Geotechnical sampling was required for the proposed design of the replacement of a 70 year old water transmission main across the Brandywine Creek in Wilmington, Delaware. The geotechnical scope consisted of the performance of multiple soil/rock borings on land along the alignment approaching the creek crossing. In addition, borings were required within the creek. The water work was performed utilizing an all- terrain vehicle mounted drill rig in shallow areas during low water flow periods, and using a modular floating platform with electric drill equipment and tripod drill setups in the deeper areas of the creek, which was workable in low flow periods and required vigilance in weather monitoring to assure safety of the crew. Borings were performed to depths of up to 30 feet below grade in boulder-laden soil, and included standard penetration test (SPT) borings as well as rock coring.