  H10757/97-98--OPR-E346-AHP; AN UNCHARTED OBSTRUCTION IN LAT 39-10-02.70N, LONG 076-25-43.39W (NAD 83) WITH A LEAST DEPTH OF 15 FEET (4.7 METERS) WAS LOCATED BY SIDE SCAN SONAR IN THE PRESENT SURVEY.  THIS OBSTRUCTION IS APPROXIMATELY 46 FEET BY 105 FEE