Simply defined, aquifer characterization is the process of quantifying the physical and chemical features of an aquifer which control ground water or contaminant movement in the subsurface. These features are associated with both the saturated and unsaturated zones and can be quantified in one, two or three dimensions. These aquifer characteristics are the controlling features of a wide variety of environmental management programs, including:
- Wellhead Protection
- Groundwater Recovery
- Well Field Management
- Vacuum Extraction
- Contamination Investigations
The proper engineering of these programs is controlled by the aquifer characteristics of the site. Therefore, proper determination of the site aquifer characteristics is essential to the success of these, and other programs.
Methods and Techniques
Characterizing subsurface saturated and unsaturated zones requires methods which can measure the physical or chemical features of concern either in-place (in-situ) or using representative samples (ex-situ). The in-situ methods consist of active and passive techniques. Step-drawdown, constant rate and variable rate withdrawal/injection tests using single or multiple wells are representative active techniques. Determination of aquifer characteristics from barometric pressure changes is an example of a passive technique. Laboratory measurements of the permeability and porosity of soil cores illustrate typical ex-situ methods.
There are two general methods of data analysis. Analytical solutions generally solve a set of equations developed for a known set of boundary conditions, and often involve curve matching techniques. Numerical solutions utilize equations which can be adapted to interpret complex systems, and often involve computer modeling.
Terran Corporation specializes in the design and implementation of unique, cost effective aquifer characterization investigations. Our in-situ evaluations of subsurface conditions utilize state-of-the-art field equipment and computer data acquisition techniques. We have successfully conducted multiple-well, multiple-level aquifer tests involving near real-time data collection from more than 60 wells at discharge rates from 0.5 to 1200 gallons per minute. Because we own and maintain our own field instruments, Terran provides rapid mobilization and deployment, reliable data acquisition, and complete data recovery. This data recovery has been conducted under a variety of contamination exposure levels using required health and safety and quality assurance/quality control procedures. Terran's staff of experienced hydrogeologists and modelers perform comprehensive data analysis and interpretation, and explain results in professional technical reports delivered on time and within budget.