Mining hydrogeology
Hydro-Ressources specializes in hydrogeology applied to mining. This expertise is divided into three main parts, namely 1) the analysis of the impacts caused by the presence of a mine on the environment, 2) the dewatering of a mine and 3) the analysis of soil or water. contaminated in a mining environment.
L’analyse d’impacts
During new mining projects, it is necessary to carry out an analysis which will make it possible to evaluate the impacts, from a hydrogeological and hydrological point of view, that a possible mine may have on the immediate environment. Indeed, a mine must necessarily dewater its facilities, whether by pumping in the bottom of a pit, at the lowest level of an underground mine or on the outskirts of the mine. This dewatering can generate impacts on the environment by drying up watercourses or reducing their flow.
The analysis of these impacts is often done using numerical simulation. This method of analysis effectively makes it possible to make predictions on the flow that will be required to be pumped and on the influence of this pumping on the neighboring watercourses. To perform a good analysis, field trials are required. These tests may include drilling, permeability testing and packer testing. The profile tracing test method recently adapted by Hydro-Resources shows much more conclusive results than most other techniques (shutters, speed measurements, etc.). This method is very useful for acquiring information on the underground flow, whether for a feasibility analysis, or the dewatering of a mine.
The dewatering of a mine
When a mine is in operation, it is necessary to dewater the mine. If the walls are stable, dewatering can be carried out at the bottom of the mine with suitable pumps. On the other hand, if the walls are unstable or if the water inflows reduce productivity, it is more appropriate to carry out the dewatering on the periphery with collection wells, or angled boreholes, acting as drains.
The capture wells on the periphery therefore make it possible to eliminate the seepage on the walls which affects the stability of the latter. In underground mines, peripheral dewatering eliminates or limits water infiltration in certain galleries. However, drainage from galleries is often the best method to adopt because it is more advantageous from an economic point of view.
Various analytical methods can help optimize dewatering. Once again, numerical simulation is an effective tool and tracing tests can be particularly useful for properly targeting the position of wells/drains or for planning adequate cementation.
Case of contamination
Mining environments can generate contaminants often from tailings facilities. It is therefore necessary to carry out an analysis of the impact of the presence of these contaminants in groundwater or to define solutions to eliminate the contamination. Sometimes the water from dewatering is a contaminant in itself because the groundwater captured at depth often contains a high mineral content.
Various methods of analysis allow valid predictions to be made. In all cases, it is necessary to obtain information from the field which helps to carry out the analysis.
Profile Tracing Test (PTT)
Patented methodology
A profile tracing test is an application recently adapted by our firm. The concept is very simple; it consists of mixing a tracer as uniformly as possible in a single open hole (for example, a diamond drill hole for exploration). Once the tracer is mixed in the hole, the concentration is measured at different time periods in the same vertical borehole. Concentration profiles are created and the concentration variations indicate the location of the natural active flow zone. In fact, when the concentrations decrease, it means that a flow is present.
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