@Colorado
I only started reading this thread a while ago and when I got to the video of the tanks I decided to see how big the top opening was. I got an 8" flan tin, removed the base and discovered that it fitted over my head (obviously I'm not a child), but there is no way that I could see that the children's shoulders would fit even if you twisted them severely. I saw your post and read the comment made by your source and decided to transcribe the the conversation between AB and Wesley. I don't know if this will help but for what it's worth ...
AB: If in fact the opening on the top – and again I’ll hold it up – is too small for Chris Watts to – as he apparently, according to the police, admitted, too small for him to put those children through, he would have had to do it from the bottom which means the tank would have had to be empty …
Wesley: Mm mm.
AB: … or he’d have been gushed on by a full tank of oil. So you’re saying that there’s a pump that goes between those two tanks and he could pump …
Wesley: Yes.
AB: … one tank empty and put the chil… – and that’s, there’s the thief hatch and you can – I think that’s your hand, Wesley, correct, right next to the thief hatch at the top?
Wesley: Yeah.
AB: Okay. So we can have the relative size.
Wesley: Yeah, that’s my hand to give you scale. Yeah, mm mm.
AB: And that’s at the top.
Wesley: Yeah. So they do have …
AB: So this is an example tank that’s similar.
Wesley: Yeah. That’s part of what kind of bent my brain is, you know, I really don’t think you could easily get anything that’s designed that way for you to not drop anything through that top hatch. They keep it very small, so 8” is quite small. That’s what made me think you pretty much have to take that bottom manway open, and the standard design, you know, there’s 64 bolts and you’ve got to drain all of the liquids out to really, you know, …
AB: We have a picture of that.
Wesley: … let all the fluids out.
AB: Put the picture up of the bottom manway because Wesley’s also given us an example photo of this tank where he’s standing next to the manway. …
AB: It’s called the clean-out manway. There it is, and you can see Wesley’s hand. Now you can see the relative size of that opening, and all those bolts that would have to be opened, unscrewed and screwed back on and clearly it is at the bottom of the tank. So it’s going to have to be – really, the tank’s gonna have to be literally dry.