GROUND PENETRATING RADAR AND THE SURVEYOR w/ Case Studies

Transcription

1 GROUND PENETRATING RADAR AND THE SURVEYOR w/ Case Studies Joseph D. Fenicle, PS Ohio & Michigan Professional Surveyor Office of the Fulton County Engineer Wauseon, Ohio Angular By Nature, LLC Adrian, MI POB - Point of Beginning April 2009 Article POB - Point of Beginning April 2009 Article 1

2 POB - Point of Beginning April 2009 Article GPR John Kessinger, Regional Director Ground Penetrating Radar Systems, Inc. Sylvania, OH Michael Friedhoff, Project Geologist Mannik Smith Group, Inc. Canton, MI 2

3 What is GPR? GPR works by sending a tiny pulse of energy into a material and recording the strength and the time required for the return of any reflected signal. A series of pulses over a single area make up what is called a scan. Reflections are produced whenever the energy pulse enters into a material with different electrical conduction properties or dielectric permittivity from the material it left. What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger 3

4 What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger What GPR is not! Radiography (X-Ray Technology) Radiography uses a very small dose of ionizing radiation to produce pictures of the body s internal structures. 4

5 What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger Metal Detector What GPR is not! Metal Detectors detect the presence of metal nearby. What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger 5

6 Gradiometer What GPR is not! A gradiometer is an instrument for measuring the gradient of an energy field, especially the horizontal gradient of the earth s gravitational magnetic field. What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger What GPR is not! Acoustic Technology Acoustic Technology is the science of using sound to determine the distance and direction of its source. 6

7 What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger What GPR is not! New Technology (i.e. Spar Utility Locator) According to Optical Ranging the technology is based on the optimization of data from many sensors against a physical model of the magnetic field expected from a utility line. What GPR is not! Radiography (X-Ray Technology) Metal Detector Gradiometer Acoustic Technology New Technology (i.e. Spar Utility Locator) Curb Box Charger 7

8 What GPR is not! Curb Box Charger The Curb Box Charger simply puts a magnetic charge on ferrous metal objects. How Does GPR Work? Antenna Control Unit Power Supply 8

9 Antenna How Does GPR Work? The antenna receives the electrical pulse produced by the control unit, amplifies it and transmits it into the ground or other medium at a particular frequency. Antenna frequency is one major factor in depth penetration. The higher the frequency of the antenna, the shallower into the ground it will penetrate. A higher frequency antenna will also see smaller targets. Antenna choice is one of the most important factors in survey design How Does GPR Work? Control Unit The control unit contains the electronics which triggers the pulse of radar energy that the antenna sends into the ground. It also has a built-in computer and hard disk/solid state memory to store data for examination after fieldwork. How Does GPR Work? Power Supply GPR equipment can be run with a variety of power supplies ranging from small rechargeable batteries to vehicle batteries and normal 110/220-volt. Connectors and adapters are available for each power source type. 9

10 How Does GPR Work? GPR operates much like a sophisticated and superexpensive fish finder. POB April 2009 How Does GPR Work? How Deep Does GPR Work? 10

11 How Deep Does GPR Work? How Deep Does GPR Work? How Deep Does GPR Work? 11

12 How Deep Does GPR Work? How Deep Does GPR Work? How Deep Does GPR Work? 12

13 How Deep Does GPR Work? 13

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15 Ground-penetrating radar (GPR) is a geophysical method that is often mentioned in news commentaries for its use in locating unmarked graves, clandestine burials and tunnels, terrorism and military hazards, and disaster victims. However, the effectiveness of GPR in these activities is highly site-specific and soil dependent. A common concern of GPR service providers is whether or not GPR will be able to achieve the desired depth of penetration in the soils of an assignment area. In many soils, high rates of signal attenuation severely restrict penetration depths and limit the suitability of GPR for a large number of applications. Knowledge of the probable penetration depth and relative suitability of soils can help service providers assess the appropriateness of using GPR and the likelihood of achieving acceptable results. Soil attribute data contained in the State Soil Geographic (STATSGO) and the Soil Survey Geographic (SSURGO) databases have been used to develop thematic maps showing, at different scales and levels of resolution, the relative suitability of soils for many GPR applications. 15

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17 Why Use GPR? 17

18 Why Use GPR? Why Use GPR(for surveying)? WHAT LIES BENEATH 18

19 Why Use GPR(for surveying)? Why Use GPR(for surveying)? When a corner is positioned in accordance with the lost corner theory of proportioning, the surveyor must be convinced that no future surveyor or court will be able to locate the original corner in a different place. Proportionate measurement is always a rule of last resort. Walt Robillard, et al. Brown s Boundary Control & Legal Principles 19

20 B. Description of corner evidence found and/or method applied in restoring or re-establishing corner. October 11, I traversed to tie together existing monumentation in 4 cardinal directions from this corner from A-12, T5S, R6E to M-3, T6S, R5E on the Range Line, as well as L-13, T5S, R5W and B-1, T6S, R6E. The Baldwin survey notes 3 plow points and 2 stones between A-1 and A-3. Warnke recovered the 3 plow points in Using the angles and chainage of the Baldwin survey with the recovered points, I proportioned several positions to look for the stone at this corner, as well as the stone ¼ mile south. With Glenn Richard s help, we drilled thru the pavement in approximately 30 locations to a depth of 18 and probed to about 40. We also checked on the occupied line ¼ mile south of this corner in the middle of the pavement. We also checked around the Marino corner. We did not find any evidence worthy of proceeding to excavate thru the asphalt. Using the data I obtained, as well as traverse work done by Richard and Warnke in Section 6, T6S, R6E, and monumentation found by Warnke from the 1890 Baldwin survey, it is clear there are inconsistencies between the Baldwin survey, the road survey, and measured distances between found monumentation and this corner is considered lost. The position determined by double proportionate measurement would best fit the pipe as set by Glenn Richard in December 1, 2011 at 2 depth, found a 1 O.D. iron pipe, being 18 ½ in length. Found no further evidence. I accept the position of the iron pipe as set by Richard in 1974 as the best available evidence of the position of the original corner. Set a 5/8 by 36 rebar in place of the pipe in a set monument box. Courtesy of: Consumers Energy, Jackson, MI - Phil Norder, PS GPR Case Studies 20

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29 Thank You - Questions 29