Pit dewatering remains a vital activity for all opencast operations, as ground water not only poses an operational challenge but can also become a safety hazard if not attended to appropriately.
Interestingly, it is not a simple case of one pump fits all dewatering application requirements and it is advisable to deal with a reputable pump supplier to ensure that the most appropriate solution is selected.
Lee Vine, managing director of Integrated Pump Rental, explains that there is no such thing as a standard pit dewatering system as each instance requires a site-specific solution.
“There are numerous options available in terms of the actual pump and ancillary equipment, as well as the choice between rental and outright purchase,” he says. “The differentiator that our team offers is the ability to assess a given application and provide a pit dewatering solution with the correctly sized pump.”
There are several factors that can have an impact on the pump selection, and this includes available power sources, the volume of water to be pumped, the condition of the dirty water including size and type of particles in the water.
“What adds complexity to pit dewatering applications is that, and in many cases, the need to dewater a pit can be urgent and customers are forced into making an incorrect pump selection or tying themselves into a contract that does not work in the longer term,” Vine says.
He says that while the decision to hire or purchase is an important commercial one, so is the actual selection of the pump itself. “If the pump is not sized correctly for the dewatering application at hand, it will not perform as required. This, in turn, leads to further operational challenges including production losses and sometimes even the need to change the pump resulting in further costs.”
One of the most important factors to consider is the available energy source, and if there is no access to power options such as diesel-driven or pumps fitted with hydraulic power packs must be explored.
When selecting the pump, it is also important to understand the specifics of the water ingress conditions and whether this is a long-term issue or simply a short-term challenge. This scenario will dictate the pump size, its rated output and what ancillary equipment is required.
As an example, Vine points to a recent dewatering application on a mine in Lesotho where a constant flow of water into the mine’s pit area demanded that water be urgently and reliably pumped out.
Over time the pit depth had increased, and the groundwater level had been exacerbated by the winter snowfall in the highlands of Lesotho. As a result, the total dynamic head for the duties of the installed dewatering pump installation changes and the mine required an urgent solution.
Initially a Sykes XH150 diesel driven pump was deployed, pumping at 120 litres per second at 150 metre head. Subsequent to this, a second Sykes pump was dispatched to site to ensure that the level of water remained at an acceptable level.
With the two Sykes pumps on site, the mine was assured of sufficient pumping capacity, should the groundwater level increase.
Commenting on the responsiveness exhibited by Integrated Pump Rental in this instance, Vine says this is not unusual at all. “While not a standard across the industry, our teams are known for this, and the primary reason why we can respond rapidly is our comprehensive fleets of pumps that are capable of handling varying dewatering applications.”
He sketches the scenario where the call from the mine came in and with 24 hours, the first Sykes pump was installed on site. “This is very significant, when one considers that the mine is situation some 500 km from the company’s front door and across the border into a neighbouring country.”
“More often than not, and this was indeed the case here, our teams have existing relationships with the customers that have been built up and maintained over time. Our repeat customers know they can rely on us,” he continues.
Integrated Pump Rental not only rents out Sykes diesel driven pump sets, the company is also responsible for the sale of these robust dewatering pumps across southern Africa. The robust units are designed for reliable performance, under even the harshest operating conditions.
Vine concludes by saying that operating in Africa requires a certain mindset and skill set, and most importantly suppliers need to be responsive to customer requests. “Many mines are situated in outlying areas and this calls for a very customer focused approach, particularly when groundwater in a pit becomes an issue.”