I’ll need to get it drained and see what’s going on in there and where the waters coming from but my guess it’s seeping in through the walls. The place hasn’t been used in years and it’s just filled up over time.
My thinking is fill with hardcore compacting it down as I go, every foot or so and then top with concrete. I want to sink a couple of ground anchors into the concrete top to chain the wife’s motorbike down and secure it.
I wouldn’t want to store anything in the pit, it’s too damp.