What's the huge dam-like structure for?

[Brundageba]

Every time we pass the huge excavation between the two main roads to and from David from Boquete, not far from the bridge over Rio David, we ponder what they are doing there.  Who's doing it?  What for?   Lots of dirt removed, lots of rocks placed in rows.  Mighty puzzling.   Nobody seems to know.  Anybody know?????

[JohnF13]

It looks like they are leveling the area to make it useable.  Guess they don't need rocks in the infill down below, so are setting them aside.