   H10675/96-97--OPR-C309-RU; INVESTIGATED USING 200% SIDE SCAN SONAR, SEABAT YIELDED A LEAST DEPTH OF 26 FEET.  SONAGRAMS SHOWED A LARGE RECTANGULAR MANMADE OBSTRUCTION.  DIVER INVESTIGATION FOUND A BARGE WITH SURROUNDING SCOUR OF ABOUT 8 FEET.  HYDROGR