Apparatus for establishing {HEAD ~ electrical conductivity} between a reference electrode and {TAIL ~ soil} under a pavement layer comprising: 
between
Apparatus for establishing { HEAD ~ electrical conductivity } between a reference electrode and { TAIL ~ soil } under a pavement layer comprising :
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH