I remember when I was asked to approve a temporary CO for a new Home Depot the pad mount tranny was in what had become a retention pond, and at the bottom of it. The EC told me that when the tranny was set there was no retention pond on the drawings; he was correct. I called my POCO contact and they showed up quick and told me that the tranny was submersible. I asked them to open it and they did. It was indeed submersible. We put that issue to rest.
This was as we were under a hurricane warning during the 5th of 7 hurricanes to whack us in a 2 year period and HD was anxious to open the store. So the moral here is, when POCO says something is submersible, they can probably prove it.
Have you asked the POCO engineer what meter sockets are submersible?