Lee-Ann Dippenaar, an up-and-coming young woman engineer, is among the members of the Tango’s Consulting team that participated in the design and is now overseeing the construction of a unique precast-concrete 30ML reservoir in Selcourt, Springs.

Notably, the reservoir wall, roof, columns and beams consist of precast-concrete elements that are being manufactured and installed by Corestruc, which is working alongside Selby Construction, the principal contractor, on this project.

Tango’s Consulting decided to use this technology instead of traditional construction methods to significantly accelerate the construction of the reservoir in a rapidly developing area of the East Rand on behalf of the City of Ekurhuleni Metropolitan Municipality. The system will also provide a higher-quality final structure considering that the components are being manufactured in a controlled factory environment that is far removed from the many variables encountered on a traditional construction site.

This project is the Junior Resident Engineer’s (RE) first construction supervision assignment since she joined Tango’s Consulting in 2018 after completing her Bachelor of Science Degree in Civil Engineering at the University of the Witwatersrand in 2017.

The valuable experience gained on this project will also contribute towards achieving one of her short-term career goals, namely registering as a Professional Engineer with the Engineering Council of South Africa.

Dippenaar lauds her colleagues, especially Nadia Stoycheva, a Senior Professional Engineer with Tango’s Consulting, for a willingness to share their experience with her, as well as providing the support she needed to settle in at this leading firm of consulting engineers.

“While I learnt a lot during the early engineering design phases, construction of the reservoir has provided immense opportunity for further mentoring from Wayne Wentworth, who is the Senior RE on this project and another reservoir build in Pam Brink, Springs, that is also based on the same modular system. I have learnt a lot from Wayne, considering his extensive experience helping to deliver complex water infrastructure and his background working with precast-concrete specialists, such as Corestruc, over the years,” she says.

Dippenaar is also joined on site by other young built-environment professionals, such as Gift Mohwaduba Moroe, a Director of Pamsensive Projects Pamsensive Projects. The Springs-based small, medium and micro enterprise was appointed to undertake parts of the in-situ concrete

work, including the column bases and ring-beam foundation which supports the precast wall panels.

This has contributed towards the excellent team dynamics between the engineer and the various contractors as is mirrored by the favourable outcome thus far, despite the severe interruptions that the Covid-19 Level 5 lockdown had on most construction projects in the country.

For example, all the precast-concrete columns that support the roof structure, comprising beams and hollow-core slabs, were installed in only three weeks to enable the centre-portion of the roof structure to be completed by March 2020.

Corestruc will commence installing the wall panels and buttresses that reinforce the reservoir, while it completes the in-situ concrete floor slab.

Working towards completing the reservoir by the end of this year, the specialist contractor will then install the post-tensioning ducts and cables between the joints of the wall panels, in addition to the numerous three-dimensional printed components to secure the rubber cast through which the grout will be pumped.

The grout has been designed to reach a compressive strength of 100 MPa within four days and to further react when the medium comes into contact with water when the reservoir is being filled.

It has a low viscosity making it more effective for pumping through all the post-tensioning ducts from a single position. Pumped continuously and in a controlled manner, the grout’s working time is extended by cooling it down to seven degrees Celsius.

The ability to construct various components, which make up a reservoir structure, simultaneously has significantly accelerated construction time, with the professional team having shaved as much as five months off the construction schedule by using Corestruc’s technology.

Savings in construction costs have also been achieved by eliminating the need for extensive formwork and shuttering for the walls and roof. This is a significant additional benefit for municipalities, especially at time when budgets for essential infrastructure services have come under severe pressure.

“Certainly, I am proud to be overseeing one of the first reservoirs of this magnitude in the country to be built in this manner. It is a unique technology that will assist in fast-tracking the delivery of essential infrastructure, especially in the under-serviced outlying areas of the country,” she concludes.