RESISTIVITY SURVEYS TO EVALUATE SOIL/BEDROCK PROPERTIES
The geophysical example shows the results of a dipole-dipole
resistivity survey conducted immediately adjacent to a bridge pier
that was encountering scour problems. The survey was conducted
to determine the competency and stability of rock or soil beneath
the bridge pier. The survey consisted of one resistivity array having
a maximum length of 270 feet that yielded 230 data points within
the depth interval of 0 to 50 feet.  Low resistivity values of 20 to 200
ohm/meters recorded around the base of the pier suggest the pier
rests on a five-foot layer of soil and/or highly fractured, broken or
weathered rock and not on competent bedrock.
P.O. BOX 16265                                    Greensboro, North Carolina 27416-0265                             Office: (336) 286-9718
Mark J. Denil, P.G.                                                 denilm@bellsouth.net                                                 Cell: (336) 339-8390