Geotechnical partnerships that work

Geotechnical partnerships that work CAPABILITIES & SERVICES

Solving the most difficult geotechnical challenges requires a combination of expertise and applied experience, and a proactive relationship with the client’s professional team. IMIESA speaks to Dawie Nell, managing director of Makarios Geotechnical Dynamics, about his company’s multifaceted solutions.

Makarios Geotechnical Dynamics was established towards the end of 2019, having acquired the business of Makarios Geotechnical Contractors (MRPI) as a going concern, along with its equipment and personnel.

“As we started to ramp up operations in early 2020, Covid-19 hit, but despite this we had an exceptional year, with an excellent pipeline of new work,” says Nell, who previously served as operations manager at MRPI and is now a majority owner of Makarios Geotechnical

Dynamics. “One of the main reasons for this is our historical and loyal customer base, which we retained following the MRPI buyout.”

“The company's highly skilled management, staff and workforce share an accumulative experience totalling some 158 years. This combination makes for a dynamic, ambitious team with the desire to succeed and deliver quality projects, within established timeframes,” Nell explains. Makarios Geotechnical Dynamics is a Level 3 BBBEE supplier and has programmes in place to move to Level 2 during 2022.

“We pride ourselves on being a niche player in the market, providing costcompetitive and best-practice responses to found both smaller and larger structures within the private and public sector, from low-cost housing developments to building super basements, mining infrastructure, and municipal installations that include bridges and reservoirs,” he continues.

Turnkey solutions

Working with external consulting engineers, the company provides a turnkey design and build solution, which includes geotechnical investigations. Core geotechnical engineering disciplines offered include compaction grouting, dynamic compaction and dynamic replacement, piling, and lateral support. The latter includes geonails, concrete soldier piles, self-drilling anchors, as well as strand anchor systems.

Specific piling capabilities include mini/micro piles (from 50 mm to 300 mm diameter), 250 mm diameter CFA piles, and 450 mm to 1 200 mm diameter bored auger piles.

Milestone lateral support projects include the 10 m deep super basement establishment for the Masingita Towers residential development in Sandton, Gauteng, and the Morningside Clinic extension, also in Sandton.

Running in parallel are a diverse range of piling projects completed. These include works at Linksfield Hospital; the Carstenhof Clinic; Brooklyn House in Brooklyn, Pretoria; Urban Quarters in Hatfield; and The Point residential development in Bedfordview.

• Compaction Grouting • Dynamic Compaction & Replacement • Design & Construct Turnkey Solutions • Geotechnical Investigations • Lateral Support • Piling • Micro Piling

Ground improvement leaders

“We are proficient in all areas, especially in terms of ground improvement technologies, which need a specialised understanding of where and when these techniques can best be applied,” Nell explains.

Alongside its grouting and guniting machines, lateral support, auger piling and micro-piling fleet, Makarios Geotechnical Contractors has a dedicated fleet of six dynamic compaction rigs, with pounders ranging from 8 t to 15 t, and capable of going up to 20 t. This enables high-energy compaction for soil depths down to 10 m.

The pounder is lifted and dropped by the rig from a height of around 18 m on to presurveyed grid points to consolidate the soil mattress. The technique has successfully been used for applications that include opencast mine

rehabilitation, sinkhole rehabilitation, consolidation of collapsible soils, treatment of old dump sites, and reclaimed land rehabilitation.

According to the Council for Geoscience, up to 25% of Gauteng, as well as parts of Mpumalanga, Limpopo, the North West and Northern Cape are underlain by dolomitic zones. The resulting problematic ground conditions require some form of geotechnically engineered response. However, by using dynamic compaction, even the worst ground conditions can be reinstated for development.

Past dynamic compaction projects include the Dayizenza Plaza retail development in Hazyview, Mpumalanga (47 700 m2), and the 15 000 m2 Edenvale mine shaft rehabilitation project. The latter entailed the pre-collapse of old mine shafts to make way for a warehousing development.

The Thembisa Ext 25 low-cost housing development (39 000 m2) was another key project. Makarios Geotechnical Dynamics also completed a dynamic replacement project for the Mall of Thembisa, which entailed the installation of some 200 stone columns. Meanwhile, recent examples executed by Makarios Geotechnical Dynamics include the Midstream residential development in Gauteng. One section had previously served as an informal landfill for building rubble to a depth of up to 3.5 m. This needed to be consolidated using dynamic compaction over an area of approximately 167 000 m2 .

A similar residential project was recently completed in Fairlands, Johannesburg, where the site of an old brick quarry needed to be consolidated to make way for a housing development. Brick debris in this case went as deep as 14 m.

“In these examples, using dynamic compaction proves to be far more costeffective than excavating the material,” Nell explains.

Our objective is to develop the most cost-effective, bestpractice project solutions for our clients, and their professional teams.”

Sinkholes

Other projects include the reinstatement of the R103 Vosloorus. A sinkhole had occurred on a main road intersection bordering a mall. The repair solution was resolved within the shortest possible timeframe. Similar work was carried out on the R31 towards Danielskuil in the Northern Cape; on the R55 in Laudium, Pretoria; and at Snake Road in Benoni.

Makarios Geotechnical Dynamics also completed a dynamic compaction project at the Waterkloof Airforce Base in Pretoria in 2020. A total of eight sinkholes were rehabilitated.

“It’s important to emphasise that every dynamic compaction remediation project is different, so there’s not a ‘one size fits all’ solution. That’s where our expertise and experience come into play to perfect the best approach,” says Nell.

Compaction grouting

Another proven technique for deep-level dolomitic fault zones is the employment of compaction grouting. Within the Gauteng region, these depths can range anywhere from 30 m to 60 m.

“Low-mobility grouting densifies loose granular soils, reinforces fine-grained soils and stabilises subsurface voids or sinkholes highly effectively,” Nell explains, adding that compaction grouting often offers an economic advantage over conventional approaches.

The cementitious grout is injected under pressure to fill the underground voids, with a superplasticiser typically used to improve flowability. Makarios Geotechnical Dynamics executes these projects using a 5 m3 grouting plant, combined with pumping systems.

Among Makarios Geotechnical Dynamics’ landmark compaction grouting projects were the solutions delivered for the Khutsong township in Carletonville, comprising two key contracts. One was for a low-cost housing development, where sinkhole formations needed to be remediated. The second was for an allied reservoir and pipeline. Some 2 500 m3 of grouting was installed.

In terms of new work, Makarios Geotechnical Dynamics is currently working on a project in Katlehong, Gauteng, where a reservoir needs to be constructed in a dolomitic zone.

The makings of a great geotechnical contractor

“Competition in any business spectrum is intense and remaining relevant is critical, and it begins and ends with a passion for excellence. At Makarios Geotechnical Dynamics, we invest in our people because they are the crucial customer interface,” adds Nell.

“Throughout our organisational culture, adherence to safety, quality, health and environmental compliance standards is mandatory, as is a commitment to exceptional service – and it shows on every project,” he continues.

“In the end, our objective is to consistently deliver sustainable and world-class solutions, and leave behind a proud legacy, whether in our local market or beyond. We’re excited about the road ahead,” Nell concludes.

www.makariosgd.co.za