We have to have them installed / in place, all the time. Not sure of the rules, but it only took once of being hit on an audit. Now the crew constantly checks each containment daily, particularly if it rains. The plug is there only to drain rain water, it’s not practical for anything else. Spillage will be pumped out, then cleaned with absorbent. That’s what I tell the crew and what we go by…minus any rules, I exercised my own common sense with that one, in my explanation to the crew, and why I require them to constantly check containment plugs. Funny thing, I don’t have to ask, or question these issues anymore. Once you have a culture, it takes care of itself, and reinforced every time we do a DOI, where they have to be checked again.