Ground-penetrating radar

Gronnd penetrating radar (GPR) is an electromagnetic technique that has been nsed for many years with the engineering industry to supply information on construction and condition detail of various types of structure. GPR also known as impulse radar gives valuable information on the location of reinforcement and can often supply information where cover meters cannot, snch as lapping bars, multiple layers and tendon ducts behind cover reinforcement. There has already been some discussion of its application for delamination measurement in Section 4.6. 

The GPR equipment is generally portable and self-contained enabling access to most structures. The antenna can be operated from the end of a long cable enabling large areas to be covered relatively easily. The technique demands hand access to the structure so hoists or scaffolding are often required. In North America vehicle mounted systems are nsed, as described in Section 4.4, on concrete and asphalt-covered bridge decks. 

In order to accurately relocate any features identified from the investigation it is recommended that an electronic distance measuring (EDM) wheel is linked to the GPR system. This enables scans to be taken at fixed distance intervals and removes the necessity for surveying at a constant speed that is required from time triggered systems. Typically scans would be taken at c.5-10mm intervals to give the required lateral resolution. 

It is essential that all collected data are recorded digitally in order that post-processing and quality control can take place. Filtering of data off site can often result in higher levels of quality as well as reducing errors from digitizing of analogue plots. 

Data collection is far more rapid than using cover meters or other hand-held instruments. However, interpretation is far more complex as many features 

Ground penetrating radar (GPR) can locate major soil disturbances, which would occur in a large burial, as well as individual ordnance items. It is dependent upon a skilled operator experienced with the local geology. Of course, an oblong rock could be misinterpreted as an ordnance item but a false positive is better than a false negative in this business. 

GPR has the advantages of deep penetration (up to 30 feet or more) in soil or water, and a visual picture as compared to a metal detector or magnetometer. The GPR can also see glass chemical carboys, bottles, and potentially a quantity of CAIS, which are usually small glass vials in cardboard boxes. 

GPR can also be used for underwater dumps by floating the antenna on top of the water. Only after a suspected ordnance item is located and identified can an informed decision be made as to how to remove the threat. 

---

Out-of-tank leak detection ground penetrating radar and inventory methods... 

Ground Penetrating Radar (GPR), Electromagnetic Conductivity (EM), Electrical Resistivity Surveys, or Seismic Surveys. 

Conyers, L. B. (2004), Ground-Penetrating Radar for Archaeology - Geophysical Methods for Archaeology, AltaMira Press, Walnut Creek, CA. 

Using Ground Penetrating Radar to delineate sub-surface calcrete in the Great Victoria Desert, South Australia implications for gold exploration... 

KEYWORDS calcrete, gold exploration, ground penetrating radar, mineral exploration, calcium... 

In places where there are concerns about buried materials or sources of contamination, ground penetrating radar (GPR) surveys may be helpful in determining the best sampling approach. GPR can also detect coarse textured subsoils and water relationships in soils having these types of horizons. However, there are some limits as to where GPR can be used and the equipment for doing a GPR survey is expensive [3],... 

Jol HM. Ground Penetrating Radar Theory and Applications. Amsterdam, Holland ... 

Doolittle JA, Collins ME. Use of soil information to determine application of ground penetrating radar.J.Appl. Geophys. 1995 33 101-108. 

It may be possible that ground-penetrating radar (GPR) could be tuned to preferentially indicate masses of particular chemicals, but such work is not known to have been reported. 

Annan, A.P. (1992) Ground Penetrating Radar, Workshop Notes, Sensors and Software, Mississauga... 

GROUND PENETRATING RADAR ELECTROMAGNETIC INDUCTION RESISTIVITY SEISMIC METAL DETECTOR MAGNETOMETER... 

Currently available geophysical methods most applicable in hazardous waste site investigations include metal detectors, magnetometers, ground-penetrating radar (GPR), electromagnetic induction (EM), resistivity, and seismic refraction. These methods should be regarded as complementary, since no one method... 

Johnson, R. W. Glaccum, R. Wojtasinski. "Application of Ground Penetrating Radar to Soil Surveys," Proceedings of the Soil and Crop Science Society of Florida, Vol. 39,... 

In October 1999, an expert team scanned the soil of the alleged extermination camp Treblinka with a ground penetrating radar. This device detects any disturbances of the soil layers, caused either by objects or by former digging activities, uj) to a depth of 65 feet. The data gathered showed no evidence of disturbance in the soil whatsoever. 19... 

Analysis of German air photos as well as recent data gathered with ground penetrating radar has shown that no major disturbances of the natural ground structure occurred within Treblinka II or in its vicinity. 

---