Engineering Resilience at Work: The Khumani Mine DWT Project

At Euler Structural Engineering, our passion lies in solving complex structural challenges with innovative, cost-effective, and safe engineering solutions. One such standout project was the structural reinforcement of the Dirty Water Tank (DWT) at the Khumani Parsons Mine, a vital part of the mine’s water treatment infrastructure.

Identifying the Problem: Progressive Wall Movement

The DWT had shown signs of distress as early as 2010, with measurable radial wall movements recorded relative to its foundation. These subtle shifts were monitored over time, but by 2021, significant cracking appeared on the outer surface—marking the need for immediate structural assessment and intervention.

These cracks were not just cosmetic. Survey results revealed radial deviations in the tank’s geometry, most prominent in the northeastern and southwestern quadrants—clear indicators of structural stress and internal pressure imbalances.

Root Cause Analysis: Sediment Build-up and Uneven Pressure

Upon investigation, the primary cause was revealed: fine material (solids) entering the tank, settling over time and building up at the bottom. This build-up created surcharge pressures on parts of the tank wall that were not originally designed to bear such loads.

Further compounding the problem was the asymmetrical layout of the outlet pipework. This design flaw caused localized sediment accumulation, which exerted unequal force on the walls, eventually leading to cracking and wall movement.

Exploring Feasible Solutions

Before structural reinforcement, our engineering team worked with the mine’s process engineers to explore three main potential solutions:

Preventing Fine Entry via Process Change

A proposed addition of a cyclone separator to the incoming stream aimed to stop fines from entering the tank. However, operational constraints rendered this solution unfeasible.

Mechanical Agitation (Rake System)

Considered as a way to keep solids in suspension, a rake system was assessed. Yet, with the wall already structurally compromised, further agitation risked exacerbating the issue.

Optimizing Outlet Layout

Revising the outlet pipe positions to promote more uniform settlement was explored. But due to the complexity of redesign and risk of system failure, this too was ruled out.

The Euler Solution: External Prestressed Concrete Shell

With all other routes closed, Euler Structural Engineering proposed and executed a prestressed concrete shell solution—a robust, long-term structural reinforcement system.

Key Features of the Reinforcement:

• Wrap-Around Concrete Shell: Designed to resist internal pressure from settled material.

• Optimized Shell Height: Prevented clashes with existing plant infrastructure and piping.

• Uninterrupted Operation: Construction occurred without halting the tank’s operational duties—a major win for production continuity.

• Pre-stressed Design: The shell actively counteracts internal forces, preventing further movement or cracking.

This solution not only stabilized the existing structure but also extended the lifespan of the DWT significantly.

✅ Project Outcome: A Safe, Operational Tank

Euler’s involvement ensured:

• Stabilization of the wall movements

• Enhanced structural integrity under asymmetric load

• Minimized downtime

• Long-term performance of a mission-critical asset

💬 Final Thoughts

This project highlights how modern structural engineering, when paired with a practical understanding of operational constraints, can solve even the most complex issues. At Euler Structural Engineering, we pride ourselves on designing solutions that are innovative, practical, and sustainable for the mining and industrial sectors.