I have a brick patio that has railroad ties around the perimeter. It also has several narrow openings for drainage holes next to the railroad ties. The drainage holes are about 1/2 inch by 3 inches. During rainstorms, it seems like the holes are constantly getting clogged by dirt and other debris which prevent the patio from draining. Should I put something in the draining openings (such as gravel or sand) to allow draining but stop obstructions from entering? Thanks.