"It is well above 70', probably closer to 400-500' AGL. Is there an
airport
or hospital nearby?"

The nearest hospital in the direction from which the helicopter came is
several miles away. I don't know of any airport in that direction.

I had the impression that the helicopter took off from the construction
site across the street, about 500 feet away, though I did not see it
actually take off. The construction is building a road through a vacant
field. In fact, most of the land in that direction for several miles is
farmland or vacant fields.

The Wal-Mart in the photo is near the intersection of Ohio Street and
121 in Plano, Texas. It should not be difficult to find that on a map.