Indirect Investigation Methods
The indirect approach to evaluating subsurface conditions includes all methods that acquire information without physically invading or penetrating the ground surface. Such methods include interpreting and evaluating aerial photographs, geologic maps, groundwater contour maps, topographic maps and other types of published information, along with geophysical methods such as electromagnetism and ground penetrating radar.
Ardaman maintains a full library of information relating to geotechnical engineering, hydrology and geoenvironmental sciences. Our librarian makes sure that the most recent maps, photographs, and reports are readily available to our engineers and scientists. Our information resources include a database containing information on over 140,000 projects completed by Ardaman since 1959. These resources are routinely tapped for preliminary evaluations, to help develop a field investigation program, and to augment the data obtained from the field program.
Ardaman's personnel are capable of applying and evaluating geophysical investigation procedures. Our staff is equipped with ground penetrating radar, electromagnetic equipment and soil resistivity devices to explore underground conditions. Most importantly, we are aware of the limitations of these methods and recognize that they are interpretive in nature and are best used when complemented with direct exploration techniques.
Direct Investigation Methods
A more detailed description of underground conditions at specific locations are revealed with direct investigation methods that obtain information by physically sampling or testing soil, rock and groundwater. The sampling or testing devices are inserted into a borehole advanced into the ground by drilling methods, and either samples are returned to the surface for evaluation and testing, or the properties of the underground profile are measured by in-place testing.
Ardaman maintains a fleet of more than 25 drilling rigs mounted on various platforms including trucks, all-terrain vehicles, narrow-access track and a barge. These rigs employ both rotary fluid and hollow stem auger methods to perform soil borings.
Soil and rock samples are obtained through the boreholes using a variety of sampling devices. Ardaman's drill crews are well trained and proficient with all of the drilling and sampling tools at their disposal, and they have received the OSHA 40 hour training and annual refresher courses required for working on hazardous waste projects.
Ardaman employs numerous in-place testing methods, many of which have been developed in-house, and define "state-of-the-art" geotechnical testing. Devices such as the cone penetrometer, flat plate dilatometer, vane shear device, and piezometer probe can evaluate through either direct measurement or empirical correlation, geotechnical properties such as shear strength, compressibility, temperature and pore pressure. In addition, Ardaman uses equipment for instrumenting soil behavior such as inclinometers for measuring horizontal deformation, vertical settlement profile detection devices, and total earth pressure cells.