Good day.
Right now Packaged Sand is available at RU_08_01_FACTORY_WEREHOUSE in quantity of 6 units and used in:
- RU_08_01_VILLAGE_RENOVATION: 2 units
- RU_08_01_WIND_POWER: 4 units
As far as I can tell there is no way to get any additional Packaged Sand in the entire rest of the region in case any of those units happen to be lost or the missions are restarted after some of that cargo was delivered.