When undertaking a project that requires access beneath the earth’s surface, knowing the exact location and depth of objects buried underneath the surface can mean the difference between a successful project and a catastrophic venture. Any individual who has worked at a construction site will confess that finding and identifying the utilities, objects and obstructions beneath the earth’s surface may seem just like a minor issue but it is a huge headache that can pose a lot of risk to the continuity of a project. For millenniums, people have struggled with how to find items located beneath the earth’s surface, how to identify the objects they find, and, how to mark the precise locations of these objects so that they are avoided so as to minimize the risk of site damage and injury to workers at the site.
The history of the science behind locating buried objects and utilities is varied and diverse not to mention sometimes amusing and absurd.
Some of the methods used by people in the past to locate underground items are bizarre such as the use of dowsing rods which are depicted in illustrations dating back to Ancient Egypt. The dowsing rods used during this period were used as a low-frequency antennas which had the capability of identifying sub-surface fresh water reserves and buried metal deposits. Some of the other methods that have been used to find and locate items below the earth’s surface may seem even more absurd especially if you consider the modern innovations we use today. For example, if you look at modern history, you will find that people often used brute force to search for antique treasures said to have great financial value – a great example being the plunder and destruction done on ancient burial grounds (necropolises) by people of dubious qualifications in the name of archeological studies. Some of the most well-known individuals who used some of these dubious methods include Howard Carter and Lord Carnarvon – the English ‘archeologists’ behind the find and excavation of Ancient Egypt’s most famous Pharaoh – Tutankhamen, and the men associated with the so called ‘Curse of Pharaoh’.
Fortunately, the innovations made in the early 21st Century and the 2020s have provided more accurate and affordable ways of finding and identifying underground objects and utilities with the most renowned being GPR.
GPR is an acronym for Ground Penetrating Radar. This technology is sometimes referred to as Ground Probing Radar or “GeoRadar.” In recent years, this technology has been put to a lot of uses including data acquisition, location mapping for different branches of science including environmental geophysics, forensics and geology. It has also been used in rescue operations after building collapses, natural and manmade disasters, and, avalanches. For Mobile Ground Penetration (GPR) Surveys | Precision Utility Mapping UK get in touch.
A Quick Guide to Ground Penetrating Radar (GPR) Technology
GPR technology works in a very simple way…
First, probes are inserted underneath the ground’s surface and analyzed. In the process, these probes create electrical radar pulses within the zone covered by the probes and produce sub-surface reflections of the objects underneath the surface. By moving the probes around a ‘boxed area’ within the search zone, one usually gets a complete image of the object(s) underneath as well as a record of the location of the object(s) as far down as the radio frequencies used with the probes can reach.
The GPR antenna found within the control unit of the setup usually measure the difference between the areas of high and low conductivity within the search zone by reading the two-way travel times of the signal being reflected by the object(s) underground. This usually works akin to the way a radar wave bounces off solid objects under water or in the air. Today, there are modern state-of-the-art multi-channel GPR units which can bounce across GPR frequencies to provide the best balance between the depth of frequency penetration and accuracy of object location. These units usually use advanced radio frequency signal processing technology to provide the most accurate and complete picture of the object buried underneath the search zone. This image is usually known as a GPR cross-section. For example, if you are using this type of GPR technology to study a section of a pipe in a search area, any old-fashioned iron pipe or underground copper storage tank will show up in the GPR cross-section because the highly conductive metal part of the buried object is surrounded by soils that have a lower conductivity.
Today, GPR wave technology is usually used in situations where there is little margin for error in identifying underground objects and understanding their precise location. Simply put, this technology is often employed where the search results could make the difference between life and death.
