Two market leading professional firms sustain a successful collaborative relationship over 10+ years, bringing deep-technical expertise, innovation and project oversight to Gold Fields South Deep Gold Mine.
In 2007 Golder Africa (now WSP in Africa) and Metago (now SLR Consulting) were appointed by Gold Fields and in 2009 completed the design of the Doornpoort Tailings Storage Facility (TSF), a 400Ha TSF with a 14Ha, one million cubic meter HDPE lined Return Water Dam (RWD). The design of the TSF included, but was not limited to, the following infrastructure:
- Earthfill starter walls,
- Concrete encased penstock decant outfall pipeline including six temporary penstock intakes and one permanent penstock,
- Underdrainage systems within the TSF (toe drain, main drain and cut-off curtain drains) along with a drainage collection system downstream of the TSF wall,
- Catchment paddocks with associate decant structures,
- Silt trap,
- Three pump stations (2x slurry and 1x water),
- Three motor control centres,
- 12km of overhead powerline,
- Two provincial road crossings,
- 35km of steel HDPE lined pipelines.
Following the successful completion of the design, Gold Fields South Deep Gold Mine (the client) appointed an owners’ team in 2009 consisting of Golder Africa (now WSP in Africa) and Metago (now SLR Consulting) to manage the execution of the construction of Phase 1 (260Ha) with WBHO as the contractor and in 2011, after a 2-year construction period, the commissioning of Phase 1.
Up to date work in progress
Due to WSP and SLR’s history with providing project management and resident engineering support during the success of Phase 1, the client saw the benefit of appointing the same consultants as the owners’ team for Phase 2 (140Ha) and again WBHO was appointed as the main contractor for a 1-year project. The main components of the Phase 2 project consisted of bulk earthworks, main and toe drains, two concrete penstock towers, choke station and 4.6km of steel HDPE lined pipelines.
In March 2021, WSP and SLR assisted South Deep Gold Mine with the Phase 2 tender process as well as the technical and commercial adjudication. Construction commenced in June 2021 – and the project reached practical completion at end of August 2022.
Collaboration underpinned by technical expertise, innovation and expediency
For Phase 2, it was important for the client to have team members who designed all the components of the TSF to be physically on-site either full or part-time. It was of importance to the client to have an experienced client owners’ team on-site to manage design risks, contractor claims, technical issues, value engineering requests and client risks.
With WSP appointed as the lead consultant for both phases, and SLR being the responsible design engineer for the TSF and RWD as well as the appointed Engineer of Record (EOR), it was imperative to have strong representation from both consultants to manage the challenges and ensure a successful project.
On Phase 2, WSP was appointed as the project manager and owners representative responsible for managing the owners’ teams and the project as a whole, including the main contractor. Duties involved appointing the owners’ team members which included a project administrator, quantity surveyors, health and safety officer, resident engineers and off-site quality inspections.
Considering the size of the project and potential construction risks, WSP provided a full-time senior health and safety officer to support WBHO and assist with identifying and mitigating any health and safety risks, to implement and enforce client health and safety policies and to create a healthy safety culture on-site.
To ensure that the project budget was correct from the onset, WSP appointed Bossert KPO as the professional quantity surveyors (QS) to measure the detailed design and draw up the project Bill of Quantity (BoQ). Throughout the construction phase the QS’s were responsible for cost reports, contractor monthly certificates verification, variation management and other claims.
SLR, as the appointed EOR, provided full time on-site senior Construction Quality Assurance (CQA) services as well as design and geotechnical support on a part time basis. The senior CQA engineer oversaw all mandatory hold point inspections, approval on materials used, sign-off on method statements and ensured that the contractor constructs according to the design intent, specifications and drawings.
Due to a large number of off-site manufactured products, history has shown the value of having a senior quality inspector confirming on behalf of the client if the suppliers have kept to their own quality control plan before approving and releasing for delivery to site.
Project design challenges
There were several setbacks on the project, including but not explicitly limited to:
During the construction of the penstock towers which was on the critical path, one of the 72No. piles failed. This called for the piling contractor to re-establish and a remedial design to be implemented, which took a month to complete. WBHO was required to bring in an extra team to site to make up for the lost time.
During the latter part of the project, there were some challenges with finding a suitable supplier that could meet the filter sand design specification, which resulted in a few months delay in sourcing the required 24 000 cubic meters of filter sand.
The project received more than double the average rainfall during the rain season which caused many construction challenges and delays, especially on the bulk earthworks, subsoil drains and penstock outfall pipeline.
Approach and solutions
As WSP and SLR were involved from 2007 with the design and construction of Doornpoort TSF Phase 1 and the same owners’ team members were again available for Phase 2, this benefitted the project tremendously as many of the lessons learned during the construction of Phase 1 as well as any issues identified over the 10-years of operation were used to update the design for Phase 2. The owners’ team also applied years of design experience from other similar projects to provide state of the art features especially on the drains and penstocks systems.
Globally, WSP and SLR are well known for providing tailings dam solutions in the mining and other industries. What makes this project unique is how two professional firms – and under other circumstances may compete in the tailing industry - worked so closely together to produce a fit-for-purpose design and provide support to the client for the construction of the TSF for two different Phases of the project, over 10-years apart (total duration of the project of 14-years).
Additionally, any project of this size and which involves many stakeholders is a challenge to manage. One aspect that has been a golden thread throughout the 14-years of this project has been the fun that the project owners’ team has had. The client created a very pleasant working atmosphere which made working for Gold Fields an unforgettable experience.
Andre Richardt, Director: Project, Delivery, WSP in Africa
Sharon Wetton, Senior Tailing Engineer, SLR Consulting Africa
Facts and figures
Client: Gold Fields South Deep Gold Mine
Location: Witwatersrand Basin, near Westonaria & 50km south-west of Johannesburg, South Africa
Project Scope Value: ZAR204 million
Status: Practical Completion date – 31 August 2022