One of the problems with open pit mines is that they have a tendency to fill up with water over time. This water sometimes comes from rain, but can also be present because the bottom of the mine excavation is lower than the top of the surrounding water table. This causes water to continually seep into the mine pit.
There are three main methods used to control water in open pit mines:
- Exclusion – Using solid walls to stop the water from entering the excavation (similar idea to a small dam wall).
- Pumping – Excess water in the pit is pumped out, usually into a deep well sunk specifically for this purpose. This has the effect of returning the water to the water table from where most of it originally came.
- Wells – Deep wells are sunk in the area around the pit mine. This has the effect of lowering the local water table, as most of the water will drain down the well shafts.
In many cases, a combination of two, or even all three, of the above methods will be used, depending on the situation. This process of removing water from an open pit mine is often referred to as “dewatering.”
Once dewatering procedures have been implemented, it is important to monitor the results to see if the measures are effective. Monitoring the water levels can also give an indication that more groundwater is seeping in. Pumps and other equipment can then be adjusted to deal with the increased water flow.
One of the most common ways of monitoring water levels in an open pit mine is with a series of surface piezometers. These devices can be connected (up to four at a time) to MDT VW-RTU wireless nodes in order to form a comprehensive wireless water level monitoring system that can be monitored from a single point.