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h Mwj 7si.1 .s 5_ 1 W11 w _ Fywn SE _ 1. NOgCAI CH2M-Hill May 10, 1991 page 2 ie length from 11 to 15 feet for we performed 6 Werth-south and B east-west traverses as s own on plate 1 . These traverses range We also performed severe} a total coverage of 193 line feet' at•ion to confirm - traverses to the south ofthe apQpelinenVeOur9scope of work the GPR data and presenting our findings in the location of an underground includes interpreting a written report• GROUND PENETRATING RADAR Ground penetrating radar (GPR) is a method that provides a con- ting tins in uous, high resolute°escross-section s hallow esubsurfaceT.�aThe nmethod ivi- the electrical proper is particularly sensitive to variations inveofcarmaterialical dtothold ty and electrical permittivity (the abi] it, a charge when an electrical field is app lied) . continuously radiates an electromagnetic In operation, the systemas it is moved " pulse into the ground from a transducer (antenna) along a traverse. Since most aeaterialsthe radarrsignaleis to electromagnet energy, only portion resenting varia- whin the signal encounters a reflected back to the surface from interfaces r is reflected. tions in electrical properties. metal object, however, all of the in ' +-he and are pals are received by = records can The reflected signals hical recorder. The resulting the stratification, the thickness transmitted to a grail acts such provide infarmetion regarding the location of buried obi and extent of fill material , when the as utilities, and changes in material conditions such as satura- in some instances, chemical differences (when rela- tion and, properties are altered) , eneralltion subsurface electrical tively high electrical conductivities reduce the r capability and limit radar P Geophysical Survey Systems, Fez" this investigation, we use! RadarSystem equipped with a 500 inc. SIR-3 Subsurface Inerfacc antenna. This antenna is near the center of the megaHertz. (MHz) range and was used to provide high resolution available frequency at shallow depths. PROCEDURES We obtained GFR data by hand towing the 500 MHz antenna along the Horizontal control along each a- traverses shown on Plate electronically annotating there- verse was established by These distances were determined the from cords at 5 foot intsthe round along the length of a fibergiass tape placed an traverse.