With the high level of risk associated with the design and construction of dam walls and bulkheads, we selected a New South Wales client where a combination of bulkheads and dam walls were constructed with Aquacrete Wet-Repel TM.
Our observations and experiences in designing water-retaining structures with Wet-RepelTM confirmed that the most significant factors influencing long-term bulkhead performance are the interface of the bulkhead with the surrounding strata as well as the potential magnitude of the hydraulic pressure to which they may be subjected.
Over a period of two years regular site audits included a combination of visual inspections and non-destructive testing. Key areas of assessment included an inspection of surrounding strata to identify leakage, potential softening of the devices, erosion and breakdown of structural integrity and measurement of the devices’ thickness. In addition, ‘health’ of the devices was verified using echo impact testing.
Following one event on site, where an unplanned power outage prevented water from being pumped outbye, the site engineer reported that the water head reached a height of 2.5m. The water pressure as a result of this incident was well in excess of the design specifications. While site engineers took all necessary precautions to maintain site safety during the event, inspection of the dam walls after the event confirmed that no water leakage occurred and the dam wall maintained full integrity.
Figure 1 - Dewatering sump dam wall and bulkhead design
Using Aquacrete’s proprietary structural design specifications as a benchmark, and then applying an audit process that combined visual inspections with non-destructive testing, the trial verified the long term structural integrity of the devices.
More importantly, though, the trial has contributed to the development of new engineering and measurement standards for structural devices.
Figure 2 - Dam wall design, side view shown
Mine managers are looking for solutions that are not just cost-effective, but more importantly provide long term reassurance that installations are still safe and strong. Having a reliable and accurate audit process – including our ability to non-destructively test devices in-situ – provides substantial operational and safety benefits for the industry.
As the demand for more verification has grown, it is anticipated that other importers and suppliers of ventilation control and strata support products will be under pressure to benchmark their product’s effectiveness.