Founding the right approach

Time and cost pressures have placed increasing emphasis on purposedesigned solutions for building and infrastructure roll-outs that achieve valueadded results. Shaun Nell, managing director, Terra Strata, says it all comes down to experience, expertise and service. By Alastair Currie

Within a highly competitive sector, Terra Strata has progressively evolved its marketing strategy from inception in 2011 to meet South African and broader African continental demand for geotechnical services.

Core Terra Strata capabilities encompass: piling (CFA, oscillator, micro, and percussion); lateral support, consolidation and compact grouting, shotcrete, gunite, and sprayed concrete; marine work; as well as geotechnical investigations. These solutions are backed by a modern capital equipment fleet that includes CFA (continuous flight auger) rigs capable of establishing large-diameter holes to depths of up to 24 m.

“Our starting point from inception has focused on recruiting and retaining the best talent to sustain business excellence through the peaks and troughs of the construction market,” says Nell. “Over time, we have successfully diversified into key industry segments that include industrial, marine, building, mining and civil infrastructure.”

In terms of the Construction Industry Development Board grading system, Terra Strata is a Grade 8CE (Civil engineering), Grade 8SC (Building excavations, shaft sinking, lateral earth support), and Grade 7SJ (Piling and specialised foundations for buildings and structures) contractor.

Within this multifaceted mix, Terra Strata also offers turnkey design and construction services, and geotechnical investigation services. In-house professionally registered engineers work with external firms that include ARQ Consulting Engineers to execute pricecompetitive design and build solutions.

Terra Strata is also a licence holder for French multinational Menard – a global leader in ground improvement technologies.

Marine projects

In the marine infrastructure field, major projects completed include a quay wall reinstatement at the Port of East London. Undertaken for Transnet, the project commenced in June 2015 and was completed in January 2018.

The scope included removing an existing 101 m long capping beam and installing fifty 165 mm diameter micro piles 17 m deep to protect the platform (the existing dead-man anchors were rusted through).

This was followed by installing 31 m of 900 mm diameter tubular and sheet pile combi wall, vibrated to 15 m below the existing platform, and then hammered down into the rock.

Other works entailed coring a 2 m rock socket in 65 MPa rock, vibrating sheet piles to the same level, and filling between the old and new quay wall. This entailed some 527 m3 of concrete and 586 m3 of stone.

Terra Strata secured a piling contract for a new methane power station development on the shores of Lake Kivu in Rwanda

The Mohembo Bridge in Botswana. Terra Strata was awarded an approximately 18-month sheet piling project by the Itinera and Cimolia JV

Our starting point from inception has focused on recruiting and retaining the best talent to sustain business excellence through the peaks and troughs of the construction market.”

The construction of the new capping beam entailed the installation of 572 kN permanent anchors (between 25 m and 30 m) through the newly constructed capping beam. Final measures entailed pumping 689 m3 of compaction grouting into the platform through 106 percussion-drilled holes to a respective depth of 15 m.

A current marine project is ongoing for the new Mohembo Bridge in Botswana. Terra Strata’s approximately 18-month sheet piling project has been executed for the Itinera and Cimolia JV.

Terra Strata’s scope has entailed the following: • installation of the original two boxes around the bridge towers and the quay wall • installation and removal of the sheet pile walls on the sides of 14 piers • installation and removal of three additional boxes around three piers of the bridge • installation and removal of two sheet pile walls for the fixing of the riverbanks to the construction sites. “The bridge is virtually complete. We are now going back to site to extract the last sheet piles,” says Nell.

Super basements

Alongside its marine capabilities, Terra Strata is a renowned specialist in the establishment of super basements for landmark building projects. The largest to date is an approximately R150 million lateral support project for Phases I and II of Sun International’s Time Square development in Menlyn, Pretoria. The scope here included bulk excavations, the drilling and installation of soil nails, and guniting.

More recently, works include the Mall of Africa in Midrand, Gauteng. Here, Terra Strata constructed a 13.5 m high lateral support wall, entailing 70 soldier piles and 140 anchors, ranging between 450 kN and 600 kN.

Another landmark retail project is the Mall of Thembisa in Ekurhuleni, Gauteng. Undertaken for Tembisa Property Investments, this project was divided into two parts, namely a geotechnical investigation to determine the rock profile, and the piling phase. The geotechnical investigation took more than seven weeks to complete and entailed proof drilling across the entire site.

“This included drilling 418 holes (foundation positions) to an average depth of 19 m in order to inform the design engineer as to the suitable foundation type for each of the required footing positions. The piling project that followed was successfully completed and handed over to a satisfied customer within the 12-week contract duration,” says Nell.

Mining

Within the project mix, Terra Strata has a well-established track record for executing geotechnical solutions in the mining sector. Current examples include the establishment of a box cut for Exxaro’s Matla coal mine in Mpumalanga. This approximately 10-month project is due for completion in September 2021. Past work at Matla has included piling on the new silo development.

Another ongoing mining project entails the installation of 610 mm diameter ODEX casings up to 26 m in depth for a client in Steelpoort, Limpopo.

Cross-border expansion

Terra Strata has traditionally had a strong presence in neighbouring countries such as Botswana and Namibia. This focus is now moving deeper into Africa in search of new opportunities.

“Victor Ferreira, a seasoned professional in the industry, has joined in our team to focus on the expansion into Africa,” say Nell. Success to date includes projects awarded in Rwanda. This entails piling work for a new methane power station development on the shores of Lake Kivu. Terra Strata is also actively seeking to expand into key West and East African countries that include Ghana, Kenya and Tanzania. This African focus runs in parallel with its national business expansion in South Africa.

“Currently, the bulk of our work in South Africa is being sourced from the building, marine and mining sectors. Going forward, we hope to also secure new work in the roads sector, as Sanral starts to roll out new projects. The South African government’s Infrastructure Fund also offers major promise,” adds Nell.

“In the meantime, we continue to update our equipment to ensure that the work we deliver is on time, within budget, and adheres to best-in-class quality and execution,” Nell concludes.

Terra Strata completed an intricate quay wall reinstatement project at the Port of East London in 2018

In terms of super basements, Terra Strata’s largest works to date is an approximately R150 million lateral support project for Phases I and II of Sun International’s Time Square development in Menlyn, Pretoria