Geotechnical engineers use soil samples to evaluate the subsurface.
Soil and groundwater investigations reveal vast information about the subsurface. Scientists use a variety of investigative techniques to evaluate soil and groundwater properties and the presence or absence of contamination. These techniques range from simple sample collection to sophisticated underground imaging.
Soil Boring Installation and Sample Collection Methods
Geologists and geotechnical engineers use soil boring and soil sample collection to evaluate the subsurface. You can use hand augers, direct push rigs and drill rigs to collect soil samples. These samples may provide you with information concerning the type of soil present, the physical properties of the soil and a determination concerning the presence or absence of contamination. Soil scientists use auger buckets, split-spoons, Shelby tubes, large bore, macro-core and dual tube sampling devices to collect soil samples for testing.
Groundwater Monitoring Well Installation and Sample Collection Methods
Hydrogeologists use groundwater data to evaluate the subsurface. Laboratory data from the groundwater can provide information concerning the quality of the water, while water table elevation information can determine the amount of water available in the aquifer. You can use direct push rigs and drill rigs to install temporary and permanent water wells and that will provide water samples. Direct push rigs can install shallow, temporary points that you can sample immediately using a peristaltic pump before you abandon the borehole. These rigs can also install permanent, prepacked small diameter wells that you can sample multiple times. Drill rigs may install permanent monitoring wells with varying depths and diameters. Field geologists collect water samples and depth to water table information from the monitoring wells using bailers, submersible pumps and electronic water level indicators to test the quality and quantity of water.
Geophysical Investigations
Geophysicists use techniques to evaluate the subsurface both over land and in boreholes. These studies can evaluate the soil and rock and identify subsurface structures and the presence of natural resources such as water and oil. Common geophysical methods include ground-penetrating radar, electromagnetic methods, electrical resistivity, metal detection, seismic methods and magnetometers. Ground penetrating radar and electromagnet methods are useful for locating underground structures, changes in soil types, water and free phase products. Magnetometers and metal detectors are useful at underground tank sites to locate the buried tanks and lines. Electrical resistivity is a popular method to evaluate soil and rock characteristics and changes and to locate oil and water-filled zones. Seismic methods are popular for evaluating the types of soil and rock strata below ground, the fracture patterns within the rock and the location of liquids in the subsurface.
Soil Vapor Survey
Soil vapor, or soil gas, surveys are a relatively inexpensive method of obtaining information about the presence or absence of volatile contaminants in the subsurface soil. Active and passive soil gas sampling devices will collect data concerning the presence of a variety of constituents. Chemicals vary in their volatility, which makes soil vapor surveys better for certain constituents. Soil vapor surveys are often a tool in an initial subsurface investigation that will guide scientists to locations that require further evaluation using other methods.
Tags: evaluate subsurface, evaluate soil, presence absence, push rigs, rigs install, soil rock
