Seems like they are dropping super sacks of rock. They might be dropping super sacks of dry mix, but I highly doubt it - the money just wouldn't be there. If

Seems like they are dropping super sacks of rock. They might be dropping super sacks of dry mix, but I highly doubt it - the money just wouldn't be there. If they're just looking to armor then the rock would more sense. Shotcrete and concrete are difficult to place via helicopter. Both need to be pumped (or hand placed) to get a good product, which can't be done via helicopter.