GeneralQ How soon after a surface is shotcreted can it be submerged with stream water? What if the water has no velocity?
Shotcrete is a means of placing concrete and the same precautions should be taken. Once the shotcrete had taken final set, exposing it to water and submerging it in water should enhance its curing. If it is a pool or other deep structure, you should ensure that the shotcrete or concrete is strong enough to withstand any hydrostatic loading due to the filling of the structure.