In {TAIL ~ a pipe} to be used in {HEAD ~ the ground} as a culvert, the improvement comprising: 
In { TAIL ~ a pipe } to be used in { HEAD ~ the ground } as a culvert , the improvement comprising :
OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH