Televised ducts under slab floor. Ducts are corrugated metal ducts. Duct showed sign of heavy water infiltration and there was sand in a few of the runs. Ducts are also very rusted as is the plenum under the furnace. Suggest several steps be taken outside to control water issues. After the water issue is resolved the ducts should be spin cast mortared then spray lined with Duct Armor duct lining material.