  H10757/97-98--OPR-E346-AHP; AN UNCHARTED OBSTRUCTION IN LAT 39-10-47.93N, LONG 076-26-02.75W (NAD 83) WITH A LEAST DEPTH OF 15 FEET (4.6 METERS) WAS LOCATED BY SIDE SCAN SONAR IN THE PRESENT SURVEY.  EVALUATOR RECOMMENDEDS THAT A DANGEROUS SUBMERGED OB