How must the interior walls and floor of an EX/II or EX/III vehicle be maintained before loading Class 1 explosives?

1. Coated with oil or grease to make sliding pallets easier
2. Wetted down with 50 litres of standing water
3. Covered with loose gravel for traction
4. Clean, dry, smooth, free of protruding nails, bolts or abrasive grit that could tear packages or create sparks