transformer repair experts Koratech Services, who applied certain modifications to the enclosure, Trafo Power Solutions was able to meet the dimensional and electrical requirement of the application – complete with control and protection system.

“Underground mining often presents space constraints which have to be considered in the design of the transformer or the miniature substation,” he says. “With our expertise and our strategic partnership with leading Italy-based manufacturer TMC Transformers, we can readily cater for these conditions.”

He notes that Trafo Power Solutions also supplies dry-type transformers to the marine industry, which requires not only that transformers can be safely employed indoors, but that they often be accommodated in cramped spaces. This experience enhances the company’s technical capability in underground mines. 

Claassen highlights that both transformers were ordered during the tight Level 5 Covid-19 lockdown in South Africa. Despite similar restrictions in Italy, TMC Transformers proceeded with manufacturing, running a 24-hour, three shift operation to ensure the required social distancing. 

“The high level of collaboration with our strategic partner allowed us to design, build and supply the transformers despite the Covid-19 disruption in 2020,” he says. 

Claassen says the dry-type transformer is ideal for both hazardous and non-hazardous areas of coal mines, as the absence of oil as a coolant makes the solution much safer. There is also much less maintenance required on dry-type transformers.  

POPULAR VSI CRUSHER JUST GOT EVEN BETTER

Continually advancing its crushing technology, Pilot Crushtec International has released its new Pilot Modular VS100 vertical shaft impact (VSI) crusher for tertiary and quaternary applications.

The Pilot Modular VS100 is a remodelled and improved version of the company’s popular entry-level Pilot Modular AC06 VSI crusher, according to Francois Marais, sales and marketing director at Pilot Crushtec. The AC06 has, for over 25 years, been successfully serving the aggregate and mining sectors with hundreds of units in the field both locally and internationally. 

Advanced materials and manufacturing methods have enhanced the Pilot Modular VS100, while it has retained the functionality and reliability of the tried-and-tested AC06 model. The versatile crusher is used mainly for producing sand and fines, and for enhancing the quality of aggregate.

“Among the features of the new VS100 are elements that make for a safer working environment,” says Marais. “These include a new inclined staircase, and a three-sided platform that is both non‑slip and chemical resistant.”

He emphasises that this high performance machine is packed with years of experience and know-how. The hydraulic pack both opens and automatically rotates the lid, revealing the modular rock chamber and rotor. The jib crane is installed as a standard item, for safe removal of the rotor. 

“The modular rock chamber allows you to go from autogenous crushing to an anvil ring crushing configuration, and is designed for efficient rock-box build-up,” he says. “The VS100 is also future-proof – with the option of two rotor sizes, five motor sizes, five rotor speeds and a rotor by-pass system.”

Marais explains that these options allow plant capacity requirements to be optimised with economical power consumption, making the unit versatile enough to allow upgrades as plant production requirements increase. 

“Once you start the crusher and the material pours into the newly designed omni-directional feed chute, you notice how smoothly the new advanced vibration isolation keeps the plant running smoothly,” he says.

The new-generation triple bearing, grease lubricated cartridge has an optional Auto Lube system to facilitate regular lubrication for added reliability, while the modular serviceable rotors reduce operational costs. Once the worn wear parts have been replaced – and correct tip material selected to suit the stone – the rotor can be balanced using the balancing kit provided. Pilot Crushtec SupportLink technicians are available to train customers’ maintenance teams during commissioning, ensuring smooth and cost-effective operation into the future.

“Overall, the new Pilot Modular VS100 is the complete package,” says Marais. “With its improved safety features for overall compliance, this brand new design allows operations to increase tonnages from 10 tph to 100 tph, depending on the application.” 

He also points to the unit’s ease of maintenance, made possible by the smart design and the simple operations of the crusher. These factors make the new Pilot Modular VS100 a wise and operator-friendly investment for any operation making use of VSI crushing. The skid-mounted module requires only a level compact surface for installation, and no civils infrastructure.

WEBA FORGES GREEN PATH TO THE FUTURE

A new 390 panel solar plant at Weba Chute Systems’ Germiston facility is now making an active contribution to the South African economy’s environmental protection and energy efficiency efforts.

As part of its green-future strategy, the transfer point specialist commissioned a roof-top solar energy system in December 2020 as part of its integrated response, says Izak Potgieter, ISO systems manager at Weba Chute Systems.

“With a capacity of 160 kW – calculated on 85% performance – the system meets most of the energy requirements of our workshop and offices,” says Potgieter. “This takes considerable pressure off the national grid, while also allowing us to feed power back into the system when there is excess.”

The impact in the first couple of months of operation has already been substantial, he notes; the 62MW generated by the solar panels represents a reduction of about 25 tonnes of carbon dioxide emissions that would have been produced from coal fired power. Other elements of the strategy have included energy efficiency interventions such as installing LED lighting in the workplace, and the continuous monitoring of heating, ventilation and cooling (HVAC) systems to ensure moderate use. 

“Our environmental strategy is also designed to address stakeholder pressures and market opportunities,” he says. “While there is no facility yet for us to be reimbursed for the electricity that we feed back to the grid, we believe this to be an important corporate contribution at this time. We are also building up carbon credits that may be traded with other companies at a later stage.”

Potgieter highlights that the company’s approach is based on eight sustainable business practices, which include partnering with employees, conserving water and electricity, developing a recycling programme, and prioritising the management of chemicals.

“We are keenly aware that our environmental efforts are part of the broader commitment by the mining industry towards a more sustainable future,” he says. “We therefore pride ourselves on making a positive contribution to the sustainability of the mining supply chain.”

Weba Chute Systems measures its corporate environmental performance against all its impacts on the natural environment – including resource consumption, pollution, waste generation and energy use – to reduce the effect on climate change.

ZEST WEG GIVES MOTOR USERS ANOTHER EFFICIENCY BOOST

In the face of rapidly rising electricity costs in South Africa, Zest WEG is phasing in IE4 super‑premium efficiency motors in its WEG W22 range from April 2021 – which will save on customers’ bottom lines and help reduce the load on the national grid. 

According to Fanie Steyn, electric motors manager at Zest WEG, 2021 will see local energy prices rising above R1/kWh for the first time. This makes it the ideal time for the introduction of WEG IE4-rated motors, which will be available in the size range between 37 kW and 375 kW.

“Unlike many countries around the world, South Africa has not regulated the use of energy efficient motors at the level of IE2 or IE3,” says Steyn. “Nonetheless, we have taken the proactive step of making the IE4 level of efficiency available to customers at no premium on the IE3 units.”

Some years ago, Zest WEG introduced its WEG IE3 motors to the country at little or no additional cost relative to its IE2 motors, with the same goal in mind: making both customers and the country more energy efficient.

Specified under the International Electrotechnical Commission (IEC) 60034-30-1:2014 standard, IE1 refers to standard efficiency and IE2 to high efficiency; the IE3 and IE4 ratings are for premium efficiency and super-premium efficiency motors respectively.

“The efficiency of 96.3% on an IE4-rated 110kW motor, when compared to 94.1% on an IE1-rated motor, can save users hundreds of thousands of rand in energy costs over a 10 year period,” he says. “Not only will these IE4 motors be more cost effective to run, but they have been designed with a number of new features that bring considerable benefits.”

Steyn emphasises that WEG IE4 super-premium efficiency motors meet IEC efficiency levels when running on 50 to 100% of load; efficiency is kept constant, which saves energy and ensures minimal losses through various loading points. The innovative frame design also allows maximum heat dissipation.

“Motor frame design plays a crucial role in thermal performance, as it is responsible for the outward transfer of heat generated inside the motor,” says Steyn. “Running cooler means that our motors have increased life spans, allowing Zest WEG to offer a five year guarantee on our WEG W22 electric motor range.”

The motors’ increased mechanical rigidity – achieved by integrating the front and rear feet sides – affords easier installation, higher mechanical stiffness and improved distribution of the mechanical thrust imposed by the load.

“As a first of its kind, our flexible terminal box mounting means reduced inventory and quicker modification,” he says. “The terminal box can be rotated in 90° increments to facilitate supply cable connection orientated to the front, rear, top or either side of the motor.”

In addition to the benefits brought by WEG super premium efficiency motors a substantial increase in energy savings can be reliably achieved using WEG Variable Speed Drives (VSDs), which comply with the European Extended Product standard EN50598. This ensures the system efficiency of the motor and VSD combination. As an additional feature, WEG VSDs have energy savings settings which can be user activated, achieving an automatic saving under any reduced load conditions.

“We are excited to build on the phenomenal reputation of the existing WEG W22 electric motor range by offering an even more efficient motor that is truly “next level” state of the art in electric motors, having the same rock solid quality and reliability,” Steyn concludes.

BRIDGE WITH LARGEST PRECAST BEAMS IN WESTERN CAPE RELIES ON CHRYSO

A range of CHRYSO products contributed to the success of a bridge project near the historic city of Paarl in South Africa, involving the largest precast beams cast to date in the Western Cape.

Weighing 64 t each, the 18 prestressed beams for the Val de Vie Berg River bridge project measured over 35 m long and two metres high. The large volume and tight spacing of the reinforcing steel, coupled with the presence of stressing cables, meant conventional concrete would not suffice and  the local CHRYSO Southern Africa team worked in conjunction with the precast contractor to design, test and submit a self-compacting concrete mix .

CHRYSO’s CHRYSO® Premia 310 superplasticiser and CHRYSO® Dem Bio 10 environmentally-friendly release agent formed part of the solution for the successful casting of these beams, and were also used in the project’s large facing panels, coping and culverts.

Once all the beam strands were evenly stressed, readymix concrete was placed and a combination of external and poker vibration was used for compaction. This provided a good surface finish with minimal blow holes. After pouring, a tarpaulin was placed over the mould and steam was injected under the cover to accelerate hydration. Using this method, a strength of 40 MPa was achieved in 20 hours, enabling the production of one beam a day. The final strength required was 60 MPa, and this was achieved within 28 days.

Before the casting process, CHRYSO® Retarder paste was applied at the end of each beam shutter and the concrete washed off with water the following day after the shutter was removed. This created a rough exposed aggregate finish that provided a good bonding surface for the assembly of the bridge. 

The facing panels were also steam-cured, and were cast with a glass-smooth finish. They were attached using ‘fingers’, eliminating the use of visual fixing on the front face. Some panels were curved, such as those used for cladding the central viewing cove.

Once all precast beams were in position, five diaphragm transverse beams were cast in-situ between the precast beams. Permanent deck shutters measuring 1,2 m by 300 mm by 50 mm closed the remaining gaps between the precast beams, resting on recesses cast into the beams for that purpose. Readymix concrete using CHRYSO’s water-reducing plasticiser CHRYSO® Plast Omega 126 was then poured onto the shutters to create the deck. 

ABRASIVE SOLIDS HANDLING MADE SIMPLE WITH THE NEW WARMAN SUBMERSIBLE PUMP

The new, high chrome Warman® SSB-A submersible pump from Weir Minerals presents a versatile pump and robust solution for slurry and sludge removal.

“Conceptualised and commercialised by Weir Minerals Africa, the Warman® SSB-A pump is well suited for duty in Africa,” says Marnus Koorts, Product Manager – Pumps at Weir Minerals Africa. 

Engineered for abrasive applications and for handling solid particles, the pump’s applications include mine dewatering, removing mill scale and cleaning up sumps as well as moving slurry, coal-pile run-off or dirty water with a solids content of up to 60% by volume. Koorts highlights that the pump can be moved easily between applications, so is ideal for dealing with temporary problems such as pipe bursts or leakage.

The hard-wearing design includes casting the casing, impeller and wear plates from Weir Minerals’ Ultrachrome® A05 high-chrome alloy, while the motor is designed for continuous and efficient operation though using the pumped media to assist in dissipating heat build-up in the motor windings.

“This durability enhances the range of applications in which the pump can be deployed, including even hardened slurry,” he says. “Customers will move the unit around extensively to wherever it is needed, so we designed the outer housing to avoid snagging by ensuring there are no points that could potentially hook or break as the pump is transported and operated.”

The impeller radial load is balanced out by the opposing forces created by the twin-volute discharge. This stabilises the pump during operation, allowing it to be placed in any position without the risk of oscillating, he says. The design also optimises the life of the cantilevered shaft and its components. 

“Users of the Warman SSB pump can also choose to run it in manual or the optional extra, in automatic mode,” Koorts says. “The automatic mode provides the convenience of self-monitoring water levels, switching on and off as required.” 

Electrical control philosophies can be adapted to suit site applications, such as over-current protection, an earth leakage circuit breaker, while the safety delay feature can reduce the number of starts per hour. 

“The robust, fit-for-purpose design makes this pump a reliable and cost effective solution in a wide range of duties,” says Koorts. “It represents the ideal combination of wear resistant materials and specialist hydraulic engineering.”

GRUNDFOS PUMP SUPPORTS JOJOBA GROWERS IN NAMIBIA

Grundfos approved distributor ConServ Engineering Services has supplied an innovative water solution to provide sustainable employment in agriculture in rural Namibia. 

Approached by the aid project Jojoba For Namibia Trust, the company selected a Grundfos submersible groundwater pump in a water supply design for a jojoba plantation in the Omdel Dam area north-east of Hentiesbaai. 

Although the jojoba is the ideal desert plant and only requires a little water, one of the biggest challenges in the desert environment of Namibia is the lack of water. Where the plants can be successfully grown, they bear nuts once a year which can be pressed for oil of export quality. 

“In the first phase of the water supply project in October 2020, we installed a Grundfos SP7-37 pump into the jojoba plantation’s borehole,” says Mark Riehmer of Conserv Engineering Services. Drawing on renewable energy from the sun, the pump is powered by 18 solar modules which the company also installed, along with an RSI 5500 inverter. This phase will pump water about 1,5 km to the first storage tank, with a pipeline incline of a couple of metres. 

“This system has been designed in such a way that the yield of the pump can be increased in future to supply more storage tanks along a 5 km pipeline, with a total elevation of 80 m,” says Riehmer. The final layout of the system will include 36 solar modules and will have a yield of 50 m³ per day at the last water point. 

The Jojoba For Namibia Trust reported that they now have more water than they expected, and can start expanding the plantations faster than they had planned. The trust supports the establishment of jojoba plantations in the communal areas of Namibia, focusing on providing the rural population with a sustainable business model and employment opportunities. The oil that is pressed from the nuts is promoted as an antibacterial agent which is rich in pro-vitamin A, E and B. It is exported to Europe, mainly for use in the cosmetic industry.

“With this sustainable water solution, the jojoba plantation and the local community will benefit for decades to come,” says Riehmer. “A future of economic empowerment opportunities has been created for the coming generations.” 

CONCOR COMPLETES RADISSON RED HOTEL IN ROSEBANK

Concor has successfully completed South Africa’s second Radisson RED hotel – this one is situated in the vibrant Oxford Parks mixed-use precinct in Rosebank, Johannesburg.

The upmarket 222 room hotel has been designed – like all Oxford Parks Precinct buildings – to meet a minimum five-star Green Star rating. It will open its doors to guests in June, two months after Concor handed over the building in April 2020. This follows the success of the country’s first Radisson RED hotel – located at the Cape Town Waterfront – which opened in 2017.

Concor took the project through to furniture, fitting and equipment (FF&E) stage, including beds, chairs, television sets and the physical backbone for WiFi connectivity, according to Martin Muller, contract manager at Concor. 

“The basements for the building were completed as part of the first two phases of the Oxford Parks Precinct, and construction began in October 2019 with the superstructure, from ground floor up,” says Muller. Although the Covid-19 lockdown delayed the project somewhat, construction progressed well on this fast track project. A combination of good planning and full resourcing made this possible, he says, with about 500 people on site at peak including contractors. 

Comprising seven levels on top of a ground floor, as well as a roof level for plant and services, the building is a concrete structure based on post-tensioned slabs with grids to suit the room sizes. At the core of the building are four lifts: a goods lift, a fireman’s lift and two lifts for guests.

The ground floor includes the reception, restaurant, kitchens, back-of-house facilities and conference rooms, with the first level housing the management offices, staff facilities and more conference space. Floors two to six each comprise 40 rooms, while on the seventh floor there are just 22 rooms sharing the level with a pool, terrace bar and gym. 

“The compact design means that the majority of plant is located on the roof – the eighth level – including water tanks and all the heating, ventilation and cooling (HVAC) systems,” he says. 

A curtain-wall system of aluminium frames and double glazed windows characterises the east and west sides of the hotel. On the north- and south-facing sides is a facebrick patterned façade with punch-out square windows.

“Most of the internal partitions are constructed with dry-walling materials of high acoustic and fire-rated properties,” he says. “The specifications for these are highly technical, to avoid any noise transfer from room to room despite the compact design.”

Concor’s work was guided by two sets of specifications, one for back-of-house and another for front-of-house, he notes. The base build spec was provided by dhk Architects, while the interior design spec for the rooms was by Source IBA. 

“Keeping a quality building process on track demands a constant focus on information sharing with consultants and subcontractors alike,” says Muller. “This meant weekly meetings to align our building plans with any design adjustments, so we could avoid rework that could have slowed the pace and added to the cost.”

The speed of the project was enhanced by having one tower crane on site, facilitating the work of all trades through the quick delivery of concrete and other materials to the various levels. He highlights the importance of the quality assurance and quality control (QA/QC) teams that followed production and streamlined the snagging process, so that the fit-out specialists could move in to progress the rooms. 

“This allowed the production workers to fully complete their tasks before the entry of plumbers, tilers, painters, joiners, electricians and other finishing trades,” he says. Sequencing was conducted in an east-to-west direction, and these teams completed eight rooms at a time. 

The Radisson RED project also provided an opportunity for Concor to conduct enterprise development among selected subcontractors. Working with three local small businesses, Concor was able to transfer skills in 18 of the required trades, including brickwork, painting and final handover preparation.