Aquifer Studies

MEK hydrogeologists and water resources specialists have conducted detailed hydrogeological studies in different types of geological terrains worldwide. These studies usually commence with a comprehensive review of the technical literature through the collection, collation, and analysis of published and unpublished literature and data available to our consultants. Our staff may undertake additional field studies, including geophysical investigations and borehole drilling, to acquire supplementary information that may be required for in-depth understanding of the hydrogeological conditions and decision-making.

Our experiences in this sector include:

• Delineation and characterization of major aquifers and aquitards;
• Determination of the major hydrogeological parameters, such as the permeability (hydraulic conductivity) and transmissivity of the individual groundwater systems, which are relevant for the sustainable planning and management of these regional and local aquifer systems and their long-term usage; and
• Determination of groundwater flow mechanisms, preferential flow paths, and recharge and discharge areas within a given aquifer system.

MEK consultants has the expertise to model and simulate different type of aquifer systems and use the results to properly design wellfields that will stand the test of time, drastically cutting down on operational costs and ensuring the long-term sustainability of the groundwater resource and the production water well(s).

As a team, we have conducted and analyzed over 500 pumping and aquifer tests in different hydrogeological terrains. Using these test results, our team members can produce the most efficient well designs and accurately determine the most optimal pumping rates for individual wells. Additionally, through these test analyses, our team has successfully and accurately inferred relevant aquifer information, including the delineation of recharge and discharge areas, locally and regionally, within groundwater systems.

Wellhead Protection Studies

The wellhead protection area (WHPA) is defined as the area around the wellhead that contributes source water to a drinking water system (i.e., a production well). On-going activities within a wellhead protection area have the potential to affect the water quality entering the well, and as such there is a need to delineate the WHPA and take steps to protect it. The ultimate goal of protecting the WHPA is to protect public health. The major potential sources of contaminants are usually the following:

•  Non-point sources, such as fertilizer and pesticide spills;
•  Landfills;
•  Septic tanks and sewer systems;
•  Underground and above-ground storage tanks;
•  Animal feedlots; and
•  Chemical storage facilities.

The extent of the WHPA is determined by several factors, including the general topography of the land surface, the aquifer type, the direction and velocity of groundwater flow, the overlying soil around the well, and the water extraction rate.

To ensure the integrity of the aquifer (groundwater body) and prevent its pollution, a wellhead protection plan (WHPP) must be developed. In general, the WHPP will reduce the risk of contaminating the groundwater resource and therefore help to ensure the long-term supply of potable water. It will also help reduce water treatment costs. MEK has the tools and technical know-how to help accurately delineate WHPAs. Our team is experienced in using the techniques listed below to accurately delineate the WHPA, the capture zone, and the areas contributing to the pumping well upon which a WHPP can be based. Over the years, our professional staff has used the following techniques for delineating WHPAs:

•  Arbitrary fixed radius (AFR) technique;
•  Calculated fixed radius (CFR);
•  Analytical equations;
•  Hydrogeological mapping; and
•  Numerical flow modelling.

MEK would be pleased to work with you to delineate your WHPA and assist you in developing a comprehensive and effective WHPP for your wellhead.

Aquifer Modelling and Simulation

Groundwater models are necessary for understanding the behaviours of groundwater systems under specific conditions and to predict aquifer behaviour under changing hydrogeological conditions. In the broadest sense, a “groundwater model”  is the sum of the components, physical or otherwise, used to describe a groundwater system. It is a representation of the construction and working of an aquifer system of interest. The model will be similar to but simpler than the aquifer system it represents. Meanwhile, simulation is a tool for assessing the performance of the aquifer under existing, planned, or anticipated changing hydrogeological conditions.

MEK usually uses groundwater models for the following studies:

•  Conceptualization and quantification of hydrogeological conditions of aquifer systems, using the information to plan future data requirements;
•  Exploration of groundwater system dynamics, such as surface water–groundwater interactions, recharge areas, seepage rates, and transportation dynamics;
•  Prediction of changes in aquifer behaviour likely to result from the anticipated changes in water abstraction rates;
•  Identification of WHPAs and capture zones;
•  Design and refining of existing monitoring well networks to better understand the behaviour of the aquifers under changing hydrogeological conditions;
•  Evaluating mitigation options for remediation planning; and
•  Management tool for complex and extensive aquifer systems.

MEK consultants have used analytical, numerical, and stochastic models over the years to address many challenging groundwater flow and contaminant fate and transport problems in porous and fractured media in different hydrogeological terrains. Our team has developed numerous (finite difference and finite element) groundwater flow and solute transport models to conducts studies related to leachate movement from landfills, saltwater intrusions, contaminant movement from seepage ponds, and pesticide movement from agricultural fields.

The MEK groundwater modelling team will be pleased to provide its expertise for the development of sound and professional solutions to address your groundwater management problems.

Saltwater Intrusion Studies

Saltwater intrusion is the induced flow of seawater into freshwater aquifers primarily due to the withdrawal of groundwater from production water wells. When groundwater is pumped from aquifers that are hydraulically connected to the sea, induced gradients cause the migration of seawater from the ocean toward the production well being pumped, eventually rendering the freshwater bodies unsuitable for domestic and other uses.

The phenomenon of saltwater intrusion from the ocean occurs for two main reasons: lateral encroachment of seawater from the ocean due to excessive water withdrawal and the upward movement of water from deeper saline zones due to coning in the area around the well. However, saltwater intrusion may also be influenced by factors such as tidal fluctuations and long-term climate and sea level changes.

MEK consultants has planned and successfully carried several saltwater intrusion studies and, in the process, provided sustainable solutions to mitigate the impact. Our approach typically entails a combination of techniques, including well logging, chemical analysis of groundwater samples, chloride concentration profiling, vertical conductivity and temperature profiling, and geophysical investigation techniques. When required, we also put groundwater level and quality monitoring systems in place. MEK consultants are always ready to assist in the design and placement of associated monitoring well programs, particularly for the continuing monitoring of the saltwater interface after management strategies have been put in place, to provide early warnings of saltwater intrusion and track the effectiveness of the management strategies.

Our consultants are also very knowledgeable and have been engaged in projects tailored to mitigate or prevent saltwater movement into freshwater aquifers. Our consultants are conversant with and have been involved in numerous projects that have addressed the problem, using techniques such as ponding surface water and stormwater runoff to recharge the groundwater table and placement of Aquifer Storage and Recovery (ASR) systems to sustain aquifers that have experienced long-term declines in water level due to over-exploitation.

Groundwater Under the Direct Influence of Surface Water

Groundwater is a major source—and in some areas the only reliable source—of potable water. In some areas, these aquifers are recharged locally and therefore exhibit characteristics of the surface recharge source and contain surface water contaminants, such as various protozoa (cryptosporidium and Giardia Lamblia) and bacteria (E. Coli). Groundwater sources with significant surface water characteristics are referred to as “Groundwater under the Direct Influence of Surface Water” (GUDI). Drinking water wells in these aquifer systems thus present a health risk. Illness may result from drinking water from these wells, particularly for children and elders.

MEK’s accredited professional hydrogeologists are very knowledgeable and have the experience to systematically assess any groundwater system and determine whether it is a GUDI or non-GUDI water system and tailor a suitable solution to address any problems identified during the investigation.

Acid Mine Drainage

Acid Mine Drainage (AMD) is a major problem in mining areas. This is because most minable minerals, such as gold, copper, and silver, naturally occur with sulphide. During the mining of these metals, the sulphide bodies are exposed to air and groundwater and other chemical reactions, resulting in the formation of acidic water, which in turn dissolves other harmful metals in the rock. The toxic products resulting from these reactions, which are usually referred to as AMD, can run off into surface and even groundwater bodies and become hazardous to both aquatic life and humans.

Our team has addressed some interesting AMD problems over the years and fully understands the mechanisms behind this process. Our team will carry out systematic investigations to identify the existing sources or any potential source that could lead to AMD and provide a timely solution to either forestall or attenuate AMD on your property or mine concession.