Part 107 UAS pilot reported an airborne conflict with a helicopter. The UAS avoided the helicopter.

Narrative

I was at Location A to take some construction progression photos.After arriving; I spoke with some workers on-site to get permission to be on the property.Eventually; I received approval from Person A after explaining my purpose for being there.Earlier that morning; I checked the METAR; TAF; and NOTAMs for the area. The weather had warmed up to 37°F after a stretch of freezing temperatures.The area is approximately several hundred thousand square feet accounting for a perimeter of dirt and the surrounding terrain. Launching from near the top; I set the maximum altitude to 378 feet on the controller and limited the maximum speed to 11 mph.The first flight; which lasted approximately 35 minutes; went smoothly. After a short rest; I changed the batteries and prepared for a second flight.This time; I aimed to capture images of a bulldozer moving dirt in the center of the area. I initiated a slow; straight flight from one side of the area toward the other side.I was maintaining VLOS and heard sounds of a helicopter. I scanned around the area and saw the helicopter approaching from my 9 o'clock position at the far end of the southside of the area. I began descending the UAS for a few seconds.Then the helicopter flew over the area and near the UAS. I'm not certain if the UAS was directly in the helicopter's path or off to the side. The UAS was under the helicopter from my position as it passed.