SOIL SURVEYS

 

                (word processor parameters LM=8, RM=78, TM=2, BM=2)

                      Taken from KeelyNet BBS (214) 324-3501

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                                   SOIL SURVEYS

         Accurate soil   surveys   are   necessary  for  soil  conservation

       measures, determining building  sites,   selecting  park  locations,

       siting sewage plants and a variety of other reasons.

         The traditional method of surveying requires auger boring into the

       ground to obtain subsurface soil samples for classification,  a slow

       and fatiguing process  since a typical survey might require hundreds

       of depth measurements.

         The U.S. Department of Agriculture's Soil Conservation Service

       (SCS) is now employing an easier  and  faster  method,  developed in

       cooperation with NASA, that involves use of ground penetrating radar

       to produce subsurface graphs for interpretation by soil scientists.

         The radar antenna is pulled by a four-wheel-drive  vehicle along a

       transect line, a  straight  line  across  the surface where normally

       many borings would be made.

         As it moves along the transect line  at about five miles per hour,

       the antenna transmits radio waves downward that are  reflected  back

       to the antenna  when they strike layers--soil, rock, water, man-made

       objects--of different electromagnetic properties.

         The antenna relays the reflected  pulses  to  a  graphic  recorder

       mounted in the vehicle.  The system analyzes the data  and  produces

       images on the  recorder  of subsurface "interfaces", areas where two

       different types of features meet.

         Soil scientists examine the recorder's  printout.  The information

       does not entirely eliminate the need to dig holes,  but  only  a few

       are required to double-check the radar's findings.

         The radar   can  penetrate  to  depths  of  seven  to  eight  feet

       routinely; in some types of soil it can reach 30 feet or more.

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           Jerry W. Decker.........Ron Barker...........Chuck Henderson

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