Non-destructive Subsurface Investigation

Three-dimensional Mapping

A-E-I has been performing subsurface investigations since 1996. The company offers multiple non-destructive subsurface investigation services including ground-penetrating radar (GPR), electromagnetic (EM) detectors, resistivity sensors, shallow seismic, in-line cameras and magnetometer. There are specific projects that may require a combination of these technologies to obtain the most accurate results. A-E-I will evaluate your project and determine the most accurate and cost-effective equipment for the site. In many cases we recommend the GPR due to its versatility and multiple capabilities. The staff at A-E-I is trained and experienced in a wide variety of subsurface investigations including mining, environmental, structural, archeological and utility projects.

ABOUT GROUND PENETRATING RADAR

Ground Penetrating Radar can be pulled across a surface either by hand or by vehicle. The data is transferred from the antenna to an on site color monitor and data interpretation can often be made immediately. In some cases where small objects or minor changes in ground characteristics are being examined, it is necessary to post-process the data to enhance and improve interpretation of subsurface conditions.

The system operates by transmitting electromagnetic impulse energy into the ground via an antenna that also receives reflections from subsurface targets. The data is based on the variation in the dielectric properties of the soil types and objects or contamination in the ground. The larger the differences in dielectric properties in the target material and the surrounding soil, the more effective the system works. GPR does not require that the materials be metallic in order to identify them.

Applications:

Utility location: GPR mapping can significantly reduce the potential for digging or drill into underground piping and power lines.

Structural Evaluation: Locates reinforcing steel, tensioning cables, air voids and faults in concrete. It is safe for use around personnel and computers.

Underground drums and storage tanks: GPR can precisely locate buried drums, underground storage tanks, burial trenches, and boundaries of abandoned landfills.

Locating sites for monitoring wells: GPR can map hazardous waste disposal sites, making it possible to perform accurate site evaluations and allow for optimal placement of monitoring wells.

Site evaluations: GPR can be used to assure that a site is free of subsurface contamination or locate specific contaminated areas.

Geological applications: Changes in the soil, faults and other irregularities can be located without digging or drilling.

Archeological: GPR can be used to help pinpoint location and depth of artifacts, allowing recovery to proceed quickly with lower risk of damage.

Advantages:

Non-destructive - profiles objects and natural conditions below ground or embedded in concrete and other manmade materials, without breaking the surface.

Fast - from one to thirteen acres can be evaluated in one day depending on the scale of grid required for the search.

Accurate - pinpoints exact locations.

Complete presentation of data - uses full color video display that can be printed through a computer.

Versatile - finds metallic, nonmetallic materials, contained, and non-contained materials.

Reliable - uses most advanced digital technology.

Safe – can be used around personnel and equipment.

Limitations:

Skilled operators are required - experience and training are required to interpret data. (A-E-I offers the solution to this limitation.)

Soil conditions - high conductivity overburden (wet soil or clay) will limit exploration depth. The system will work up to three feet in depth for virtually any soil type.

Surface conditions – extremely rough, irregular or wet surfaces will make scanning an interpretation difficult.

Depth Calculations – depths can be calculated relatively accurately is a known object can be calibrated over. (i.e.: storm sewer or sanitary sewer at a manhole)

*Information based on training material furnished by Geophysical Survey Systems, Inc., field experience, and an article in POLLUTION ENGINEERING, October 1992, Peering Beneath the Surface, by Sam Heald, applications engineer with Geophysical Systems, Inc.

CAMERA INVESTIGATION

A-E-I offers a unique capability with the Envirosite Quickview video camera. We have the capability to quickly access remote areas including crawl spaces, above ceiling areas, tanks and storage vessels. It gives ground level access to pipelines and manholes. The camera looks up to 250 feet down a 6" to 60" pipeline zooming in on details. The entire area can be video taped and specific areas can be photographed.